HomeMy WebLinkAbout2015-04-15 PACKET 04.K.
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
Page 1
The 2015 Update text is Colored Brown and is bold italicized.
Executive Summary
.................................................................................................................................... 4
Alternative Urban Areawide Review (AUAR) Worksheet Form
........................................................... 9
1. Title .................................................................................................................................................. 9
2.Proposer ............................................................................................................................................ 9
3. RGU ................................................................................................................................................. 9
4. Reason for EAW preparation ........................................................................................................... 9
5. Location and maps ......................................................................................................................... 10
6. Description ..................................................................................................................................... 11
7.Project magnitude data ................................................................................................................... 14
8. Permits and approvals required ...................................................................................................... 16
9. Land use ......................................................................................................................................... 17
10.Cover types ..................................................................................................................................... 18
11. Fish, wildlife, and ecologically sensitive resources ....................................................................... 19
12. Physical impacts on water resources .............................................................................................. 28
13. Water Use ....................................................................................................................................... 28
14. Water-related Land Use Management Districts ............................................................................. 29
15. Water surface use ........................................................................................................................... 29
16. Erosion and sedimentation ............................................................................................................. 29
17. Water Quality-stormwater runoff ................................................................................................... 29
18. Water Quality-Wastewater ............................................................................................................. 30
19. Geologic hazards and soil conditions ............................................................................................. 31
20. Solid wastes; hazardous wastes; storage tanks ............................................................................... 32
21. Traffic ............................................................................................................................................. 33
22. Vehicle-related air emissions ......................................................................................................... 34
23. Stationary source air emissions ...................................................................................................... 36
24. Dust, odors, noise ........................................................................................................................... 36
25. Sensitive resources ......................................................................................................................... 39
26. Adverse visual impacts ................................................................................................................... 41
27. Compatibility with Plans ................................................................................................................ 41
28. Impact on infrastructure and public services .................................................................................. 42
29. Cumulative impacts ........................................................................................................................ 43
30. Other potential environmental impacts .......................................................................................... 43
31. Summary of Issues ......................................................................................................................... 43
Mitigation Initiatives
32. .................................................................................................................... 43
Figure 5.1Project Location
Figure 5.2AUAR Boundary/USGS Map
Figure 5.3East Ravine Districts/Aerial Photo
Figure 5.4Traffic Analysis Zones (TAZ)
Figure 5.5Existing Municipal Service Area (MUSA) and 2020 MUSA Expansion
Figure 6.1East Ravine Development Scenario/Master Plan
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
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Figure 6.2Preliminary Phasing Plan
Figure 9.1Existing Land Use
Figure 10.1Land Cover-Natural Resource Inventory
Figure 10.2Watercourses, Wetlands, Lakes and Streams
Figure 10.3Natural Resources Overlay
Figure 17.1Existing Storm Water System
Figure 17.2Proposed Storm Water Syste
Figure 19.1Soils Map
Figure 21.1Existing Roadway System (2003 Functional Class)
Figure 21.22002 2014 ADT (Average Daily Traffic)
Figure 21.3Build Out Average Daily Traffic (2020)
Figure 25.1Cultural Resources Overlay
Figure 27.1City of Cottage Grove 2030 Comprehensive Land Use Plan...
Figure 27.2Washington County Comprehensive Plan
Figure 27.3Upper Ravine District Development Update Detail.
Figure 27.4
Figure 27.32014 Stormsewer Utilities Map
Table 6.1 - Development Scenario Future Land Use Acreages ............................................................. 14
Table 7.1 - Project Magnitude Data - 20 Year Residential Growth .......................................................... 15
Table 7.2 - Project Magnitude Data - 20 Year Commercial Growth ........................................................ 16
Table 8.1 - Permits and Regulatory Review/Approvals ............................................................................. 16
Table 9.1 - Existing Land Use .................................................................................................................... 18
Table 10.1 - Current Natural Community Land Cover ............................................................................. 19
Table 11.1 - Open Space/Green Land Uses in the Development Scenario .............................................. 26
Table 18.1 - Summary of Current and Future Residential Waste Generation ........................................ 30
Table 20.1 - Summary of Current and Future Residential Waste Generation ........................................ 32
Table 20.2 - Summary of Current and Future Non-Residential Waste Generation ................................ 33
Table 22.1 - Top Ten Intersections Twin Cities CO Maintenance Area .................................................. 34
Table 22.2 - Future (2020) Average Daily Traffic ........................................ Error! Bookmark not defined.
Table 24.1 - Noise Analysis Instrumentation Summary ........................................................................... 36
Table 24.2 - Nighttime Noise Monitoring Summary ................................................................................. 37
Table 24.3 - Peak Hour Traffic Volumes .................................................................................................. 38
Table 24.4 - Distance to Contours ............................................................................................................. 38
Appendix 1 Technical Memorandum. Cottage Grove East Ravine Planning Study: Watermain. Howard R. Green
Company. February 05
Appendix 2 Technical Memorandum. Cottage Grove East Ravine Planning Study: Sanitary Sewer. Howard R. Green
Company. February 05
Appendix 3 Technical Memorandum. Secondary Traffic Impacts East Ravine Community. Howard R. Green Company.
February 05
Appendix 4 Technical Memorandum. Traffic Noise and Air Quality Study for the East Ravine Community. Earth Tech.
March 05.
Appendix 5 Stormwater Management Report: Cottage Grove East Ravine. Emmons and Olivier Resources, Inc. March
05
Appendix 6 Resolution Ordering AUAR
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
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Appendix 7 Summary of Technical Advisory Committee meetings and Agency Involvement
Appendix 8 Summary of Public Involvement
Appendix 9 Comments Received and Response to Comments
Appendix 10 Adopting Resolution
Appendix 11 East Point Douglas Traffic Study
WAUAR?
HAT IS AN
An Alternative Urban Areawide Review (AUAR) is authorized under Minnesota Rules Chapter 4410.3610 as an
alternative form of environmental review for development projects. Generally, the AUAR consists of one or more
impacts that the development scenarios may have on these resources as well as public infrastructure services, and a set
of mitigation measures that reduce or eliminate the potential impacts generated by the development. The AUAR is
ing from a sequence of related development projects as opposed to
an Environmental Assessment Worksheet (EAW) or Environmental Impact Statement (EIS) which simply looks at a
WAUARP?
HY AN FOR THIS ROJECT
An AUAR was chosen for the Cottage Grove East Ravine project area because it will provide a better framework for
coordinating a number of future development projects that will occur over a long period of time, identifying potential
impacts, and focusing on effective, efficient mitigation strategies.
HAUAR?
OW IS AN USED
An AUAR is used as a tool to help parties interested in development within the project area understand the existing
environmental and cultural resources present on a site prior to initiating detailed planning and design. It is also used to
identify key initiatives that must or should be undertaken to minimize negative impacts generated by proposed
development.
Any proposed development in the project area would need to be reviewed for consistency with the AUAR and
Mitigation Plan. If a development plan is not consistent with these documents or other statutory requirements, the
developer may need to conduct additional environmental documentation or review or request an amendment to the
AUAR. Natural and cultural inventory information in the AUAR and the Mitigation Plan will be used to guide
development. Design and construction would proceed only after all approvals and appropriate agreements are complete.
OAUARP
VERVIEW OF THE ROCESS
The City of Cottage Grove last adopted its Comprehensive Plan in October of 2000. This plan identified the eastern
portion of the community as a future phase for development with urban services and generally a low density residential
land use pattern. The Metropolitan Council recently completed a regional sanitary sewer project that makes sanitary
sewer services available. The City of Cottage Grove began a significant master planning effort in 2002 to help define a
more specific land use and development pattern and to address the implications of future development on a number of
important public infrastructure systems including surface water management, traffic and transportation, sanitary sewer
and public water supply.
The East Ravine Planning District is a roughly 3,800-acre portion of largely undeveloped land stretching along County
establishes a vision of what this area will
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
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area developed. The process establishes a framework to ensure that development occurs efficiently and complies with
the vision that Cottage Grove residents and landowners aspire to.
As the availability of developable land in those parts of the city already built up begins to disappear, developers and the
City have turned their sights towards the land in the East Ravine Planning District. The City of Cottage Grove, with a
population of slightly more than 30,000, wants to avoid the out-of-control growth that other metropolitan communities
have experienced, because such rapid growth can be accompanied by a host of problems such as traffic congestion and
inadequate amenities and infrastructure. Such difficulties could become unmanageable without an effective planning
process because of the unusual size of the area.
In order to help the City develop a framework that city staff and decision makers will use to evaluate future
development proposals within the area, the City hired a multi-firm consultant team led by the Minneapolis-based
planning firm Hoisington Koegler Group Inc. With the assistance of the consultant team, the City conducted a three year
process that, among other things, helped residents and landowners articulate a vision for the area, as well as establish a
set of goals and objectives for how, where, and what type of development should occur in the East Ravine Planning
District. This AUAR is one product of that process.
DDS
ESCRIPTION OF THE EVELOPMENT CENARIO
The East Ravine Pre-Design Planning Project consists of roughly 3,800 acre area of largely undeveloped land that
generally lies north of 70th Street, east of County Road 19, and west of Lamar and Kimbro Avenues.
Large areas of predominantly Single Family residential housing are interspersed with a combination of medium and
higher density attached residences to provide a balance of housing opportunities and meet the lifecycle housing needs
and desires of the community.
The development scenario identifies two commercial areas or "nodes." One in the Cedarhurst area at 70th Street and
Keats Avenue would have a smaller scale, integrated neighborhood commercial emphasis. The Cottage View area node
in the south near Highway 10/61 is being oriented toward larger scale community commercial uses. One of the primary
goals of the planning process is to design an efficient, safe, and interconnected system of local and collector streets.
One of the major features to meet that goal to emerge from the process is the Ravine Parkway. The parkway will
provide both a transportation corridor and a major design feature for the project. As a new collector street, the parkway
will traverse the entire project area beginning in the northwest and meandering east and south towards Highway 10/61.
Portions of the parkway will include natural landscaped areas, trailways, ponds, and wetlands. Other portions will
appear more like Summit Avenue in St. Paul with large green boulevard and median areas. Along the parkway, local
residential street loops will create neighborhood focal points and amenities out of green island areas. Sidewalks and
trails linking area homes to the parkway, will allow safe and convenient movement throughout the eastern portion of
Cottage Grove and connect to the remainder of the community.
Transportation planning also includes the proposal to realign portions of Military Road to correct system design
inefficiencies. The proposal would use a realigned portion of existing Jamaica Avenue to connect southward to 70th
Street. Given the historic role of Military Road, the character and location of the former road alignment will be reflected
in a new system of local streets and trails.
Major roadways and streets including 70th Street, 80th Street and Keats Avenue (County Road 19) will be established as
green corridors throughout the project area. Expanded right-of-way and easement areas will create larger scale open
spaces that will provide buffers to adjacent land uses and a continuati
green corridors will include trails and landscaping treatments that will vary in form and style depending on the specific
location in the project area.
The City is utilizing current management practices and policies to plan for local ponding and surface water management
needs in the planned neighborhoods. The City is also coordinating with the South Washington Watershed District to
address regional storm water drainage needs to minimize redundant expenditures and loss of taxable development area.
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
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IPI
DENTIFICATION OF OTENTIAL MPACTS
Natural, Cultural and Physical Resources
Past and current land uses in the project area have primarily been agricultural. Some farmsteads exist which generally
consist of a residential structure and various outbuildings such as barns, sheds or silos. Other uses include large lot
residential development on individual septic systems and private wells, a couple of golf courses, and a campground.
th
Wetlands are few within the project area. A small complex of wetlands exist west of Jamaica Avenue north of 80
Street. The primary natural resource feature in the project area is the Central draw or east ravine feature which serves as
a natural drainage way for much of the region.
Natural resources are prominent within the East Ravine Planning District. A large portion the natural resource base is
contained within the Cottage Grove Ravine Regional Park. Cottage Grove has a commitment to natural resources as
evident by past efforts to identify and protect natural resources. The City of Cottage Grove currently has a Sensitive
Environmental Areas Overlay District and a Tree Preservation Ordinance in place providing a foundation for protection
of environmental resources. The impact on these resources from future urban development and infrastructure systems
can be mitigated through the use of these types of existing tools. A significant amount of land in the East Ravine Pre-
design study area falls in the Sensitive Environmental Areas Overlay District.
The Comprehensive Plan contains a significant chapter on Historic Preservation which lays the policy guidance for
decision making relative to preservation of historical and cultural resources. Also serving as a guide for future
community development decision making that acknowledges need for change while providing protection for historically
significant buildings and sites is the Old Cottage Grove Historic District Preservation Planning Report, 2002. The report
contains a comprehensive inventory of all the heritage resources within the district.
Municipal Infrastructure
The City of Cottage Grove presently obtains its raw water supply from deep wells in the Prairie du Chien-Jordan
aquifer. The preliminary plan for the Public Water Supply and Impact improvements in the East Ravine area consists
of approximately 290,000 linear feet (55 miles) of watermain pipe and 3.0 MG of storage to serve an estimated 5400
th
units. This system is described in a detailed technical memorandum dated February 7, 2005 titled Cottage Grove East
Ravine Planning Study Watermain and attached as Appendix 1.
Sanitary sewer service is provided through the Metropolitan Council Environmental Services regional collection and
treatment systems. The recently completed South Washington County Interceptor project provides services to the East
Ravine Planning District. The preliminary plan for sanitary sewer serving the East Ravine area includes roughly 242,000
feet of sanitary sewer pipe with a total estimated design flow of approximately 12.13 million gallons per day (MGD).
This system is outlined in a technical memorandum dated February 7, 2005 titled Cottage Grove East Ravine Planning
Study Sanitary Sewer and included as Appendix 2.
Storm Water Management
The overall goal of the stormwater practices being proposed for the East Ravine area of Cottage Grove is to minimize
the generation of stormwater runoff created by urbanization and to retain the runoff in a series of natural infiltration
basins rather than concentrate to a single point for collection, treatment and discharge. This approach mimics the
current infiltration patterns that presently exist in the study area of Cottage Grove. The net result will be minimization
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
Page 6
and, in some areas, avoidance of discharge of stormwater to surface waters; which in turn will lessen the overall amount
of pollutants associated with the stormwater like the Mississippi River; resulting in less burden on the environment.
The South Washington Watershed District (SWWD) has begun to implement a regional project which will convey
runoff through the East Ravine project area in a system of detention areas and interconnecting pipes. As of the date of
this report, the SWWD has completed land acquisition for an approximately 150 acre area of Neighborhood 1 North.
When fully complete, the SWWD system will create a stormwater link to the Mississippi River. The SWWD has
expressed a willingness to work with the City of Cottage Grove towards a combined City/Watershed District stormwater
management system. The proposed Cottage Grove stormwater plan utilizes the natural detention areas acquired by the
SWWD, but does not anticipate the need to rely on the proposed connecting storm drains, thereby protecting the
Mississippi River and minimizing inputs to Cottage Grove Ravine Regional Park from the effects of local urbanization.
The detailed storm water management report documenting the approach to the East Ravine area is included as Appendix
5.
Traffic Related Impacts
The East Ravine planning project evaluated the traffic impacts of the development scenario. The East Ravine area is
expected to reach full build-out in 20 years. However, the travel demand model used for the traffic analysis used Year
2020 conditions in Washington County with full build-out of the East Ravine. The detailed methodology and analysis of
traffic impacts is contained in a technical memorandum included as Appendix 3 of the AUAR. Seven key roadways
(broken into twenty-four segments for analysis) and eighteen key intersection listed below were selected for this study
because they will provide primary access to the regional road system and will likely be the primary roadways when the
area develops.
Key Roadways
US 61 between Glen Road and Kimbro Avenue
CSAH 20 (Military Road) between Ideal Avenue and Lamar Avenue
CSAH 22 (70th Street) between US 61 and CSAH 19 (Keats Avenue)
80th Street between US 61 and Kimbro Avenue
Jamaica Avenue between CSAH 20 (Military Road) and US 61
CSAH 19 (Keats Avenue) between Dale Road and US 61
Lamar Avenue/Kimbro Avenue between 70th Street to US 61
Key Intersections
US 61/70th Street Ramps (3 intersections)
US 61/80th Street Ramps (2 intersections)
US 61/Jamaica Ave Ramps (2 intersections)
US 61/CSAH 19 (Keats Avenue) Ramps (2 intersections)
US 61/Kimbro Avenue
80th Street/Jamaica Avenue
80th Street/CSAH 19 (Keats Avenue)
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80th Street/Kimbro Avenue
CSAH 20 (Military Road)/Lamar Avenue
CSAH 22 (70th Street)/CSAH 19 (Keats Avenue)
CSAH 22 (70th Street)/Jamaica Avenue
CSAH 20 (Military Road)/Jamaica Avenue
CSAH 20 (Military Road)/CSAH 19 (Keats Avenue)
An operation analysis was completed for roadway segments and intersections. Roadway operations were evaluated by
comparing average daily traffic counts with level of service bar charts developed using methodologies from the
Highway Capacity Manual. Intersections were evaluated using the expected intersection delay. In the existing year, the
intersection of CSAH 22 (70th Street)/Jamaica Avenue is the only intersection operating below the desired level of
service. Forecasted average daily traffic volumes were used to estimate future roadway operations. These forecasted
were developed using the Washington County 2020 Travel Demand Model. Assuming the existing geometry, two of the
seven roadways operated under congested conditions. Eleven of the eighteen intersections operated below the desired
level of service. The following projects are recommended to mitigate the impacts:
Roadway Improvements
Reconstruct CSAH 20 (Military Road) as a four-lane facility with turn lanes.
Reconstruct CSAH 19 (Keats Avenue) as a four-lane facility with turn lanes.
Realign the intersection of CSAH 20 (70th Street) and CSAH 19 (Keats Avenue) to be the major connection to US 61
(Round about installed and
and close the intersection of CSAH 20 (Military Road) and CSAH 19 (Keats Avenue)
Realignment Complete 2015)
Discuss the possible closure of US 61 and Kimbro Avenue and a possible future interchange at US 61 and TH 95
(Manning Avenue) with Mn/DOT and other authoritative jurisdictions.
Intersection Improvements (Installation of Traffic Signals at the Following Locations)
US 61 SB Ramp/CSAH 22 (70th Street)
US 61 SB Ramp/Jamaica Ave
US 61 NB Ramp/Jamaica Avenue
US 61 SB Ramp/CSAH 19 (Keats Avenue)
US 61/Kimbro Avenue, 80th Street/Jamaica Avenue
80th Street/CSAH 19 (Keats Avenue)
CSAH 22 (70th Street)/CSAH 19 (Keats Avenue)
CSAH 22 (70th Street)/Jamaica Avenue
Jamaica Avenue/Ravine Parkway
CSAH 19 (Keats Avenue) /Ravine Parkway
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
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MI
ITIGATION NITIATIVES
The Mitigation Plan identifies key steps that the City will take to mitigate potential impacts identified in the AUAR. In
addition to general mitigation initiatives, the mitigation plan includes strategies in the following areas:
Natural and Physical Resources
Cultural Resources
Land Use Management
Erosion Control and Sedimentation
Water Supply and Appropriation
Wastewater System
Storm Water Management
Traffic Management
A full mitigation plan will be is included in the final AUAR document.
This section consists of the Environmental Assessment Worksheet (EAW) form and response to questions as modified
by Environmental Quality Board (EQB) AUAR Guidance as of July, 2004 September, 2008. The EAW question is
shown in bold uppercase text, AUAR guidance is shown in faded italicized text, and the response to the question is
shown in regular text.
The 2015 Update text is Colored Brown and is bold italicized.
1.T
ITLE
Cottage Grove 2015 East Ravine AUAR Update.
2.P
ROPOSER
John M. Burbank
City of Cottage Grove
12800 Ravine Parkway South
Cottage Grove, MN 55016
jburbank@cottage-grove.org
3.RGU
City of Cottage Grove
12800 Ravine Parkway South
Cottage Grove, MN 55016
www.cottage-grove.org
4.RAUAR
EASON FOR AND UPDATE PREPARATION
In conjunction with the East Ravine Master Planning process, the City of Cottage Grove prepared the environmental
assessment document in the form of an AUAR to understand the cumulative impacts of future development and to
.
develop mitigation strategies to minimize potential environmental impactsThe East Ravine AUAR and Mitigation
Plan received final approval in March of 2006,
Plan amendment.
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
Page 9
The Cottage Grove 2015 East Ravine AUAR Update Report is being completed in conformance with MN Rules
4410.3610, Subpart 7(A).
5.L
OCATION AND MAPS
The AUAR Project Area is located on the east side of the City Cottage Grove. Figure 5.1 shows the project location.
No changes have been made in relation to the scope, size or location of the
AUAR project area.
County
: Washington
City
: Cottage Grove
Locations
: The Cottage Grove East Ravine Planning District, is an approximately 4,000 acre portion of largely
undeveloped land stretching along the east side of County Road 19 from Highway 61 north to the City of Cottage
and including a portion north of 70 th Street east of CR 19 generally to Ideal Avenue.
The following figures are included within the AUAR:
Figure 5.1Project Location
Figure 5.2AUAR Boundary/USGS Map
Figure 5.3East Ravine Districts/Aerial Photo
Figure 5.4Traffic Analysis Zones (TAZ)
Figure 5.5Existing Municipal Service Area (MUSA) and 2020 MUSA Expansion
Figure 6.1East Ravine Development Scenario/Master Plan
Figure 6.2Preliminary Phasing Plan
Figure 9.1Existing Land Use
Figure 10.1Land Cover
Figure 10.2Watercourses, Wetlands, Lakes and Streams
Figure 10.3Natural Resources Overlay
Figure 17.1Existing Storm Water System
Figure 17.2Proposed Storm Water System
Figure 19.1Soils Map
Figure 21.1Roadway System
Figure 21.22000 2014 Average Daily Traffic
Figure 21.3Build Out Average Daily Traffic
Figure 25.1Cultural Resources Overlay
Figure 27.1City of Cottage Grove 2030 Comprehensive Land Use Plan
Figure 27.2Washington County Comprehensive Plan
Figure 27.3Upper Ravine District Development Update Detail
Figure 27.42014 Roadway Functional Classification Map
Figure 27.32014 Storm Sewer Management Map
The following figures have been added to the AUAR.
Figure 27.3-- Development Update Exhibit
Figure 27.42014 Roadway Jurisdiction Map
Figure 27.52014 Revised Storm Sewer Map
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
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The planned development scenario for the East Ravine has not been modified since the adoption
of the AUAR, but certain components of the plan need to be modified to address current market
conditions and development practices. Smaller lot sizes appear to be the biggest change from the
original development scenario in the residential subdivisions that have been approved. In
exchange for the relaxation of the standards, the City has been exacting extensive park, open
space and trailway improvements. The higher density resulting from the decreased lot sizes are
consistent with regional growth policies.
6.D
ESCRIPTION
The originaldevelopment scenario was derived with input from a group of area residents on a Community Advisory
Team, City Advisory Commissions, and from two workshop meetings of the City Council and Planning Commission
held in the spring and summ
features, transportation corridors, greenways, and development patterns to establish a plan for new neighborhood areas,
distinct to Cottage Grove, interconnected by a network of parks, trails, and storm water drainage features.
The development scenario is illustrated in Figure 6.1 and consists of the following components:
Housing
- Large areas of predominantly Single Family residential housing are interspersed with a combination of
medium and higher density attached residences to provide a balance of housing opportunities and meet the lifecycle
housing needs and desires of the community. Housing types include single family detached, multi-family attached
(townhomes, rowhouses, twinhomes) and multi-family stacked (condominiums and apartments). Housing densities
type neighborhoods such as Cedarhurst ranging from 6 to 12 units per acre. The most intense residential uses would be
located in the Cottage View and Cedarhurst areas with densities in the 6 to 12 unit per acre range.
Since adoption of the AUAR, only four single family residential developments have been
approved by the City and constructed. The projects were located in Upper Ravine
Neighborhood One North and consisted of278 total single family lots. The acreage for
these subdivisions totaled 149 gross buildable acres and was within the scope of the
original development scenario.
Commercial
- The development scenario identifies two commercial areas or "nodes." One in the Cedarhurst area at 70th
Street and Keats Avenue would have a smaller scale, integrated neighborhood commercial emphasis. This pattern of
commercial use would typically include smaller building footprints on smaller parcels. The Cottage View area node in
the south near Highway 10/61 is more oriented toward larger scale community commercial uses
. Larger parcels are required for this type of use. Floor area
ratios (square feet of gross leasable area to gross site acreage) for commercial uses would range from 0.2 for the larger
scale community commercial to .5 for the more village oriented commercial uses.
Cottage Grove East Ravine AUAR
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Since adoption of the AUAR, the only commercial development activity that was approved
was an 180,000 square foot Walmart store located on 23.5 acres of commercially guided
land located in the Cottage View area of Neighborhood One South. Additional traffic
studies were completed in conjunction with the development review process for this project.
The recommendations found in the traffic studies were incorporated into the approval of
the Walmart project. Construction for this project was completed in the first quarter of
2014. This project is within the scope of the original development scenario. The Traffic
Study is included as Appendix 11.
Transportation
-
One of the primary goals of the planning process is to design an efficient, safe, and interconnected system of local and
collector streets. One of the major features to meet that goal that emerged from the process is the East Ravine Parkway
which essentially runs through both neighborhoods and provides a connecting link for the entire East Ravine
community. The parkway will provide both a transportation corridor and a major design feature for the project. As a
new collector street, the parkway will traverse the entire project area beginning in the northwest and meandering east
and south towards Highway 10/61. Portions of the parkway will include natural landscaped areas, trailways, ponds, and
wetlands. Other portions will appear more like Summit Avenue in St. Paul with large green boulevard and median areas.
Along the parkway, local residential street loops subdivision entrance outlots and buffers will create neighborhood
focal points and amenities out of green island areas. Sidewalks and trails linking area homes to the parkway, will allow
safe and convenient movement throughout the eastern portion of Cottage Grove and connect to the remainder of the
community.
Since the adoption of this AUAR, the East Ravine Parkway was formally named as Ravine
Parkway South by the Cottage Grove City Council. Two segments of this roadway have been
completed to date in conjunction with the construction of the Washington County South
Service Center and the new Cottage Grove City Hall and Public Safety facility. The City is
currently working with Washington County on identifying controlled access points within
Upper Ravine Neighborhood One North, which includes segments of the Ravine Parkway.
The City has also coordinated with Washington County on the realignment of the
Comprehensive Plan. This realignment project is currently under construction and is
anticipated for completion in the spring of 2015. These roadway projects were analyzed in
the original AUAR and adopted Comprehensive Plan. Portions of the 70th Street
realignment were incorporated into the South Washingt
regional storm sewer extension project. This portion of the project was included in a separate
AUAR that was prepared by the SWWD. Access to a copy of this document can be found at
http://www.swwdmn.org/.
Transportation planning also includes the proposal to realign portions of Military Road to correct system design
inefficiencies. The proposal would use a realigned portion of existing Jamaica Avenue to connect southward to 70th
Street. Given the historic role of Military Road, the character and location of the former road alignment will be reflected
in a new system of local streets and trails.
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
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As a component of the 70th Street realignment project and in conjunction with the concept
review of several new residential developments for the Upper Ravine Neighborhood One
North that have occurred recently, the City has begun to refine the design concepts for the
new Historic Military Road Trail Corridor and new intersection geometrics for Military Road
and Jamaica Avenue in Woodbury. Completion of this realignment project is expected in
2015 or 2016 depending on development activity.
Green Corridors
- Major roadways and streets including 70th Street, 80th Street and Keats Avenue (County Road 19)
will be established as green corridors throughout the project area. Expanded right-of-way and easement areas will
create
open space heritage. These green corridors will include trails and landscaping treatments that will vary in form and style
depending on the specific location in the project area. Park and recreation features will also be included in these green
corridors or will be connected to them via trails and sidewalks.
All new developments along the major roadways within the district are required to have a
landscape buffer component that averages 75 feet and is protected by easements and
covenants. The design criteria within this dedicated buffer area are expected to be
consistent from subdivision to subdivision along the major roadways. The required buffer
area was successfully implemented in the design approval for the four single family
residential subdivisions recently approved along 70th Street and Jamaica Avenue.
Surface Water Management
- The City is utilizing current management practices and policies to plan for local
ponding and surface water management needs in the planned neighborhoods. The City is also coordinating with the
South Washington Watershed District (SWWD) to address regional storm water drainage needs to minimize redundant
expenditures and loss of taxable development area. The overall goal of the stormwater practices being proposed for the
East Ravine area of Cottage Grove is to take advantage of the suitable soils in this area to infiltrate urban runoff in
both City and SWWD facilities. minimize the generation of stormwater runoff created by urbanization and to retain the
runoff in a series of natural infiltration basins rather than concentrate to a single point for collection, treatment and
discharge. This approach mimics the current infiltration patterns that presently exist in the study area of Cottage Grove.
The net result will be to use infiltration in a strategic way to manage urban runoff volumes and pollutant loads within
.
the East Ravine area minimization and, in some areas, avoidance of discharge of stormwater to surface waters;
which in turn will lessen the overall amount of pollutants associated with the stormwater like the Mississippi River;
resulting in less burden on the environment.
Amajor portion of the planned trunk sanitary sewer for the Upper Ravine District was installed
by the City in 2007 in order to serve the first two residential subdivisions located west of Jamaica
Avenue. The additional two residential developments approved in this district are benefiting from
the use of this infrastructure.
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
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Development Staging/Phasing
Development staging for the project is for Upper Ravine Neighborhood 1 to be served
first followed by Neighborhood 2. Services to Neighborhood 1 could begin as soon as all approvals and permits are in
place. Neighborhood 2 is anticipated to be provided infrastructure facilities by roughly 2015 or when Neighborhood 1
has become substantially developed. A phasing plan is included as Figure 6.2.
The following table provides a breakdown of Future Land Use by acreage according to Neighborhood 1 and
Neighborhood 2 and the total project area. Road right-of-way is not included in these land use acreages.
Table 6.1 - Development Scenario Future Land Use Acreages
CategoryTotal Project Area8SSHU /RZHU5DYLQH'LVWULFW(DVW5DYLQH'LVWULFW
12 + DU/Acre543717
1-5 DU/Acre1,357750607
2 Acre Lots Unsewered4650465
6-12 DU/Acre15130121
Cedarhurst880
Civic391326
Civic Campus49049
Commercial1298049
Easement13013
Mixed Use21615
Park/Open Space/Ponding1,4994571,042
Grand Total3,7851,3812,404
The residential and commercial development that occurred within the East Ravine did not
modify the described land use categories identified in the table 6.1. Within the civic campus
land use area, the City and Washington County each constructed new government buildings.
Hall/Public Safety building is 66,335 square feet on 6.82 acres of land. The remaining 24.28
acres remain vacant and may be developed further in the future with a regional joint effort
public safety training facility.
7.P
ROJECT MAGNITUDE DATA
The following tables represent project magnitude data for the Cottage Grove East Ravine project. This data was
generated with an understanding of the market forces and land development interests in the project areas trade market.
Residential and commercial development trends were reviewed in conjunction with building permit data to support
market research conducted by McComb Group, Ltd. in Fall of 2003. A report titled East Ravine Development Potential:
Retail and Residential completed by the McComb Group was published in December of 2003 and is available from the
City.
The Cottage Grove Demographic Characteristics and Retail Sales Potential Study was
updated in September 2009.This Study is included in the Appendix of this report.
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
Page 14
Residential Demand:
Residential demand was estimated at over 10,000 new homes by 2025. The East Ravine planning
process was conducted to test the land capacity for new housing consistent with City policies and directions provided
through the planning process. More detailed site design testing and planning resulted in approximately 6,500 housing
units over the next 20 year period as depicted in Table 7.1 below. Housing unit types would be mixed between single
family detached at 46%, single family attached (twinhomes, townhomes) at 24% and multi-family stacked
(condominiums, apartments) at 30%. Average densities across all residentially guided land areas would be slightly over
4 units per net acre. Density is based on developable land area less major road right-of-way, protected water bodies,
NWI wetlands, lands owned by the South Washington County Watershed District for stormwater management, and
park/open space areas not intended for development. Residential densities in Neighborhood 2 also do not include the
land use category of 2 acre lots un-sewered. If this land area were to be included in the calculation for density,
Neighborhood 2 would have a net density of 2.8 units per acre as opposed to 4.4. Densities are presented in Table 7.1.
The timing of the residential growth in Cottage Grove was delayed by the downturn in the
economy and housing market which impacted the development staging of the growth and
is covered elsewhere in this document. Unless subjected to a major change in regional
forecasting methodologies, the projected growth figures included below are still
considered accurate minus the 120 single family units platted to date.
Table 7.1 - Project Magnitude Data - 20 Year Residential Growth
Percent of Overall
Total Project Area Housing UnitsUnitsTotal
Single Family Detached2,99446%
Multi-Family Attached1,60224%
Multi-Family Stacked1,95830%
Total Units6,554100%
Residenital Total Density - Units
Acres*Unitsper Acre
Neighborhood 1 8233,2073.90
Neighborhood 2 7603,3474.40
Total Project Area1,5836,5544.14
GRHVQRWLQFOXGHH[LVWLQJODUJHORWXQVHZHUHGUHVLGHQWLDOLQQHLJKERUKRRG
er, regional parks
and greenways and major road right-of-way.
There are two primary Commercial land use nodes in the project area. Neighborhood 1 includes the bulk of the
th
commercial area at the Cottage View area at CR 19 and Highway 61. The other area is the Cedarhurst area at 70 Street
east of CR 19 in Neighborhood 2. Collectively, these two areas could accommodate approximately 850,000 square feet
of new commercial retail development. The East Ravine Development Potential: Retail and Residential market study
provided the research to support this level of retail growth over the next 20 year period.
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January 2015 ~ Update Document
Page 15
In 2012, the City Council approved a 23.5-acre commercial development that is located in
the Cottage View Area of Neighborhood 1 South. The project completed construction in
March of 2014.
Table 7.2 - Project Magnitude Data - 20 Year Commercial Growth
Commercial Total Units
Acres Sq. ft.
64 200,000
Neighborhood 1 - Undeveloped
0
Neighborhood 1 - Developed
62.5 470,000
Neighborhood 2 - Undeveloped
23.5 180,000
Neighborhood 2 - Developed
150 850,000
Total Project Area
8.P
ERMITS AND APPROVALS REQUIRED
Table 8.1 presents a list of known local, state, and federal permits and approvals. The specific permits and approvals
will depend on the type and magnitude of a particular development project. Additional consultation with city and agency
staff will be needed to clarify whether a permit or approval is necessary.
Table 8.1 - Permits and Regulatory Review/Approvals
There have been no modifications to the information reported in Table 8.1.
Type of Permit/review or Regulatory Citation
Unit of Government approval (as may be noted)
City of Cottage Grove Subdivision Approval
Planned Unit Development
Approval
Rezoning
Flood Fringe and Floodway Overlay
Conditional Use Permit Approval
Grading Permit/Drainage and
Stormwater
Site Plan Review Approval
Comprehensive Plan Amendments
Zoning Ordinance Amendments
Variance
Washington County Roadway Access Permit
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January 2015 ~ Update Document
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Type of Permit/review or Regulatory Citation
Unit of Government approval (as may be noted)
Utilities in Right-of-Way Permit
Minnesota Department of Utility Crossings Permit MN Statute 103G, MN Rules
Natural Resources 6115.0810
Federal Endangered Species
Preservation Act of 1973, as
Natural Heritage Program amended in 1978, 1982, and
Coordination 1988; MN Statutes Chapter
84.0895; MN Rules Chapter
6134
Wetland Permit
U.S. Army Corps of Engineers Clean Water Act Section 404/10 Section 404 Of The Clean
Wetland Permits Water Act Title 33CFR26 -
Water Pollution Prevention and
Control Subchapter IV - Permits
and Licenses
Minnesota Department of Water Main Plan Review MN Rules 4720
Health
Minnesota Pollution Control NPDES Permit MN Statute 115, MN Rules
Agency 7002
Sanitary Sewer Extension Permit
401 Water Quality Certificate
Surface Water Discharge Permit
Wastewater Permit
Indirect Source Permit (ISP)
South Washington County Grading/Drainage/Storm sewer
Watershed District Permit
Metropolitan Council
Environmental Services
Section 106 of the Historic
Preservation Act, Protection of
Minnesota State Historic Historic Properties" (36 CFR
Cultural Resource Coordination
Preservation Office Part 800), MN Statutes 138.31-
.42, MN Private Cemeteries
Act- MN Statute 307.08
Utilities in Right-of-Way Permit
Minnesota Department of
Transportation
Access Permit
Minnesota Environmental Minnesota Rules 4410
Environmental Assessments (AUAR)
Quality Board (EQB)
9.L
AND USE
Past and current land uses in the project area have primarily been agricultural. Some farmsteads exist which generally
consist of residential structures and outbuildings such as barns, sheds or silos. Other uses include large lot residential
development on individual septic systems and private wells. This type of use is primarily focused on the eastern edge of
the project area in what is commonly known as Old Cottage Grove, along Military Road or along Keats Avenue. Figure
9.1 illustrates existing land use in the project area.
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January 2015 ~ Update Document
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Table 9.1 - Existing Land Use
There have been no changes in the information reported in Table 9.1.
Existing Land UseTotal Acres
Agricultural Use2,441
Commercial61
Park/Open Space568
Public / Semi Public53
Road Right of Way70
Rural Residential738
Urban Residential69
Grand Total4,000
Adjacent land uses consist of a combination of urban land uses to the west of the project area (predominantly a single
family, low density residential use) and rural land uses to the east of the project area (farm fields). Highway 61 is
located to the south of the project area and The City of Woodbury is located to the north. In Woodbury, land uses are
currently agriculture oriented with longer term plans for residential growth.
A site owned by 3M Corporation is located at the northern boundary of Cottage Grove, east of CR 19. The site has
extensively been monitored by both 3M Corporation and the Minnesota Pollution Control Agency. Additional
documentation as to the status of this site is available through the City of Cottage Grove or through the MPCA.
10. C
OVER TYPES
Cover Type Map
Figure 10.1 shows natural resources such as threatened and endangered species and cover types such as cropland,
basswood forest, brushland, coniferous plantation, dry oak forest, dry oak savanna, dry prairie, lowland hardwood
forest/wet meadow, lowland hardwood forest, maple-basswood forest, mesic oak forest, mixed hardwood forest, oak
woodland-brushland, old field, and wetland/open water marshes. Figure 10.2 presents mapping of watercourses,
wetlands, lakes, and floodplains. Figure 9.1 shows existing development patterns.
Current natural community land cover is presented in Table 10.1. The future level of impact cannot be predicted at this
time since specific development plans are not in place.
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January 2015 ~ Update Document
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Table 10.1 - Current 2006 Natural Community Land Cover
Land Classification Existing Acres Land Classification Existing Acres
Coniferous Forest 5.14 Maple-Basswood 63.13
Forest
Agricultural Land 2050.15 Mesic Prairie 2.38
Deciduous Forest 8.35 Mixed 36.03
Coniferous/Deciduous
Forest
Dry Prairie 17.73 Oak Forest 682.28
Floodplain Forest 1.60 Oak Savanna 57.49
Grassland/Brushland 240.70 Oak 149.46
Woodland/Brushland
Other/Transitional 25.65
Impervious Surfaces 220.11
Land
Lawn/Landscaping 252.02 Planted Coniferous 62.02
Forest
Lowland-Hardwood 28.13 Wetland 104.92
Forest
Total Acres4007.29
Overlay
Figure 9.1 presents existing land use and Figure 6.1 presents the development scenario representing future land use that
can be viewed in conjunction with Figures 10.1 Natural Resources and 10.2 Water Features. Cottage Grove has a
commitment to natural resources and has prepared a Natural Resource Inventory completed by BRAA in 1998.
Community woodlands and wetlands are also
Conservation Act. Figure 10.3 presents a Natural Resources Overlay identifying Environmentally Sensitive Features as
With urban development, the face of the existing landscape is inevitably and irreparably modified.
The City recognizes that the areas identified for growth on the approved 2030 land use plan will
Park and Open Space Plan and the Tree Preservation Ordinance, the natural communities that
have a significant local value have and will be preserved. The current development review process
does not break out the land use classification changes to the level of detail identified initially in
Table 10.1 and is not a component of review for development of the East Ravine Planning Area.
11. F,,
ISH WILDLIFE AND ECOLOGICALLY SENSITIVE RESOURCES
Wildlife and Fish Resources
There is a variety of wildlife in the AUAR study area due to the diverse types of habitat available. Wetlands,
woodlands, grasslands, and croplands found in the area provide good cover and habitat for many common species found
in the upper Midwest. Development will result in an overall loss of habitat quantity and quality in the area. In the short
term, animals will be displaced by construction activities, moving into other areas where they will be forced to compete
for resources and typically experience higher rates of mortality than resident wildlife. In the long term, the ability of the
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
Page 19
area to support wildlife will be diminished. The frequency of conflicts between humans and wildlife will increase in the
form of nuisance wildlife complaints.
The statements in this section remain unchanged.
Wetlands
There are approximately 105 acres of wetlands within the project area. Wetlands were identified using National
Wetland Inventory (NWI) Maps, the Cottage Grove Natural Resources Inventory (Cottage Grove Natural Resource
Inventory 1998), MnDNR Public Water Inventory (PWI) Maps, and the Minnesota Land Cover and Classification
System (MLCCS). There are four MnDNR public water wetlands located in the project area (82W-Gables Lake, 83W-
Unnamed wetland, 84W-Unnamed wetland, and 87W-Regional Park Lake). The wetlands that are present within the
project area are depicted on Figure 10-2. These wetlands provide habitat for numerous waterfowl, amphibians, reptiles,
and upland wildlife species. Several species of migratory birds (ducks, geese, and cranes) commonly use wetlands.
Only one of the residential subdivisions that developed since the adoption of the AUAR
had a wetland identified during the required wetland delineation reports that were
completed as a part of the development process. That project was The Waters at
Michaels Pointe, which is adjacent to a deep, open water marsh that is one of the few
natural wetlands in Cottage Grove that is of a considerable size. This designated
wetland was protected during construction in accordance with the requirements of
Minnesota DNR and the South Washington Watershed District. The Watershed District
has this wetland identified as Protect 1 which requires a 100-foot wide average wetland
buffer. There were no other non-residential developments that had a wetland identified
or impacted.
Watercourses
The City of Cottage Grove, MLCCS, MCBS, Metropolitan Council, and MnDNR information was used to classify and
map woodland areas. Cottage Grove Ravine Creek is a watercourse that runs through the project area and a portion of it
th
is a MnDNR public water. The portion that is a MnDNR public water starts just north of 80 Street and flows south
through Neighborhood 2. There are approximately 143,000 linear feet of watercourses within the project area. In
general, watercourse corridors provide habitat for upland wildlife and migratory birds. Migratory birds, amphibians,
reptiles, and waterfowl are common types of species found along creeks.
The only impact to the reported watercourse was that additional public drainage and utility
easements were acquired over a portion of the creek in Section 23 as a part of a minor
subdivision that was a component of the acquisition of parkland by Washington County.
Lakes
The City of Cottage Grove, MLCCS, MCBS, Metropolitan Council, and MnDNR information was used to classify and
map woodland areas. Gables Lake and Regional Park Lake are both located within the project area and are both
identified by the MnDNR PWI map as public water wetlands (82W and 87W, respectively). Gables Lake and Regional
Park Lake account for the approximately 26 acres of lakes within the project area. Lakes provide habitat for migratory
birds, fish, waterfowl, amphibians, and reptiles.
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January 2015 ~ Update Document
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Gables Lake is upstream of all development that occurred in the East Ravine. The
Regional Park Lake is downstream from the Washington County Government Center and
the New Cottage Grove City Hall that were constructed since the approval of the AUAR.
This water body was not compromised by these two projects as the sites were developed
with surface water rate and quality controls that were constructed in accordance with the
water management plan.
Woodland Areas
Woodland areas comprise approximately 27 percent of the total project area, accounting for an estimated 1,094 acres.
Several forest stands are found throughout the project area while others align the Cottage Grove Ravine Creek corridor.
Similar to agricultural/open lands, the woodlands provide habitat areas to numerous wildlife species described above.
The City of Cottage Grove, MLCCS, MCBS, Metropolitan Council, and MnDNR information was used to classify and
map woodland areas. The forest cover classifications within the project area are depicted on Figure 10.3 Natural
Resources. The majority of the woodlands were classified as oak forest and oak woodland/brushland. The City of
Cottage Grove had a natural resource inventory completed for the city in 1998 and the information is summarized below
for the project area.
The residential and commercial developments that occurred in the East Ravine since the
adoption of the AUAR were subject to the submission and review of tree preservation
inventories. In instances when tree removal related to development consistent with the
2030 Land Use Plan was in excess of ordinance criteria, the projects were subject to tree
replacement or cash mitigation approval conditions.
11.a.1.4.1 Neighborhood 1 (North) Natural Communities
thth
Neighborhood 1 (north) is located north of 70 Street South and south of Military Road. Just north of 70 Street South
is a fairly large (117 acre) oak forest. This area has been logged in recent years. Oaks are the dominant tree species, but
a much greater proportion of the canopy is made up of other tree species such as aspen (Populus tremuloides), butternut
(Juglans cinerea), black cherry (Prunus serotina) , hackberry (Celtis L.), and bitternut hickory (Carya nutt). The shrub
layer is dominated by buckthorn (Plantago aristata).
Just north of this large oak forest is a mature oak forest. According to Constance Otis, this area was last logged during
the late 1800s. Since then, the canopy has recovered and today is dominated by white oak (Quercus alba) and bur oak
(Quercus macrocarpa) with a good diversity of other species in the subcanopy including bitternut hickory, butternut,
basswood (Tilia linden), red oak (Quercus borealis), and hackberry. There are also scattered sugar maple (Acer
saccharum) and red maple (Acer rubrum) in this community. The shrub layer is fairly diverse containing elderberry
(Sambucus canadensis), chokecherry (Aronia medikus), and several species of currant and pagoda dogwood (Cornus
alternifolia). The ground cover is very diverse containing such species as jack-in-the-pulpit (Arisaema triphyllum),
(Circaea L.), bloodroot (Sanguinaria L.), and several species of ferns including sensitive and
maidenhair fern (Adiantum pedatum). Unfortunately buckthorn has invaded this community and will likely become
dominant in the future.
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11.a.1.4.1 Neighborhood 1 (North) Natural Communities
Neighborhood 1 (north) is located north of 70Street South and south of Military Road. Just north of 70
th th
Street South is a fairly large (117 acre) oak forest. This area has been logged in recent years. Oaks are the
dominant tree species, but a much greater proportion of the canopy is made up of other tree species such as
aspen (Populus tremuloides), butternut (Juglans cinerea), black cherry (Prunus serotina), hackberry
(Celtis occidentalis), and bitternut hickory (Carya cordiformis). The shrub layer is dominated by buckthorn
(Rhamnus cathartica). Just north of this large oak forest is a mature oak forest. According to Constance
Otis, this area was last logged during the late 1800s. Since then, the canopy has recovered and today is
dominated by white oak (Quercus alba) and bur oak (Quercus macrocarpa) with a good diversity of other
species in the subcanopy including bitternut hickory, butternut, basswood (Tilia americana), red oak
(Quercus rubra), and hackberry. There are also scattered sugar maple (Acer saccharum) and red maple
(Acer rubrum) in this community. The shrub layer is fairly diverse containing elderberry (Sambucus
canadensis), chokecherry (Prunus virginiana), and several species of currant and pagoda dogwood
(Cornus alternifolia). The ground cover is very diverse containing such species as jack-in-the-pulpit
(Arisaema triphyllum), (Circaea lutetiana), bloodroot (Sanguinaria canadensis.),
and several species of ferns including sensitive and maidenhair fern (Adiantum pedatum). Unfortunately
buckthorn has invaded this community and will likely become dominant in the future.
The Dodge Nature Center became the owners of this property in 2013 and has already
begun a buckthorn management program.
A wetland is located west of this mature oak forest. The majority of this wetland consists of a deep, open water marsh.
Along the edges of the wetland, species such as sedge, cattail, rice cutgrass (Leersia oryzoides), river bulrush (Scirpus
fluviatilis), and blue flag iris (Iris versicolor), dominate. Within shallow areas along the wetland edge, there are
numerous mudflats containing plantain, cow parsnip (Heracleum lanatum), broad-leaved arrowhead (Sagittaria
latifolia), and marsh fern (Thelypteris palustris). These same species, along with cattail, are also present on several
floating bog mats. Submergent plants and floating leaf species such as yellow water lily (Nuphar lutea) and duckweed
(Lemna minor) are present in many open water areas of the wetland. Invasion by reed canary grass (Phalaris
arundinacea) and buckthorn has occurred along much of the wetland margin. However, these species have not moved
much beyond the wetland edges.
Just west of this large wetland is a small, shallow, open water/emergent marsh, containing many of the same species
found in the large wetland. Some of the common species include lake sedge (Carex lacustris), blue flag iris, plantain
(Alisma subcordatum), and broadleaf arrowhead. At the time of the original survey, this wetland contained only a small
pool of water in its center. Buckthorn has encroached into the wetland margin.
A degraded wet meadow dominated by reed canary grass is located east of the large wetland. This area appears to have
been farmed at one time.
The rest of Neighborhood 1 (north) consists of farm/agriculture land except for two small areas on the north side of
Military Road. One area is a conifer plantation dominated by scotch pine (Pinus sylvestris) with boxelder (Acer
negundo) and trembling aspen mixed along the plantation edges. West of this conifer plantation is an old field
dominated by introduced grasses such as smooth brome (Bromus ciliatus), bristly foxtail (Setaria spp.), and kentucky
bluegrass (Poa pratensis).
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A wetland is located west of this mature oak forest. The majority of this wetland consists of a deep, open
water marsh. Along the edges of the wetland, species such as sedge, cattail, rice cutgrass (Leersia
oryzoides), river bulrush (Schoenoplectus fluviatilis), and blue flag iris (Iris versicolor), dominate. Within
shallow areas along the wetland edge, there are numerous mudflats containing plantain, cow parsnip
(Heracleum lanatum), broad-leaved arrowhead (Sagittaria latifolia), and marsh fern (Thelypteris
palustris). These same species, along with cattail, are also present on several floating bog mats.
Submergent plants and floating leaf species such as yellow water lily (Nuphar lutea) and duckweed (Lemna
minor) are present in many open water areas of the wetland. Invasion by reed canary grass (Phalaris
arundinacea) and buckthorn has occurred along much of the wetland margin. However, these species have
not moved much beyond the wetland edges. Just west of this large wetland is a small, shallow, open
water/emergent marsh, containing many of the same species found in the large wetland. Some of the
common species include lake sedge (Carex lacustris), blue flag iris, plantain (Plantago major), and
broadleaf arrowhead. At the time of the original survey, this wetland contained only a small pool of water
in its center. Buckthorn has encroached into the wetland margin.
A degraded wet meadow dominated by reed canary grass is located east of the large wetland. This area
appears to have been farmed at one time. The rest of Neighborhood 1 (north) consists of farm/agriculture
land except for two small areas on the north side of Military Road. One area is a conifer plantation
dominated by scotch pine (Pinus sylvestris) with boxelder (Acer negundo) and trembling aspen mixed along
the plantation edges. West of this conifer plantation is an old field dominated by introduced grasses such as
smooth brome (Bromus ciliatus), bristly foxtail (Setaria spp.), and Kentucky bluegrass (Poa pratensis).
The residential development that occurred in Neighborhood 1 did not impact the Dodge Nature Center
Property which is protected by a land conservation easement or any of the identified wetlands. In 2013,the
Minnesota List of Eendangered, Threatened and Special Concern Species was amended to include
butternut (Juglans cinerea)
11.a.1.4.2 Neighborhood 1 (South) Natural Communities
Neighborhood 1 (South) is located north of Highway 61 and west of County State Aid Highway (CSAH) 19. This area
contains low to moderate quality, dry, sand gravel prairie and some old fields now grown over with trees, shrubs, and
grasses. Wildlife values for this area were rated as low due to the lack of natural community diversity and poor
connectivity to other natural areas.
The few communities that exist in this area are all located near the intersection of Highway 61 and CSAH 19A. One
community is an old field dominated by introduced graminoids (grasses) and weedy forbs. Common graminoids include
smooth brome and Kentucky bluegrass. Common forbes include common milkweed (Asclepias L.), daisy fleabane
(Erigeron strigosus), spotted knapweed (Centaurea maculosa), and goatsbeard (Tragopogon pratensis). This field was
probably cultivated in the recent past.
East of the old field is a young mixed hardwood forest dominated by boxelder, green ash (Fraximus pennsylvanica), and
Chinese elm (Ulmus parvifolia). Both the shrub and ground cover layer contain mostly exotic and/or weedy shrubs and
herbaceous plants. The shrub layer is dominated by buckthorn, the ground layer by wood nettle (Laportea Canadensis)
and Virginian stickseed (Lappula redowskii).
East of the drive in movie theatre is a dry prairie occurring on a very doughty site with numerous areas of exposed fine
sand. In general, Kentucky bluegrass and smooth brome dominate this site. Where the site contains exposed sand,
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
Page 23
small patches of little bluestem (Andropogon scoparius) along with a fair diversity of dry prairie forbs occur. Some of
the more common forbs include whorled milkweed, daisy fleabane, common milkweed, flowering spurge (Euphorbia
corollata), sulfer cinquefoil (Potentilla recta), and thimbleweed (Anemone patens).
A poor quality dry prairie almost completely overgrown by woody vegetation and leafy spurge is located east of the dry
prairie.
A mixed hardwood forest that contains mostly non-native and/or weedy tree species and shrub and ground cover species
is located south of the drive-in movie theater.
The rest of the Neighborhood 1 (south) consists of farm/agriculture land.
The 23.5-acre Walmart development is located in the Cottage View area west of the
former drive-in theatre site. As a component of that project, there was tree removal and
grading of the Walmart site and the western half of the former drive-in site now
referenced as the Apache Parcel. A tree inventory and mitigation plan was completed in
Forester reviewed the plan for accuracy and conformance. Tree mitigation fee of
$148,000 was required as per the ordinance and collected with the building permit foe
Initiative Fund, which is
designated for landscape improvements in major transportation corridors, trailway
corridors, and park and open space areas.
11.a.1.4.3 Neighborhood 2 Natural Communities
Neighborhood 2 is located north of Highway 61 and east of CSAH 19. As a whole the natural resources in the area
consists mainly of dry oak forest, mesic oak forests, and conifer plantations. Historic items such as the historic Dr.
William Furuse is valued for its eclectic
th
Century German immigrants.
The northern area of Neighborhood 2 consists of woodland-brushland, dry oak savanna, mesic oak forest, basswood
forest, and maple forest. In addition, this area also contains a small lake and a wetland. The diversity of different
natural communities is high.
Oak forests along with a variety of other community types including conifer plantation and lowland hardwood forest
dominate the central area of Neighborhood 2.
The southern area of Neighborhood 2 consists mainly of mesic and dry oak forests. This area also includes several
small dry, sand gravel prairies, a wet meadow/fen wetland, and a number of conifer plantations.
The only development activity that occurred in Neighborhood 2 was the construction of the
Washington County South Service Center and the Cottage Grove City Hall/Public Safety
facility, and the realignment of 70th Street (CSAH 20) which Washington County is in the
process of completing. This realignment project only impacted the built environment along the
corridor and active agricultural fields. The government campus projects contain rain gardens,
native plantings, prairie, and Oak Savannah restorations.
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January 2015 ~ Update Document
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11.a.1.5 Grassland/Shrubland and Lawn/Landscaping
The City of Cottage Grove, MLCCS, MCBS, Metropolitan Council, and MnDNR information was used to classify and
map grassland/shrubland and lawn/landscaping areas. Grassland/shrubland and lawn/landscaping comprise
approximately 13 percent of the total project area, accounting for 513 acres. Grassland and shrubland within the project
area are depicted in Figure Natural Resources. Similar to agricultural/open lands, the grassland/shrubland and
lawn/landscaping areas provide habitat to numerous wildlife species described above.
No areas of grassland/shrubland were disturbed beyond the areas identified as
development area within the original approved East Ravine Master Plan. Areas developed
as residential will have lawn and landscaping areas established as theydevelop.
11.a.1.6 Agricultural/Other Transitional Land
The City of Cottage Grove, MLCCS, MCBS, Metropolitan Council, and MnDNR information was used to classify and
map woodland areas. Agricultural/other transitional land comprises the largest portion of the entire project area,
accounting for 2,076 acres, approximately 52 percent of the project area. The agricultural/other transitional is defined as
agricultural land, undeveloped land, and land that was not classified during the biological inventory of the area and is
not differentiated from cropland. Some overlapping of other land types already described are included in this area.
The agricultural/other transitional areas provide nesting habitat, cover, and food for wildlife. There are numerous small
and medium sized mammals that utilize these lands including white-tailed deer, raccoons, red and gray fox, woodchuck,
squirrel, and other small mammals. Song and game birds may also be present throughout the project area and include a
variety of edge, open, and woodland species.
No areas of Agricultural or Transitional lands were disturbed beyond the areas
identified as development areas within the original approved East Ravine Master
Plan.
11.a.1.7 Impervious Surfaces
The City of Cottage Grove, MLCCS, MCBS, Metropolitan Council, and MnDNR information was used to classify and
map impervious surface areas. Impervious surface areas comprise approximately 220 acres of the project area,
primarily roadways, parking areas, and buildings associated with development.
The statements in this section remain unchanged.
11.a.1.8 Proposed Development
The proposed development pattern seeks to preserve a significant portion of the project area as park or open space area.
Approximately 1,580 acres or just over 41% of the project area is in some form of green space as itemized in Table 11.1.
Cottage Grove East Ravine AUAR
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subdivisions are consistent with the East Ravine Master Plan. In
The four approved
addition, the City worked with Washington County in the expansion of the Ravine
Regional Park along Kimbro Avenue. The acquisition financing of the new parkland was
a component of the negotiated agreement relating to the offset of regional parkland
utilized for the Civic Campus.
Table 11.1 - Open Space/Green Land Uses in the Development Scenario
The park and open space development that has occurred to date is in significant
conformance with the green space identified in Table 11.1 and the correlating areas
found on the 2030 Land Use Plan, the future park and open space plan, and Figure 6.1
of this document.
11.a.1.9 Potential Habitat Impacts
The conversionof open land, agricultural land, woodland, grassland, shrub land, and wetlands to urban types of
development will disturb the habitat and feeding areas, and affect current wildlife species. Increased runoff volumes
during construction and from developed areas will drain to wetlands and creeks in the area (see the response to
Questions 16 and 17). Presently, development and infrastructure design plans are largely unknown for properties within
the project area. Due to the unknown nature of future development within the project area, the extent of impacts on
wildlife and natural resources is not fully known. Alternative site design to help to maintain areas for natural habitat are
supported by the subdivision design policies as identified in the
help to maintain areas for natural habitat.
.
The statements in this section remain unchanged
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11.b.1 Natural Heritage Program
The MnDNR NHP, data was obtained from the MnDNR and is included in Figure Natural Resources. In addition, the
City of Cottage Grove also purchased the electronic database containing NHP data from the MnDNR to review for the
AUAR.
There is one natural heritage recorded wildlife species and one recorded plant species that occur within the project area,
turtle (state listed threatened) and Kitten-tails (state listed threatened). There are no state listed
endangered species recorded for the project area.
In addition, the MnDNR NHP database has two recorded natural communities that occur within the project area, the Dry
Prairie (Southeast) Sand-Gravel Subtype and the Mixed Emergent Marsh (Prairie). These natural communities are
recorded in the NHP database because they are uncommon, but are not protected by State or Federal laws.
The natural communities and the species referenced in this section were not
impacted by the development that occurred since the adoption of the AUAR.
11.b.1.1
(Emydoidea blandingii) is a state-listed threatened species associated with sandy soils and a
variety of wetland types. A species is ranked as threatened, if the species is likely to become endangered within the
foreseeable future throughout all or a significant portion of its range. Threatened species are protected under the Federal
Endangered Species Preservation Act of 1973, as amended in 1978, 1982, and 1988; Minnesota Statutes Chapter
84.0895; Minnesota Rules Chapter 6134.
nesting. Studies by Congdon et.al. (1983) in Michigan and by Linck in Massachusetts have shown that nesting females
may travel considerable distances (200 to 400 meters) to a nesting area, passing enroute what appears to be suitable
nesting habitat immediately adjacent to the marsh in which they reside (Coffin and Pfannmuller 1988).
The loss of wetland habitat
through drainage or flooding to convert wetlands into ponds or lakes, loss of upland habitat through development or
conversion to agriculture, human disturbance (including collection for pet trade, road kills during seasonal movements),
and increases in predator populations (skunks, raccoons, etc.) that prey on nests and young all contribute to a decline in
this species.
In long-lived species, protecting the adults is critical to any conservation strategy. A female turtle may produce as many
as 500 eggs during her life. Losing many of these long-lived females, through habitat loss or direct mortality, would
seriously jeopardize the ability of a population to maintain itself. One of the potential threats is mortality while crossing
roadways. Roadway design and large culverts or tunnels may provide an alternative route for turtles, but requires
further evaluation to refine design and effectiveness (Lang 2000).
The species referenced in this section were not reported to have been impacted or
potentially impacted by the development that occurred since the adoption of the
AUAR.
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11.b.1.2 Kitten-Tails
The Kitten-tail (Besseya bullii) is a state-listed threatened plant species. A species is ranked as threatened, if the species
is likely to become endangered within the foreseeable future throughout all or a significant portion of its range.
Threatened species are protected under the Federal Endangered Species Preservation Act of 1973, as amended in 1978,
1982, and 1988; Minnesota Statutes Chapter 84.0895; Minnesota Rules Chapter 6134.
The Minnesota Kitten-tail populations are largely restricted to the bluffs and terraces of the St. Croix, Mississippi, and
Minnesota river valleys, specifically where the three rivers converge in the Twin Cities area. The plants prefer gravelly
soil in dry prairies, savannas, and open woods (Coffin and Pfannmuller 1988).
The Kitten-tail is quite distinctive and bears no close resemblance to any other species encountered in Minnesota. It is
characterized by a dense spike of sessile, yellowish flowers, each with two long exerted stamens. The basal leaves are
large and heavily veined. The stem leaves are small and alternate and partially clasp the stem. The plants flower early
in the spring, but the spike and the basal leaves remain visible throughout most of the summer (Coffin and Pfannmuller
1988).
The kitten-tails that were identified within the East Ravine development area were located
within the borders of the Cottage Grove Regional Park, so no negative impact occurred as
a result of the development that occurred within the planning area.
11.b.1.3 Other Information
U.S. Fish and Wildlife Service (USFWS) resources indicate that the bald eagle (Haliaeetus Leucocephalus
roseroot (Sedum integrifolim spp. Leedyi), and prairie bush clover (Lespedeza leptostachya) are listed as federally
threatened in Minnesota and documented to occur in Washington County. However, there are no records indicating that
these species occur within the project area. Given the location and type of activity proposed, the USFWS determined
that the project is not likely to adversely affect any federally listed or proposed federally threatened or endangered
species or adversely modify their critical habitat. This precludes the need for further action on this project as required
under Section 7 of the Endangered Species Act of 1973.
The statements in this section remain unchanged.
12. P
HYSICAL IMPACTS ON WATER RESOURCES
There will be no physical impacts on water resources within the project area.
13. WU
ATER SE
Based on information obtained from existing water supply studies and consultation with City engineering consultants at
Bonestroo Rosene Anderlik and Associates (now Stantec), the existing water supply and treatment for the East Ravine
area will be provided off site. In addition, the existing well field is felt to be adequate for the needs that will be
generated by the development scenario envisioned for the East Ravine area. The proposed East Ravine plan would
increase the water demand by approximately 13.0 Million Gallons per Day. Appendix 1 contains a technical
memorandum titled Cottage Grove East Ravine Planning Study: Watermain prepared by Howard R. Green Company in
February of 2005. This memo provides the methodology and details concerning impacts on future water usage for the
project area. Figures illustrating the water systems are included in Appendix 1.
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Contact inquiries in relation to this study are to be directed to Stantec.
14. W-LUMD
ATERRELATED AND SE ANAGEMENT ISTRICTS
There are no water related land use management districts that are impacted by the project.
The statements in this section remain unchanged.
15. W
ATER SURFACE USE
There are no recreational water bodies in the project area.
The statements in this section remain unchanged.
16. E
ROSION
AND SEDIMENTATION
Normal grading practices associated with urban development will be associated with future development in the Cottage
Grove East Ravine. Certain areas where topographic relief is dramatic have been placed in an open space or green land
use pattern to minimize potential for erosion and sedimentation problems. Best management practices will be applied to
all construction projects in the area to prevent erosion and sedimentation during construction projects.
The statements in this section remain unchanged.
17. WQ-
ATER UALITYSTORMWATER RUNOFF
Stormwater management was studied at depth for the Cottage Grove East Ravine project. A detailed analysis of
stormwater issues and plans is provided as Appendix 5 to this AUAR. The report analyzes existing stormwater systems
and drainage patterns as well as site characteristics that would promote environmentally friendly storm water
management practices. Figure 17.1 illustrates the existing storm water management system which uses a series of
existing small swales and depressions. The area is favorable to infiltration due to the sandy soils and significant depth to
groundwater or bedrock.
The stormwater management goal for this project is to utilize the natural drainage and infiltration capabilities of the
existing land. Stormwater management areas along planned parkways (as illustrated in Figures 6.1 and 17.2 will be
utilized to collect, infiltrate and direct overflow of runoff from adjacent neighborhoods. Overflow from the parkway
stormwater basins will be directed to larger natural infiltration basins which have the capacity to infiltrate all the runoff
from a 100-year storm event. Emergency overflow from the larger infiltration basins for events greater in intensity than
a 100-year event could be provided either through the existing Cottage Grove drainage system and/or through the future
regional stormwater conveyance system being planned by the South Washington Watershed District. The future
stormwater management system is illustrated in Figure 17.2.
The statements in this section remain unchanged.
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18. WQ-W
ATER UALITYASTEWATER
A detailed analysis of sanitary sewer infrastructure systems and wastewater generation was conducted for this project.
The analysis is included as Appendix 2, a Technical Memorandum from Howard R. Green Company titled Cottage
Grove East Ravine Planning Study: Sanitary Sewer dated February of 2005.
The City of Cottage Grove has a Comprehensive Sewer Policy Plan that was completed in May of 1992 by Bonestroo,
Rosene, Anderlik & Associates (now Stantec). The purpose of the Comprehensive Sewer Policy Plan was to provide the
City with
system to serve its saturation population. The report served as the sewer element of the public facilities plan for the
Metropolitan Council and the Comprehensive Sewer Policy Plan (CSPP) for the Metropolitan Waste Control
Commission (MWCC). d inventory of the sanitary
sewer systems and projections for waste water flows based on the updated future land use plan. This update provided the
data to assist the Metropolitan Council Environmental Services (MCES) in planning for the now constructed Eagles
Point Plant and the South Washington County Interceptor Sewer which will provide trunk sanitary sewer facilities to the
East Ravine area. This background data served as a starting point for the East Ravine sanitary sewer analysis.
There are eight major sanitary sewer districts in the city of Cottage Grove, each defining the limits of service for a
separate trunk system. The East Ravine is in the Cottage Grove Ravine District (6,993 acres). This area is served by the
South Washington County Interceptor which will service the eastern 35% of Cottage Grove, the Central and Cottage
Grove Districts in Woodbury, and possibly other communities to the north in Washington County.
The treatment and disposal of wastewater occurs at the Cottage Grove Treatment Plant which is under the jurisdiction of
the MCES.
This preliminary sanitary sewer design for the East Ravine area (as detailed in Appendix 2) was accomplished in
accordance with Metropolitan Council Environmental Service (MCES) and Ten State Standards guidelines.
Construction plans for South Washington County Gravity Interceptor Phase 1 and South Washington County Gravity
Interceptor Phase 2 were used to determine the existing location of the trunk interceptor running along Keats Avenue
(CSAH 19). Existing sanitary stubs as indicated on the interceptor plans were utilized where possible. However, In
order to provide an efficient design some new connections to the interceptor are included in this preliminary plan. The
1
study area is primarily divided into two sections, Neighborhood One located west of Keats Avenue and Neighborhood
2
Two located east of Keats Avenue. Design characteristics for each neighborhood are presented within Appendix 2.
Future domestic wastewater flows were estimated for the East Ravine area based on a series of sub areas established for
Neighborhoods 1 and 2. The flows were based on the projected land uses as described in question 6 and illustrated in
Figure 6.1. Table 18.1 provides a summary of flows by each sub area. A map of the identified sub-areas and other
figures are included within Appendix 2.
The statements in this section remain unchanged.
Table 18.1 - Summary of Current and Future Residential Waste Generation
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No new on-site systems are proposed to serve the East Ravine area.
The information in this table remains unchanged.
19. G
EOLOGIC HAZARDS AND SOIL CONDITIONS
Most of the project area is located in a groundwater recharge area due to the predominantly sandy soils, underlain by
gravel and rock, which allows rapid percolation of water into the aquifer. Groundwater depth ranges from a shallow of
40 feet to upwards of 300 feet in places. The Prairie du Chien aquifer is located close to the surface and is accessed by a
limited number of rural homes for private well water. The Jordan aquifer is much deeper ranging in depth from 150 to
300 feet and is the princip
The bulk of the project area is classified as
bedrock. The areas of shallow bedrock are located on the western edge of Neighborhood 1 and in the central portion of
Neighborhood 2. Areas of shallow bedrock are most prominent east of Keats Avenue, and east of the project area.
Figure 19.2 illustrates the general depth to bedrock.
Sensitivity to Pollution: The Geologic Atlas (MGS 1989) maps the sensitivity to pollution of the water table aquifer.
The water table aquifer in the area is within the glacial material that consists of glacial till or outwash. The map
a general gauge of the overall
susceptibility to pollution based on the travel time of pollutants from a surface source to the water table aquifer. A
shorter anticipated time of travel translates into a higher sensitivity rating for the aquifer. The majority of the East
Ravine (and the entire City of Cottage Grove) has a high susceptibility of groundwater to pollution.
A standard soils map is included as Figure 19.1. Soils are predominantly of a sandy loam nature, highly permeable with
relatively good agricultural suitability.
The statements in this section remain unchanged.
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20.
S;;
OLID WASTES HAZARDOUS WASTES STORAGE TANKS
A) Solid Wastes
The development scenario includes a mixture of residential and commercial uses. These uses will generate additional
municipal solid waste (MSW) and recycling products. Based on information provided by Dan Schoepke, Sr.,
Environmentalist for Washington County, estimates for MSW and recycling on a household and employee basis were
generated. These numbers are as follows:
MSW per HH/year . 820 tons
MSW per employee/year 1.407 tons
MSW recycled per HH/year 0.356 tons
MSW recycled per employee/year 0.847 tons
Estimates are based on the total household and employment projections for Washington County as of 2012 (89,875
HH and 74,605 jobs) and the total amount of MSW collected (178,673 tons) and recycled (32,023 tons of residential
and 63,227 tons non-residential) in Washington County. An assumption was made that the total amount of MSW is
split 50/50 residential/commercial.
S;;
OLID WASTES HAZARDOUS WASTES STORAGE TANKS
A) Solid Wastes
The development scenario includes a mixture of residential and commercial uses. These uses will generate additional
municipal solid waste (MSW) and recycling products. Based on information provided by Dan Schoepke, Sr.
Environmentalist for Washington County, estimates for MSW and recycling on a household and employee basis were
generated. These numbers are as follows:
MSW per HH/year 1.248 tons
MSW per employee/year 1.335 tons
MSW Recycled per HH/year 0.385 tons
MSW Recycled per Employee/year 0.757 tons
Estimates are based on the total household and employment projections for Washington County as of 2003 (77,456 HH
and 72,442 jobs) and the total amount of MSW collected (193,366 tons) and recycled (29,829 tons of residential and
54,803 tons non-residential) in Washington County. An assumption was made that the total amount of MSW is split
50/50 residential/commercial.
Using the average waste and recyclables per household and employee, waste generation and recyclable materials were
estimated based on future development projections in the East Ravine. These numbers are presented in Tables 20.1 and
20.2.
Table 20.1 - Summary of Current and Future Residential Waste Generation
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The statements in this section remain unchanged.
Table 20.2 - Summary of Current and Future Non-Residential Waste Generation
* Employment estimates based on project magnitude data of 850,000 square feet of commercial space at one employee per 500
square feet of space.
The information in this table remains unchanged.
B) Hazardous Wastes
No response required.
The statements in this section remain unchanged.
C) Storage Tanks
There are no specific locations for above or below ground storage tanks known at this time. If any business should need
above or below ground storage tanks, it would need to follow MPCA and other applicable standards and procedures.
The statements in this section remain unchanged.
Traffic
21.
A detailed traffic study was completed and is included as Appendix 3. This traffic study provides an analysis of existing
traffic volumes, patterns and roadway characteristics for the East Ravine project area, provides analysis on impacts on
traffic that would be caused by the development scenario and offers mitigation measures in the form of roadway
improvements, intersection and signal adjustments and traffic management measures. The complete response to question
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
Page 33
21 is referenced to the technical memorandum included as Appendix 3. This includes all figures illustrating existing
traffic/transportation systems and future traffic impacts.
A component of the Walmart commercial development included the completion of traffic studies
that can be referenced in appendix 11. Phase I of the infrastructure improvements
recommended in these studies were completed in 2013. Any significant additional commercial
growth in this neighborhood will require Phase II of the traffic improvements identified.
22. V-
EHICLERELATED AIR EMISSIONS
For roadway projects, the two pollutants of concern are carbon monoxide (CO) and PMThe EPA and the Minnesota
10.
Pollution Control Agency (MPCA) do not require PM analysis. To assure that a project is not in violation of the
10
National Ambient Air Quality Standards (NAAQS), the need for an air quality analysis to address emissions of CO must
be determined.
The East Ravine project is in Washington County, one of the Twin Cities seven-county metropolitan areas considered a
CO maintenance area. To determine the need for a hot-spot analysis, the Twin Cities has a screening method to compare
project locations to a s
one of these intersections, then it is presumed it will not cause any violations. There are three MPCA monitored
locations and seven top intersections (see Table 22.1). The East Ravine project area does not include any of these
locations.
Table 22.1 - Top Ten Intersections Twin Cities CO Maintenance Area
ID DESCRIPTION 1998 AADT*
Top 7 Intersections
1 TH 169 at CSAH 81 77,200
2 TH 101 at TH 7 65,000
3 TH 100 at CSAH 81 71,150
4 TH 10 at University Avenue 63,600
5 TH 252 at 85 th Avenue 61,700
6 TH 252 at 66 th Avenue 64,500
7 TH 252 at Brookdale Drive 58,550
3 MPCA Monitored Locations
8 University and Lexington Avenue 54,500
9 Snelling at University Avenue 57,750
10 Hennepin Avenue at Lake Street 35,800
ID DESCRIPTION 2007 AADT*
Top 7 Intersections
1 TH 169 at CSAH 81 79,400
2 TH 7 at TH 101 66,600
3 TH 252 at 85th Avenue 66,800
4 University Avenue at Snelling Avenue 59,700
5 TH 252 at Brookdale Drive 61,300
6 Cedar Avenue at County Road 42 75,100
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7 TH 7 at Williston Road 54,900
3 MPCA Monitored Locations
8 University and Lexington Avenue 59,700
9 TH 252 at 66th Avenue 72,500
10 Hennepin Avenue at Lake Street 37,000
* Most current AADT available
The Table22.1 was updated with the latest figures from the MPCA.
The final screening criteria is whether the project roadways will have traffic levels in excess of the benchmark AADT
level of 77,200 79,400. The East Ravine project is not forecasted to have traffic levels this high. The results of the
screening procedure show that the East Ravine development project does not require a hot-spot analysis.
The statements in this section remain unchanged, but table 22.1 was modified as noted.
2002
AADT 2020 ADT
Counts
Location
US 61 North of 70th Street 53,000 69,300
US 61 Between 70th Street and 80th Street 42,000 51,100
US 61 Between 80th Street and Keats Avenue 31,000 42,800
Between Keats Avenue and Kimbro
US 61 26,000 32,700
Avenue
70th Street Between US 61 and Jamaica Avenue 6,400 10,400
Between Jamaica Avenue and Keats
70th Street 2,200 10,100
Avenue
80th Street Between US 61 and Hinton Avenue 22,300 28,000
80th Street Hinton Avenue and Ideal Avenue 12,600 16,100
80th Street Ideal Avenue and Jamaica Avenue 10,100 12,700
Between Jamaica Avenue and Keats
80th Street 7,400 9,300
Avenue
80th Street Keats Avenue to Kimbro Avenue 1,200 6,600
Jamaica Avenue Between Military Road and 70th Street 4,200 15,900
Jamaica Avenue Between 70th Street and 80th Street 7,400 10,500
Jamaica Avenue Between 80th Street and US 61 11,200 17,700
Keats Avenue North of Military Road 5,600 12,600
Keats Avenue Between 70th Street and Military Road 7,600 12,600
Keats Avenue Between 70th and 80th Street 6,200 11,000
Keats Avenue Between 80th Street and 90th Street 6,200 11,000
Keats Avenue Between 90th Street and US 61 6,200 13,800
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Kimbro Avenue Between Lamar Avenue and US 61 500 4,000
Between Ideal Avenue and Jamaica
Military Road 5,000 14,100
Avenue
Between Jamaica Avenue and Keats
Military Road 1,450 -
Avenue
Military Road Keats Avenue to Lamar Avenue 3,000 6,000
Lamar Avenue 70th Street to Kimbro Avenue 1,200 2,000
Source: Mn/DOT Year 2002 ADT Flow Maps and Howard R Green Company
23. S
TATIONARY SOURCE AIR EMISSIONS
No response required.
The statements in this section remain unchanged.
24. D,,
UST ODORS NOISE
Existing noise levels were measured at two locations in the project area. Monitoring locations represent undeveloped
lands expected to experience commercial and residential development or impacts from commercial and residential
development. The future Build alternative and associated traffic volumes expected in the year 2020 were modeled using
the Minnesota Department of Transportation traffic noise model, MINNOISE. Monitoring data and modeling results
were compared with the Minnesota Pollution Control Agency (MPCA) Noise Rules to evaluate traffic noise impacts and
recommend mitigation measures. Modeling results were used to create noise contours showing the location of the
residential daytime and nighttime L10 and L50 noise contour lines. L10 and L50 are sound levels in decibels (dBA) that
are exceeded in 10 percent or 50 percent, respectively, of the time for a one-hour survey.
Existing Noise Levels
On March 3, 2005, noise monitoring was conducted at two locations in the project area. The purpose of the noise
monitoring was to document existing noise levels. Noise measurements were conducted in accordance with Minnesota
Rules Chapter 7030, Noise Pollution Control. The meteorological conditions were as follows:
Temperature - +2 degrees
G
Humidity 76%
Wind Calm
Barometric Pressure
Table 1 summarizes the equipment Earth Tech staff used to collect monitoring data for this noise analysis.
Table 24.1 - Noise Analysis Instrumentation Summary
Instrument Make Model Calibration Date Serial Number
Dosimeter 1 Quest Q-300 2/28/05 at 114.0 dBA QC6030052
Dosimeter 2 Quest Q-30 2/28/05 at 114.0 dBA QC2921212
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The monitoring sites were selected at locations where existing noise levels could not be modeled with MINNOISE or to
compare measured noise levels to modeled noise levels to confirm the validity of the model. The results of the noise
measurements at the monitoring locations are listed in Table 2 and the locations of the sites are indicated on Figures 2
and 3. MPCA maximum allowable daytime noise levels are 65 dBA for L10 and 60 dBA for L50. The maximum
nighttime noise levels are 55 dBA (L10) and 50 dBA (L50).
Table 24.2 - Nighttime Noise Monitoring Summary
Site Date Time Distance L10 L50 MPCA Exceeding
Sampled Sampled from CL (dBA) (dBA) Nighttime (Yes/No)
L10 L50
(dBA) (dBA)
Gordon and March 3, 6:00 am 150 feet 56 46 55 50 Yes
Bonnie 2005 to 7:00
Tank am
Property
Washington March 3, 6:00 am 600 feet 51 54 55 50 Yes
County 2005 to 7:00
Property am
Future Noise Levels
The traffic noise model analyzed the existing roadway network and proposed East Ravine Parkway. The Howard R.
Green Company supplied the existing traffic levels in 2003 and the predicted traffic levels in 2020. Earth Tech adjusted
the 2003 traffic data to 2005 conditions. The Washington County Department of Transportation provided information
regarding truck percentages, speed limits, and nighttime peak hour volumes. Earth Tech used aerial orthographic
mapping to determine roadway alignments and digitized the existing and proposed roadway alignments for use in the
MINNOISE noise model. Keats Avenue, Kimbro/Lamar Avenue, Jamaica Avenue, 80th Street, 70th Street, and Military
Road were modeled in the for year 2005 and 2020 peak hour traffic. The proposed East Ravine Parkway was modeled
only for year 2020 peak hour traffic. The highest peak hour traffic volume (PHV) for each modeled roadway is shown in
Table 24.3.
The traffic stream in the MINNOISE model was determined to be 95% cars, 2% medium trucks, and 3% heavy trucks
for all roadways except Keats Avenue. The traffic stream for Keats Avenue was determined to be 93% cars, 3% medium
trucks, and 4% heavy trucks. Roadway speeds were modeled as follows:
Keats Avenue 55 mph
GG
Kimbro/Lamar Avenue 55 mph
GG
Jamaica Avenue 45 mph
GG
80th Street 45 mph
GG
70th Street 45 mph
GG
Military Road 55 mph
GG
East Ravine Parkway 45 mph
GG
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Table 24.3 - Peak Hour Traffic Volumes
Location Existing (2005) Predicted (2020)
Daytime* Nighttime* Daytime* Nighttime*
Keats Avenue
70 th Street to Military Road 1000 750 1680 1260
Kimbro/Lamar Avenue
US 61 to Lamar Avenue 740 555 480 360
Jamaica Avenue
70 th Street to Military Road 560 420 1510 1135
80 th Street
Jamaica Avenue to Keats Avenue 760 570 980 735
70 th Street
Jamaica Avenue to Keats Avenue 590 445 1520 1140
Military Road
Ideal Avenue to Jamaica Avenue 750 565 1090 820
East Ravine Parkway
80 th Street to 70 th Street N/A N/A 1190 850
*Daytime is defined to mean those hours from 7:00 am to 10:00 pm. Nighttime is defined to mean those hours from
10:00 pm to 7:00 am.
Results
Modeling results are shown as contours on Figures 2 and 3 of Appendix 4. Traffic noise levels between the roadway
centerline and the contour line are predicted to exceed the corresponding MPCA Daytime L10 and L50 noise levels.
Table 24.4 shows the distances from roadway centerline to the noise contour.
Table 24.4 - Distance to Contours
Approximate Distance from CL in Feet
2005 MPCA Daytime 2020 MPCA Daytime
Location
L10 L50 L10 L50
(65 dBA) (60 dBA) (65 dBA) (60 dBA)
Keats Avenue (70 th Street to Military Road) 197 164 262 262
Kimbro Avenue (US 61 to Lamar Avenue) 131 82 115 33
Jamaica Avenue (70 th Street to Military Road) 262 203 197 190
80 th Street (Jamaica Avenue to Keats Avenue) 108 69 135 85
70 th Street (Jamaica Avenue to Keats Avenue) 115 59 152 150
Military Road (Ideal Avenue to Jamaica Avenue) 161 121 205 164
East Ravine Parkway (80 th Street to 70 th Street) N/A N/A 118 80
Residences located within the distances above, as measured from the roadway centerline, are predicted to experience
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The Nighttime peak hourly volumes are approximately 75% of the Daytime peaks. Due to the nominal reduction in
traffic and the substantial reduction (10 dBA) of the allowable L10 and L50, the distance from the roadway centerline to
the nighttime noise contour is approximately 700 feet. At the present time, existing noise levels at monitored locations
exceed MPCA Nighttime criteria. The Tank monitoring site is located 150 feet north of 80th Street and exceeds the L10
during the 6:00 am to 7:00 am time period. The Washington County monitoring site is located 600 feet east of Keats
Avenue (CSAH 19) and exceeds the L50 during the 6:00 am to 7:00 am time period.
Mitigation
near roadways in the project area. The City of Cottage Grove is required to comply with Minnesota Rules 7030.0030.
This statute requires municipalities to ensure that existing noise levels comply with state noise limits prior to occupants
moving into residences in the proposed development. Barriers such as earthen berms or landscaping can reduce traffic
noise levels. Increasing the distance between the source and the receiver also reduces traffic noise levels (i.e. larger
setbacks from arterial or collector roadways).
The information above continues to be valid. A component of the Walmart commercial development
included the completion of Noise Impact Study that can be referenced by contacting the City. Findings
of the study indicated that the planned commercial growth will not have a negative impact on the
surrounding area. The City recently adopted Ordinance No. 923, which modifies the way the City
monitors and addresses noise complaints within the community. The ordinance can be found on the
www.cottage-grove.org
S
ENSITIVE RESOURCES
A combination of existing resources and inventory reports were used to assess the impacts on sensitive resources in the
East Ravine Area. These resources included the Old Cottage Grove Historic District Preservation Planning Report
(Vogel 2002), Preservation Planning Report: Documentation Supporting the Nomination of the Military Road Heritage
Corridor to the City Register of Historic Sites and Landmarks ( Historic Preservation Division, Department of
Community Development, City of Cottage Grove, July 1999), the Comprehensive Plan (City of Cottage Grove, 2000),
the Comprehensive Plan (City of Cottage Grove, 2030)the Natural Resource Inventory (BRA, 1998), South
Washington Watershed District CD-P86 Natural Resource Management Plan (SWWD and EOR, 2002) and resource
information from the State Historic Preservation Office.
Archeological, historic and architectural resources
The most notable resources are the Comprehensive Plan, The Old Cottage Grove Historic District Preservation Planning
Report and the Documentation Supporting the Nomination of the Military Road Heritage Corridor on the City Register
of Historic Sites and Landmarks. These reports present documentation
preservation and supporting the nominations of the Old Cottage Grove Historic District and the Military Road Heritage
Corridor to the City Register of Historic Sites and Landmarks. The intent of historic district designation is to provide a
guide for future community development decision making that acknowledges need for change while providing
protection for historically significant buildings and sites. The report also contains a comprehensive inventory of all the
heritage resources within the district. Though the Old Cottage Grove Historic District and the Military Road Heritage
Corridor have they have not been nominated to the
National Register of Historic Places.
th
Old Cottage Grove is in the NW part of the City and extends roughly from 70 Street (CSAH 22) south along Lamar
Ave, including side streets, to 77 th. The area is also known as Cottage Grove Village and East Cottage Grove. Most of
the land and buildings in the area are private property. Lamar Ball fields, Old Grove Community Park, and Fire Station
No.4 are publicly owned. The district has 9 sites of primary significance which are properties that have been
Cottage Grove East Ravine AUAR
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individually listed or eligible for nomination to the City Register of Historic Sites and Landmarks. There are also 42
sites of secondary significance. This category consists of properties more than fifty years old and that contribute to the
historic character of the district but lack individual distinction.
The village was platted with a linear plan and a clear distinction between the village and the surrounding countryside.
Expansion of the town was constrained by the northern limit of the Cottage Grove Ravine. The original 40 acre plat in
1871 did not allow for a business district o
the plated area.
The heart of the historic district is Lamar Avenue, which is the old village main street. Traditional streetscape on Lamar
Ave includes little or no setback from the street and narrow side yards. Trees were planted to define property edges and
they continue to be one of the defining features of the district.
Today, Old Cottage Grove historic district is a mix of residential, commercial, funerary, religious and agricultural
buildings. Several preserved architectural landmarks represent Greek Revival, Italian Villa, Queen Anne, Arts and
thth
Crafts, and Colonial Revival building styles. There are also modest homes built in the 19 and 20 Centuries.
Architectural features include: 1-2 story facades; low to medium pitch gable roof shapes; formal entrances; and one-
story porches. Most of the remaining buildings built prior to 1950 are residences as many of the non-residential
buildings have been razed or converted. Wood agricultural outbuildings, detached garages, and sheds also contribute to
Two properties are on the National Register of Historic Places. These include the Historic Mary and Cordenio
Severance House/Cedarhurst Mansion at 6940 Keats Avenue South and the John Furber House at 7310 Lamar Avenue
South. A number of additional sites have been placed on the City Register of Historic Sites. These locations are
illustrated in Figure 25.1.
No archeological surveys have been conducted within the historic district but there are several potentially significant
pioneer home, church, and school sites that need to be considered in development planning.
The Military Road Heritage Corridor through Cottage Grove is part of a larger historic military road that connected
Point Douglas with Fort Ripley. The Point Douglas and Fort Ripley Military Road resources is designated WA-CGC-
186 in the State Historic Preservation Office inventory database.
The Military Road Corridor incorporates all of Lehigh Road and Military Road within the city limits and that part of
Lamar Avenue between Lehigh Road and 70 th Street; CSAH 22 west of Lamar Avenue; and the abandoned roadway
segment west of Old Cottage Grove village in Section 11, Township 27 North, Range 21 West. Military Road was laid
out by the Federal government in 1851-1853. In 1914 it became a state aid road. The corridor was a popular place for
early settlement (mid to late 1800s) and has long been a major transportation corridor connecting south Washington
County to St. Paul and Minneapolis.
The Documentation Supporting the Nomination of the Military Road Heritage Corridor to the City Register of Historic
Sites and Landmarks contains a greater account of the historical significance of the corridor and should be referenced
for further details on the corridor.
The referenced areas continue to be identified as being eligible to be listed on the
have not been registered to date.
Prime or unique farmland
It is not anticipated that existing farmlands will be protected through special programs, deed restrictions, conservation
easements or other means. As anticipated in both
project area will be developed over time.
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
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The statements in this section remain unchanged.
Designated parks, recreation areas or trails
The 2014 East Ravine residential development, the 2013 East Point Douglas Road
improvement project, and the construction of the Ravine Parkway Civic Campus, provided a
key link in the local and regional trailway system of south Washington County with the
Cottage Grove Ravine Regional Park. Since the adoption of the original AUAR, the
Mississippi River Trail (USBR #45) was established and also provides a connection to the
region, state, and nation. http://www.mississippirivertrail.org/index.html .
A major feature of the project area is the Cottage Grove Ravine Regional Park. This regional park provides an
abundance of passive natural areas, picnic areas and trail corridors. The development scenario for the East Ravine
project includes the addition of a number of park and open space features that provide connections to Cottage Grove
Ravine Regional Park. The park features include a variety of community and neighborhood parks with active and
passive play areas.
26. A
DVERSE VISUAL IMPACTS
The AUAR anticipates a development pattern similar to those uses in the surrounding area and does not anticipate any
adverse visual impacts as a result of the development scenario.
The statements in this section remain unchanged.
27. CP
OMPATIBILITY WITH LANS
The City of Cottage Grove completed a previous comprehensive plan update in October of 2000. This plan update
identified the East Ravine area as a future development phase (or MUSA expansion area) that was dependent upon
completion of the South Washington County Interceptor. The plan established a strategy for detailed master planning of
the East Ravine as an implementation initiative. This project implements that initiative. The 2000 Comprehensive Plan
update included the necessary components to comply with the requirements set out in 4410.3610, subpart 1. A
comprehensive plan amendment will be completed as part of this project to update land use and infrastructure systems
.
according to the East Ravine Development Scenario
In March of 2011, the City adopted the 2030 Comprehensive Plan which succeeded the 2000 plan that implemented
the East Ravine master planning process.
The current Washington County land use plan has not been updated to reflect the land uses in the East Ravine
approved by the City and the Metropolitan Council. Future updates should be updated to current information.
The Washington County Comprehensive Plan guides the project area as long term agriculture with a density of 1 unit
per 40 acres. This plan is illustrated in Figure 27.2.
The Metropolitan Land Planning Act requires Comprehensive Plans to be updated by 2008. Future plan updates will
need to take into consideration the various land use patterns established in the development scenario master plan.
Cottage Grove East Ravine AUAR
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Plan was adopted by the City Council on March 2, 2011. This document reflects the
development scenarios identified in the AUAR. Future updates will reassess and reflect development scenarios that
have occurred or are to be modified in the East Ravine. The City has been working closely with the City of Woodbury
as land use and transportation changes related to development occur or are planned.
28. I
MPACT ON INFRASTRUCTURE AND PUBLIC SERVICES
WaterSee Appendix 1
SewerSee Appendix 2
Electricity
Electric utilities will be provided by local electric utility companies as guided by current codes and ordinances. Where
possible, electric utility lines will be buried under ground. Easements will be integrated into the system of open space
networks and road rights-of-way.
As development and road projects have been occurring since the adoption of the AUAR,
the City has been working with utility companies to place infrastructure underground. In
some instances, this action is not cost feasible.
Storm Water ManagementSee Appendix 5
TransportationSee Appendix 3
TransitSee Appendix 3
Police and Fire Services
Police and fire service will be adequate to serve this area with the addition of employees in conjunction with added
population and commercial services.
The statements in this section remain unchanged.
School District
School districts will face added population as a result of this growth and will need to plan accordingly for added school
capacity. Areas within the development scenario do not specifically identify school sites but do provide opportunities to
incorporate elementary and secondary school facilities into future subdivisions.
The school district added the East Ridge High School and campus in Woodbury since the
adoption of the AUAR. This school serves portions of Cottage Grove including the East
Ravine. Additional planning on school needs is currently being completed by the school
district.
Telephone and Cable
It is assumed that telephone and cable services would be extended to the area consistent with current services and
expansion policies. These would be underground services most likely placed in public right-of-way.
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The statements in this section remain unchanged.
29.
C
UMULATIVE IMPACTS
No response required.
The statements in this section remain unchanged.
O
30.
THER POTENTIAL ENVIRONMENTAL IMPACTS
There are no other environmental impacts to note.
The statements in this section remain unchanged.
31. SI
UMMARY OF SSUES
See the Executive Summary.
The statements in this section remain unchanged.
MI
ITIGATION NITIATIVES
IMP
NTENT OF ITIGATION LAN
The development of the AUAR project area could have impacts on the environment and existing development. This plan
identifies existing tools and policies that the City of Cottage Grove has in place, as well as additional initiatives that will
need to be implemented to mitigate potential impacts. There are multiple ways in which Mitigation Initiatives may be
implemented such as:
Enforcing existing zoning and subdivision ordinances and other development regulations at the time of development
concept submittals, preliminary and final platting, and during construction monitoring activities
Referencing and implementing policy directions provided in the Comprehensive Plan and the East Ravine Master Plan
during the review and approvals of development projects
Planning and building public infrastructure (local roads, parks, trunk sewer and water systems) in conjunction with
private development initiatives
Maintaining and updating existing plans and studies for the community
Requiring additional field work/investigation as part of pre-development planning where potential environmental or
cultural resources may exist but have not been verified or where more detailed air quality testing or noise monitoring
may be needed.
The statements in this section remain unchanged.
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GMI
ENERAL ITIGATION NITIATIVES
This section identifies a series of mitigation initiatives that are general in nature and apply to all public and private
development within the AUAR.
1.
All permits identified in the AUAR (see Question 8), as well as other necessary permits that may be
required will be secured by private parties, or the City as appropriate, for all development activities within
the project area.
2.
The City will follow its own regulations, ordinances, plans, and policies currently in place in the review and
approval of all development activities within the project area. These items include the Comprehensive Plan,
the East Ravine Master Plan, and the official zoning and subdivision ordinances.
3.
The City will extend public sewer and water services in a manner consistent with existing plans and
policies. The City will monitor capacities, update plans, and extend services as necessary to ensure
sufficient supply and quality of services.
4.
The City will implement a development tracking mechanism to monitor development within the AUAR
project area and its conformance with the development scenario using Geographic Information System
(GIS) Software and mapping.
5.
The City will enforce its parkland dedication policies consistent with the goals and policies of the
Comprehensive Plan and Growth Area Plan, as well as the requirements of the subdivision ordinance.
The statements in this section remain unchanged.
FMI
OCUSED ITIGATION NITIATIVES
Mitigation initiatives that are explicitly intended to mitigate or minimize impacts on a particular resource or action are
outlined by topic in this section.
Natural and Physical Resources
Historical and Cultural Resources: follow guidance in Comprehensive Plan and existing codes and ordinances.
The Documentation Supporting the Nomination of the Military Road Heritage Corridor to the City Register of Historic
Sites and Landmarks contains a greater account of the historical significance of the Military Road Heritage Corridor and
should be referenced for further details on the corridor. The report also contains a number of recommendations that lend
support to mitigation initiatives for the Cottage Grove East Ravine Pre-Design project. Those recommendations include:
The Military Road Heritage Corridor that are currently active roadways should be retained and preserved as an historic
route within the existing city-county roadway system. The segment that is no longer a roadway cutting diagonally across
Section 11 should be preserved as a rural historic landscape.
heritage education program. Possible interpretive resources include publications, wayside exhibits, bicycle tour cassette
tapes and guides, and school programs.
Maintain, whenever possible, the alignment, width, and grad of existing roadways that comprise the Military Road
Heritage Corridor. Roadway maintenance and reconstruction should comply with highway safety standards in such a
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manner that the essential historic character of the Military Road corridor is preserved intact, respecting the existing
shape, slope, elevation, aspect and contour of the historic route.
Minimize disturbance of terrain in the abandoned segment of the corridor through Section 11 to reduce the possibility of
destroying unknown archeological features. When this area is developed, archeological surveys should be carried out in
acc
The statements in this section remain unchanged.
Land Use Management
The city will continue to implement its Comprehensive Plan policies, as well as zoning and subdivision
regulations to ensure a development pattern consistent with the East Ravine Master Plan. New and existing
Comprehensive Plan and City Code regulations will be used to incorporate the design objectives of the Master
Plant. These include:
Existing Subdivision Ordinance requirements for preservation of natural features
New requirements for establishing landscaped buffer areas along major roadways.
New requirements for residential and commercial landscaping which provide sufficient green space which
minimizing irrigation requirements.
New residential design standards which ensure a variety of housing design.
New requirements on screening requirements between commercial and residential areas. Particular emphasis
will be places on providing adequate screening between the existing residential areas and the future Cottage
View commercial area.
The statements in this section remain unchanged.
Erosion Control and Sedimentation
The city will enforce existing erosion control regulation for all new developments. These regulations are based
y and other
resources. These measures greatly reduce erosion and sedimentation during and after construction.
The statements in this section remain unchanged.
Water Supply and Appropriation
The East Ravine Master Plan includes a Public Water Supply Plan, which describes trunk watermain
improvements necessary to extend municipal water service to the area. The city will apply its Wellhead
Protection Plan to new and existing wells in the East Ravine area. This plan calls for abandonment and
sealing existing residential and agricultural irrigation wells to reduce the likelihood of future contamination of
groundwater supplies. Measures are also included in the plan for protecting future municipal well in the area
from contamination and to ensure regular testing of water supplied by these municipal wells.
The statements in this section remain unchanged.
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Wastewater System
The East Ravine Master Plan includes a Sanitary Sewer Plan which describes trunk sanitary sewer
improvements necessary to serve the area. The city through its development review process will monitor and
verify estimated wastewater flows for conformance to the Sanitary Sewer Plan and treatment capacities of the
Metropolitan Council Environmental Services facilities.
The statements in this section remain unchanged.
Storm Water Management
Development within the project area will increase the amount of storm water runoff. The City will ensure
require
the development of a storm water management system which limits flooding and negative impacts on
water quality within the watershed. Key strategies will include:
, or as required in t Surface Water
Maintaining discharge rates at or below current levels
Management Plan or by the South Washington Watershed District.
requirements of the South Washington Watershed District
to a downstream natural receiving water
Pre-treatment of runoff prior to discharge into the Mississippi River
Adoption and enforcement of a Storm Water Ordinance
Cooperation with MPCA and other partners in development and implementation of strategies to meet the
Total Maximum Daily Load (TDML) standard yet to be determined
the stormwater management systemMinnesota Stormwater
Design ponds
Manual
Protecting Water Quality in Urban Areas Best Management Practices for Dealing with Storm Water
Runoff from Urban, Suburban and Developing Areas of Minnesota
Conformance to National Urban Runoff Pond (NURP) standards
Conformance to National Pollution Discharge Elimination System (NPDES) Phase II requirements as outlined
unicipal Separate Storm Sewer System (MS4) Permit.
in the EPA Clean Water Act
Developments within the AUAR project area which impact wetlands will be subject to regulation under the
Wetland Conservation Act, Chapter 103G Waters of the State (i.e. Department of Natural Resources), and
possibly Section 404 of the Clean Water Act (i.e. Army Corps of Engineers). The City of Cottage Grove will
South Washington Watershed
work with the Washington County Soil and Water Conservation District
District,
the local government unit responsible for administering the MN Wetlands Conservation Act, on any
development impacting wetlands. Should wetland impacts be part of a development within the project area,
these regulatory programs have sequencing requirements which require applicants to demonstrate that
wetlands impacts have been avoided and minimized to the extent practical and, if impacts cannot be avoided,
these programs require replacement of wetlands impacted by fill or excavation.
Traffic
Traffic will continue to grow as development occurs within the project area and as regional growth continues
to add traffic to the system. Appendix 3 contains a number of roadway and intersection improvements that
will serve to mitigate future congestion levels associated with growth in the region.
Results
allowable noise levels near major arterial and collector roadways in the project area. The City of Cottage
Grove is required to comply with Minnesota Rules 7030.0030. This statute requires municipalities to ensure
Cottage Grove East Ravine AUAR
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that existing noise levels comply with state noise limits prior to occupants moving into residences in the
proposed development. Barriers such as earthen berms or landscaping can reduce traffic noise levels.
Increasing the distance between the source and the receiver also reduces traffic noise levels (i.e. larger
setbacks from arterial or collector roadways). The Master Plan includes areas along major roadways that serve
as buffers that will offer separation between the noise source and the receivers.
The statements in this section remain unchanged.
Monitoring of Development and Future Updates to the AUAR
The AUAR assumes a hypothetical development scenario. Since it is based on assumptions it is important that
actual development be monitored and compared to the development that was assumed in the development of
final plat process the developer will submit electronic plats consistent with city development requirements in a
of platted lots and the ability to tie building permits to the lots so that occupied housing units could be tracked
As required by Minnesota Rule 4410.3610 Subpart 7, to remain valid, the AUAR must be updated if any of
the following events should occur:
Five years have passed since the AUAR and mitigation plan were adopted and all development within the
project area has not been given final approval.
A comprehensive plan amendment is proposed that would allow an increase in development than what was
assumed in the development scenario.
Total development within the area would exceed the maximum levels assumed in the environmental analysis
document.
Development within any subarea delineated in the AUAR would exceed the maximum levels assumed for that
subarea in the document.
A substantial change is proposed in public facilities intended to service development in the area that may
result in increased adverse impacts on the environment.
Development or construction of public facilities will occur differently than assumed in the development
scenario such that it will postpone or alter mitigation plans or increase the development magnitude.
New information demonstrates that important assumptions or background conditions used in the analysis
presented in the AUAR are substantially in error and that environmental impacts have consequently been
substantially underestimated.
The RGU determines that other substantial changes have occurred that may affect the potential for, or
magnitude of, adverse environmental impacts.
Cottage Grove East Ravine AUAR
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The AUAR is being updated because it has been over five years since the adoption of
the document. None of the other triggering events detailed above have been met.
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East Ravine AUAR -2015 Update
City of Cottage Grove
Figure 21.2
2014 Daily Traffic Count Map
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East Ravine AUAR -2015 Update
City of Cottage Grove
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Figure 27.1
2030 land Use Plan
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East Ravine AUAR -2015 Update
City of Cottage Grove
Figure 27.3
Upper Ravine District Development Update Detail
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East Ravine AUAR -2015 Update
City of Cottage Grove
Figure 27.4
2014 Roadway Functional Classification Map
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East Ravine AUAR -2015 Update
City of Cottage Grove
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East Ravine AUAR -2015 Update
City of Cottage Grove
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M
EMO
To:
BrianJohnson
From:
BrentThompson
Subject:
CottageGroveEastRavinePlanningStudy-Watermain
Date:
February7,2005
TECHNICALMEMORANDUM
ThepurposeofthismemoistooutlinethemethodologiesandassumptionsusedinthePublic
WaterSupplyandImpactImprovementPlansfortheCottageGroveEastRavineStudy,and
presentkeyfeaturesofthepreliminarylayouts.
Methodology
TheWaterSupplyDistributionPlanDatedDecember1995,byBonestrooRoseneAnderlik
andAssociates(BRAA)wasusedasaguidelinein:
Locatingexistingtrunklines
S
Locatingexistingtowers
S
Determiningproposedtrunkpipesizesandlocations
S
Locatingandsizingproposedwatertowers
S
Watersupplysystemdesignandimpactswerebasedonthedetailedmasterplanfor
NeighborhoodOneandthegeneralplanforNeighborhoodTwoprovidedbyHoisington
KoeglerGroup,Inc.(HKgi).
Thestudyareaisdividedintotwosections.NeighborhoodOneislocatedwestofKeats
th
Avenueandisfurthersubdividedintoanareanorthof70Streetandanareaalong
th
KeatsAve.southof80Street.NeighborhoodTwoislocatedeastofKeatsAvenue.
Designcharacteristicsforeachneighborhoodarepresentedbelow.
Theprojectwasalsobrokenoutintophases.Phasingoftheoverallprojectislargely
dependentuponthesanitarysewerinfrastructure.Watermainconstructionwillfollow
alongwiththesanitarysewerconstruction.
DesignCharacteristics
NeighborhoodOne
NeighborhoodOneislocatedwestofKeatsAvenue.Trunkwatermainlocationswerelaidout
basedontheCity
WYPXMQEXI[EXIVHMWXVMFYXMSRTPER8LMWTPERWLS[WKIRIVEPXVYRO[EXIVQEMR
locationsintheunservedareaslocatedat
¡QMPIWTEGMRK7MRGIXLI)EWX6EZMRITPERTVSZMHIH
byHKgiwasmoredetailed,indicatingstreetandlotdetails,thewatermainroutingwaslaidout
tofollowtheproposedstreets.Connectionstotheexistingwatermainsystemwouldbemade
Exhibits6&7
whereappropriate.ThewatermainlayoutforNeighborhoodOneisshownon.
O:\PROJ\819070J\5.0-InfrastructureAssessment\TechMemo-Watermain-020705.doc1
th
NeighborhoodOnewasdividedintotwosubareas.TheNorthAreaislocatednorthof70
th
Street.TheSouthAreaislocatedsouthof80Street.
NorthArea:
24-inchand16-inchtrunkwatermainwouldbeextendednorthalongInwoodAvenuefromthe
th
existingwatertoweratInwoodAvenueand68StreettoprovideaconnectiontotheCityof
Woodbury
W[EXIVW]WXIQ8LMWGSRRIGXMSR[SYPHFIYWIHSRP]MRXLIGEWISJERIQIVKIRG]
ThedesignofthewatersupplysystemwaslaidouttominimizetheimpacttoJamaicaAvenue,
whichisassumedtocontinuetoserveasahighervolumeroadway.
Withtheexceptionofthetrunkwatermainshownontheexhibits,allotherwatermaininthe
NorthAreais8-inchdiameter.Itwaslaidouttofollowtheproposedstreetsandloopedthrough
cul-de-sacswherepossible.
Thisareawouldhaveapproximately131,000linearfeetofwatermainpipetoservean
estimated1889units.
SouthArea:
12-inchthrough24-inchtrunkwatermainisproposedintheSouthAreaofNeighborhoodOne.
12-inchwatermainisrecommendedforthecommercialareasinordertoprovideadequatefire
flowtothebuildings.Inadditiontothetrunkwatermains,8-inchlateralwatermainislaidoutto
followtheremainingproposedstreets.
Thisareawouldhaveapproximately52,000linearfeetofwatermainpipetoserveanestimated
1272units.TheestimatedcostofimprovementsforNeighborhoodOneis$8,600,000.
NeighborhoodTwo
NeighborhoodTwoislocatedeastofKeatsAvenue.TheEastRavineplanindicatedamore
generallayoutoflanduses,withlessstreetand
TPEXPIZIPHIXEMPXLER2IMKLFSVLSSH3RI
Again,watermainwasdesignedwithtrunklocationandsizingaccordingusingtheBRAAplan
asaguide.AnattemptwasmadetominimizetheimpacttoKeatsAvenue,however,some
disruptionmayoccurwhenconnectionsareamadetoexistingwatermainalongandonthewest
sideofKeatsAvenue.Werecommendtheuseoftrenchlesstechnologiestominimizetraffic
impactsonmajorcountyroadssuchasKeats(CSAH19).Onewatertowerisproposedwithin
th
theNeighborhoodTwoarea,locatedattheintersectionofKeatsAvenueand70Street(CSAH
20),withastoragecapacityof2.0MG.Theexactlocationofthetowerisnotdeterminedand
th
canbeadjustedbasedonlanddevelopmentprioritiesanddemands.Generalproximityto70
Exhibit6
Streetisdesirable.ThewatermaindesignforNeighborhoodTwoisshownon.
Thisareawouldhaveapproximately86,000linearfeetofwatermainpipetoserveanestimated
2241units.Includingthewatertower,theestimatedcostofimprovementsforNeighborhood
Twois$8,030,000.
O:\PROJ\819070J\5.0-InfrastructureAssessment\TechMemo-Watermain-020705.doc2
OldCottageGrove
thth
ToserveOldCottageGrove,trunkwatermainwouldbeextendedeastalong70and80
th
StreetsaswellasalongLamarAvenuefrom80StreettothenorthernCitylimits.A1.0MG
th
watertowerisproposedattheintersectionof70StreetandLamarAvenue.Theproposed
watermainextensionstoservethisareawouldcontainapproximately20,000linearfeetofpipe.
TheestimatedcostofimprovementsfortheOldCottageGrovearea,includingthewatertower,
is$2,630,000.
ProjectPhasing
Asmentionedabove,theprojecthasbeenbrokenoutintophasestoidentifythoseareasthat
arereadilydevelopable,andotherareasthataredependentuponprecedingdevelopment
Exhibits1&2
construction.Seeforphasingareas.
Approximatecostsperdevelopmentareaforwatermainimprovements:
NeighborhoodOne
A1$1,310,000
A2$1,090,000
A3$960,000
A4$1,070,000
A5$1,200,000
B$180,000
C$520,000
D$1,310,000
E$0existinginfrastructurewouldallowimmediateserviceconnections
F$130,000
G$440,000
H$390,000
Total$8,600,000
NeighborhoodTwo
I$400,000
J1$4,890,000
J2$1,170,000
K$1,420,000
L$150,000
Total$8,030,000
$2,630,000
OldCottageGrove
Note:Theabovecostsdonotincludeadditionalwellsortreatmentplantcosts,should
theyberequiredinthefuture.
Recommendations
TheCitycurrentlyhasmanylateralwatermainsthatare6-inchdiameterpipe.Our
recommendationistouse8-inchdiameterfortheminimumpipesize(exceptforhydrantleads
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whichcouldbe6-inch).Ourrecommendationisbasedonprovidingadequatefireflowwhilestill
maintainingresidentialservice.
PortionsofAreaA-5areaboveanelevationof978andmayrequirespecialconsiderationfor
lowpressure.ThemajorityofAreasG,HandLarebelowanelevationof863andmayrequire
pressurereducingvalvesontheservices.
ExistingWaterTreatmentCapacityandimpactofadditionaldemand
BasedoninformationobtainedfromBRAA,theexistingwatersupplyandtreatmentfortheEast
Ravineareawillbeprovidedoffsite.Inaddition,theexistingwellfieldisfelttobeadequatefor
theneedsoftheEastRavinearea.
TheproposedEastRavineplanwouldincreasethewaterdemandbyapproximately13.0MGD.
Summary
ThepreliminaryplanforthePublicWaterSupplyandImpactImprovementsintheEastRavine
areaconsistsofapproximately290,000linearfeet(55miles)ofwatermainpipeand3.0MGof
storagetoserveanestimated5400units.Thetotalestimatedcostoftheseimprovementsis
$19,260,000.
Amoredetailedmodelingofthewatersystemwouldneedtobeconductedtoaddressthe
numberofwellsthatwouldbeneeded,exactlocationofnewtowers,thresholddemandlevels
fortheadditionofnewtowers,high&lowpressureareas,andoverallsystemperformance.
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EMO
To:
BrianJohnson
From:
GregRobinson
Subject:
CottageGroveEastRavinePlanningStudySanitarySewer
Date:
February7,2005
TECHNICALMEMORANDUM
Thepurposeofthismemoistooutlinethemethodologyandassumptionsusedinthesanitary
sewerandimprovementplansfortheCottageGroveEastRavineStudy,andpresentkeyfeatures
ofthepreliminarydesign.
Methodology
Thispreliminarysanitarysewerdesignwasaccomplishedinaccordancewith
MetropolitanCouncilEnvironmentalService(MCES)andTenStateStandards
guidelines.
SanitarysewersystemdesignandImpactswerebasedontheDetailedMasterPlanfor
NeighborhoodOneandtheGeneralPlanforNeighborhoodTwo.
ConstructionplansforSouthWashingtonCountyGravityInterceptorPhase1andSouth
WashingtonCountyGravityInterceptorPhase2wereusedtodeterminetheexisting
locationofthetrunkinterceptorrunningalongKeatsAvenue(CSAH19).
ExistingSanitarystubsasindicatedontheinterceptorplanswereutilizedwhere
possible.However,Inordertoprovideanefficientdesignsomenewconnectionstothe
interceptorareincludedinthispreliminaryplan.
Thestudyareaisprimarilydividedintotwosections,NeighborhoodOneislocatedwest
ofKeatsAvenueandNeighborhoodTwoislocatedeastofKeatsAvenue.Design
characteristicsforeachneighborhoodarepresentedbelow.
Assumptions
Designmustmaximizetheareaservedperavailabletrunkinterceptorconnection.
InNeighborhoodTwotheassumedsewerrequirementis150linealfeetperacreforall
landuses.
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DesignFlowParameters
NeighborhoodOne
Residentialdesignflowunitswerebasedon
100gallonsperdaypercapita.
S
4peopleperUnit
S
PeakFactorof4
S
LowandMediumDensityparcelswereassignedoneunitperpropertyasshownin
DetailedMasterPlanforNeighborhoodOne.
AttachedHousingparcelswereassigned6unitsperacreasshownintheDetailedMaster
planforNeighborhoodOne.
HighDensityparcelswereassigned24unitsperacreasshownintheDetailedMaster
planforNeighborhoodOne.
MixedUseparcelswereassigned24unitsperacreasshownintheDetailedMasterPlan
forNeighborhoodOne.
CommercialUnitswerebasedon5,000GallonsPerDayPerAcre.
Aminimum10-footdepthofpipeisrequired.
Pipemustbewithintheright-of-wayasindicatedontheDetailedMasterPlanfor
NeighborhoodOne.
NeighborhoodTwo
Residentialdesignflowunitswerebasedon
100gallonsperdaypercapita.
S
4peopleperUnit
S
PeakFactorof4
S
LowDensityparcelswereassigned5unitsperacreasshownintheGeneralPlanfor
NeighborhoodTwo.
MediumDensityparcelswereassigned12unitsperacreasshownintheGeneralPlanfor
NeighborhoodTwo.
HighDensityparcelswereassigned24unitsperacreasshownintheGeneralPlanfor
NeighborhoodTwo.
MixedUseparcelswereassigned24unitsperacreasshownintheGeneralPlanfor
NeighborhoodTwo.
CommercialUnitswerebasedon5,000GallonsPerDayperAcre.
Aminimum10-footdepthofpipeisrequired.
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Pipemustbewithintheright-of-wayasindicatedontheGeneralPlanforNeighborhood
Two.
DesignCharacteristics
NeighborhoodOne
NeighborhoodOnewasdividedintoeightsubareaseachconnectingtotheexistingsanitary
systematdifferentlocations.TheareasaredesignatedasAreasAandBonExhibit1and
AreasCthroughHonExhibit2.Specificdesigncharacteristicsofeachareaarepresented
below.
AREA-A:
Thisarearepresentsapproximately100,000feet(19Miles)ofnewsanitarysewerwithadesign
flowrateof3MillionGallonsperDay(MGD).ConnectiontotheInterceptorwouldbedoneviaa
th
24jack-boringunderKeatsAvenuenear70Street.Theexisting18stubattheinterceptoris
notadequatetoservethisArea,andwouldneedtobereplacedwitha24pipe.
th
Duringthedesignprocesswediscoveredthatportionsofthepipealong70streetwouldhave
lessthanthreefeetofcoveriftheexistingsurfaceelevationsweremaintained.Atthattimewe
believedthattheareasinquestionwouldneedtobegradedtoprovideadequatecover.Since
thentheissuehasbeenfurthercomplicatedbythenecessityofaboxculvertinthissame
locationthatwoulddirectlyconflictwiththeproposed24-inchdiametersanitarysewer.
Thisinitialdesigncallsfortheremovaloftheexisting18stubattheinterceptorandreplacingit
witha24pipeatalowerelevation,thusprovidingadequatesizeandalleviatingtheconflictwith
theproposedboxculvert.Thisupsizingwouldberequiredforallthreealternativesmentioned
below.
th
TheCriticalsegmentinArea-Aisthe24pipeon&70Streetbetweentheinterceptorand
th
JensenAvenue.Oncethissegmentisconstructedareasnorthof70Streetcanthenbe
developed.
PartofArea-A,maybedifficulttoservewithgravitysewerwithoutsignificantgrading,orthe
installationofaliftstation.ThisareaisshownshadedredonExhibit3C.Thisstudyexamined
threedesignalternativesforthisarea:
AlternativeOne(Preferred)
ThisdesignalternativeisdepictedonExhibit3-A,andcallsfortheinstallationof
oversizedsewerpipesalongtheMilitaryRoadright-of-wayandNorthfromJensen
Avenue.Mostareasmeetaminimum10-footdepthofpipe,andthepipewouldbe
installedwithintheright-of-wayasdepictedontheDetailedPlanforNeighborhoodOne.
Installationofanoversizedpipewouldallowthesewertobeinstalledataflattergrade.
Thiswouldhelpprovideadequatepipecover.Thedownsidetoinstallingalargerpipeis
thatitwouldrequiremoremaintenanceintheformofregularflushingwithwaterto
preventthebuildupofhydrogensulfideandsolids.
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Areasnearthe900-footcontourmayrequirefillinginordertoassureadequatepipe
coverandservicetolots.Theextentoftherequiredgradingwilldependonthefinalplat
design.
AlternativeTwo
ThisdesignalternativeisdepictedonExhibit3-B,andcallsforinstallingoversizedsewer
pipestoallowforflatterpipegradeandgreaterpipedepth.Likealternativeonethese
pipeswouldrequireregularflushingtopreventthebuildupofhydrogensulfideand
solidsinthepipe.
th
Thisalternativeconnectstothetrunkon70streetinthreelocations.Utilityeasements
wouldberequiredintwoofthelocations,andthethirdwouldbewithintheJensen
Avenueright-of-way.
Areasnearthe900-footcontourmayrequirefillingtoassureadequatepipecoverand
servicetolots.Basementdepthsmayneedtoberestrictedinsomeareasinorder
assureservice.Theextentoftherequiredgrading,andrestrictionswoulddependonthe
finalplatdesign.
AlternativeThree
ThisdesignalternativeisdepictedonExhibit3-C,andcallsfortheinstallationofalift
th
stationat70StreetandJensenAvenue.
Thisisdesignalternativeassuresthatadequatepipecoversothatlotscanbeserviced
withoutrestrictingbasementdepths.Thesystemwouldbeinstalledwithintheright-of-
wayasdepictedontheDetailedPlanforNeighborhoodOne.
ThetotalestimatedconstructioncostforArea-A,AlternativeThreeis$4,390,000.Thisincludes
anestimated$200,000foraliftstationanddoesnotconsiderregularmaintenancecosts.The
estimatedconstructioncostforArea-A,AlternativeOneorAlternativeTwowouldbesimilarto
AlternativeThreelesstheliftstationcost.
AREA-B:
Thisareahasadesignflowofapproximately0.05MGD,andwouldrequireapproximately
3,000-feet(0.6miles)ofsanitarysewerpipe.Connectiontotheinterceptorwouldbemadeatan
existing18-inchdiameterstub.Thispreliminarydesignandthecostestimatebelowconsider8-
inchdiametersanitarysewermainthroughoutthisarea.Ifsanitarysewerserviceistobe
extendedtotheCityofWoodburythroughthisarea,thesewermaincouldbeincreasedinsize
uptoan18-inchdiameterpipe.Thiswouldofcourseincreasetheestimatedconstructioncost.
SeeservingtheCityofWoodburybelowformoredetails.
ThetotalestimatedconstructioncostforArea-Bis$310,000
AREA-C:
Thisareawouldconsistofapproximately4,800-feet(0.9Miles)of8-inchdiametersanitary
sewer,andhasadesignflowrateofapproximately0.20MGD.Thestudylookedatconnecting
ndth
thisareatoexistingsanitaryseweron82Streetand85Street,howevertheinvertsofthe
existingstructureswerehigherthanrequired.Thedesignalternativeswereeitherinstallalift
th
stationon85Streetorjack-boreunderKeatsAvenueandconnectwiththeinterceptoronthe
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EastsideofKeatsAvenue.Thelaterwaschosenasthepreferredalternativebeingitwould
eliminatetheneedtoconstructandmaintainaliftstation.
ThetotalestimatedconstructioncostforArea-Cis$280,000.
AREA-D:
ThisAreahasadesignflowrateofapproximately0.75MGD,andwouldconsistof
approximately13,000-feet(2.5miles)ofsanitarysewerpipe.
ThereisadesignconflictbetweenthedetailedmasterplanforNeighborhoodOneandthe
th
SouthWashingtonCountyGravityInterceptorplan,on90Street.Thispreliminarysewerplan
followstheinterceptorconstructionplan.Thepipelayoutmayneedtobechangedifthe
interceptorplansetdoesnotreflectwhatwasconstructed.
ThetotalestimatedconstructioncostforArea-Dis$670,000.
AREA-E:
ThisareaconsistsofsixlotsonJewelAvenueSouth.Accordingtotheas-builtdrawingfor
th
JewelAve.Sanitarysewerhasalreadybeenextendedto90Street.Theselotstherefore
shouldbeabletoconnecttothisexistingsewerline.
AREA-F:
Thisareawouldconsistofapproximately2,000feet(0.4miles)ofsanitarysewerwithadesign
flowrateofapproximately0.10MGD.Connectiontotheinterceptorwouldbemadeatan
existing12-inchdiameterstub.
ThetotalestimatedconstructioncostforArea-Fis$100,000.
AREA-G:
Thisareawouldconsistofapproximately8,500feet(1.6miles)ofsanitarysewerpipeandhas
anapproximatedesignflowrateof1.00MGD.Connectiontotheinterceptorwouldbemadeat
anexisting12-inchdiameterstub.
ThetotalestimatedconstructioncostforArea-Gis$500,000.
AREA-H:
Thisareawouldconsistofapproximately2,000feet(0.4miles)ofsanitarysewerpipeandhas
anapproximatedesignflowof0.20MGD.Connectiontotheinterceptorwouldbemadeatan
existing30-inchdiameterstub.
ThetotalestimatedconstructioncostforArea-His$90,000.
NeighborhoodTwo
TheeastsideofKeatsAvenueisdividedintofourmoregeneralsubareas,eachconnectingto
theinterceptorindifferentlocations.TheseareasaredesignatedIthroughKonExhibit1and
AreaLonExhibit2.Specificdesigncharacteristicsofeacharea,andthefeasibilityof
connectingOldCottageGrovetotheinterceptorarediscussedbelow.
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Area-I:
Thisareawouldhaveapproximately11,000feet(2miles)ofsanitarysewerwithanapproximate
designflowrateof0.5MGD.Anew10-inchdiameterconnectionwouldberequiredatthe
interceptor.
ThetotalestimatedconstructioncostforArea-Iis$340,000.
Area-J:
Therearetwointerceptorstubsinthisarea.However,oneofthemwouldneedtobereplaced
withalargerstubandbothoftheirlocationsmadeforaninefficientdesign.Thispreliminary
th
designthereforedisregardsthetwoexistingstubsandextendsanewtrunklinealong70
th
StreetstartingatKeatsAvenue.Laterallinesthenfeedintothe70Streettrunkfromthenorth
andsouth.ThistrunklinecouldalsoberesizedandextendedtotheEasttoserveOldCottage
Grove.Thiswillbepresentedinmoredetailbelow.Area-Jwouldhaveapproximately57,000
feet(10.8miles)ofsanitarysewerpipeandhaveanapproximatedesignflowrateof4.5MGD.
ThetotalestimatedconstructioncostforArea-Jis$2,635,000.
Area-K:
Theconnectionattheinterceptorforthisareaisanexisting30-inchdiameterstub.Thisisthe
sameconnectionutilizedbyArea-CinNeighborhoodOne.Atrunklinewouldbeextendednorth
thth
onthenewparkwayto80Street,andthenEastalong80Street.Laterallineswouldthen
connecttothistrunk.ThistrunklinecouldberesizedtoaccommodateservicetoOldCottage
Grove.SeeServingOldCottageGrove,Below.Thisareawouldhaveapproximately38,000-feet
(7.2miles)ofsanitarysewerpipeandadesignflowofapproximately1.7MGD
ThetotalestimatedconstructioncostforArea-Kis$1,550,000.
Area-L:
Thisareawouldhaveapproximately4,000-feet(0.75miles)ofsanitarysewer,andadesignflow
ofapproximately0.13MGD.ConnectiontotheinterceptorwouldbemadethroughArea-Hin
Neighborhood-One
ThetotalestimatedconstructioncostforArea-Lis$160,000.
ServingOldCottageGrove:
WelookedattwoscenariostoserveOldCottageGrove:
th
1.ExtendthetrunkthatservesArea-J,approximately2,2000-feet,along70Streetto
th
LamarAvenueandthenSouthalongLamarAvenueto80Street.
th
2.ExtendthetrunkthatservesArea-Kapproximately1,800-feet,along80StreettoLamar
th
AvenueandthenNorthonLamarAvenueto70Street.Thisscenariowouldrequire
th
crossingaravineon80Street.Forthistobeaccomplishedwithgravitysewerwould
requirepartoftheroadtoberaisedapproximately25-feet.Analternativetoraisingthe
th
roadwouldbetoinstallaliftstationon80StreetontheWestsideoftheravine.
Thisareawouldconsistofapproximately26,000-feet(5miles)ofsanitarysewerpipeandwould
haveadesignflowrateofapproximately1.26MGD.
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ServingtheCityofWoodbury
TheWoodburyneighborhoodabuttingAreaBtothenorthcouldbeservedthroughAreaB.If
theexisting18sanitarysewerlinewereextendedtothecityofWoodburyweestimatethat
therewouldbeenoughavailablecapacitytoserveapproximately1,300residentialunits.
Summary
Thispreliminaryplanconsistsofapproximately242,000feet(46miles)ofsanitarysewerpipe
withatotalestimateddesignflowofapproximately13MGD.
EstimatedConstructionCostsincludethecostofinstallingthesanitarysewerpipeonly.The
totalestimatedconstructioncostforNeighborhoodOneis$6,340,000.Thetotalestimated
constructioncostforNeighborhoodTwois$4,700,000.TheestimatedConstructionCostfor
eachareaasdepictedinExhibits1and2areoutlinedinTable1below.
Table1EstimatedConstructionCosts
AreaEstimatedEstimatedTotals
Cost/SubAreaCost/Area
TrunkExtensionto$390,000
AreaA-1
LiftStation$200,000
A-1$650,000
A-2$900,000
A-3$700,000
A-4$700,000
A-5$850,000
TotalAreaA$4,390,000
B$310,000
C$280,000
D$670,000
F$100,000
G$500,000
H$90,000
TotalNeighborhood1$6,340,000
I$340,000
J-1$2,100,000
J-2$550,000
TotalAreaJ$2,650,000
K$1,550,000
L$160,000
TotalNeighborhood2$4,700,000
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LEGEND
3
358
8"SANITARY
10"SANITARY
63
316
12"SANITARY
15"SANITARY
157
18"SANITARY
315
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156
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612
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70THSTREET
70THSTREET
10
HoisingtonKoeglerGroupinc.
EarthTech
Emmons&OliverResources
HowardR.GreenCompany
IBIGroup
McCombGroupLtd
610
609
327
606
608
605
321
320
2
607
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317
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LEGEND
3
358
8"SANITARY
10"SANITARY
63
316
12"SANITARY
15"SANITARY
157
18"SANITARY
315
314
24"SANITARY
156
630
629
316
626
360
628
155
308
632
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307
154
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621
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100
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611
615
70THSTREET
70THSTREET
10
HoisingtonKoeglerGroupinc.
EarthTech
Emmons&OliverResources
HowardR.GreenCompany
IBIGroup
McCombGroupLtd
610
609
327
606
608
605
321
320
2
607
604
319
603
317
318
LEGEND
3
358
8"SANITARY
10"SANITARY
63
316
12"SANITARY
15"SANITARY
157
18"SANITARY
315
314
24"SANITARY
156
630
629
316
626
360
628
155
308
632
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154
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70THSTREET
70THSTREET
10
HoisingtonKoeglerGroupinc.
EarthTech
Emmons&OliverResources
HowardR.GreenCompany
IBIGroup
McCombGroupLtd
MEMO
March 3, 2005
To: Mr. Brad Scheib
From: Nathan Lipinski
Traffic Noise and Air Quality Study for East Ravine
Subject:
Community, MN AUAR
Thank you for the opportunity to assist you in preparing the Alternative Urban Areawide
Review (AUAR) for the East Ravine Community in Cottage Grove, Minnesota. The
following are the results of the traffic noise and air quality analyses performed for this
project.
NOISE ANALYSIS
Introduction
Earth Tech measured existing noise levels at two locations in the project area.
Monitoring locations represent undeveloped lands expected to experience commercial
and residential development or impacts from commercial and residential development.
Earth Tech modeled the future Build alternative and associated traffic volumes expected
in the year 2020 using the Minnesota Department of Transportation traffic noise model,
MINNOISE. Monitoring data and modeling results were compared with the Minnesota
Pollution Control Agency (MPCA) Noise Rules to evaluate traffic noise impacts and
recommend mitigation measures. Modeling results were used to create noise contours
showing the location of the residential daytime and nighttime L10 and L50 noise contour
lines. L10 and L50 are sound levels in decibels (dBA) that are exceeded in 10 percent or
50 percent, respectively, of the time for a one-hour survey. A Project Location Map is
included in Figure 1-1. Daytime and Nighttime Noise Contours are included in Figure 2
and Figure 3.
Existing Noise Levels
On March 3, 2005, Earth Tech performed noise monitoring at two locations in the project
area. The purpose of the noise monitoring was to document existing noise levels. Noise
measurements were conducted in accordance with Minnesota Rules Chapter 7030,
Noise Pollution Control. The meteorological conditions were as follows:
Temperature - +2
Humidity – 76%
Wind – Calm
Barometric Pressure – 30.27” Hg
Mr. Brad Scheib
East Ravine AUAR
Page 2
Table 1 summarizes the equipment Earth Tech staff used to collect monitoring data for
.
this noise analysis
Table 1
Noise Analysis Instrumentation Summary
Instrument Make Model Calibration Date Serial Number
Dosimeter 1 Quest Q-300 2/28/05 at 114.0 dBA QC6030052
Dosimeter 2 Quest Q-30 2/28/05 at 114.0 dBA QC2921212
The monitoring sites were selected at locations where existing noise levels could not be
modeled with MINNOISE or to compare measured noise levels to modeled noise levels
to confirm the validity of the model. The results of the noise measurements at the
monitoring locations are listed in Table 2 and the locations of the sites are indicated on
Figures 2 and 3. MPCA maximum allowable daytime noise levels are 65 dBA for L10
and 60 dBA for L50. The maximum nighttime noise levels are 55 dBA (L10) and 50 dBA
(L50).
Table 2
Nighttime Noise Monitoring Summary
Site Date TimeDistance L10L50MPCAExceeding
SampledSampledfrom CL (dBA)(dBA)Nighttime(Yes/No)
L10L50
(dBA)(dBA)
Gordon and March 3, 6:00 am 150 feet 56 46 55 50 Yes
Bonnie2005to 7:00
Tankam
Property
Washington March 3, 6:00 am 600 feet 51 54 55 50 Yes
County2005to 7:00
Propertyam
Mr. Brad Scheib
East Ravine AUAR
Page 3
Future Noise Levels
The traffic noise model analyzed the existing roadway network and proposed East
Ravine Parkway. The Howard R. Green Company supplied the existing traffic levels in
2003 and the predicted traffic levels in 2020. Earth Tech adjusted the 2003 traffic data to
2005 conditions. The Washington County Department of Transportation provided
information regarding truck percentages, speed limits, and nighttime peak hour volumes.
Earth Tech used aerial orthographic mapping to determine roadway alignments and
digitized the existing and proposed roadway alignments for use in the MINNOISE noise
thth
model. Keats Avenue, Kimbro/Lamar Avenue, Jamaica Avenue, 80 Street, 70 Street,
and Military Road were modeled in the for year 2005 and 2020 peak hour traffic. The
proposed East Ravine Parkway was modeled only for year 2020 peak hour traffic. The
highest peak hour traffic volume (PHV) for each modeled roadway is shown in Table 3.
The traffic stream in the MINNOISE model was determined to be 95% cars, 2% medium
trucks, and 3% heavy trucks for all roadways except Keats Avenue. The traffic stream
for Keats Avenue was determined to be 93% cars, 3% medium trucks, and 4% heavy
trucks. Roadway speeds were modeled as follows:
Keats Avenue – 55 mph
Kimbro/Lamar Avenue – 55 mph
Jamaica Avenue – 45 mph
th
80 Street – 45 mph
th
70 Street – 45 mph
Military Road – 55 mph
East Ravine Parkway – 45 mph
Table 3
Peak Hour Traffic Volumes
Location Existing (2005) Predicted (2020)
Daytime* Nighttime* Daytime* Nighttime*
Keats Avenue
th
70 Street to Military Road 1000 750 1680 1260
Kimbo/Lamar Avenue
US 61 to Lamar Avenue 740 555 480 360
Jamaica Avenue
th
70 Street to Military Road 560 420 1510 1135
th
80 Street
Jamaica Avenue to Keats Avenue760 570 980 735
th
70 Street
Jamaica Avenue to Keats Avenue590 445 1520 1140
Military Road
Ideal Avenue to Jamaica Avenue 750 565 1090 820
East Ravine Parkway
thth
80 Street to 70 Street N/A N/A 1190 850
*Daytime is defined to mean those hours from 7:00 am to 10:00 pm. Nighttime is defined to mean
those hours from 10:00 pm to 7:00 am.
Mr. Brad Scheib
East Ravine AUAR
Page 4
Results
Modeling results are shown as contours on Figures 2 and 3. Traffic noise levels between
the roadway centerline and the contour line are predicted to exceed the corresponding
MPCA Daytime L10 and L50 noise levels. Table 4 shows the distances from roadway
centerline to the noise contour.
Table 4
Distance to Contours
Approximate Distance from CL in Feet
2005 MPCA Daytime 2020 MPCA Daytime
Location
L10L50L10L50
(65 dBA) (60 dBA) (65 dBA) (60 dBA)
th
Keats Avenue (70 Street to Military Road) 197 164 262 262
Kimbro Avenue (US 61 to Lamar Avenue) 131 82 115 33
th
Jamaica Avenue (70 Street to Military Road) 262 203 197 190
th
80Street (Jamaica Avenue to Keats Avenue) 108 69 135 85
th
70Street (Jamaica Avenue to Keats Avenue) 115 59 152 150
Military Road (Ideal Avenue to Jamaica Avenue) 161 121 205 164
thth
East Ravine Parkway (80 Street to 70 Street) N/A N/A 118 80
Residences located within the distances above, as measured from the roadway
centerline, are predicted to experience roadway noise levels that exceed MPCA’s
maximum allowable noise levels.
The Nighttime peak hourly volumes are approximately 75% of the Daytime peaks. Due
to the nominal reduction in traffic and the substantial reduction (10 dBA) of the allowable
L10 and L50, the distance from the roadway centerline to the nighttime noise contour is
approximately 700 feet. At the present time, existing noise levels at monitored locations
exceed MPCA Nighttime criteria. The Tank monitoring site is located 150 feet north of
th
80 Street and exceeds the L10 during the 6:00 am to 7:00 am time period. The
Washington County monitoring site is located 600 feet east of Keats Avenue (CSAH 19)
and exceeds the L50 during the 6:00 am to 7:00 am time period.
Mitigation
Results of these analyses suggest that future traffic noise levels will exceed MPCA’s
maximum allowable noise levels near roadways in the project area. The City of Cottage
Grove is required to comply with Minnesota Rules 7030.0030. This statute requires
municipalities to ensure that existing noise levels comply with state noise limits prior to
occupants moving into residences in the proposed development. Barriers such as
earthen berms or noise walls can reduce traffic noise levels. Increasing the distance
between the source and the receiver also reduces traffic noise levels. A more detailed
noise analysis should be performed before mitigation measures are pursued.
Mr. Brad Scheib
East Ravine AUAR
Page 5
AIR QUALITY
For roadway projects, the two pollutants of concern are carbon monoxide (CO) and
PMThe EPA and the Minnesota Pollution Control Agency (MPCA) do not require PM
10.10
analysis. To assure that a project is not in violation of the National Ambient Air Quality
Standards (NAAQS), the need for an air quality analysis to address emissions of CO
must be determined.
The East Ravine project is in Washington County, one of the Twin Cities seven-county
metropolitan areas considered a CO maintenance area. To determine the need for a hot-
spot analysis, the Twin Cities has a screening method to compare project locations to a
set of the Twin Cities “worst” intersections. If the project has better conditions and does
not affect one of these intersections, then it is presumed it will not cause any violations.
There are three MPCA monitored locations and seven top intersections. See Table 5
below. The East Ravine project area does not include any of these locations.
Table 5
Top Ten Intersections
Twin Cities CO Maintenance Area
IDDESCRIPTION1998 AADT*
Top 7 Intersections
1 TH 169 at CSAH 81 77,200
2 TH 101 at TH 7 65,000
3 TH 100 at CSAH 81 71,150
4 TH 10 at University Avenue 63,600
th
5 TH 252 at 85 Avenue 61,700
th
6 TH 252 at 66 Avenue 64,500
7 TH 252 at Brookdale Drive 58,550
3 MPCA Monitored Locations
8 University and Lexington Avenue 54,500
9 Snelling at University Avenue 57,750
10 Hennepin Avenue at Lake Street 35,800
The final screening criteria is whether the project roadways will have traffic levels in
excess of the benchmark AADT level of 77,200. The East Ravine project is not
forecasted to have traffic levels this high. See Table 6 on the following page. The results
of the screening procedure show that the East Ravine development project does not
require a hot-spot analysis.
Mr. Brad Scheib
East Ravine AUAR
Page 6
Table 6
Future (2020) Average Daily Traffic
2002 AADT
Location2020 ADT
Counts
US 61 North of 70th Street 53,000 69,300
US 61 Between 70th Street and 80th Street 42,000 51,100
Between 80th Street and Keats
US 61 31,000 42,800
Avenue
Between Keats Avenue and Kimbro
US 61 26,000 32,700
Avenue
70th Street Between US 61 and Jamaica Avenue 6,400 10,400
Between Jamaica Avenue and Keats
70th Street 2,200 10,100
Avenue
80th Street Between US 61 and Hinton Avenue 22,300 28,000
80th Street Hinton Avenue and Ideal Avenue 12,600 16,100
80th Street Ideal Avenue and Jamaica Avenue 10,100 12,700
Between Jamaica Avenue and Keats
80th Street 7,400 9,300
Avenue
80th Street Keats Avenue to Kimbro Avenue 1,200 6,600
Between Military Road and 70th
Jamaica Avenue 4,200 15,900
Street
Jamaica Avenue Between 70th Street and 80th Street 7,400 10,500
Jamaica Avenue Between 80th Street and US 61 11,200 17,700
Keats Avenue North of Military Road 5,600 12,600
Between 70th Street and Military
Keats Avenue 7,600 12,600
Road
Keats Avenue Between 70th and 80th Street 6,200 13,000
Keats Avenue Between 80th Street and 90th Street 6,200 11,000
Keats Avenue Between 90th Street and US 61 6,200 12,000
Kimbro Avenue Between Lamar Avenue and US 61 500 4,000
Between Ideal Avenue and Jamaica
Military Road 5,000 14,100
Avenue
Between Jamaica Avenue and Keats
Military Road 1,450 -
Avenue
Military Road Keats Avenue to Lamar Avenue 3,000 6,000
Lamar Avenue 70th Street to Kimbro Avenue 1,200 2,000
Source: Mn/DOT Year 2002 ADT Flow Maps and Howard R Green Company
L:\WORK\PROJECTS\67033\ADMIN\CORRESPONDENCE\FINAL TECHNICAL MEMO.DOC
East Ravine Pre-Design
City of Cottage Grove
¯
Woodbury
Woodbury
Afton
Afton
19
20
Neighborhood 1
22
20
(
/
10
Neighborhood 2
39
(
/
61
95
Old
Cottage
Grove
Cottage
Cottage
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(
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61
Anoka
Ramsey
Project
Hennepin
Washington
Area
Legend
_
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Project Area
Lakes
Streams
Dakota
04,800
Scott
Feet
00.250.50.751
Goodhue
Miles
Rice
Hoisington Koegler Group Inc.
Project Location
Earth Tech
Emmons & Olivier Resources
Howard R. Green Company
Figure 1-1
February 4, 2005
IBI Group
McComb Group, Ltd.
...\67033\Cadd\Figure2.dgn 03/01/2005 03:52:42 PM
...\67033\Cadd\Figure3.dgn 03/01/2005 04:49:20 PM
TechnicalMemorandum
SECONDARYTRAFFICIMPACTS
EASTRAVINECOMMUNITY
COTTAGEGROVE,MN
June2005
Preparedby:
CourtInternationalBuilding
2550UniversityAveW,Suite400N
St.Paul,Minnesota55114
www.hrgreen.com
TABLEOFCONTENTS
1.0Introduction............................................................................................................................1-1
2.0ExistingConditions................................................................................................................2-1
2.1KeyRoadways.................................................................................................................2-1
2.2KeyIntersections..............................................................................................................2-6
2.3ExistingLandUse............................................................................................................2-8
2.4ExistingOperationsAnalysis............................................................................................2-8
2.4.1AnalysisMethodology.............................................................................................2-8
2.4.2ExistingLevelofServiceSummary.........................................................................2-13
3.0FutureConditions...................................................................................................................3-1
3.1Year2020LandDevelopmentScenario............................................................................3-1
3.2Future(2020)TrafficForecasts.........................................................................................3-1
3.3FutureOperationsAnalysisandDeterminationofDeficiencies.........................................3-7
3.4RoadwayImprovementsandPhasing................................................................................3-15
3.5Transit..............................................................................................................................3-20
4.0Summary................................................................................................................................4-1
iJune2005
EastRavinePre-Design,CottageGrove,MN
TrafficImpactStudyHRGProject819070J
LISTOFFIGURES
Page
1-1ProjectLocation................................................................................................................1-2
2-1KeyRoadwaysandIntersections.......................................................................................2-2
2-2Existing(2002)ADTVolumes..........................................................................................2-4
2-3ExistingFunctionalClassification.....................................................................................2-5
2-4Existing(2003)TurningMovementVolumes....................................................................2-9
2-5EstimatedArterialandCollectorSegmentLevelofService...............................................2-11
2-6EstimatedExpresswayandFreewaySegmentLevelofService.........................................2-12
2-7Existing(2002)RoadwayandIntersectionLOS................................................................2-14
3-1LandUseScenario............................................................................................................3-3
3-2LandUseScenario............................................................................................................3-4
3-3LandUseScenario............................................................................................................3-5
3-4ProjectAreaTrafficAnalysisZones..................................................................................3-6
3-5Future(2020)AverageDailyTraffic.................................................................................3-9
3-6Future(2020)AverageDailyTrafficComparison.............................................................3-10
3-7Future(2020)PMPeakHourTurningMovementVolumes...............................................3-12
3-8Future(2020)RoadwayandIntersectionLOS...................................................................3-16
3-9Future(2020)ADTVolumeswithClosureofKimbroAvenueatUS61............................3-17
3-10RecommendedRoadwayImprovements............................................................................3-19
LISTOFTABLES
Page
2-1ExistingRoadwaySegmentCharacteristics.......................................................................2-3
2-2ExistingIntersectionGeometryandTrafficControl..........................................................2-7
2-3ExistingPMPeakHourTrafficTurningMovementCountsatKeyIntersections...............2-10
2-4IntersectionLevelofServiceMeasures.............................................................................2-13
2-5Existing(2002)SegmentLevelofService.........................................................................2-15
2-6Existing(2003)PMPeakHourIntersectionLevelofService............................................2-16
3-1BuildingPermitPotential..................................................................................................3-2
3-2Future(2020)SocioeconomicDatabyTAZ......................................................................3-7
3-3Future(2020)AverageDailyTraffic.................................................................................3-8
3-4Future(2020)PMPeakHourTurningMovementVolumes...............................................3-11
iiJune2005
EastRavinePre-Design,CottageGrove,MN
TrafficImpactStudyHRGProject819070J
3-5Future(2020)SegmentLevelofService...........................................................................3-13
3-6Future(2020)IntersectionPMPeakHourLevelofService...............................................3-14
3-7Future(2020)IntersectionPMPeakHourLOSwithAdditionalTrafficSignals................3-18
3-8TrafficSignalPhasing.......................................................................................................3-21
iiiJune2005
EastRavinePre-Design,CottageGrove,MN
TrafficImpactStudyHRGProject819070J
1.0INTRODUCTION
TheCityofCottageGroveisintheprocessofplanningthedevelopmentoftheEastRavinearea.To
initiatethisprocess,theCityisrequiredbyMinnesotaStateRule4410.3610,Subpart1tocompletean
AlternativeUrbanAreawideReview(AUAR).TheAUARwillincludetheevaluationofpotential
environmental,waterresources,waterquality,andtrafficimpacts.Additionally,amitigationplanwillbe
establishedwhichwillpreventorlimitthelevelofimpactsresultingfromanticipateddevelopment.
Figure1-1
TheEastRavineprojectareaisillustratedon.Asshown,thedevelopableareawassplitinto
twoneighborhoodsbaseduponwhentheareasareexpectedtourbanize.Neighborhood1incorporates
about1,185acres,locatedintwosectionsofthecity.ThefirstsectionislocatednorthUS61andwestof
CSAH19(KeatsAvenue).TheothersectionislocatedbetweentheCottageGrovenortherncitylimits
th
andCSAH22(70Street)andInwoodAvenuetothewestandCSAH19(KeatsAvenue)totheeast.
Neighborhood2isboundedbyUS61andthenorthernCottageGrovecitylimitstothenorthandsouth
andCSAH19(KeatsAvenue)andOldCottageGrovetotheeastandwest.Thisareaincludes
approximately560acresofdevelopablelandand450acresofparkland.
AspartofthisAUARdocument,atrafficimpactstudywascompletedtoanalyzeanddocumentthe
expectedtrafficimpactsofpotentialfuturelanddevelopmentinthesewerandwaterextensionarea.This
reportdocumentstheresultofthetrafficstudyandprovidesinformationnecessarytocompletethe
AUARdocument.Theanalysiswithinthisstudyareaconsistsofthefollowingelements:
Identificationofexistingroadwayandintersectioncharacteristics.
Estimationoffuturetrafficvolumes.
Assessmentofexistingandfuturetrafficoperations.
Recommendationofstrategiestomitigatedeficiencies.
1-1June2005
EastRavinePre-Design,CottageGrove,MN
TrafficImpactStudyHRGProject819070J
EastRavinePre-Design
CityofCottageGrove
;SSHFYV]
;SSHFYV]
19
%JXSR
%JXSR
20
Neighborhood1
22
20
10
Neighborhood2
39
61
95
Old
Cottage
Grove
'SXXEKI
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+VSZI
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61
Anoka
Ramsey
Project
Hennepin
Washington
Area
Legend
Carver
BC
ProjectArea
Lakes
Streams
Dakota
04,800
Scott
Feet
00.250.50.751
Goodhue
Miles
Rice
HoisingtonKoeglerGroupInc.
ProjectLocation
EarthTech
Emmons&OlivierResources
HowardR.GreenCompany
Figure1-1
June10,2005
IBIGroup
McCombGroup,Ltd.
2.0EXISTINGCONDITIONS
Thetrafficimpactsoftheexistingandanticipateddevelopmentwereevaluatedatkeyroadwaysand
intersections.Thesekeylocationswereselectedbecausetheyprovideprimaryaccesstotheregionalroad
systemandwilllikelybetheprimaryroadwayswhentheareadevelops.Thissectionidentifiesthese
roadwaysandintersections,documentstheirexistingtransportationcharacteristics,andquantifiesthe
trafficoperationsattheselocations.Trafficdataincludedroadwaygeometry,trafficvolumes,and
roadwayfunctionalclassifications.
2.1KeyRoadways
(Figure2-1)
Thekeyroadwaysanalyzedforfuturetrafficimpactsinclude:
1.US61betweenGlenRoadandKimbroAvenue
2.CSAH20(MilitaryRoad)betweenIdealAvenueandLamarAvenue
3.CSAH22(70thStreet)betweenUS61andCSAH19(KeatsAvenue)
4.80thStreetbetweenUS61andKimbroAvenue
5.JamaicaAvenuebetweenCSAH20(MilitaryRoad)andUS61
6.CSAH19(KeatsAvenue)betweenDaleRoadandUS61
7.LamarAvenue/KimbroAvenuebetween70thStreettoUS61
Table2-1
Associatedtransportationcharacteristicsaredisplayedon.Inthetable,theroadwaysare
brokendownintosegmentstoprovideamoreaccurateanddetaileddescription.Theexistingroadway
cross-sectionsaredocumented,alongwiththeexistingannualaveragedailytraffic(AADT)and
functionalclassifications.TheAADTvolumesonstateandcountyroadwayswereobtainedfromYear
Figure2-2
2002Mn/DOTTrafficFlowMaps.Thesetrafficvolumesarealsoillustratedin.Existing
functionalclassificationwastakenfromMetropolitanCouncilFunctionalClassMetadata,asillustrated
Figure2-3
in.
TheUS61Corridorisaprincipalarterial,runningnorthwest-southeastthroughthestudyareawiththe
primarypurposeofmobility.NorthofCSAH19(KeatsAvenue),thecorridoractsasaninterstatewith
limitedaccess.Interchangesexistataboutone-milespacing.SouthofCSAH19(KeatsAvenue),US61
connectstointersectionsat-grade.Thefour-lanedividedfacilityhasADTvolumesfrom53,000vehicles
th
perday(vpd)northofCSAH22(70Street)to26,000vpdsouthofCSAH19(KeatsAvenue).Landuse
tothenorthofUS61isretailandresidential.Tothesouth,landuseconsistsofmostlyindustrialwith
smallclustersofresidentialandretail.
CSAH20(MilitaryRoad)isaminorarterialwiththeprimaryfunctionofmobility.However,the
roadwaycurrentlyalsoprovidesaccesstoanumberofhomesteads.Thecross-sectionisa2-lane
undividedfacility,surroundedbyruralresidentialandagricultural.TheroadwaysegmentbetweenIdeal
AvenueandJamaicaAvenueCSAH20(MilitaryRoad)carriesabout5,000vpd.BetweenJamaica
AvenueandCSAH19(KeatsAvenue)carriesabout1,450vpd,whilethevolumeincreasedto3,000vpd
totheeast.
th
CSAH22(70Street)isatwo-lanefacility,runningeast-westthroughthestudyareafromUS61to
CSAH19(KeatsAvenue).Asaminorarterial,thecorridorprovidesmobilityandaccessislimited.
th
TrafficvolumesalongCSAH22(70Street)rangefrom6,400vpdbetweenUS61andJamaicaAvenue
to2,200vpdbetweenJamaicaAvenueandCSAH19(KeatsAvenue).Landusesurroundingthecorridor
consistsprimarilyofsingle-familyresidentialalongwithsmallportionsofmediumdensityresidentialand
commercial.
2-1June2005
EastRavinePre-Design,CottageGrove,MN
TrafficImpactStudyHRGProject819070J
EastRavinePre-Design
CityofCottageGrove
19
20
Neighborhood1
22
20
10
Neighborhood2
39
61
95
10
Legend
ProjectArea
61
Intersection
Roadway
Lakes
Streams
04,800
Feet
00.250.50.751
Miles
HoisingtonKoeglerGroupInc.
KeyRoadwaysandIntersections
EarthTech
Emmons&OlivierResources
Figure2-1 HowardR.GreenCompany
June10,2005
IBIGroup
McCombGroup,Ltd.
Table2-1
ExistingRoadwaySegmentCharacteristics
FunctionalYear2002AADT
Location
RoadwaySection
ClassificationCounts
US61Northof70thStreet4-LaneFreewayPrincipalArterial53,000
US61Between70thStreetand80thStreet4-LaneFreewayPrincipalArterial42,000
US61Between80thStreetandCSAH194-LaneFreewayPrincipalArterial31,000
BetweenCSAH19andKimbro4-LaneExpresswaywithR/LTurn
US61PrincipalArterial26,000
AvenueLanes
BetweenIdealAvenueandJamaica2-LaneUndividedwithRTurn
CSAH20(MilitaryRoad)MinorArterial5,000
AvenueLanes
BetweenJamaicaAvenueandCSAH2-LaneUndividedwithRTurn
CSAH20(MilitaryRoad)MinorArterial1,450
19Lanes
CSAH20(MilitaryRoad)CSAH19toLamarAvenue2-LaneUndividedMinorArterial3,000
2-LaneUndividedwithRTurn
CSAH22(70thStreet)BetweenUS61andJamaicaAvenueMinorArterial6,400
Lanes
BetweenJamaicaAvenueandCSAH2-LaneUndividedwithRTurn
CSAH22(70thStreet)MinorArterial2,200
19Lanes
4-LaneDividedwithL/RTurn
80thStreetBetweenUS61andHintonAvenueCollector22,300
Lanes
4-LaneDividedwithL/RTurn
80thStreetHintonAvenueandIdealAvenueCollector12,600
Lanes
4-LaneDividedwithL/RTurn
80thStreetIdealAvenueandJamaicaAvenueCollector10,100
Lanes
BetweenJamaicaAvenueandCSAH4-LaneUndividedwithLTurn
80thStreetCollector7,400
19Lanes
2-LaneUndividedwithRTurn
80thStreetCSAH19toKimbroAvenueCollector1,200
Lanes
JamaicaAvenueBetweenMilitaryRoadand70thStreet4-LaneDividedw/oTurnLanesMinorArterial4,200
JamaicaAvenueBetween70thStreetand80thStreet4-LaneDividedwithLTurnLanesMinorArterial7,400
JamaicaAvenueBetween80thStreetandUS614-LaneDividedwithLTurnLanesMinorArterial11,200
2-LaneUndividedwithRTurn
CSAH19(KeatsAvenue)NorthofCSAH20MinorArterial5,600
Lanes
2-LaneUndividedwithRTurn
CSAH19(KeatsAvenue)BetweenCSAH20andCSAH22MinorArterial7,600
Lanes
2-LaneUndividedwithRTurn
CSAH19(KeatsAvenue)BetweenCSAH22and80thStreetMinorArterial6,200
Lanes
2-LaneUndividedwithRTurn
CSAH19(KeatsAvenue)Between80thStreetand90thStreetMinorArterial6,200
Lanes
2-LaneUndividedwithRTurn
CSAH19(KeatsAvenue)Between90thStreetandUS61LocalRoad6,200
Lanes
2-LaneUndividedwithRTurn
KimbroAvenueBetweenLamarAvenueandUS61MinorArterial500
Lanes
LamarAvenue70thStreettoKimbroAvenue2-LaneUndividedCollector1,200
Year2002Mn/DOTTrafficFlowMaps
Source:
2-3June2005
EastRavinePre-Design,CottageGrove,MN
TrafficImpactStudyHRGProject819070J
EastRavinePre-Design
CityofCottageGrove
20
19
Neighborhood1
20
22
10
Neighborhood2
39
61
95
Legend
ProjectArea
AnnualAverageDailyTraffic(ADT)
Lakes
10
Streams
04,800
61
Feet
00.250.50.751
Miles
SOURCE:Year2002MnDOT
TrafficFlowMap
HoisingtonKoeglerGroupInc.
Existing(2002)AADTVolumes
EarthTech
Emmons&OlivierResources
Figure2-2
HowardR.GreenCompany
June10,2005
IBIGroup
McCombGroup,Ltd.
EastRavinePre-Design
CityofCottageGrove
19
20
Neighborhood1
22
20
10
Neighborhood2
39
61
95
Legend
ProjectArea
PrincipalArterial
10
"A"MinorArterial
"B"MinorArterial
61
MajorCollector
MinorCollector
NeighborhoodCollector
Lakes
Streams
04,800
Feet
00.250.50.751
Miles
SOURCE:MetropolitanCouncil
FunctionalClassMetadata(2003)
HoisingtonKoeglerGroupInc.
Existing(2003)FunctionalClassification
EarthTech
Emmons&OlivierResources
HowardR.GreenCompany
Figure2-3
June10,2005
IBIGroup
McCombGroup,Ltd.
th
80Streetrunseast-westfromHadleyAvenue(justwestofUS61)toCSAH19(KeatsAvenue).Asa
minorarterial,thecorridorprovidesmobility,andaccessislimited.Theroadwayisafour-lanefacility
withturnlanesfromUS61toCSAH19(KeatsAvenue),whereitcontinuestothewestasatwo-lane
facility.Trafficvolumesare22,300vpdnearUS61,7,400vpdbetweenJamaicaAvenueandCSAH19
th
(KeatsAvenue),and1,200vpdeastofCSAH19(KeatsAvenue).NearUS61,landusesurrounding80
Streetisprimarilycommercial.Totheeast,landuseissingle-familyresidential.
JamaicaAvenueisaminorarterial,runningnorth-southfromCSAH20(MilitaryRoad)toUS61.The
corridorisafour-laneundividedroadwaywithtrafficvolumesvaryingfrom11,200vpdnearUS61to
thth
4,200vpdsouthofCSAH22(70Street).NorthofCSAH22(70Street),landuseonbothsidesof
th
Jamaicaisruralresidentialandagricultural.Single-familyresidentialislocatedsouthofCSAH22(70
Street)untilitnearsUS61,wherecommercialpropertyexists.
CSAH19(KeatsAvenue)isatwo-laneundividedwithrightturnlanes.Theroadwayfunctionsasa
minorarterialwithvolumesrangingfrom7,600vpdbetweenCSAH20(MilitaryRoad)andCSAH22
thth
(70Street)and6,200vpdsouthofCSAH22(70Street).LandusenearCSAH19(KeatsAvenue)
includessingle-familyresidential,ruralresidential,andagriculturalland.
LamarAvenueisatwo-lanefacility,runningnorth-souththroughtheOldCottageGrove.Theroadway
th
extendsfromCSAH22(70Street)toStateHighway95asacollector.WithinOldCottageGrove,
trafficvolumesare1,200vpdwithmultipleaccessesexistforcommercialandsingle-familyhomes.To
thesouth,landuseconsistsofruralresidentialandagriculturalland.
KimbroAvenueconnectsOldCottageGrovetoUS61.Theroadwayisatwo-lanefacilitywithrightturn
lanes.Currentlyclassifiedasalocalroadway,trafficvolumesarearound500vpd.Thelandaround
KimbroAvenueconsistsofruralresidentialandagricultural.
2.2KeyIntersections
Eighteenintersectionswereselectedbecausetheyconnecttworoadwaysthatprovidetheprimaryaccess
totheregionalroadsystemandwilllikelybemajorintersectionswhentheareadevelops.Thevast
majorityoftrafficexitingandenteringtheprojectareawouldhavetouseatleastoneofthese
Figure2-1
intersections.Thelocationofthesekeyintersectionsisshownon.Thekeyintersections
selectedtoevaluateaspartofthistrafficstudyinclude:
1.US61/70thStreetRamps(3intersections)
2.US61/80thStreetRamps(2intersections)
3.US61/JamaicaAveRamps(2intersections)
4.US61/CSAH19(KeatsAvenue)Ramps(2intersections)
5.US61/KimbroAvenue
th
6.80Street/JamaicaAvenue
th
7.80Street/CSAH19(KeatsAvenue)
th
8.80Street/KimbroAvenue
9.CSAH20(MilitaryRoad)/LamarAvenue
10.CSAH22(70thStreet)/CSAH19(KeatsAvenue)
11.CSAH22(70thStreet)/JamaicaAvenue
12.CSAH20(MilitaryRoad)/JamaicaAvenue
13.CSAH20(MilitaryRoad)/CSAH19(KeatsAvenue)
Table2-2
Theexistinglanegeometryandtrafficcontrolforeachintersectionisshownon.Two
th
intersections,theUS61northandsouthboundrampsand80Streetaresignalized.Theremaining
intersectionsarecontrolledbySTOPsigns,includingThru-STOPandAll-WaySTOPcontrol.
2-6June2005
EastRavinePre-Design,CottageGrove,MN
TrafficImpactStudyHRGProject819070J
Table2-2
ExistingIntersectionGeometryandTrafficControl
WestSouthNorth
IntersectionEastApproach
ApproachApproachApproach
US61SBRamp/CSAH22(70thStreet)
n.a.
STOPSTOPSTOP
US61NBOffRamp/CSAH22(70thStreet)
n.a.
STOP
n.a.
US61NBOnRamp/CSAH22(70thStreet)
STOPSTOPSTOP
n.a.
US61SBRamp/80thStreet
TrafficSignal-ProtectedandPermitted
n.a.
US61NBRamp/80thStreet
TrafficSignal-ProtectedandPermitted
n.a.
US61SBRamp/JamaicaAvenue
STOPThruThru
n.a.
US61NBRamp/JamaicaAvenue
STOPThruThru
n.a.
US61SBRamp/CSAH19(KeatsAvenue)
STOPThruThru
n.a.
US61NBRamp/CSAH19(KeatsAvenue)
STOPThruThru
n.a.
US61/KimbroAvenue
80thStreet/JamaicaAvenue
STOPSTOPSTOPSTOP
80thStreet/CSAH19(KeatsAvenue)
STOPSTOPSTOPSTOP
n.a.
80thStreet/KimbroAvenue
STOPThruThru
n.a.
CSAH22(70thStreet)/LamarAvenue
ThruThruSTOP
n.a.
CSAH22(70thStreet)/CSAH19(KeatsAvenue)
STOPThruThru
CSAH22(70thStreet)/JamaicaAvenue
STOPSTOPSTOPSTOP
n.a.
CSAH20(MilitaryRoad)/JamaicaAvenue
ThruThruSTOP
CSAH20(MilitaryRoad)/CSAH19(KeatsAvenue)
STOPSTOPSTOPSTOP
Source:HowardR.GreenCompany
2-7June2005
EastRavinePre-Design,CottageGrove,MN
TrafficImpactStudyHRGProject819070J
PMpeakhourturningmovementcountswerecollectedattheeighteenkeyintersectionsinJuly2003.
Table2-3Figure2-4
Thiscountdataisdisplayedonand.ItshouldbenotedthatcountsnearCSAH20
(MilitaryRoad)werecompletedafterconstructioninthisareawascompleted.Additionally,Ideal
th
AvenuewasunderconstructionnorthofCSAH22(70Street).
2.3ExistingLandUse
Currently,theprojectareaislargelyundeveloped,consistingmostlyofgrasslands,agriculturallandand
farmsteads.Neighborhood1hasalreadyexperiencedsomeurbanizedgrowth.BetweenCSAH20and
CSAH22,limitedcommercialandsinglefamilyresidentialexists.Commercialpropertiesinclude
Cedarhurst,along-termeventcenterandtheLightofWayChurch.NearUS61,currentcommercial
propertiesincludetheCottageGroveDriveInnMovieTheatreandCottageGroveVFWPost8752.The
southernportionofNeighborhood2ismadeupoftheCottageGroveRavineRegionalPark.Thepark
consistsofapproximately450acres.OldCottageGroveislocatedontheeastsideofthestudyarea,and
consistsofamixofcommercialandsinglefamilyresidential.TherestofNeighborhood2ismadeupof
ruralresidentialandfarmsteads.
2.4ExistingOperationsAnalysis
2.4.1AnalysisMethodology
Theapproachtothetrafficoperationsanalysisisderivedfromtheestablishedmethodologiesdocumented
intheHighwayCapacityManual(TRB,2000).TheHighwayCapacityManual(HCM)containsaseries
ofanalysistechniquesthatareusedtoevaluatetheoperationoftransportationfacilitiesunderspecific
conditions.
TheresultsofanHCManalysisaretypicallypresentedintheformofalettergrade(A-F)thatprovidesa
qualitativeestimateoftheoperationalefficiencyoreffectiveness.Thelettergradedeterminedbythe
HCManalysisisreferredtoaslevelofservice(LOS).Bydefinition,LOSAconditionsrepresenthigh-
qualityoperations(i.e.,motoristsexperienceverylittledelayorinterference)andLOSFconditions
representverypooroperations(i.e.,extremedelayorseverecongestion).TheLOSofanintersectionor
roadsegmentisbasedonthreemainelements:
RoadwayGeometry(i.e.Howmanylanesarethere?)
TrafficControl(i.e.Isthereasignalorstopsign?)
TrafficVolume(i.e.Howmanyvehiclesareusingthisintersection/roadsegment?)
ItisimportanttonotethatLOSisdefineddifferentlyforthetwoHCManalysistechniquesappliedinthis
study.Thearterialroadwayanalysisfocusesontheaveragedailyvolumetocapacityratioalonga
roadwaysegment,andtheintersectionanalysisfocusesondelaycausedbythePMpeakhourcritical
movements.Itisthereforepossibletohaveanefficientintersectionlocatedalongapoorlyoperating
roadwaysegment,orapoorlyoperatingintersectionalonganotherwisefree-flowingarterial.
ThearterialroadwayLOSwasdeterminedbyconductingaplanninglevelanalysis.Thisanalysisconsists
ofcomparingtheaveragedailyflowratesonaroadwaysegmenttotheLOSbreakdownofADTvolumes
Figure2-52-6
forthatfacilitytype.andprovidesabreakdownofroadwayLOSbypeakhourly
directionalflowforthedifferentfacilitytypesanalyzedaspartofthisstudy.Thefigurewasbasedon
capacityinformationfoundintheHCM2000.
2-8June2005
EastRavinePre-Design,CottageGrove,MN
TrafficImpactStudyHRGProject819070J
EastRavinePre-Design
CityofCottageGrove
19
20
Neighborhood1
22
39
10
Neighborhood2
61
10
61
Legend
ProjectArea
TurningMovements
Lakes
Streams
04,800
Feet
00.250.50.751
Miles
SOURCE:TrafficData,Inc.
Existing(2003)TurningMovementVolumes
HoisingtonKoeglerGroupInc.
EarthTech
Emmons&OlivierResources
HowardR.GreenCompany
Figure2-4
IBIGroup
June10,2005
McCombGroup,Ltd.
emuloV)TDA(ciffarTyliaDegarevA
emuloV)TDA(ciffarTyliaDegarevA
Forintersections,LOSisprimarilyafunctionofpeakhourturningmovementvolumes,intersectionland
configuration,andtrafficcontrol.Theintersectionanalysiswascompletedusingaveragecontroldelayas
Table2-4
definedbytheHCM.TheLOSforsignalizedandunsignalizedintersectionsisshownon.
Table2-4
IntersectionLevelofServiceMeasures
Delay(seconds)
LOS
SignalizedUnsignalized
IntersectionIntersection
A1010
B10-2010-15
C20-3515-25
D35-5525-35
E55-8035-50
F>80>50
Source:Tables16-2and17-2,HighwayCapacityManual(2000)
Thethresholdvaluesforunsignalizedintersectionsareslightlylessthanforsignalizedintersectionsbecause
driverexpectationoftheintersectionperformancevariesfordifferenttypesoftrafficcontrol.Also,forthe
purposesofthisstudy,thelevelofservicereportedforunsignalizedintersectionisbasedonatleastoneof
themovementsattheintersectionoperatingataLOSDorgreateranddoesnotnecessarilymeanthatthe
operationsoftheentireintersectionisovertheLOSDthresholdvalue.ForaThru-STOPcontrolled
intersection,themovementsthatmostoftenexperiencesignificantdelaysinclude:minorstreetthrough,
minorstreetleftturnontomajorstreet,andmajorstreetleftturnontotheminorstreet.Typicalmitigative
strategiestoaddresslongminorstreetdelayscouldinvolveinstallingatrafficsignalattheintersectionor
prohibitingsomeoftheminorstreetmovementsaspartofacomprehensiveaccessmanagementplanforthe
corridor.
AlthoughLOSAconditionsrepresentthebestpossibleleveloftrafficflow,itisnotfeasibletobuildurban
roadwaysandintersectionstosuchhighstandards.ThereforeintheTwinCitiesregion,theindexof
congestionisattheLOSD/Eboundary.
2.4.2ExistingLevelofServiceSummary
Figure2-7
Asummaryoftheexistingsegmentandintersectiontrafficoperationsisdisplayedon.For
purposesofthisstudy,theroadwaysandselectedintersectionsareclassifiedaseitheruncongested,
approachingcongestion,orcongestedbasedontheestimatedLOS.Ascanbeseenonthefigure,roadways
andintersectionswereidentifiedascongestediftheyexceededanLOSDcondition.
Table2-5
Thesegmentoperationsarealsodisplayedon.Asshown,nodeficienciescurrentlyexist.Portions
th
ofUS61,80StreetandCSAH19(KeatsAvenue)areapproachingcongestionatLOSC,whilethe
remainingroadwaysareuncongestedatLOSAandB.
Table2-6
ThePMpeakhourintersectionoperationsaredocumentedon.TheUS61Southboundoff-ramp
atJamaicaAvenueisoperatingatLOSFduringthePMpeakhourduetocongestionontheoff-ramp.This
intersectionishasThru-STOPtrafficcontrolwithfreeflowonJamaicaAvenue.Motoristshavedifficulty
findinggapsonJamaicaAvenueinordertomakealeftturntowardsthedevelopmentonthenorthsideof
2-13June2005
EastRavinePre-Design,CottageGrove,MN
TrafficImpactStudyHRGProject819070J
EastRavinePre-Design
CityofCottageGrove
19
20
Neighborhood1
22
20
10
Neighborhood2
39
61
95
Legend
ProjectArea
IntersectionLOS
NotCongested(LOSA-B)
NearCongested(LOSC-D)
10
Congested(LOSE-F)
SegmentLOS
61
NotCongested(LOSA-B)
NearCongested(LOSC-D)
Congested(LOSE-F)
Lakes
Streams
04,800
Feet
00.250.50.751
Miles
HoisingtonKoeglerGroupInc.
Existing(2002)RoadwayandIntersectionLOS
EarthTech
Emmons&OlivierResources
HowardR.GreenCompany
Figure2-7
June10,2005
IBIGroup
McCombGroup,Ltd.
Table2-5
Existing(2002)SegmentLevelofService
Location
LOS
US61Northof70thStreetC
US61Between70thStreetand80thStreetC
US61Between80thStreetandCSAH19B
US61BetweenCSAH19andKimbroAvenueC
CSAH20(MilitaryRoad)BetweenIdealAvenueandJamaicaAvenueB
CSAH20(MilitaryRoad)BetweenJamaicaAvenueandCSAH19A
CSAH20(MilitaryRoad)CSAH19toLamarAvenueA
CSAH22(70thStreet)BetweenUS61andJamaicaAvenueB
CSAH22(70thStreet)BetweenJamaicaAvenueandCSAH19A
80thStreetBetweenUS61andHintonAvenueC
80thStreetHintonAvenueandIdealAvenueB
80thStreetIdealAvenueandJamaicaAvenueA
80thStreetBetweenJamaicaAvenueandCSAH19A
80thStreetCSAH19toKimbroAvenueA
JamaicaAvenueBetweenMilitaryRoadand70thStreetA
JamaicaAvenueBetween70thStreetand80thStreetA
JamaicaAvenueBetween80thStreetandUS61B
CSAH19(KeatsAvenue)NorthofCSAH20B
CSAH19(KeatsAvenue)BetweenCSAH20andCSAH22C
CSAH19(KeatsAvenue)BetweenCSAH22and80thStreetB
CSAH19(KeatsAvenue)Between80thStreetand90thStreetB
CSAH19(KeatsAvenue)Between90thStreetandUS61B
KimbroAvenueBetweenLamarAvenueandUS61A
LamarAvenue70thStreettoKimbroAvenueA
Source:HowardR.GreenCompany
thth
US61.US61SouthboundRamp/CSAH22(70Street)and80Street/JamaicaAvenueareapproaching
congestionatLOSC.TheremainingintersectionsareuncongestedatLOSAorB.
2-15June2005
EastRavinePre-Design,CottageGrove,MN
TrafficImpactStudyHRGProject819070J
Table2-6
Existing(2003)PMPeakHourIntersectionLevelofService
LevelofService
Intersection
WestEastSouthNorth
Intersection
ApproachApproachApproachApproach
US61SBRamp/CSAH22(70thStreet)CB--BC
US61NBOffRamp/CSAH22(70thStreet)C--AAA
US61NBOnRamp/CSAH22(70thStreet)B--BBB
US61SBRamp/80thStreetBA--CB
US61NBRamp/80thStreetAAC--B
US61SBRamp/JamaicaAvenueF--AAF
US61NBRamp/JamaicaAvenue--FAAA
US61SBRamp/CSAH19(KeatsAvenue)C--AAA
US61NBRamp/CSAH19(KeatsAvenue)--BAAA
US61/KimbroAvenueAA--EA
80thStreet/JamaicaAvenueCCCAC
80thStreet/CSAH19(KeatsAvenue)BBCBB
80thStreet/KimbroAvenueA--AAA
CSAH22(70thStreet)/LamarAvenueAAB--A
CSAH22(70thStreet)/CSAH19(KeatsAvenue)A--AAA
CSAH22(70thStreet)/JamaicaAvenueBBBBB
CSAH20(MilitaryRoad)/JamaicaAvenueAAB--A
CSAH20(MilitaryRoad)/CSAH19(KeatsAvenue)AABCB
Source:HowardR.GreenCompany
2-16June2005
EastRavinePre-Design,CottageGrove,MN
TrafficImpactStudyHRGProject819070J
3.0FUTURECONDITIONS
Thepurposeofthissectionistoidentifytrafficimpactsassociatedwithfuturedevelopmentwithinthe
projectarea.ForthepurposesofcompletingtheEastRavinedevelopment,afuturelandusescenariowas
establishedusingthehighestintensityoflanduseexpectedatfullbuild-out.Itshouldbenotedthatthe
WashingtonCountytraveldemandmodel(TDM),usedtodevelopfuturetrafficvolumes,wasbasedupon
2020landuseprojectionsoutsideofthestudyarea.
3.1Year2020LandDevelopmentScenario
Inordertoanalyzethetrafficimpactsforthefullbuild-outoftheEastRavinearea,landuseswere
definedfortheentirestudyarea.Thenumberandtypeofvehicletripsvarywithdifferingtypesofland
use.Forexample,ashoppingcenterislikelytohavelargertrafficvolumesthananindustrial
development.However,alargerpercentageofthetripstoanindustrialdevelopmentarework-relatedand
takeplaceduringthemorningandeveningrushhours,whileshoppingcentersattracttrafficthroughout
theday.
McCombGroup,Ltd.projectedthequantityofresidentialandcommercialpotentialbasedupondemand
andwhatthecitycanreasonablesupport.Futureresidentialdevelopmentwasestimatedbyexamining
trendsinsingleandmulti-familydevelopmentwithCottageGroveandthesoutheastmetropolitanarea.
Anadditional10,750householdswillbeconstructedinCottageGrovebyYear2025.Thedevelopment
isexpectedtobesplitevenlybetweensinglefamilyandmulti-familydwellings.Fortypercentofall
buildingpermitsareestimatedtobetownhomes,twinhomes,andothermediumdensitydevelopments,
whilehigherdensityunitswillaccountfortheremainingmulti-family.Theestimatedannualgrowthof
Table3-1
singleandmulti-familyhouseholdsislistedon.
Commercialdevelopmentwasprojectedintwoareasoftown:TH61/KeatsAvenueandKeatsAvenue
andMilitaryRoad.NeartheTH61/KeatsAvenueInterchange,commercialisexpectedtogrowfrom
295,900squarefeetin2010to646,800squarefeetin2025.Themajorityofthisgrowthisexpectedtobe
groceryanddiscountstores,withadditionalgrowthinconveniencegoods,services,buildingmaterials,
foodservice,medical,autoparts,andconvenience/gas.NeartheintersectionofMilitaryRoadandKeats
Avenue,commerciallanduseisexpectedtoincreasefrom18,000squarefeetin2005to204,200square
feetin2025.
Usingtheresidentialandcommercialprojectionsabove,HoisingtonKoeglerGroupInc.developedaland
Figures3-13-3
usescenarioforbothneighborhoodsillustratedinto.Inordertoanalyzethetraffic
impactsassociatedwiththislanddevelopmentscenario,theareawasdividedintosegmentscalledtraffic
analysiszones(TAZ).LandusewasdistributedintoeachTAZtodeterminehowmanyvehicletrips
wouldenterorexiteachzoneperday.ThesetripswereappliedtoacomputerrepresentationofCottage
GroveyYear2020TravelDemandModel.
WVSEH[E]RIX[SVOGSRXEMRIHMRXLI;EWLMRKXSR'SYRX
Figure3-4
depictsthelocationoftheseTAZsintheprojectarea.Thenumberofprojectedhouseholds
Table3-2
andemployeesbyzoneisdisplayedon.
3.2Future(2020)TrafficForecasts
Year2020trafficforecastsforacompletebuild-outoftheEastRavineareaweredevelopedusingthe
WashingtonCountyTravelDemandModel.Dailytrafficforecastsweredevelopedforeachofthekey
Section2.1
roadwaysegmentslistedin,andturningmovementprojectionswereestimatedforeachofthe
Section2.2
keyintersectionslistedin.ThemodelincludedtheadditionoftheEastRavineParkwayand
3-1
June2005
EastRavinePre-Design,CottageGrove,MN
TrafficImpactStudyHRGProject819070J
Table3-1
BuildingPermitPotential
YearSingleFamilyMulti-FamilyTotalHouseholds
20065858116
2007134134268
2008160160320
2009211211422
2010223223446
2011264264528
2012276276552
2013283283566
2014288288576
2015292292584
2016297297594
2017301301602
2018306306612
2019311311622
2020316316632
2021321321642
2022326326652
2023331331662
2024336336672
2025341341682
Source:McCombGroup,Ltd.
theclosureoftheCSAH20(MilitaryRoad)andCSAH19(KeatsAvenue)intersection.Itshouldalsobe
notedthatalternativemodesoftransportationwerenotrepresentedinthismodelsincethepercentageof
useisinsignificant.AccordingtotheU.S.CensusBureau,transit,bicycling,andwalkingaccountedfor
atotalof2.5percentofcommutersinCottageGroveinYear2000.
Figure3-5Table3-3
Year2020ADTvolumesareillustratedonand.Trafficisexpectedtogrowrapidly
withdevelopment.Anadditional80,000dailyvehicletripsareforecastedwithintheprojectarea.
Generally,trafficvolumesonkeyroadwaysrangefrom69,000vpdontheexpresswayto2,000vpdon
collectors.Itshouldbenotedthatadjustmentsweremadetothedailyforecaststoaccountforthe
deviationsbetweenthecorrespondingbaseyeartrafficcountsandthemodeledassignments.
3-2
June2005
EastRavinePre-Design,CottageGrove,MN
TrafficImpactStudyHRGProject819070J
EastRavinePre-Design
CityofCottageGrove
Source:HoisingtonKroeglerGroup,Inc.
HoisingtonKoeglerGroupInc.
LandUseScenario
EarthTech
Emmons&OlivierResources
Figure3-1
HowardR.GreenCompany
June10,2005
IBIGroup
McCombGroup,Ltd.
EastRavinePre-Design
CityofCottageGrove
Source:HoisingtonKroeglerGroup,Inc.
HoisingtonKoeglerGroupInc.
LandUseScenario
EarthTech
Emmons&OlivierResources
Figure3-2 HowardR.GreenCompany
June10,2005
IBIGroup
McCombGroup,Ltd.
EastRavinePre-Design
CityofCottageGrove
Source:HoisingtonKroeglerGroup,Inc.
HoisingtonKoeglerGroupInc.
LandUseScenario
EarthTech
Emmons&OlivierResources
Figure3-3
HowardR.GreenCompany
June10,2005
IBIGroup
McCombGroup,Ltd.
EastRavinePre-Design
CityofCottageGrove
19
1084C
1080B
1084B
1080C
1084D
1084E
1080A
20
Neighborhood1
22
20
1080F
1080D
1086
1083
10
39
1081A
61
95
1087
1082A
1081E
1082B
1081C
10
Legend
ProjectArea
61
TrafficAreaZoneBoundaries
TrafficAreaZoneNumber
1080
Lakes
Streams
04,800
Feet
00.250.50.751
Miles
HoisingtonKoeglerGroupInc.
ProjectAreaTrafficAnalysisZones
EarthTech
Emmons&OlivierResources
Figure3-4 HowardR.GreenCompany
June10,2005
IBIGroup
McCombGroup,Ltd.
Table3-2
Future(2020)SocioeconomicDatabyTAZ
CityofCottageGroveComprehensive
Zone
Plan2020FullBuild-OutofEastRavine
HouseholdsEmployeesHouseholdsEmployees
1,106653,800570
1080
1,237250275660
1081
1,9511,0901,2001,530
1082
1,2241821,224182
1083
645221,8000
1084
1,21651,2165
1085
2,5811,2802,5811,280
1086
1,8721,0401,8721,040
1087
3162,1953162,195
1088
45504550
1089
10902,0572,3252,0572,325
10919410794107
Total14,3448,61116,4809,944
Source:CityofCottageGroveComprehensivePlan(2020)andHowardR.GreenCompany
Fullbuild-outisbaseduponlandusescenariosdevelopedbyHoisingtonKoeglerGroupInc,
TheYear2020ADTprojectionswerecomparedagainstprojectionsfromtheWashingtonCounty2020
TrafficForecastMapdevelopedasapartoftheWashingtonCountyComprehensivePlan(1996).The
previousplanhadestimatedsomedevelopmentinCottageGrove,butnottotheextentofthefull
developmentreviewedinthisstudy.ThefulldevelopmentoftheEastRavineareaisexpectedtoincrease
th
trafficprojectionsonmostmajorroadways.However,somereductionsareseenonCSAH20(70
Street)eastofCSAH19(KeatsAvenue)andonCSAH19(KeatsAvenue).Thisisdueinparttothe
additionoftheEastRavineParkwaytothemodel.Theparkwayisexpectedtocarryover5,000vpdinall
Figure3-6
locations.Thecomparisonisillustratedon.
PMpeakhourturningmovementsforeachofthekeyintersectionsbyapplyinggrowthratesofdaily
Section2.2
countstoexistingPMpeakhourturningmovementvolumesshownin.Thesevolumesare
Table3-4Figure3-7
displayedonand.
3.3FutureOperationAnalysisandDeterminationofDeficiencies
Table3-5
isasummaryoftheexpectedfuturetrafficoperationsforthesevenkeyroadwaysegments.
Section2.4.1
Themethodologyusedfortheoperationsanalysiscanbefoundin.Asnotedpreviously,the
LOSD/EboundarywasusedastheindexofcongestionfortheCityofCottageGrove.Usingthis
guideline,congestionisexpectedonCSAH20(MilitaryRoad)andtwoareasofCSAH19(Keats
th
Avenue):northofCSAH20andbetween90StreetandUS61.
Table3-6
Asummaryoftheexpectedtrafficoperationsontheeighteenkeyintersectionsisdisplayedon.
ElevenoftheeighteenkeyintersectionsareexpectedtooperateatLOSFwiththeexistinglanegeometry
Table2-2
andtrafficcontrolasnotedon.TheseintersectionsincludeUS61SBRamp/CSAH22(70th
Street),US61SBRamp/JamaicaAve,US61NBRamp/JamaicaAvenue,US61SBRamp/CSAH19
(KeatsAvenue),US61/KimbroAvenue,80thStreet/JamaicaAvenue,80thStreet/CSAH19(Keats
Avenue),CSAH22(70thStreet)/CSAH19(KeatsAvenue),CSAH22(70thStreet)/JamaicaAvenue,
3-7
June2005
EastRavinePre-Design,CottageGrove,MN
TrafficImpactStudyHRGProject819070J
Table3-3
Future(2020)AverageDailyTraffic
Location
Year2002AADTCountsExpectedYear2020ADT
US61Northof70thStreet53,00069,300
US61Between70thStreetand80thStreet42,00051,100
US61Between80thStreetandCSAH1931,00042,800
US61BetweenCSAH19andKimbroAvenue26,00032,700
CSAH22(70thStreet)BetweenUS61andJamaicaAvenue6,40010,400
CSAH22(70thStreet)BetweenJamaicaAvenueandCSAH192,20010,100
80thStreetBetweenUS61andHintonAvenue22,30028,000
80thStreetHintonAvenueandIdealAvenue12,60016,100
80thStreetIdealAvenueandJamaicaAvenue10,10012,700
80thStreetBetweenJamaicaAvenueandCSAH197,4009,300
80thStreetCSAH19toKimbroAvenue1,2006,600
JamaicaAvenueBetweenMilitaryRoadand70thStreet4,20015,900
JamaicaAvenueBetween70thStreetand80thStreet7,40010,500
JamaicaAvenueBetween80thStreetandUS6111,20017,700
CSAH19(KeatsAvenue)NorthofCSAH205,60012,600
CSAH19(KeatsAvenue)BetweenCSAH20andCSAH227,60012,600
CSAH19(KeatsAvenue)BetweenCSAH22and80thStreet6,20013,000
CSAH19(KeatsAvenue)Between80thStreetand90thStreet6,20012,000
CSAH19(KeatsAvenue)Between90thStreetandUS616,20013,800
KimbroAvenueBetweenLamarAvenueandUS615004,000
CSAH20(MilitaryRoad)BetweenIdealAvenueandJamaicaAvenue5,00014,100
CSAH20(MilitaryRoad)BetweenJamaicaAvenueandCSAH191,450-
CSAH20(MilitaryRoad)CSAH19toLamarAvenue3,0006,000
LamarAvenue70thStreettoKimbroAvenue1,2002,000
Source:Mn/DOTYear2002ADTFlowMapsandHowardR.GreenCompany
3-8
June2005
EastRavinePre-Design,CottageGrove,MN
TrafficImpactStudyHRGProject819070J
EastRavinePre-Design
CityofCottageGrove
20
19
Neighborhood1
20
22
10
Neighborhood2
39
61
95
Legend
ProjectArea
AverageDailyTraffic(ADT)
ProposedRavineParkway
Lakes
10
Streams
04,800
61
Feet
00.250.50.751
Miles
SOURCE:HowardR.Green
Company
HoisingtonKoeglerGroupInc.
Future(2020)ADTVolumes
EarthTech
Emmons&OlivierResources
Figure3-5
HowardR.GreenCompany
June10,2005
IBIGroup
McCombGroup,Ltd.
EastRavinePre-Design
CityofCottageGrove
20
19
Neighborhood1
20
22
10
Neighborhood2
39
61
95
Legend
ProjectArea
AverageDailyTraffic(ADT)
2020WashingtonCountyProjection
withDevelopment
AverageDailyTraffic(ADT)
2020WashingtonCountyProjection
withoutDevelopment
ProposedRavineParkway
Lakes
10
Streams
04,800
61
Feet
00.250.50.751
Miles
SOURCE:HowardRGreenCompany&
BRW-WashingtonCounty2020Traffic
Forecast
NOTE:LocationADTVolumesareonly
shownwhereavailableforbothexisting
andnewconditions.
HoisingtonKoeglerGroupInc.
Future(2020)ADTVolumesComparison
EarthTech
Emmons&OlivierResources
Figure3-6
HowardR.GreenCompany
June10,2005
IBIGroup
McCombGroup,Ltd.
EastRavinePre-Design
CityofCottageGrove
20
19
22
39
10
Neighborhood2
61
10
Legend
61
ProjectArea
TurningMovements
ProposedRavineParkway
Lakes
Streams
04,800
Feet
00.250.50.751
Miles
SOURCE:HowardRGreen
Company
Future(2020)TurningMovementVolumes
HoisingtonKoeglerGroupInc.
EarthTech
Emmons&OlivierResources
HowardR.GreenCompany
Figure3-7
IBIGroup
June10,2005
McCombGroup,Ltd.
Table3-5
Future(2020)SegmentLevelofService
Location
LOS
US61Northof70thStreetD
US61Between70thStreetand80thStreetC
US61Between80thStreetandCSAH19C
US61BetweenCSAH19andKimbroAvenueC
CSAH22(70thStreet)BetweenUS61andJamaicaAvenueD
CSAH22(70thStreet)BetweenJamaicaAvenueandCSAH19C
80thStreetBetweenUS61andHintonAvenueD
80thStreetHintonAvenueandIdealAvenueB
80thStreetIdealAvenueandJamaicaAvenueB
80thStreetBetweenJamaicaAvenueandCSAH19A
80thStreetCSAH19toKimbroAvenueA
JamaicaAvenueBetweenMilitaryRoadand70thStreetD
JamaicaAvenueBetween70thStreetand80thStreetB
JamaicaAvenueBetween80thStreetandUS61C
CSAH19(KeatsAvenue)NorthofCSAH20D
CSAH19(KeatsAvenue)BetweenCSAH20andCSAH22D
CSAH19(KeatsAvenue)BetweenCSAH22and80thStreetD
CSAH19(KeatsAvenue)Between80thStreetand90thStreetD
CSAH19(KeatsAvenue)Between90thStreetandUS61E
KimbroAvenueBetweenLamarAvenueandUS61A
CSAH20(MilitaryRoad)BetweenIdealAvenueandJamaicaAvenueE
CSAH20(MilitaryRoad)BetweenJamaicaAvenueandCSAH19-
CSAH20(MilitaryRoad)CSAH19toLamarAvenueB
LamarAvenue70thStreettoKimbroAvenueA
Source:HowardR.GreenCompany
3-13June2005
EastRavinePre-Design,CottageGrove,MN
TrafficImpactStudyHRGProject819070J
JamaicaAvenue/RavineParkway,andCSAH19(MilitaryAvenue)/RavineParkway.However,the
th
intersectionofCSAH19(KeatsAvenue)andCSAH22(70Street)wasmodeledasafour-leg
intersectioninsteadoftheexistingT-intersection.Theassumedlaneconfigurationincludedleftandright
Figure
turnlanesonalllegs.Expectedsegmentandintersectiontrafficoperationsarealsodisplayedon
3-8
.
3.4RoadwayImprovementsandPhasing
Thepurposeofthissectionistoidentifyfuturedevelopmentimprovementsbasedonthefullbuild-outof
theEastRavinearea.Improvementsincludedrecommendedroadwaycross-sectionsandintersection
controlmeasuresnecessarytoeliminatetheroadwaydeficienciesforthelandusescenario.An
approximatetimingplanwasdeveloped,butitshouldbenotedthatthetimingandintensityofadditional
developmentintheprojectareawilldictatewhatroadwayenhancementsareneededandonwhenthey
shouldoccur.
Asnotedintheprevioussection,twoofthesevenkeyroadwaysectionsareexpectedtobedeficientwith
thefullbuild-outoftheEastRavineprojectarea.AsnotedintheprevioussectionCSAH20(Military
Road)andCSAH19(KeatsAvenue)arenotexpectedtomeetcapacityneedsinthefuture,andshouldbe
upgradedfromtwo-lanefacilitiestofour-lanefacilities.
WhiletheentirelengthofCSAH20(MilitaryRoad)isexpectedtobedeficient,onlysegmentsofCSAH
19(KeatsAvenue)operatedpoorly.However,thetwosegmentswithdeficienciesareonthenorthand
southareasofthecity,withthreemilesofseparation.Providingaconsistentlaneconfigurationwould
provideasafersection,eliminatingthemerginganddivergingalongtheroadway.
Additionally,Mn/DOTshouldconsidertheclosureofUS61andKimbroAvenuesincethisintersection
willrequiresignalsinthefuture.Mn/DOThasdesignedUS61tooperateasanexpresswaywiththe
placementofinterchangesatone-milespacing.ThenextlogicalinterchangewouldbeTH95(Manning
Avenue).Withthisclosure,amajorityoftrafficvolumesonKimbroAvenuewillrelocatetoCSAH19
Figure3-9
(KeatsAvenue)andTH95(ManningAvenue)asshownon.
Lastly,theCityofWoodburyhasapproveddevelopmentofamallandadditionalcommercial
developmentnearInterstate94andCSAH19.Thisdevelopmentwasnotincludedinthemodel.Itis
anticipatedthatthisdevelopmentwillbeadrawforadditionaltrafficalongCSAH19(KeatsAvenue)in
CottageGrove.
Therefore,theentirelengthofCSAH20(MilitaryRoad)andCSAH19(KeatsAvenue)shouldbe
upgradedfromtwo-lanefacilitiestofour-lanefacilities.Therecommendedroadwaysectionsshouldbe
usedatthistimeforestimatingfutureright-of-wayneedsandjurisdictionalpriority.
Asnotedintheprevioussection,thetraveldemandmodelassumedtheCSAH20(MilitaryRoad)and
CSAH19(KeatsAvenue)intersectionwasclosed.Becauseofthecloseproximityofthisintersectionto
th
CSAH22(70Street)andCSAH19(KeatsAvenue),theintersectionshaveoperationalandsafety
deficienciesthatareexpectedtoescalateinthefutureastrafficvolumesincrease.Thecityhas
th
determinedthatCSAH22(70Street)isthepreferredroutebecauseofitsconnectiontoUS61.Concern
hasbeenraisedaboutthetimeimpactsthismayputuponmotoriststravelingfromtheeastofCottage
GroveandtakeCSAH20(MilitaryRoad)astheshortestpath.Motoristwillnowbeexpectedtouse
JamaicaAvenueasanalternateroute.Itshouldbenotedthatinthefuture,bothoftheserouteswilllikely
havethreetrafficsignals.EventhoughtheextensionofCSAH20(MilitaryRoad)isshorter,thetime
differenceisexpectedtobeminimal.Thecitycanreducetheseimpactsbyprovidingadequatelane
geometryatintersectionsandbysynchronizingtrafficsignalsalongtheroutes.
3-15June2005
EastRavinePre-Design,CottageGrove,MN
TrafficImpactStudyHRGProject819070J
EastRavinePre-Design
CityofCottageGrove
20
19
22
20
10
39
61
95
Legend
ProjectArea
IntersectionLOS
NotCongested(LOSA-B)
NearCongested(LOSC-D)
Congested(LOSE-F)
10
SegmentLOS
NotCongested(LOSA-B)
61
NearCongested(LOSC-D)
Congested(LOSE-F)
ProposedRavineParkway
Lakes
Streams
04,800
Feet
00.250.50.751
Miles
HoisingtonKoeglerGroupInc.
Future(2020)RoadwayandIntersectionLOS
EarthTech
Emmons&OlivierResources
HowardR.GreenCompany
Figure3-8
June10,2005
IBIGroup
McCombGroup,Ltd.
EastRavinePre-Design
CityofCottageGrove
20
19
Neighborhood1
20
22
10
Neighborhood2
39
61
95
NoAccess
Legend
ProjectArea
AverageDailyTraffic(ADT)
ProposedRavineParkway
Lakes
10
Streams
04,800
61
Feet
00.250.50.751
Miles
SOURCE:HowardR.Green
Company
Future(2020)ADTVolumeswithClosure
HoisingtonKoeglerGroupInc.
EarthTech
ofKimbroAvenueatUS61
Emmons&OlivierResources
HowardR.GreenCompany
June10,2005
IBIGroup
Figure3-9
McCombGroup,Ltd.
ForthePMpeakhour,allelevenintersectionslistedasdeficientintheprevioussectionwereanalyzed
withtheadditionoftrafficsignals.AlllocationsmettheLOScriteriawiththechangeintrafficcontrolas
Table3-7
notedon.
Table3-7
Future(2020)IntersectionPMPeakHourLevelofServicewithAdditionalTrafficSignals
LevelofService
Intersection
WestEastSouthNorth
Intersection
ApproachApproachApproachApproach
US61SBRamp/CSAH22(70thStreet)BB--AB
US61SBRamp/JamaicaAveE--CDD
US61NBRamp/JamaicaAve--CBAB
US61SBRamp/CSAH19(KeatsAvenue)C--ABC
US61/KimbroAvenueAA--CA
80thStreet/JamaicaAvenueCCCCC
80thStreet/CSAH19(KeatsAvenue)CCBAB
CSAH22(70thStreet)/CSAH19(KeatsAvenue)CCBCC
CSAH22(70thStreet)/JamaicaAvenueCCBBC
JamaicaAvenue/RavineParkwayAAAAA
CSAH19(MilitaryAvenue)/RavineParkwayABBBB
Source:HowardR.GreenCompany
Figure3-10
Theroadwayandintersectionimprovementsaredisplayedon.Theproposeddevelopmentof
thesignalandmulti-familyresidentialunitsandcommercialdevelopmentisexpectedtooccur
incrementallyoverthenext20years.Therefore,implementationofallimprovementandmitigations
listedareexpectedtobeneededovertime.Thetimingandmagnitudeoftheimprovementsand
mitigationswillbedependentonthesize,type,andlocationofthedevelopmentsthatoccureachyear
bothinsideandoutsidetheprojectarea.Whichimprovementsandmitigationswillbeneededfirstwill
dependonwhereandwhendevelopmentsoccur.
Itmustberememberedthatthedevelopmentscenarioexaminedhereishypothetical.Iffutureland
developmentdeviatessignificantlyfromtheproposedscenario,thetrafficimpactsandensuingpotential
improvementsandmitigationsmightdifferfromwhathasbeenpresentedinthisreport.
Giventhattherearemanyuncertaintiessurroundingthetimingandneedforroadwayimprovements
associatedwithdevelopmentinthestudyarea,isrecommendedthattheinitialmitigationstrategy
associatedwithtrafficimpactsshouldbetheestablishmentofatrafficmonitoringprogramtotracktraffic
growthonarearoadways.Thepurposeofthetraffic-monitoringprogramistoidentifyifthetraffichas
increasedonthekeyroadwaysandtoidentifywhethertheincreaseintrafficisofsuchmagnitudeto
warrantinitiationoffurtherassessment,projectdevelopment,andprogrammingrecommendations.
Theresultsfrothe2025developmentscenarioidentifieddelaysoccurringontheminorstreetapproaches
atseveralthru-STOPintersections.Onepotentialsolutiontoimprovetheoperationsfortheseminor
streetmovementsistoinstallatrafficsignal.Withtheinstallationofatrafficsignal,therewouldnowbe
aportionoftimeinwhichthemajorstreettrafficwouldberequiredtostopattheintersectionwhilethe
signalisservicingtheminorstreetmovements.Therefore,thedelaysfortheminorstreetwouldbe
expectedtodecrease;however,thedelaysforthemajorstreetwouldbeexpectedtoincrease.Typically,
3-18June2005
EastRavinePre-Design,CottageGrove,MN
TrafficImpactStudyHRGProject819070J
EastRavinePre-Design
CityofCottageGrove
4Lane
20
19
2Lane
Neighborhood1
22
20
10
39
61
95
Legend
4Lane
ProjectArea
10
ExpectedSignalizedLocation
RoadwayImprovement
61
ProposedRavineParkway
Lakes
Possible
Streams
Closure*
04,800
Feet
00.250.50.751
Possible
Miles
Interchange*
*NOTE:Theseimporvement
projectsarebasedupon
Mn/DOTapproval.
HoisingtonKoeglerGroupInc.
RecommendedRoadwayImprovements
EarthTech
Emmons&OlivierResources
HowardR.GreenCompany
Figure3-10
June10,2005
IBIGroup
McCombGroup,Ltd.
themajorstreetapproacheshaveasignificantlyhighervolumeoftrafficthantheminorstreetapproaches.
Ifagreatervolumeofvehicles(majorstreetapproaches)isnowexperiencingagreaterdelay,theoverall
intersectionLOSwouldbeexpectedtodecreasewiththeinstallationofatrafficsignalcomparedtoa
thru-STOPcondition.
Therefore,theMinnesotaDepartmentofTransportation(Mn/DOT)andotheragencieshaveestablished
supplementaryguidelinebesidesminorstreetdelayforwhenandwheretopotentiallyinstalltraffic
signals.Twooftheseguidelinesincludesignaljustificationreports(SJR)andrecommendedminimum
signalspacing.
AnSJRisadocumentthatexaminestheexistingconditions,providesadescriptionoftheproject,
discussestheneedfortheproject,includesasignalwarrantanalysis,andstatesthereasonsasignal
systemisjustifiedatthespecificlocation.Warrantshavebeendevelopedthatprovideaguidelinefor
intersectionsignalization.ThecriteriaformeetingtheseguidelinesarelistedintheMinnesotaManualon
UniformTrafficControlDevices(MMUTCD).Justificationforasignalizedintersectionshouldbebased
onmeetingoneormoreoftheestablishedwarrantsintheMMUTCD.However,satisfyingtheconditions
ofoneormoresignalwarrantsdoesnotalonejustifytheinstallationofasignal.Additionalstudies
shouldbeconductedbytheappropriateroadwayauthoritiestodetermineiftheinstallationofatraffic
signalwillimproveoverallsafetyand/ortheoperationsoftheintersection.AnSJRmustbeapprovedby
theappropriateroadwayauthoritiespriortosignalinstallation.
Mn/DOThasalsoestablishedrecommendedaccess/signalspacingguidelinesfordifferentfunctionally
classifiedroadways.Therefore,priortoinstallationofatrafficsignal,theserecommendedsignalspacing
guidelinesmustalsobeconsidered.Inanurbanorurbanizingarea,signalspacingonarterialsand
collectorsshouldbeaminimumof
QMPIWETEVX
However,apossibletimelineforsignalplacementwasdevelopedinordertoassistlocaljurisdictionsin
Table3-8
fiscalplanning.liststhelocationsofexpectedsignalsysteminstallations,brokenintofive-year
increments.ThesouthboundrampofUS61andJamaicaAvenueiscurrentlydeficient,andshouldbe
assessedforapotentialtrafficsignal.Theremainingsignalinstallationsareexpectedtovarywithtime,
basedupondevelopmentoccurringfirstinNeighborhood1,withdevelopmentofNeighborhood2
followingafterYear2010.
3.5Transit
Asnotedpreviously,theuseofalternativemodeswithintheCityofCottageGroveislimited.The2000
Censusestimatesthatabout1.3percentofcommutersusepublictransportationastheirmeanstowork.
However,theCitywouldliketoexpandthetransitopportunitiestoresidents.AccordingtotheCityof
CottageGroveComprehensivePlan(October2000),theCityhasrequestedmorecapacityatthe
temporaryparkandridelot,andhasbegunexplorationofamulti-modaltransithub.Additionally,the
CityisinsupportoftheRedRockCorridorCommuterRail.TherailwouldrunfromHastingtoSt.Paul.
Afeasibilitystudyforthisprojectwascompletedin2000,andthealternativesanalysisandenvironmental
processhasbeguntonarrowalternatives.
3-20June2005
EastRavinePre-Design,CottageGrove,MN
TrafficImpactStudyHRGProject819070J
Table3-8
TrafficSignalPhasing
YearIntersection
CSAH22(70thStreet)/CSAH19(KeatsAvenue)
2005-2010
US61SBRamp/JamaicaAve
80thStreet/JamaicaAvenue
US61NBRamp/JamaicaAve
US61SBRamp/CSAH19(KeatsAvenue)
2010-2015
80thStreet/CSAH19(KeatsAvenue)
CSAH22(70thStreet)/JamaicaAvenue
US61SBRamp/CSAH22(70thStreet)
US61/KimbroAvenue
2015-2020
JamaicaAvenue/RavineParkway
CSAH19(MilitaryAvenue)/RavineParkway
Source:HowardR.GreenCompany
3-21June2005
EastRavinePre-Design,CottageGrove,MN
TrafficImpactStudyHRGProject819070J
4.0Summary
Thisstudyevaluatesthetrafficimpactsofthedevelopmentofapproximately560acresofdevelopable
landontheeastsideofCottageGrove.TheEastRavineareaisexpectedtoreachfullbuild-outin20
years.However,thetraveldemandmodelusedforthetrafficanalysisusedYear2020conditionsin
WashingtonCountywithfullbuild-outoftheEastRavine.Sevenkeyroadways(brokenintotwenty-four
segmentsforanalysis)andeighteenkeyintersectionlistedbelowwereselectedforthisstudybecause
theywillprovideprimaryaccesstotheregionalroadsystemandwilllikelybetheprimaryroadways
whentheareadevelops.
KeyRoadways
US61betweenGlenRoadandKimbroAvenue
CSAH20(MilitaryRoad)betweenIdealAvenueandLamarAvenue
CSAH22(70thStreet)betweenUS61andCSAH19(KeatsAvenue)
80thStreetbetweenUS61andKimbroAvenue
JamaicaAvenuebetweenCSAH20(MilitaryRoad)andUS61
CSAH19(KeatsAvenue)betweenDaleRoadandUS61
LamarAvenue/KimbroAvenuebetween70thStreettoUS61
KeyIntersections
US61/70thStreetRamps(3intersections)
US61/80thStreetRamps(2intersections)
US61/JamaicaAveRamps(2intersections)
US61/CSAH19(KeatsAvenue)Ramps(2intersections)
US61/KimbroAvenue
th
80Street/JamaicaAvenue
th
80Street/CSAH19(KeatsAvenue)
th
80Street/KimbroAvenue
CSAH20(MilitaryRoad)/LamarAvenue
CSAH22(70thStreet)/CSAH19(KeatsAvenue)
CSAH22(70thStreet)/JamaicaAvenue
CSAH20(MilitaryRoad)/JamaicaAvenue
CSAH20(MilitaryRoad)/CSAH19(KeatsAvenue)
Anoperationanalysiswascompletedforroadwaysegmentsandintersections.Roadwayoperationswere
evaluatedbycomparingaveragedailytrafficcountswithlevelofservicebarchartsdevelopedusing
methodologiesfromtheHighwayCapacityManual.Intersectionswereevaluatedusingtheexpected
intersectiondelay.Intheexistingyear,theintersectionofCSAH22(70thStreet)/JamaicaAvenueisthe
onlyintersectionoperatingbelowthedesiredlevelofservice.
Forecastedaveragedailytrafficvolumeswereusedtoestimatefutureroadwayoperations.These
forecastedweredevelopedusingtheWashingtonCounty2020TravelDemandModel.Assumingthe
existinggeometry,twoofthesevenroadwaysoperatedundercongestedconditions.Elevenofthe
eighteenintersectionsoperatedbelowthedesiredlevelofservice.Thefollowingprojectsare
recommendedtomitigatetheimpacts:
4-1June2005
EastRavinePre-Design,CottageGrove,MN
TrafficImpactStudyHRGProject819070J
RoadwayImprovements
ReconstructCSAH20(MilitaryRoad)asafour-lanefacilitywithturnlanes.
ReconstructCSAH19(KeatsAvenue)asafour-lanefacilitywithturnlanes.
th
RealigntheintersectionofCSAH20(70Street)andCSAH19(KeatsAvenue)tobethemajor
connectiontoUS61andclosetheintersectionofCSAH20(MilitaryRoad)andCSAH19
(KeatsAvenue)
DiscussthepossibleclosureofUS61andKimbroAvenueandapossiblefutureinterchangeat
US61andTH95(ManningAvenue)withMn/DOTandotherauthoritativejurisdictions.
IntersectionImprovements(InstallationofTrafficSignalsattheFollowingLocations)
US61SBRamp/CSAH22(70thStreet)
US61SBRamp/JamaicaAve
US61NBRamp/JamaicaAvenue
US61SBRamp/CSAH19(KeatsAvenue)
US61/KimbroAvenue,80thStreet/JamaicaAvenue
80thStreet/CSAH19(KeatsAvenue)
CSAH22(70thStreet)/CSAH19(KeatsAvenue)
CSAH22(70thStreet)/JamaicaAvenue
JamaicaAvenue/RavineParkway
CSAH19(MilitaryAvenue)/RavineParkway
4-2June2005
EastRavinePre-Design,CottageGrove,MN
TrafficImpactStudyHRGProject819070J
Surface Water
Management Plan
City of Cottage Grove
August 2008
"(38Ð.%Ð".33 &$Ð&1.5$ÐmÐ241% "$Ð6 3$1Ð, - &$,$-3Ð/+ -Ð
Table of Contents
EXECUTIVE SUMMARY.....................................................................................................................................i
SECTION 1 - INTRODUCTION
1.1 Overview............................................................................................................................................1
1.2 Purpose.............................................................................................................................................1
1.3 Organization......................................................................................................................................3
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2.1 Topography and Watersheds..............................................................................................................4
2.2 Soils...................................................................................................................................................5
2.3 Geology and Groundwater.................................................................................................................6
2.4 Land Use............................................................................................................................................7
2.5 Key Water Resources..........................................................................................................................8
2.5.1 Wetlands..............................................................................................................................8
2.5.2 Lakes.................................................................................................................................10
2.5.3 Draws and Ravines.............................................................................................................10
2.5.4 Streams and the Mississippi River........................................................................................11
0" 1&,+ÐÐkÐ$, )0Ð +!Ð-,)& &"0Ð
3.1 Purpose...........................................................................................................................................12
3.2 City of Cottage Grove.......................................................................................................................12
3.3 Watershed Management Organization Requirements........................................................................21
3.3.1 South Washington Watershed District (SWWD)....................................................................21
3.3.2 Lower St. Croix Watershed Management Organization (LSCWMO).......................................21
3.4 State and Federal Agency Requirements...........................................................................................22
3.4.1 Minnesota Department of Natural Resources (MnDNR)........................................................23
3.4.2 U.S. Army Corps of Engineers (USACE)................................................................................23
3.4.3 Board of Water and Soil Resources (BWSR).........................................................................23
3.4.4 Minnesota Pollution Control Agency (MPCA).......................................................................23
3.4.5 State and Federal Jurisdictional Boundaries for Public Wetlands and Waters........................24
3.5 Agency Stormwater Publications.......................................................................................................25
3.6 Agency Contacts..............................................................................................................................26
0" 1&,+ÐÐkÐ4"1) +!Ð-/,1" 1&,+Ð +!Ð* + $"*"+1Ð
4.1 Watershed Management Organizations............................................................................................27
4.2 Wetland Assessment........................................................................................................................27
4.3 Wetland Management Standards......................................................................................................28
4.3.1 Water Quality.....................................................................................................................29
4.3.2 Water Quantity...................................................................................................................29
4.3.3 Buffers...............................................................................................................................29
4.3.4 Wetland Mitigation (Adapted from the SWWD WMP)..........................................................30
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan
4.4 Summary of Wetland Management Standards...................................................................................31
4.5 Procedures for Wetlands Not Inventoried..........................................................................................32
0" 1&,+ÐÐkÐ4 1"/Ð.2 )&16Ð 00"00*"+1Ð
5.1 Background......................................................................................................................................33
5.2 Receiving Water Classification..........................................................................................................33
5.3 System Improvements for Water Quality............................................................................................34
5.4 Water Quality Cash Dedication.........................................................................................................35
5.5 Total Maximum Daily Loads and Impaired Waters.............................................................................36
5.6 NPDES MS4 Permit Program.............................................................................................................39
5.6.1 Nondegradation.................................................................................................................39
5.7 Recommendations............................................................................................................................40
0" 1&,+ÐÐkÐ4 1"/Ð.2 +1&16Ð 00"00*"+1Ð
6.1 Technical Background......................................................................................................................41
6.1.1 Design Storm......................................................................................................................41
6.1.2 Hydrologic Design Parameters.............................................................................................42
6.1.3 Conveyance System Design Parameters...............................................................................43
6.1.4 Ponding Design Parameters................................................................................................44
6.2 Stormwater Modeling Overview........................................................................................................45
6.3 System Analysis and Recommendations............................................................................................46
6.3.1 General..............................................................................................................................46
6.3.2 Central District....................................................................................................................47
6.3.3 East Draw District...............................................................................................................47
6.3.4 East Ravine District.............................................................................................................48
6.3.5 Gables Lake District............................................................................................................49
6.3.6 Grey Cloud Island District....................................................................................................49
6.3.7 Langdon District.................................................................................................................49
6.3.8 Lower St. Croix District........................................................................................................50
6.3.9 St. Paul Park District...........................................................................................................50
6.3.10 Seeger Creek District...........................................................................................................52
6.3.11 South District......................................................................................................................52
6.3.12 Southwest District...............................................................................................................53
6.3.13 Thompson Grove District.....................................................................................................53
6.3.14 West Draw District..............................................................................................................54
6.4. High Priority Stormwater Quantity Recommendations........................................................................55
0" 1&,+ÐÐkÐ&*-)"*"+1 1&,+Ð
7.1 General............................................................................................................................................56
7.2 Regulatory Administrative Responsibilities........................................................................................56
7.2.1 Erosion and Sediment Control.............................................................................................56
7.2.2 Preliminary and Final Plating Process...................................................................................57
7.2.3 Floodplain Ordinance..........................................................................................................57
7.2.4 Shoreland Ordinance..........................................................................................................57
7.3 Education.........................................................................................................................................57
7.3.1 General..............................................................................................................................57
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan
7.3.2 City Staff............................................................................................................................58
7.3.3 City Residents.....................................................................................................................58
7.3.4 Development Community....................................................................................................59
7.4 Operation and Maintenance.............................................................................................................60
7.4.1 Stormwater Basins..............................................................................................................60
7.4.2 Sump Manholes and Sump Catch Basins.............................................................................61
7.4.3 Storm Sewer Inlet Structures...............................................................................................62
7.4.4 Open Channels...................................................................................................................62
7.4.5 Piping System.....................................................................................................................62
7.4.6 De-Icing Practices...............................................................................................................62
7.4.7 Street Sweeping..................................................................................................................63
7.4.8 Litter Control......................................................................................................................63
7.4.9 Volume Control BMPs.........................................................................................................63
7.5 Trunk Surface Water System Costs....................................................................................................63
7.6 Financing.........................................................................................................................................64
7.7 Amendment Procedures...................................................................................................................64
7.8 Annual Report to Council.................................................................................................................65
7.9 System Improvement Projects and Activities......................................................................................65
0" 1&,+ÐÐkÐ02** /6Ð +!Ð/" ,**"+! 1&,+0Ð
8.1 Summary..........................................................................................................................................67
8.2 Recommendations............................................................................................................................67
0" 1&,+ÐÐkÐ/"##"/"+ "0 ...................68
0" 1&,+Ð
ÐkÐ$),00 /6Ð,#Ð1" %+& )Ð1"/*0 ....69
TABLES
Table 2.1 Soil Drainage Characteristics........................................................................................................6
Table 4.1 Wetland Management Classification..........................................................................................28
Table 4.2 Wetland Community Susceptibility to Stormwater Impacts..........................................................29
Table 4.3 Wetland Management Standards for Wetlands within SWWD.....................................................31
Table 5.1 SWWD Classified Receiving Waters and Management Standards for Cottage Grove....................34
Table 5.2 303(d) List of Impaired Waters within the City of Cottage Grove.................................................37
Table 6.1 Runoff Coefficients and Curve Numbers Assumed for Future Land Use........................................42
Table 6.2 Major Drainage Districts Abbreviations.......................................................................................46
Table 7.1 High and Moderate Priority System Improvement Projects and Activities ....................................66
FIGURES
Figure 1.1 Location Map..............................................................................................................................2
Figure 2.1 Watershed Jurisdictional Boundaries............................................................................................5
Figure 2.2 Land Use Map.............................................................................................................................8
Figure 5.1 Impaired Waters........................................................................................................................38
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan
APPENDICES
ÐkÐ*>MPÐ
*>MÐÐkÐ0ROC>@BÐ4>QBOÐ0VPQBJÐ*>MÐ
*>MÐÐkÐ0LFIPÐ*>MÐ
*>MÐÐkÐ4BQI>KAÐ*>K>DBJBnt Classification Map
*>MÐÐkÐ+>QFLK>IÐ4BQI>KAÐ&KSBKQLOV Ð*K!+/Ð-R?IF@Ð4>QBOPÐ&KSBKQLOV Ð>KAÐ0QOB>JPÐ*>MÐ
ÐkÐ!O>FK>DBÐ OB>PÐ
ÐkÐ-OLMLPBAÐ1ORKHÐ0QLOJÐ0BTBOÐ!>Q>Ð
!ÐkÐ-LKAÐ!>Q>Ð
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#ÐkÐ/RIBPÐ>KAÐ/BDRI>QFLKPÐLCÐQEBÐ)LTBOÐ0Q ÐCroix Watershed Management Organization
$ÐkÐ0VPQBJÐ&JMOLSBJBKQPÐCLOÐ4>QBOÐ.R>IFQVÐÐ
%ÐkÐ*>PQBOÐ%VAOLILDF@Ð>KAÐ%VAO>RIF@Ð*LABIFKDÐ*>MÐ
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan
"(38Ð.%Ð".33 &$Ð&1.5$ÐmÐ241% "$Ð6 3$1Ð, - &$,$-3Ð/+ -Ð
Executive Summary
This Surface Water Management Plan (SWMP) has been developed to serve as a comprehensive planning document
to guide the City of Cottage Grove in conserving, protecting, and managing its surface water resources and comply
with the Metropolitan Surface Water Management Act, Minnesota Rules 8410, and the requirements of the local
watershed management organizations. This document provides an inventory of water resource related information
including the results of assessments conducted by other governmental units, both local and state. From this
inventory and assessment, Cottage Grove sets forth its goals and policies and implementation program.
The plan is organized as follows:
Section 1 offers an introduction to and purpose of the Plan, including a location map of Cottage Grove.
j
Section 2 of this Plan describes the physical environment including watersheds and drainage patterns, dominant
j
land uses, and significant water bodies within the City.
0B@QFLKÐÐIFPQPÐQEBÐ FQVgPÐDL>IPÐ>KAÐMLIF@FBPÐ>ILKDÐTFth public agency requirements affecting surface water
j
management in the City. This section also includes general information regarding the roles of the watershed
management organizations with jurisdiction within Cottage Grove, as well as those of other state and federal
regulatory agencies influencing surface water management in the City.
0B@QFLKÐÐLRQIFKBPÐQEBÐ FQVgPÐ>MMOL>@EÐQLÐTBQI>KAÐmanagement, in accordance with the standards and
j
requirements of the jurisdictions watershed management organizations.
Section 5 presents an assessment of surface water quality issues in Cottage Grove. The section includes
j
discussion regarding the NPDES permitting process, impaired waters and TMDL implementation, and
nondegradation requirements.
Section 6 provides a current assessment of surface water quantity management in Cottage Grove, including
j
stormwater modeling, various design parameters, and identification of issues and corrective actions.
Section 7 covers regulatory responsibilities, priority implementation items, educational programs, operation and
j
maintenance, and financing considerations. A plan amendment process is also identified and the distinction
between major and minor amendment outlined.
Section 8 contains a summary of the SWMP and makes recommendations for implementing the Plan.
j
Sections 9 and 10 include the list of reference documents and a glossary of terms, respectively.
j
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page i
"(38Ð.%Ð".33 &$Ð&1.5$ÐmÐ241% "$Ð6 3$1Ð, - &$,$-3Ð/+ -Ð
Section 1 - Introduction
1.1OVERVIEW
This report provides the City of Cottage Grove with a Surface Water Management Plan (SWMP) that will serve as a
guide to managing the surface water system throughout the City. This SWMP will serve the City as a tool to protect,
preserve and enhance its water resources. The plan identifies from a regional perspective the stormwater quantity
and quality improvements necessary to allow future development to take place and minimize its impact to
downstream waterbodies. This report also benefits the planning aspects of infrastructure installation.
The City of Cottage Grove is located in the southeastern portion of the Twin Cities Metropolitan Area in Washington
County (see Figure 1.1). Cottage Grove is bounded on the north by the City of Woodbury; on the east by Denmark
Township; on the south by the Mississippi River; and on the west by Grey Cloud Township and St. Paul Park.
Settled in the 1840's with the creation of the Langdon and "Old Cottage Grove" villages, Cottage Grove
experienced relatively slow growth as a rural communiQVÐRKQFIÐQEBÐB>OIVÐ
gP Ð0FK@BÐQEBÐ
gP ÐQEBÐ FQVÐE>PÐ
experienced steady growth with current figures estimating a population of greater than 30,000 residents. As the City
continues to grow, the importance of adequate surface water management controls also grows. The intent of the
Cottage Grove SWMP is to detail what these controls are and make the connection between these controls and the
overall city goal of preserving and enhancing its natural resources and protecting its residents from flooding.
1.2 PURPOSE
The Cottage Grove SWMP will serve as a comprehensive planning document to guide the City in conserving,
protecting, and managing its surface water resources. The SWMP meets requirements as established in Minnesota
/RIBPÐ
Ð*BQOLMLIFQ>KÐ LRK@FIgPÐ04*-Ð$RFABIFKBP Ð>KAÐall rules and regulations of the South Washington
Watershed District and the Lower St. Croix Watershed Management Organization.
In a four-part process, the SWMP does the following:
1.Collects and compiles the efforts of agencies and organizations including the City, its departments and
residents. This includes past reports and studies, management plans, monitoring studies, as well as
completed and proposed improvement projects.
2./BSFBTPÐQEBÐ@ROOBKQÐPQ>QBÐLCÐQEBÐ FQVgPÐPROC>@BÐT>QBOÐOBPLRO@BPÐFKÐQEBÐ@LKQBUQÐLCÐDL>IPÐ>KAÐMLIF@FBP Ð
ordinances, operations and maintenance, flood mitigation, and achievement of targeted water quality levels
in its surface water bodies.
3.Establishes reasonable, achievable and affordable goals, and supports them by a strong regulatory and
management culture. Develops an implementation plan that includes projects and processes that derive
from a thorough assessment of current City problem areas and current City surface water regulations and
controls.
4. Provides a blueprint for construction of new surface water systems as the City expands. Using advanced
surface water modeling software, a system of pond, wetlands and pipes is developed and costs applied to
these future systems. The costs give the City a framework for understanding the impact development will
have on City finances and applying these costs equitably to development.
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 1
Figure 1.1 k Location Map
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 2
The purpose of this SWMP is identical to the purpose of the 1982 Surface Water Management Act (requiring Cities
to prepare local Surface Water Management Plans), which is to preserve and use natural water storage and retention
systems to:
1.Reduce to the greatest practical extent the public capital expenditures necessary to control excessive volumes
and rates of runoff;
2.Improve and preserve surface water quality;
3.Prevent flooding and erosion from surface flows;
4.Promote groundwater recharge;
5.Protect and enhance fish and wildlife habitat and water recreational facilities;
6.Preserve wetlands, lakes and streams;
7.Secure the other benefits associated with proper management of surface water.
1.3 ORGANIZATION
This report is a culmination of the activities described above and is organized as follows:
Section 2, Land and Water Resources - describes the physical environment including watersheds and drainage
j
patterns, dominant land uses, and significant water bodies within the City.
0B@QFLKÐ Ð$L>IPÐ>KAÐ-LIF@FBPÐ
nd policies along with public agency requirements affecting
j
surface water management in the City.
Section 4, Wetland Protection and Management - Outlines the results of the wetland inventory and assessment
j
for portions of the City within the South Washington Watershed District, establishes guidelines for completing a
similar assessment in the remainder of the City, and identifies wetland protection and buffer standards that the
City will apply.
Section 5, Water Quality Assessment - Presents a water body classification system that the City intends to use,
j
identifies high priority water bodies on which protection efforts should focus, and identifies important water
quality-related state and federal programs with which the City needs to comply.
Section 6, Water Quantity Assessment - presents the technical background on modeling and design of the
j
PVPQBJ Ð#LOÐB>@EÐLCÐQEBÐ FQVgPÐÐJ>GLOÐAO>FK>DBÐAFPQOF@QP it presents an overview of the district as well as
recommendations to address the major flood management and conveyance issues in that district.
Section 7, Implementation - covers regulatory responsibilities, priority implementation items, educational
j
programs, operation and maintenance, the capital improvement program, and financing considerations.
A plan amendment process is also identified and the distinction between major and minor amendment outlined.
Section 8, Summary and Recommendations - contains a summary of the SWMP and makes recommendations
j
for implementing the Plan.
Sections 9 and 10 include the list of reference documents and a glossary of terms, respectively.
j
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 3
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2.1 TOPOGRAPHY AND WATERSHEDS
The City of Cottage Grove is located in southern Washington County, about 10 miles southeast of St. Paul. The
EFPQLOVÐLCÐQEBÐ@FQVgPÐI>KAP@>MBÐ?BDFKPÐ>OLRKAÐ
ÐJFIIFLKÐVB>Os ago, when much of Minnesota was covered by water,
and the sedimentary rock layers that lie under the city were formed. Small areas of these layers are exposed on the
Mississippi River bluffs today, and remain in resistant bedrock knobs scattered among later glacial deposits in the
West Draw area.
Before the last advance of the glaciers into the Twin Cities area, the ancestral Mississippi River flowed in a deep,
wide gorge that passed beneath Lower Grey Cloud Island before turning south. This ancient valley, known as the
Phalen Channel, eroded downward through sedimentary rock layers, and was eventually buried by glacial deposits.
The Grey Cloud channel, which separates the Upper and Lower islands, marks the northern limit of this ancient
Mississippi Channel. This buried valley filled with sand and gravel and is now mined by Aggregate Industries on
Lower Grey Cloud Island.
With the exception of these ancient features, most of the topography of Cottage Grove was shaped by the last
period of glaciation in the Twin Cities Area, which o@@ROOBAÐ>?LRQÐ
ÐVB>OPÐ>DL Ð>KAÐT>PÐ@>IIBAÐQEBÐh4FP@LKPFKÐ
0Q>DBi Ð1EBÐDI>@FBOPÐP@RIMQBAÐQEBÐI>KAP@>MB Ð>KAÐIBCQÐ?BEFKA a variety of glacial drift deposits (primarily sand and
gravel, and windblown deposits, called loess). At the same time, as the ice melted in northern Minnesota, enormous
amounts of water flowed through the Minnesota and Mississippi River valleys (called the glacial River Warren), and
formed broad, bench-like terraces of sand and gravel along the river corridor. The Trunk Highway 61 corridor roughly
separates these two glacial features with the flat sandy terraces to the south along the river and the rolling uplands
to the north. Resistant knobs of bedrock and kettle-shaped depressions formed by melting ice blocks are also
scattered throughout the uplands.
The City generally drains from north to south, with topography within the study area varying from very flat to fairly
steep slopes. The majority of the City is well drained via numerous main ravines or draws (namely West Draw,
Central Draw, East Ravine, and Seeger Creek), ultimately discharging to the Mississippi River. Land surface
elevations range from a high of 1,000 feet above sea level to a low of 687 feet, which is the normal pool elevation
of the Mississippi River. Major and minor drainage districts, delineating drainage divides in the City, are identified on
Map 1 in Appendix A.
The majority of the City lies within the jurisdiction of the South Washington Watershed District (SWWD). The
remaining portion of the City along the eastern border, is within the jurisdiction of the Lower St. Croix Watershed
Management Organization (LSCWMO). The jurisdictional boundaries for these Watershed Management
Organizations (WMOs) are included on Figure 2.1. It should be noted that the jurisdictional boundaries for these two
WMOs vary slightly from the topographic watershed boundaries, as indicated by the major and minor drainage
district boundaries on Map 1.
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 4
Figure 2.1 k Watershed Jurisdictional Boundaries
2.2 SOILS
The soils information in this section is taken from the United States Department of Agriculture Natural Resources
Conservation Service (NRCS) Soil Survey of Washington and Ramsey Counties. The soils maps in that report are
general and intended for broad planning purposes. The soils of Cottage Grove are classified into six major soil
associations as follows:
1.Antigo-Chetek-Mahtomedi Association
2.Sparta-Dickman-Hubbard Association
3.Antigo-Comstock Association
4.Ostrander-Baytown-Ripon Association
5.Copaston-Sparta Association
6.Waukegan-Baytown-Ripon Association
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 5
Details on the soils included in each association can be found in the County soil survey. Table 2.1 shows the
drainage characteristics of each soil series from the above associations.
Table 2.1 k Soil Drainage Characteristics
Soil Series Draining Characteristic Hydrologic Soil Group
Antigo Well Drained B
Baytown Well Drained B
Chetek Somewhat Excessively Drained B
Comstock Somewhat Poorly Drained C
Copaston Poorly Drained D
Dickman Somewhat Excessively Drained A
Hubbard Excessively Drained A
Mahtomedi Excessively Drained A
Ostrander Well Drained B
Ripon Well Drained B
Sparta Excessively Drained A
Waukegan Well Drained B
The drainage nature of the soil is important for determining the surface water runoff from a given area. If the soil is
well-drained, a significant portion of the precipitation will be infiltrated into the ground, whereas if a soil is very
poorly drained, most of the precipitation will flow from the site of impact.
The Hydrologic Soil Group (HSG) defines a soils propensity to generate runoff for a given rainfall event. Four HSG
groups area identified: A, B, C, D. HSG A soils have the lowest potential to generate runoff and are typically sandy
or gravelly soils. HSG D soils have the highest potential to generate runoff and typically consist of muck, peaty muck,
and tight clay soils. The associations found within the Cottage Grove SWMP study area fall primarily into HSG A to B,
indicating a low to moderate potential to generate runoff. The soil series located within the City (identified by the
soil HSG) have been mapped, and are shown on Map 2 (located in Appendix A). The major drainage district
boundaries are also included on Map 2 to identify the prominent HSG within each district.
Hydric soils are those characteristic soils found in wetland areas. A wetland must possess three technical criteria in
order for it to be identified as a wetland. These three are: 1) hydrophytic vegetation, 2) hydric soils, and 3) wetland
EVAOLILDV Ð1EBÐABCFKFQFLKÐLCÐ>ÐEVAOF@ÐPLFIÐFPÐÐh>ÐPLFIÐthat is saturated, flooded, or ponded long enough during the
DOLTFKDÐPB>PLKÐQLÐABSBILMÐ>K>BOL?F@Ð@LKAFQFLKPÐFKÐQEBÐRMMBOÐM>OQi Ð
2.3 GEOLOGY AND GROUNDWATER
The Geologic Atlas of Washington County, Minnesota (available online at http://www.geo.umn.edu/mgs) has
detailed descriptions of the surficial geologic deposits and formations underlying Cottage Grove. A review of this
data reveals that the majority of the City is underlain by either unconsolidated St. Peter Sandstone or the soluble
Prairie du Chein group. Both of these bedrock units, when covered by less than 50 feet of soil are considered karst-
sensitive, as defined by the LSCWMO. Coordination with local agencies is recommended to verify the location of
active karst features within the City.
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 6
There are five aquifers underlying all or portions of Cottage Grove. The Quaternary aquifer has been created by
glacial meltwater that has generated outwash plains throughout much of the City, creating regionally valuable sand
and gravel deposits. The thickness of these sediments ranges from less than 10 feet to greater than 300 feet in the
@BKQO>IÐ?ROFBAÐ?BAOL@HÐS>IIBVÐ@RQQFKDÐQEOLRDEÐQEBÐ FQVgPÐ@BKQer. This aquifer is generally un-confined and recharged
through direct infiltration from precipitation and leakage from surface water bodies. It has not been a major source
for groundwater development yet.
The Prairie du Chein-Jordan aquifer is the main source for all high capacity wells in the watershed. In most areas of
Cottage Grove, this aquifer lies directly below the surficial deposits. Fractures, joints, faults, and solution cavities
largely control the flow in this aquifer. The combined Franconia-Ironton-Galesville aquifer is only used to a minor
degree for groundwater supply. However, both aquifer units provide regional groundwater discharge to the St. Croix
and Mississippi River. The other bedrock aquifers, the Mt. Simon and the Eau Claire, are not significant sources of
drinking water in the watershed.
In many areas of the City, the sensitivity to groundwater impacts is high or very high. This is generally because water
infiltrating in the watershed can reach the water table system in a very short period of time (on the order of weeks in
some cases), leaving little opportunity for attenuation of pollutants through degradation (SWWD 2007).
2.4 LAND USE
The proposed land use for Cottage Grove is shown on FiguOBÐ Ð1EFPÐI>KAÐRPBÐFPÐ?>PBAÐLKÐQEBÐ FQVgPÐ
Ð
@LJMOBEBKPFSBÐMI>K Ð1EBÐ FQVgPÐ@LJMOBEBKPive plan provides a significant amount of narrative and statistical detail
on existing and proposed land use and the reader is referred to that document for more information on land use
planning. The hydrologic modeling found in this SWMP used the 2030 land use plan to determine hydrologic
characteristics of the future landscape within the City. For areas draining from outside the City boundary, the
modeling assumed the existing land use.
As mentioned previously, Cottage Grove experienced relatively slow growth as a rural community until the early
gP Ð&KÐQEBÐ
gP ÐRO?>KÐABSBILMJBKQÐ?LQEÐ@LJJBO@F>IÐ>KAÐOBPFABKQF>IÐ?BD>KÐQLÐL@@ROÐFKÐQEBÐKLOQETBPQÐ
portions of Cottage Grove, along what is now TH 61. Since this time, the City has continued to expand to the east
and southeast along TH 61. More recently, residential development within the West Draw area (northwest corner of
the City) and commercial/industrial development within the Thompson Grove area (south of TH 61) is occurring. With
the installation of the MCES interceptor along CSAH 19, the East Ravine area is beginning to develop.
The majority of the undeveloped area within the City is located along the southern and eastern portion of
Cottage Grove, with much of this area expected to develop in the next 15 years.
The 2030 land use map identifies areas in the eastern and southwestern portions of the City as Urban Reserve. This
designation is intended to indicate that while farming will remain a viable land use in these areas for years to come,
they will ultimately be opened for urban development. For each area designated Urban Reserve, the City will develop
master plans in advance of opening the area for development. These master plans will include specific land uses,
locations for park and open space, and utility (including surface water management improvements) and
transportation improvements necessary for development.
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 7
Figure 2.2 k Land Use Map
2.5 KEY WATER RESOURCES
2.5.1 W
ETLANDS
Cottage Grove contains relatively few wetlands. This is presumably due to the presence of well drained to excessively
drained soils and undulating terrain and steep ravines covering the majority of the City.
The natural habitat quality of these wetlands is highly variable depending on past and present land use. Some
wetlands are entirely surrounded by urban development while others are located in areas which are, for the most
part, rural and undeveloped. This diversity in wetland surroundings poses a challenge for regulatory policy
development. Protection of wetland functions and values in urbanized areas should not preclude continued growth
of the City. Key wetland features can be found in Cottage Grove Ravine, the central draw, within Grey Cloud Dunes
SNA, and in the north-central portion of the city. These complexes are described briefly below. The locations of the
wetland complexes referred to are shown on Map 3 in Appendix A.
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 8
East Ravine
All of the following sites are within the SWWD Greenways Corridor, in Cottage Grove Ravine Regional Park.
Wetland RL-2-3: Ravine Park Lake
This good quality lake supports a diverse population of native, submerged aquatic plants with a high quality mixed
emergent marsh community around the perimeter. There are OB@LOAPÐCLOÐQEBÐPQ>QB
QEOB>QBKBAÐ I>KAFKDgPÐ1ROQIBÐ>QÐQEBÐ
lake, and most of the adjacent upland is mapped as high quality oak forest on the MnDNR Map of Rare Features and
Natural Communities. Other features in the vicinity of the lake include high quality dry prairie remnants, other good
quality wetlands, and a population of the state listed Threatened plant, Kittentails.
Wetland RL-2-2
This small basin is just north of Ravine Park Lake. It provides exceptional wildlife habitat, due to its overall good
quality and location within the MnDNR-mapped good quality forest and dry prairie remnants of the Cottage Grove
Ravine Regional Park.
Wetland EW 1-1
Wetland EW 1-1 is a mix of lowland hardwood forest and good to high quality emergent marsh on the east branch
of the East Ravine. The adjacent upland supports fallow pastureland with remnant good quality dry prairie, and
populations of the state listed Threatened plant, kittentails.
CP2-2
This large marsh complex is of good to high quality, and is part of a complex of good quality natural communities.
The entire oak forest around the basin is mapped by the MnDNR as a site of biodiversity significance, and the
northern portion of the woods, adjacent to the wetland, isÐ>IPLÐFK@IRABAÐLKÐQEBÐ*K!+/gPÐJ>MÐLCÐ/>OBÐ#B>QROBPÐ>KAÐ
Native Communities for Washington County.
Langdon District
This old river channel that forms the core of this area is part of the SWWD Greenway Corridor, and provides
important habitat for the state listed Threatened Loggerhead Shrike. Important wetlands include MR-3-1 and
MR-3-A.
MR-3-1
Wetland MR-3-1 is a complex of open water, emergent marsh, and wet meadow, all of medium to high quality.
&KÐ>AAFQFLKÐQLÐQEBÐPFQBgPÐFKEBOBKQÐNR>IFQy, it has added value as shrike habitat.
MR-3-A
This wetland on the 3M property was not evaluated during the survey due to lack of property access. It appears to
be of moderate quality, and should be considered an important component of shrike habitat.
South District
Several good quality wetlands occur within the Grey Cloud Dunes Scientific and Natural Area (SNA). These include
MR-6-8 and MR-6-11.
MR-6-8
This site is a mix of high quality sedge meadow, and medium to high quality shallow marsh and shrub wetland.
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 9
MR-6-11
MR-6-11 is a small basin dominated by a high quality sedge meadow, with floodplain forest and shallow open water
making up the rest of the site.
2.5.2 L
AKES
Gables Lake
Gables Lake is located in the northeast corner of the City, within the Gables Lake District. Gables Lake is
approximately 5 acres in size and has an estimated maximum depth of about 5 feet. Its drainage area is
approximately 450 acres. The drainage area is largely undeveloped and extends into the southeast portion of the
City of Woodbury. The drainage area to Gables Lake consists mainly of undevelopable wooded and agricultural
areas. Gables Lake has no natural outlet, but rather maintains a fairly constant water level by a combination of
evaporation and infiltration.
0EBM>OAgPÐ4LLAPÐ-LKA
QÐ>MMOLUFJ>QBIVÐÐ>@OBPÐFKÐPFWB Ð0EBM>OAgPÐ4LLAPÐ-LKAÐFPÐlocated in the north-central portion of the City, within
the East Ravine District. The drainage area to this pond (approximately 560 acres) includes the surrounding
undeveloped and agricultural areas, including a portion of agOF@RIQRO>IÐ>OB>ÐTFQEFKÐQEBÐ FQVÐLCÐ4LLA?ROV Ð0EBM>OAgPÐ
Woods Pond has no natural outlet, but rather maintains a fairly constant water level by a combination of
evaporation and infiltration.
Ravine Park Lake
Ravine Park Lake is approximately 16 acres in size, has a maximum depth of about 19 feet and a mean depth of
about 5 feet, and is located within Cottage Grove Ravine Regional Park, north of TH 61. This lake receives drainage
from a largely undeveloped drainage area, including the entire undevelopable park area and surrounding agricultural
areas.
2.5.3 DR
RAWS AND AVINES
The most prominent topographic feature for the majority of the City is the numerous draws and ravines that have
been worn into the landscape, providing natural stormwater conveyance from the northern reaches of the City
toward the Mississippi River in the south. As development occurs adjacent to the many draws and ravines, these
features provide opportunities for not only wonderful aesthetic benefits to development, but natural stormwater
storage and conveyance routes as well.
West Draw
The West Draw runs from the northwest corner of Cottage Grove to TH 61 and the Hamlet Park area, incorporating
approximately 1,450 acres of drainage area. An additional 620 acres of drainage area from the City of Woodbury
drains overland through the West Draw into Cottage Grove. In addition to the overland drainage area, the 1979
Woodbury Stormwater Plan proposed that 850 acres draining to a land locked basin just north of the Cottage
Grove/Woodbury border be pumped into Cottage Grove via a lift station. A lift station has been constructed to pump
flows into an existing land-locked depression on the border of Woodbury and Cottage Grove, but at this time flows
are pumped no further. If in the future it becomes necessary to connect this existing land locked depression into the
Cottage Grove stormwater conveyance system in the West Draw, in accordance with the South Washington
Watershed District Watershed Management Plan, this lift station will be operated during off-peak times.
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 10
The majority of the most recent development within Cottage Grove has occurred within the West Draw area.
The stormwater infrastructure within the West Draw E>PÐMOL@BBABAÐ>@@LOAFKDÐQLÐQEBÐ FQVgPÐÐ04*-Ð>KAÐ
subsequent drainage studies. This plan sets forth a framework for utilizing the topography within the West Draw to
provide substantial rate control measures due to the limited downstream stormwater storage and conveyance
capacity at TH 61.
Central and East Draws
The Central and East Draws incorporated approximately 1,140 and 1,080 acres, respectively. The contributing
drainage areas to these draws are almost completely developed and the draws appear to be relatively stable. Both of
these draws are integral to the regional stormwater system within the Central and East Draw Districts. The natural
stormwater conveyance within both draws is utilized, behind constructed berms or roadways providing regional
ponding areas at various points within the draws.
East Ravine
The East Ravine is the most prominent ravine within the City of Cottage Grove. This major geographic feature
extends from the north to south end of the City, conveying roughly 25% of the drainage area within the City to the
Mississippi River. With the recent construction of the Met Council Interceptor along County Road 19, the East Ravine
is now prepared to develop. The proposed regional stormwater system within the East Ravine will take advantage of
the many existing depression areas and natural conveyance routes. The East Ravine is a valuable resource within the
City of Cottage Grove that the regional stormwater system will seek to protect and enhance.
2.5.4 SMR
TREAMS AND THE ISSISSIPPI IVER
1EBÐEB>AT>QBOPÐLCÐ,g LKKBOgPÐ OBBHÐIFBÐ>ILKDÐQEBÐB>PQBOKÐJ>ODin of the City of Cottage Grove. The Creek discharges
QLÐ,g LKKBOgPÐ)>HB Ð>ÐI>KA
ip. Because of its landlocked nature, this lake will be
extremely sensitive to increases in runoff volume.
Seeger Creek and its tributary branches at located in the southeast corner of the City. This creek drains
approximately 3,600 acres of primarily agricultural drainage area from both Cottage Grove and Denmark Township,
directly to the Mississippi River.
The City of Cottage Grove is bordered to the south by the Mississippi River. Apart from a few areas within the river
floodplain, the majority of the City is located well above the river elevation. A large percentage of the City drains
directly to the river, therefore, the City desires to minimize the impact of pollutants generated from development
within the City.
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 11
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0B@QFLKÐÐkÐ$L>IPÐ>KAÐ-LIF@FBPÐ
3.1 PURPOSE
The primary purpose of the SWMP is to provide guidance on how the City of Cottage Grove intends to manage its
surface water. Over time, significant advancement has been made in our understanding of how natural and man
made systems function in the context of rainfall, infiltration and runoff. New regulations have been created that
reflect increased protection for water bodies and emphasize treatment of stormwater to protect downstream
resources and groundwater.
ÐKRJ?BOÐLCÐQEBÐ FQVgPÐDL>IPÐ>KAÐMLIF@FBPÐ>OBÐDRFABAÐ?VÐCBABral, state, regional and local mandates, while others
>OFPBÐLRQÐLCÐQEBÐ FQVgPÐLTKÐABPFOBÐQLÐMOLQB@QÐFQPÐK>QRO>IÐOBsources in light of its unique character and circumstances.
A number of regulations, strategies and tools have emerged to manage QEBÐ FQVgPÐI>KAÐ>KAÐT>QBOÐOBPLRO@BPÐ
effectively.
Together these regulations, initiatives and programs provide the basis for the strategies and requirements set forth
by the City to guide the protection and management of the water resources within the City. This section of the
04*-ÐPMB@FCF@>IIVÐLRQIFKBPÐQEBÐ FQVgPÐDL>IPÐ>KAÐMLIF@FBPÐrelated to surface water management. The goals and policies
are consistent with the requirements of Minnesota Rules 8410 and Minnesota Statute 103B.235 (Local Water
Management Plans), and demonstrate a desire, willingness, and commitment by the City to reach and sustain a high
quality of life for its residents.
3.2 CITY OF COTTAGE GROVE
Surface water management is a strong component of the CiQVgPÐLSBO>IIÐ>MMOL>@EÐQLÐMOLQB@QFKDÐ>KAÐMOBPBOSFKDÐQEBÐ
@LJJRKFQVgPÐK>QRO>IÐOBPLRO@BP Ð1EBÐ FQVÐLCÐ LQQ>DBÐ$OLSBÐrecognizes both the value and impact that surface water
can have on the quality of life in the community. In this plan, the term surface water is used broadly to refer to:
Wetlands
j
Lakes and ponds, either natural or artificial
j
The overland runoff resulting from rainfall or snow melt events
j
Streams and other natural channels
j
The Mississippi River
j
Features constructed to temporarily or permanently store runoff such as infiltration areas
j
Surface water management also includes the infrastructure designed and constructed to convey, control and protect
surface water resources.
The goals and policies form the framework of the stormwater management strategies of the City of Cottage Grove.
ÐDL>IÐFPÐ>ÐABPFOBAÐBKAÐQLT>OAÐTEF@EÐQEBÐ FQVgPÐMLIF@FBP Ðstandards, criteria and rules are directed. A policy is a
governing principle, a means of achieving an established goal. Policies prescribe a general course of conduct that
leads toward goal achievement.
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 12
Policy 1.1ÐkÐ1EBÐ FQVÐTFIIÐJBBQ ÐLOÐFCÐOBNRFOBA ÐBU@BBAÐthe adopted surface and groundwater protection and
management (including karst-sensitive areas) standards and requirements of the jurisdictional WMO, as well as
those adopted by the Metropolitan Council and the State of Minnesota, including the Total Maximum Daily Load
(TMDL) program and the National Pollutant Discharge Elimination System (NPDES) Phase 2 requirements.
The City will comply with the Lower St. Croix WatersEBAÐ*>K>DBJBKQÐ,OD>KFW>QFLKgPÐ@ROOBKQÐ-I>KÐ>ALMQBAÐ
June, 2005) and with the current rules (adopted February 2008) for those areas of the City within the LSCWMO
jurisdiction. The LSCWMO rules are attached in Appendix F. The City will comply with the South Washington
4>QBOPEBAÐ!FPQOF@QgPÐRMA>QBAÐ-I>KÐ>dopted by the SWWD in November 2007) and the Standards Manual when
it is finalized. As per past discussion and agreement with the SWWD, however, the City will administer the
runoff volume control requirements and wetland impacts in regional stormwater conveyance corridors according
to Policies 6.1-6.2 and 5.4, respectively, of this Plan.
Policy 1.2 kÐ1EBÐ FQVÐFPÐ@LJJFQQBAÐQLÐQEBÐDL>IÐLCÐKLKABDO>A>QFLn to area water resources. Upon MPCA approval
LCÐQEBÐ FQVgPÐ+LKABDO>A>QFLKÐ/BSFBT ÐQEBÐ FQVÐTFIIÐFJMIBJBKQÐQEBÐOBSFPFLKPÐQLÐQEBÐ FQVgPÐ0QLOJÐ4>QBOÐ-LIIRQFLKÐ
Prevention Program (SWPPP) to address nondegradation - as approved.
Policy 1.3ÐkÐ1EBÐ FQVÐTFIIÐ>AEBOBÐQLÐQEBÐCLIILTFKDÐMLIF@FBPÐOBI>ting to groundwater protection as contained in the
Washington County 2003-2013 Groundwater Plan:
Work to coordinate with other local government units for groundwater sensitive areas, wellhead protection
j
areas, water use contingency and allocation plans and other groundwater issue where the plans may affect
other jurisdictions.
Adopt a wellhead protection plan; where necessary, create overlay districts and standards and incorporate
j
into zoning ordinances and other related land use regulations.
Develop land use regulations to protect groundwater resources based on completed studies and rankings of
j
groundwater recharge areas.
Consider requiring a groundwater monitoring plan or groundwater protection plan as part of a permit
j
application for businesses that store, use, or transport hazardous materials and for properties formerly used
as waste disposal sites or transfer facilities. Where available, use wellhead protection plans to support this
process.
The City will also take into account the recommendations of the completed Phase 1 and 2 efforts of the
Wellhead Protection Plan and the source water assessment completed by the Minnesota Department of Health
in its management of land use activities.
Policy 2.1 kÐ ALMQÐ>MMOLMOF>QBÐMOB@FMFQ>QFLKÐBSBKts for design of system components.
Storm sewers will be sized/designed using the intensity-duration-frequency curves presented in the MnDOT
Drainage Manual for the 5-year 24-hour precipitation event. Lake, natural pond/wetland, and detention pond
high water levels will be based on a 6.3-inch 24-hour type II distribution rainfall event.
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 13
Policy 2.2ÐkÐ"PQ>?IFPEÐCOBB?L>OAÐPQ>KA>OAPÐQLÐminimize the potential for flooding of critical structures, such as
buildings.
High water levels shall be established as an area develops or when drainage facilities are constructed for an
area. For stormwater facilities with emergency overflows, the low entry elevation for all new structures must be
a minimum of 3 feet above both the peak surface water elevation for the 100-year precipitation event and 2
feet above the emergency overflow elevation of any immediately adjacent new stormwater basin. The submitted
grading plan for this basin must identify the direction of overflow and provide adequate flowage easements for
the overflow. For backyard and side-yard conveyance and temporary ponding areas, there must be at least 1
foot between the overland overflow elevation and the low entry of the adjacent structure.
In land-locked areas with no practical emergency overflow, the low entry of new structures shall be a minimum
of 2 feet above the peak water level elevation of back-to-back 100-year recurrence interval precipitation events,
and at least 5 feet above the peak water surface elevation generated by the critical 100-year recurrence interval
precipitation event. New land-locked ponds constructed in the jurisdiction of the LSCWMO are subject to the
land locked basin requirements of the LSCWMO, as identified in Section 8.0 of the LSCWMO Rules included in
Appendix F.
Policy 2.3ÐkÐ"PQ>?IFPEÐMB>HÐCILTÐIFJFQPÐQLÐ>SLFAÐFK@OB>PBPÐin downstream rates caused by development and
protect channel integrity.
At a minimum, peak flow rates after development shall not exceed pre-development peak flow rates for the
critical 1-year, 2-year, 10-year, and 100-year recurrence interval precipitation events. More restrictive rate
control criteria may be required in order to protect the integrity of downstream conveyance channels. Both the
SWWD and LSCWMO provide guidance as to the acceptable runoff parameters for characterizing an existing
condition, particularly for agricultural runoff. The City adopts the defined parameters of the jurisdictional
Watershed Management Organization (WMO).
Policy 2.4ÐkÐ#LIILTÐT>QBOPEBAÐ>RQELOFQVÐORIBPÐ>KAÐDRFABIFKBP in siting detention ponds and other stormwater
management features in karst-sensitive areas.
Guidance from the watershed authorities will be used to determine karst-sensitive areas. Watershed authority
technical guidance and rules as well as the Minnesota Stormwater Manual and guidance from the Minnesota
Department of Health will be followed in determining the suitability of specific sites for certain stormwater
management features and only those features for which the site is suitable will be approved for installation by
the City.
Policy 2.5ÐkÐ1EBÐ FQVÐTFIIÐMOBPBOSBÐCILLAÐPQLO>DB Ð
1EBÐ FQVÐPE>IIÐJ>FKQ>FKÐ>ÐMLIF@VÐLCÐhKLÐKBQÐILPPÐLCÐPQLO>DBÐ@>M>@FQViÐFKÐABPFDK>QBAÐPQLOJT>QBOÐMLKAFKDÐ>OB>P Ð
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 14
Policy 3.1ÐkÐ"K@LRO>DBÐQEBÐFK@LOMLO>QFLKÐLCÐ>@@BMQ>?IBÐ)LTÐ&JM>@QÐ!BSBILMJBKQÐ)&!ÐQB@EKFNRBP Ð
The City recognizes the water quantity and quality benefits provided by incorporating LID techniques into
development within the City. The City is committed to working with developers to incorporate suitable LID
techniques into future development.
Policy 3.2ÐkÐ*FKFJRJÐ BPQÐ*>K>DBJBKQÐ-O>@QF@BPÐ *-PÐMBOCLOJ>K@BÐ@OFQBOF> Ð
The City requires that new development projects include BMPs that at a minimum achieve post-development
reductions in TP and TSS by 50% and 80%, respectively.
Policy 3.3ÐkÐ LJMIVÐTFQEÐQEBÐ+-!"0Ð-E>PBÐ&&ÐMOLDO>JÐ>AJFKFPQBOBAÐ?VÐQEBÐ*FKKBPLQ>Ð-LIIRQFLKÐ LKQOLIÐ DBK@VÐ
(MPCA).
This program is focused on regulating stormwater runoff. The City of Cottage Grove will comply with this
program by developing and submitting appropriate documentation as required by the program and performing
related tasks as appropriate.
Policy 3.4 kÐ-OLJLQBÐ@LJMIF>K@BÐTFQEÐWBOL
MELPMELORPÐ@LKQBKQÐCBOQFIFWBOÐIBDFPI>QFLK Ð
Effective January 1, 2004, Minnesota state law bans application of fertilizer containing phosphate to lawns with
some exceptions, such as, where a recent soil test has shown the lawn soil is deficient in phosphorus. State law
also requires clean-up of any fertilizer spread or spilled on paved surfaces. The City will promote awareness of
this law in public education efforts.
Policy 3.5ÐkÐ/BAR@BÐQEBÐRPBÐLCÐP>KAÐFKÐPQOBBQÐAB
F@FKDÐMOL@BAROBP Ð
The City strives to tailor applications of sand for ice control in a way which balances public safety with
environmental quality. The City recognizes that excessive application of sand on impervious surfaces results in
significant sedimentation of downstream ponds and basins.
Policy 3.6ÐkÐ0QOBBQÐPTBBMFKDÐQLÐMOLQB@QÐT>QBOÐNR>IFQVÐTFII Ð>QÐa minimum, be carried out in the spring and fall.
The City undertakes two seasonal street sweeping efforts. Streets are swept once in the spring as soon as
practical. Streets are swept once in the autumn, generally after most leaves have fallen and targeting mature
tree areas. Sweeping operations are conducted as necessary throughout the year.
The City intends to keep informed of street sweeping technologies and evaluate replacing obsolete equipment
with more efficient updated equipment, subject to available funding and according to capital improvement
priorities.
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 15
Policy 3.7ÐkÐ&JMIBJBKQÐ>ÐPQLOJÐPVPQBJÐJ>FKQBK>K@BÐprogram based on objective standards.
The City will continue to be actively engaged in stormwater inspection, operation and maintenance, and repair
of the stormwater system on a day-to-day basis. The City will follow a formal inspection, cleaning, and repair
P@EBARIB Ð PÐOBNRFOBAÐRKABOÐQEBÐ FQVgP NPDES Municipal Separate Storm Sewer System (MS4) permit, at least
20% of the system will be inspected annually. Frequency of maintenance is event-based and driven by
experience and inspection results.
Policy 3.8ÐkÐ!RJMFKDÐLCÐT>PQBPÐFKQLÐQEBÐPQorm drainage system is illegal.
The City prohibits, through ordinance, the discharge of foreign material into the stormwater system, including
refuse, yard wastes, sewage, industrial waste or other substances. Examples of other substances include
materials such as oil, gasoline, antifreeze, paint, solvent, herbicides/pesticides, pet waste and other ecological
harmful chemicals.
Policy 3.9ÐkÐ1EBÐ FQVÐTFIIÐE>SBÐPMFIIÐOBPMLKPBÐ@>M>?FIFQV Ð
The City has access to spill clean-up kits in selected locations. The City will review its current program for spill
response capability within one year of the date of adoption of this plan by the City Council, and if warranted,
develop improvements in its spill response capability. Karst-sensitive areas as identified by the Minnesota
Department of Health and the appropriate watershed management organization will have spill response plans.
Policy 3.10ÐkÐ >OOVÐLRQÐMR?IF@ÐBAR@>QFLK Ð
The City will actively implement an ongoing public education program. The program is directed primarily at City
residents. Its objectives are to reduce phosphorus and sediment loadings to water bodies. Newsletter mailings
and brochures are primary vehicles for the program. The City also seeks out educational institutions within its
community to implement programs and/or activities. The City is participating in the Washington County shared
water resources educator program.
Policy 4.1ÐkÐ1EBÐ FQVÐ>ALMQPÐQEBÐ@I>PPFCF@>QFLKÐ>KAÐT>QBOÐNR>IFQy protection standards for significant water bodies
within the City of Cottage Grove as specified in each of the current watershed management organization plans.
The classification and standards of the South Washington Watershed District Plan, adopted in November 2007,
will be applied to Gables Lake, Ravine Lake and the Mississippi River and the classification and standards of the
)LTBOÐ0Q Ð OLFUÐ4>QBOPEBAÐ-I>K Ð>ALMQBAÐFKÐ'RKBÐ
ÐTFIIÐ?BÐ>MMIFBAÐQLÐ,g LKKBOPÐ OBBH Ð
Policy 4.2ÐkÐ!BSBILMÐDRFABIFKBPÐCLOÐJ>K>DFKDÐMLKAPÐTFQEÐKLÐABSBILMBAÐMR?IF@Ð>@@BPP Ð
The City will implement adequate maintenance for all poKAPÐQE>QÐ>OBÐM>OQÐLCÐQEBÐ FQVgPÐPQLOJT>QBOÐJ>K>DBJBKQÐ
system to minimize as much as reasonably possible blockages of inlets to- and outlets from- ponds, to maintain
the original flood storage capacity, and to insure that each pond functions adequately >PÐM>OQÐLCÐQEBÐ FQVgPÐCILLAÐ
management system.
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 16
Water quality or habitat improvement efforts for ponds without a developed public access must be balanced
against overall public benefits. Property owners abutting a pond may desire that pond to provide or improve
functions beyond what the City intends through this plan, such as improvement of aesthetics. In such cases, the
City will work with affected residents in an advisory capacity to improve the pond environment. Where a city-
wide benefit and city-wide knowledge can be gained, however, the City may elect to either assist with or
implement itself, management measures on a specific pond.
Policy 4.3ÐkÐ1EBÐ FQVÐOBNRFOBPÐ>ABNR>QBÐMOBQOB>QJBKQÐof stormwater runoff from development and
redevelopment activities prior to discharge into all waterbodies.
Policy 5.1ÐkÐ1EBÐ FQVÐTFIIÐ>PPBPPÐQEBÐCunction and value of wetlands.
Approximately 2/3 of the wetlands within the City were assessed as part of an effort by the South Washington
Watershed District in 1998. The inventory data associated with that assessment will be used by the City to guide
management of those wetlands. The City shall establish a schedule for completing a function and value
assessment for the remaining wetland complexes in the City (approximately 40, located in the eastern third of
the City). That schedule will be phased so that the assessments are completed before subdivision of the affected
areas occurs.
Policy 5.2ÐkÐ1EBÐ FQVÐTFIIÐABSBILMÐ>KAÐ>MMIVÐTBQI>KAÐ?RCCBOÐPQ>KA>OAP Ð
Wetland buffer zones are required on all public and private property which abuts water body. The City will adopt
the applicable wetland buffer standards of the jurisdictional WMO, or where no standards exist, will establish
minimum buffer widths and types based on wetland size, function, and value (see Chapter 4). The buffer
standards will be applied to wetlands within parcels that are the subject of new development activity that must
be approved by the City, or in accordance with the rules of the jurisdictional WMO.
Policy 5.3ÐkÐ1EBÐ FQVÐTFIIÐ>AJFKFPQBOÐQEBÐLSBO>IIÐTBtland protection and preservation programs.
The City will act as the Local Government Unit (LGU) for administration of the Wetland Conservation Act (WCA)
of 1991 and all subsequent amendments in all portions of the City. This will include the application of officially
adopted wetland protection standards promulgated through the WCA, NPDES MS4 permit, and the watershed
management organizations covering the City as they relate to:
wetland impact sequencing
j
pre-treatment of stormwater prior to discharge to wetlands
j
wetland replacement
j
The City will uphold the objective of no net loss in wetland functions and values within the City and comply with
the most current WCA regulations for mitigation and acreage requirements for any filling, draining, or
excavation of a wetland.
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 17
Policy 5.4ÐkÐ4EBOBÐFQÐFPÐFKCB>PF?IBÐQLÐJBBQÐT>QBOPEBAÐ>RQEority standards for wetland protection within the
regional stormwater conveyance corridors identified on Map 3 in Appendix A and also discussed in Section 4.3,
the City will work with the appropriate watershed authority to allow the corridor to serve a regional stormwater
conveyance function.
The regional stormwater conveyance corridors identified on Map 3 in Appendix A of this plan are essential
components of the natural and man-made stormwater conveyance system that carries runoff from the
communities of Lake Elmo, Woodbury, and Cottage Grove to the Mississippi River. In addition, these
conveyance routes have been identified as regionally important stormwater management features in past City
and SWWD plans. The corridors are particularly important for conveyance of flood flows that could otherwise
cause significant property damage. The City will work with the SWWD to manage wetland impacts and still
allow use of the regional conveyance corridor.
Policy 6.1ÐkÐ1EBÐ FQVÐTFIIÐ@LJMIVÐTFQEÐT>QBOPEBAÐ>RQELOity and NPDES Construction Permit standards for
management of stormwater runoff for all development activity disturbing 1 acre or more of land or according to
the rules/regulations of the appropriate watershed authority within which the project is located, which ever is
more restrictive. For projects within the jurisdiction of the LSCWMO, specific thresholds that trigger LSCWMO
rules are included in Section 1.2 of the LSCWMO rules.
For areas of the City within the Lower St. Croix Watershed Management Organization (LSCWMO), the City will
comply with LSCWMO standards for runoff volume reduction and stormwater treatment as presented in their
Rules and Regulations adopted February 13, 2008 and effective June 1, 2008. For areas of the City within the
South Washington Watershed District (SWWD), the City will comply with runoff volume reduction and
stormwater treatment as presented in SWWD Plan adopted November 2007, except that in place of the variable
area-specific volume control requirements, the City shall apply a uniform volume control requirement equal to
FKCFIQO>QFKDÐiÐLCÐORKLCCÐCOLJÐKBTÐFJMBOSFLRPÐ>OB>PÐLCÐa development. Where meeting the standards referred to
above is not adequate to meet the nondegradation requireJBKQPÐLCÐQEBÐ FQVgPÐ*0ÐMBOJFQ ÐQEBÐ FQVÐTFIIÐOBNRFOBÐ
additional controls in order to meet those MS4 permit requirements.
For re-development projects, the volume control standard will apply to new impervious area, which is the
difference between the total impervious area of the site before the re-development activity and total impervious
area for the post-re-development condition.
Where regional facilities are used to manage stormwater from development activity, the regional facilities will be
constructed and operational prior to development.
Policy 6.2ÐkÐ4EBOBÐFKCFIQO>QFLKÐQLÐCRIIVÐJBBQÐQEBÐSLIRJBÐ@LKtrol measure is not desirable or is impossible, an
Alternative Sequencing procedure will be applied to achieve compliance.
Based on guidance from the watershed authorities, the MN Department of Health, and the State of Minnesota
Stormwater Manual, the City will not allow infiltration practices:
For runoff from fueling and vehicle maintenance facilities
j
Within HSG D type soils
j
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 18
Within 100 feet of a private well, within the emergency response zone for a wellhead protection area
j
Within 50 feet of a septic tank of drain field
j
On areas with less than 3 feet of vertical separation from the bottom of the infiltration system to the
j
elevation of the seasonal high groundwater elevation or top of non-karst bedrock
Within 300 feet of an identified sinkhole or other karst feature
j
At the discretion of the City Engineer, infiltration practices may not be allowed:
Within a vulnerable (very high, high, or moderate vulnerability) Drinking Water Supply Area
j
For runoff from a Potential Stormwater Hotspot (PSH) as defined in the State of Minnesota Stormwater
j
Manual (2005)
In a known or suspected karst-sensitive area
j
For areas within the jurisdiction of the Lower St. Croix Watershed Management Organization, the Alternative
Compliance Sequencing procedure outlined in the LSCWMO rules adopted in February 2008 will be followed.
For areas outside of the LSCWMO, the following Alternative Compliance Sequencing will be followed:
The applicant will provide documentation for why infiltration is not feasible or allowable
j
The applicant will reduce impervious surface associated with the proposed action to the maximum extent
j
practical
The applicant will use to the maximum extent practical filtration and biofiltration practices, using an
j
underdrain and an impermeable liner, that are sized to meet the volume control requirement for the site.
The MN Stormwater Manual will be used as the definitive guide in designing and installing the
filtration/biofiltration feature. If the applicant can show that the full volume of runoff for the appropriate
volume control standard is filtered, the volume control requirement will be deemed to have been met. Other
alternative BMPs will also be considered by the City if the applicant can demonstrate equivalency with the
FQVgPÐOBNRFOBJBKQ ÐÐ
If the applicant has followed the Alternative Sequencing procedure above and the full runoff volume control
standard is still not met, the applicant will pay a cash dedication as a last resort. The procedure for calculating
the appropriate cash dedication amount is presented in Section 5.4 of this Plan and the revenue from cash
dedications will be ear-marked exclusively for water quality or runoff volume reduction improvements in the City.
Policy 6.3ÐkÐ-ROPRBÐFKCFIQO>QFLKÐLCÐPQLOJT>QBOÐORKLCCÐ>PÐ>MMOopriate primarily for water quality protection, stream
baseflow preservation, and channel protection.
Infiltration of stormwater should be applied as a technique to limit peak flows and runoff volumes for
precipitation events greater than a 1-year event (2.4 inches of rainfall in 24 hours) only when reviewed and
approved by the City Engineer. Even when approved, outlets/emergency overflows need to be provided for the
infiltration areas to assure that freeboard requirements in Policy 2.2 are met for adjacent low structures
Policy 6.4ÐkÐ0LFIÐAB@LJM>@QFLKÐ
The City encourages the practice of re-establishing the native infiltrative capacity of soils upon completion of
mass grading activities. During the development review process, the City will recommend that soil
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 19
decompaction, by means of deep ripping to a depth of at least 18 inches, be incorporated into site restoration
activities. The volume control benefit provided by the deep ripping activity can be >MMIFBAÐQLT>OAÐQEBÐ FQVgPÐ
volume control requirement, per the methodology outlined in the SWWD Standards Manual.
Policy 6.5ÐkÐ!BQBKQFLKÐ?>PFKÐABPFDKÐPQ>KA>OAP Ð
When new ponds are constructed for stormwater management purposes, they will be constructed to meet the
FQVgPÐPQ>KA>OAPÐCLOÐABQBKQFLKÐ?>PFKÐABPFDKÐPBBÐ0B@QFLKÐ 1.4), as well as those of the jurisdictional WMO. The
sizing of the wet volume of the pond can be adjusted to account for runoff volume reduction features in the
MLKAgPÐT>QBOPEBA ÐÐ
Policy 6.6ÐkÐ!BSBILMJBKQÐM>VPÐCLOÐFQPBIC Ð
Storm drainage system financing shall be by trunk area assessments against benefiting properties and storm
sewer facilities. All new developments shall be required to pay the prorated cost to dedicate land and construct
a stormwater treatment facility meeting City requirements.
Policy 6.7ÐkÐ AAFQFLK>IÐQOB>QJBKQÐ@>KÐ?BÐOBNRFOBAÐQLÐMOLQB@t downstream priority water bodies and/or meet
jurisdictional WMO requirements.
The City may require, as a condition of approval to develop vacant land or redevelop existing sites, the
construction by the developer of additional treatment features (to include ponds) or installation of appropriate
best management practices over and above that required under Policy 6.1-6.2. This may be required even when
existing improvements or ponds already are in place. The City can require these practices when it is necessary to
protect the water quality of downstream priority water bodies. The City shall apply these requirements if
necessary in order to meet the phosphorus load targets for Gables Lake, Ravine Park Lake and the Mississippi
River as outlined in the South Washington Watershed DiPQOF@QÐ-I>KÐ
Ð>KAÐCLOÐ,g LKKBOgPÐ OBBHÐ>KAÐ)>HBÐ>PÐ
outlined in the Lower St. Croix Watershed management organization Plan (2005).
Policy 6.8ÐkÐ LKQOLIÐBOLPFLKÐ>QÐ@LKPQOR@QFLKÐPFQBP Ð
The City requires that applications for new or redevelopment activity include in their applications for City review,
a SWPPP as required under the NPDES construction permit in effect at the time of review. Construction sites will
be inspected to ensure compliance with the existing erosion and sediment control ordinance, jurisdictional WMO
requirements, and with the construction site permit under NPDES Phase II rules administered by the MPCA.
Inspections are performed weekly during the construction period. A plan review process and a financial security
instrument are the primary instruments used to establish a basis for compliance.
Erosion and sediment control best management practicePÐ>PÐLRQIFKBAÐFKÐh-OLQB@QFKDÐ4>QBOÐ.R>IFQVÐFKÐ2O?>KÐ
OB>PÐkÐ BPQÐ*>K>DBJBKQÐ-O>@QF@BPÐCLOÐ*FKKBPLQ>iÐ?VÐQEBÐ*- Ð
ÐTFIIÐ?BÐOBNRFOBAÐ>KAÐJRPQÐ?BÐPELTKÐ
on required submittals to the City for approval. Any street sweeping conducted by the City to remove erosional
debris from streets will be charged to the owner of the property.
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 20
3.3 WATERSHED MANAGEMENT ORGANIZATION REQUIREMENTS
The City of Cottage Grove is within the jurisdiction of two watershed management organization jurisdictions, the
South Washington Watershed District and the Lower St. Croix Watershed Management Organization. The
geographical extent of each organizationgPÐGROFPAF@QFLKÐTFQEFKÐQEBÐ FQVÐLCÐ LQQ>DBÐ$OLSBÐFPÐPELTKÐFKÐ#FDROBÐ ÐÐ
Both of these entities have distinct approaches and requirements for surface water management which the City of
Cottage Grove is or will be required to follow as part of their SWMP update.
A general overview of the requirements of each organization is presented below, but readers are encouraged to
contact each organization directly to obtain the most up-to-date information on their goals, policies, and programs.
3.3.1 SWWD(SWWD)
OUTH ASHINGTON ATERSHED ISTRICT
The South Washington Watershed District covers an area of approximately 71.3 square miles in Washington County
and includes portions of the cities of Afton, Lake Elmo, Oakdale, St. Paul Park, Newport, Grey Cloud Island
Township, and Woodbury, in addition to Cottage Grove. The SWWD was formed in 1993 (it was called the Cottage
Grove Ravine Watershed District until 1995, when it changed its name to the SWWD). The SWWD officially adopted
the plan under which it is currently operating in November 2007. Significant City water resources identified in the
!FPQOF@QgPÐ
ÐMI>KÐCLOÐQEFPÐ>OB>ÐFK@IRABÐ/>SFKB Park Lake and the Mississippi River (Pool 2).
The 2007 Plan identifies eight broad goals and Policies for the SWWD. In large part, the issues that pertain to this
SWMP relate to pressures from development and urban growth. Increases in impervious surfaces have contributed to
increased flow volumes in the SWWD, impacting lakes, wetlands, and flows in ravines.
Highlights of the goals of the SWWD, developed by a ciQFWBKgPÐ>ASFPLOVÐ@LJJFQQBBÐ>KAÐ>ALMQBAÐ?VÐQEBÐ L>OAÐLCÐ
Managers, are to:
-OLQB@QÐQEBÐT>QBOPEBAgPÐT>QBOÐOBPLRO@BPÐ>KAÐK>QRO>IÐOBPLROces to benefit recreation, wildlife, and future needs.
j
Protect the water quality and quantity of surface waters and groundwater.
j
Manage the flow of water within the watershed to prevent damage to property and water resources by planning
j
for future growth.
Encourage cities to use appropriate development practices to balance growth with environmental protection.
j
Maintain a high level of public awareness on water quality and water quantity issues through education.
j
Utilize long-term planning to minimize capital expenditures to address water quality and quantity problems.
j
Prevent soil erosion and control sediment leaving construction sites.
j
Maintain an effective Watershed Management Plan (WMP) that addresses short- and long-term goals of the
j
watershed and ensure that the WMP is workable, viable, and enforceable.
3.3.2 LS.CWMO(LSCWMO)
OWER T ROIX ATERSHED ANAGEMENT RGANIZATION
The Lower St. Croix Watershed Management Organization was formed in 1985 when the cities of Afton, Cottage
Grove, and Hastings, along with Denmark Township executed a joint powers agreement to establish the WMO.
The LSCWMO encompasses only about 5.4 square miles of Cottage Grove and includes land area in the eastern
portion of the City along its border with Denmark Township.
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 21
The WMO has adopted a revised and updated watershed management plan in June 2005. Highlights of the
)0 4*,ÐMI>KÐFK@IRABÐABPFDK>QFLKÐLCÐ,g LKKBOgPÐ OBBHÐ>PÐLKBÐof the three most significant perennial streams in the
watershed and providing guidance for the development of rules for runoff volume control, rate control, water quality,
and buffers adjacent to natural waters.
In February 2008, the LSCWMO adopted a series of rules and regulations to help implement portions of their
watershed plan. A steering committee was formed to assist the Board with rule development consisting of City and
Township staff which met throughout 2006 and 2007. The LSCWMO also solicited official comments on the draft
ORIBPÐCOLJÐB>@EÐLCÐQEBÐ)$2gP ÐFK@IRAFKDÐQEBÐ FQVÐLCÐ LQQ>ge Grove, on July 30, 2007. After several other agency and
public review episodes, the rules were officially adopted by the Board of Managers on February 13, 2008 and will
become effective June 1, 2008. It is the expectation of the LSCWMO that the local government units like Cottage
Grove will assume responsibility for all permitting under these rules for activities within their jurisdictional
boundaries. The rules and regulations represent a minimum set of standards, and local governments can adopt more
restrictive standards if they feel it is appropriate.
The adopted rules and regulations address the following areas:
Administrative procedures
j
Stormwater Management
j
Erosion Controls
j
Lake, stream, and wetland buffers
j
Shoreline and streambed alteration
j
Stream and Lake crossings
j
Floodplain and drainage alteration
j
Land-locked basins
j
Groundwater management
j
Water appropriations
j
Greenways and Open space
j
Fees
j
Sureties and performance bonds
j
Variances
j
Enforcement
j
It is the intent of the City of Cottage Grove to administer its program to meet or exceed the requirements for each
subject area as presented in the LSCWMO rules and regulations within that portion of the City included in the
LSCWMO boundary.
3.4 STATE AND FEDERAL AGENCY REQUIREMENTS
This section of the SWMP presents a synopsis of the current agency requirements while acknowledging the existence
of other requirements that may be applicable. Many of these agency requirements are focused on wetland resources.
However, recent programs at the state level involve nonpoint source pollution control.
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 22
The City is committed to the preservation and enhancement of its wetlands and water resources through compliance
with local, state, and federal wetland and nonpoint source pollution regulations.
3.4.1 MDNR(MDNR)
INNESOTA EPARTMENT OF ATURAL ESOURCES N
At the state level, Types 3, 4, and 5 wetlands are protected by statute. These are areas typically recognized as
wetlands and are generally characterized by open water and emergent vegetation throughout most of the year.
The state has jurisdiction over only those wetlands appearFKDÐLKÐQEBÐPQ>QBgPÐFKSBKQLOVÐLCÐMOLQB@QBAÐT>QBOP Ð#ROQEBO Ð
wetlands in the inventory were generally those in excess of 10 acres in rural areas or in excess of 2.5 acres in
municipalities and incorporated areas.
If an area meets the jurisdictional criteria but is not on thBÐPQ>QBgPÐFKSBKQLOV ÐFQÐFPÐKLQÐOBDRI>QBA Ð&CÐFQÐALBPÐKLQÐJBBQÐ
the statutory criteria but is listed on the inventory, it still is subject to MnDNR regulation. There is no mechanism
presently for adding or deleting wetlands. The inventory was begun in the late 1970s and all state inventories were
completed during the early 1980s.
The MnDNR rules specify that permits may not be issued for any project except those that provide for public health,
safety, and welfare. Any private development projects are effectively excluded from permit consideration by this
requirement.
Information on the location of state protected waters and water courses are shown on Map 5 in Appendix A.
3.4.2 U.S.ACE(USACE)
RMY ORPS OF NGINEERS
Under Section 404 of the Clean Water Act, including subsequent modifications, the U.S. Environmental Protection
Agency (EPA) and the U.S. Army Corps of Engineers regulate the placement of fill into all wetlands of the U.S.
In 1993, there was a modification of the definition of "discharge of dredged materi>IiÐQLÐFK@IRABÐFK@FABKQ>IÐ
discharges associated with excavation. 1EFPÐJLAFCF@>QFLKÐLCÐQEBÐhAFP@E>ODBÐLCÐAOBADBAÐJ>QBOF>IiÐABCFKFQFLKÐJB>KQÐ
that any excavation done within a wetland required the applicant to go through Section 404 permitting procedures.
In 1998, however, this decision was modified so that excavation in wetlands is now regulated by the USACE only
when it is associated with a fill action.
3.4.3 BWSR(BWSR)
OARD OF ATER AND OIL ESOURCES
The local and regional wetland rules are governed by the Wetland Conservation Act (WCA). The WCA, passed in
1991, extends protection to all wetlands unless they fall under one of the exemptions of the WCA. The WCA follows
>ÐhKLÐKBQÐILPPiÐMLIF@V Ð1EBÐTBQI>KAPÐ@LSBOBAÐRKABOÐQEBÐ4 ÐJRst not be drained or filled, wholly or partially, unless
replaced by restoring or creating wetland of at least equal public value under an approved replacement plan.
Replacement ratio is typically 2:1 (2 acres created for every 1 acre filled) for wetland impacts.
A designated Local Government Unit (LGU) is responsible for making exemption and no-loss determinations and
approving replacement plans. Currently, the City of Cottage Grove acts in this capacity for WCA administration.
3.4.4 MPCA(MPCA)
INNESOTA OLLUTION ONTROL GENCY
The USACE implements provisions of Section 404 of the Clean Water Act with guidance from the EPA through a
permitting process. The Section 404 permit also requires a Section 401 water quality certification before it is valid.
The EPA has given Section 401 certification authority to the MPCA.
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 23
In addition, the MPCA also currently administers two separate programs that regulate nonpoint source pollution.
The programs are the NPDES program and the TMDL program. These two programs affect stormwater management
and address water quality impacts from watershed activities.
Generally, Phase II of the NPDES program regulates communities less than 100,000 people that are within
hRO?>KFWBAiÐ>OB>P Ð+-!"0Ð-E>PBÐ&&Ð>AAOBPPBs three areas of stormwater management:
Municipal Separate Storm Sewer Systems (MS4)
j
Construction site activity
j
Industrial site activity
j
The primary goal of the MS4 program is to restore the integrity of waters of the state through management and
treatment of urban stormwater runoff. This program was implemented by the MPCA in 2003. Regulated
communities are required to submit a permit to the MPCA every five years. As part of the permit, MS4 communities
must develop a Storm Water Pollution Prevention Program that details the use of appropriate Best Management
Practices. A copy of the most current version of thBÐ FQVgPÐ04---Ð@>KÐ?BÐCLRKAÐMLPQBAÐLKÐQEBFOÐTB?PFQBÐÐ
www.cottage-grove.org.
As part of the NPDES Phase II MS4 program, Cottage Grove is one of thirty MS4s in the state selected by the MPCA
to complete an assessment so that PCA can determine ifÐQEBÐOBNRFOBJBKQPÐLKÐQEBÐPQ>QBgPÐKLKABDO>A>QFLKÐORIBPÐ>OBÐ
being met. This part of the MS4 permit requires certain cities to quantify loadings of total phosphorus, total
suspended solids, and runoff volume for current and projected (2020) land use conditions and determine whether
they exceed the calculated loads for 1988. As a result, the City of Cottage Grove has conducted an analysis of
pollutant loadings and other factors and provided it to MPCA so they can determine whether additional control
measures are necessary and reasonable under the terms of the nondegradation rules. The nondegradation analysis
and proposed modifications in the CitygPÐ04---ÐTBOBÐPR?JFQQBAÐQLÐQEBÐ*- Ð?VÐQEBÐAB>AIFKBÐFKÐQEBÐ FQVgPÐMBOJFQÐ
(February 1, 2008). As of May, 2008, the City is awaiting the completion of the review of the document by MPCA.
The TMDL program seeks to address waters (lakes, streams or rivers) that do not meet their designated use; these
waters are considered impaired. Every two years the MPCA must publish a list of state-wide impaired waters.
Surface waters listed as impaired on the draft 2008 impaired waters list developed by MPCA listed in Section 5.5 of
this report. Broadly, the TMDL process identifies the sources and relative load contributions of all inputs to a water
body for a given pollutant. Through this process, pollutant reduction strategies can be developed to allow a water
body to meet its designated use. Specifically, a TMDL is a calculation of the maximum amount of a pollutant that a
water body can receive and still meet its designated use, and anÐ>IIL@>QFLKÐLCÐQE>QÐ>JLRKQÐQLÐQEBÐMLIIRQ>KQgPÐPLRO@BP Ð
This calculation must also include a Margin Of Safety (MOS).
3.4.5 SFJBPWW
TATE AND EDERAL URISDICTIONAL OUNDARIES FOR UBLIC ETLANDS AND ATERS
Wetlands are delineated in accordance with the Federal Manual for Identifying and Delineating Jurisdictional
Wetlands (1987). Wetlands must have a predominance of hydric soils. Hydric soils, by definition, are inundated or
saturated by surface water or groundwater at a frequency and duration sufficient to support, under normal
circumstances, a prevalence of hydrophytic (water tolerant) vegetation typically adapted for life in saturated soil
conditions. The USACE and the BWSR regulate wetlands as defined by a jurisdictional delineation.
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 24
For wetlands that fall under the MnDNR jurisdiction, the Ordinary High Water Level (OHW) determines the boundary
of MnDNR jurisdiction. The OHW is established by the MnDNR.
3.5 AGENCY STORMWATER PUBLICATIONS
Best Management Practices (BMPs) are techniques, methods, and measures that prevent or reduce water pollution
from stormwater runoff. These practices may include regulations, structural features, and operation/maintenance
MOL@BAROBP Ð1EBÐ FQVÐLCÐ LQQ>DBÐ$OLSBÐTFIIÐ>ALMQÐQEBÐ*- gPÐ
as a guiding document for erosion and sediment control measures.
The Metropolitan Council has published the
(2001). This resource provides information on tools and techniques to assist
1TFKÐ FQVgPÐJRKF@FM>IFQFBPÐ>KAÐ4*Os in guiding development and redevelopment. The manual includes detailed
information on 40 BMPs that are aimed at managing stormwater pollution for small urban sites in a cold-climate
setting. The goal of the manual is to support the principles of accommodating growth while preserving the
environment.
Progress continues in the state for advancing BMPs and improving surface water conditions. In 2004, the MPCA
gathered representatives from nearly 30 public and private organizations to form the Minnesota Stormwater Steering
Committee. Among other tasks, this Committee was charged with guiding the development of state stormwater
performance criteria and recommended Best Management Practices for Minnesota. This result is the publication of a
in November 2005. This publication provides a state-sponsored and endorsed single
source reference that helps the everyday user better manage stormwater. Among other valuable information, it
provides BMP sizing criteria for different purposes including:
Recharge and infiltration
j
Water quality protection
j
Channel protection
j
Overbank flood protection
j
Extreme flood control
j
Finally, the South Washington Watershed District is in the process of developing a Standards Manual. This manual,
TEF@EÐBUFPQBAÐFKÐAO>CQÐCLOJÐ>QÐQEBÐQFJBÐQEBÐ FQVgPÐ-I>K was being developed, provides guidance on meeting the
MBOCLOJ>K@BÐBKAMLFKQPÐLRQIFKBAÐFKÐQEBÐ!FPQOF@QgPÐ
ÐMIan for managing runoff and protecting water resources.
Among other purposes, it is intended to provide guidance on the means and methods for achieving watershed
standards by providing technical guidancBÐLKÐPFWFKDÐ>KAÐPFQFKDÐPMB@FCF@Ð *-gPÐand quantifying the benefits of those
*-gPÐFKÐMLIIRQ>KQÐIL>AÐ>nd runoff volume reduction.
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 25
3.6 AGENCY CONTACTS
The primary contacts for local regulating agencies described above are presented below.
These contacts are accurate as of May, 2008.
South Washington Watershed District
2301 Tower Drive
Woodbury, MN 55125
Phone: (651) 714-3729
Fax: (651) 714-3721
Website: www.swwdmn.org
Lower St. Croix Watershed Management Organization
c/o Emmons and Olivier Resources
651 Hale Avenue North
Oakdale, MN 55128
Phone: (651) 770-8448
Fax: (651) 770-2552
Website: www.denmarktownship.org
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 26
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4.1 WATERSHED MANAGEMENT ORGANIZATIONS
There are two watershed management organizations which have regulatory authority within the city:
the South Washington Watershed District, which includes the majority of Cottage Grove, and the Lower St. Croix
Watershed Management Organization, which covers the eastern edge of the City. Both organizations have
developed Watershed Management Plans that include required standards for wetland protection and management.
&KÐQEBÐI>QBÐ
gP ÐQEBÐ0LRQEÐ4>PEFKDQLKÐ4>QBOPEBAÐ!FPQOFct began the process of creating a Wetland Management
Plan for the wetlands within the watershed. During the initial phases of that project, the wetlands within the SWWD,
including 82 of the approximately 140 wetlands within the City of Cottage Grove, were evaluated for specific
functions and values using a modified version of the Minnesota Routine Assessment Method (MnRAM) version 2.0.
In 2003, the SWWD sent the draft Wetland Management Plan for review; this document establishes standards for
wetland management including water quality, water quantity, and buffer widths. The wetland management
standards in this 2003 draft Wetland Management Plan has since been incorporated into the SWWD approved
Watershed Management Plan. As part of this SWMP, the city will adopt the standards of the SWWD for city wetlands
that are within the SWWD.
The LSCWMO Watershed Management Plan has requirements for pre- and post development function and values
assessments for wetlands, and has established management standards for wetlands. Buffer requirements are
included in the plan. Updated, performance based standards are anticipated within five years of the 2005 Watershed
Management Plan. As part of this SWMP, the city will adopt the standards of the LSCWMO for city wetlands that are
within the LSCWMO, including the updated performance based standards once they are developed.
4.2 WETLAND ASSESSMENT
1TLÐC>@QLOPÐABQBOJFKBÐ>ÐTBQI>KAgPÐPRP@BMQF?FIFQVÐQLÐA>J>DBÐfrom stormwater input: community type and community
quality (as measured by floral diversity). Some wetland community types, such as sedge meadows, are highly
susceptible to damage and degradation if exposed to repeated and/or extreme fluctuation in water levels (bounce).
Other community types, such as floodplain forests, contain PMB@FBPÐQE>QÐ>OBÐ>A>MQBAÐQLÐQEFPÐQVMBÐLCÐh?LRK@BiÐFKÐ
water levels and can tolerate stormwater impacts with fewer negative effects on the vegetation.
Similarly, the overall quality of the community affects how susceptible an area is to stormwater impacts. Because a
high quality area is more diverse, it is likely to contain species that are somewhat conservative in habitat. These
conservative species have a lower tolerance for disturbance and usually drop out of a community as disturbance
pressures increase. Thus, stormwater impacts can reduce the diversity at a site and alter the condition of good
quality areas. Since low quality areas, by definition, have reduced species diversity and tend to be dominated by
disturbance-adapted species, stormwater impacts are unlikely to cause further degradation at the site.
In order to provide appropriate management standards for each wetland, it is therefore essential to understand the
community type (for managing stormwater runoff quantity) and community quality (for managing stormwater runoff
quality). This information can be gained through completing a Functions and Values Assessment for each wetland for
which management standards are needed.
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 27
4.3 WETLAND MANAGEMENT STANDARDS
All of the inventoried wetlands within the SWWD study area were classified for management based on wetland type
and quality. For wetlands of moderate or low quality, other criteria such as floodplain management were also
considered when determining the wetland management class.
An additional category, Wetlands within Critical Stormwater Conveyance Corridor, was added by the City of Cottage
Grove. These wetlands lie within corridors in the Langdon, West Draw, and East Ravine Districts (as identified on
Map 3 in Appendix A) that are critical as regional conveyance features for stormwater from portions of the the cities
of Cottage Grove, Lake Elmo, Oakdale, Afton, and Woodbury. For example, the conveyance corridor in the Langdon
District is the ultimate conveyance route for over 7,800 acres (including 600 acres from the City of Woodbury) and
the East Ravine District is the ultimate conveyance route for over 20,000 acres (including 14,500 acres from the
Cities of Woodbury, Lake Elmo, Oakdale, and Afton). In addition, these corridors have been part of the regional
PQLOJT>QBOÐ@LKSBV>K@BÐPQO>QBDVÐPFK@BÐ LQQ>DBÐ$OLSBgPÐfirst surface water management planning efforts. Finally,
significant regional rate control will need to be accomplished in order to protect the integrity of steep ravines at the
lower end of each corridor that carry the regional discharge to the Mississippi River. There are no viable alternatives
to these major regional conveyance routes.
Flexibility for using these wetlands for stormwater management is also critical for preservation of the ecological value
in other priority natural areas, including corridors near the Grey Cloud Dunes, along the terraces adjacent to the
Mississippi River, and in portions of the Cottage Grove East Ravine. Certain wetland management standards are
adjusted for wetlands within a Critical Stormwater Conveyance Corridor to allow maximum flexibility in their
management. The adjustment of these standards will be based on a mutual agreement between the City and
SWWD. A summary of the management classes, and the number of wetlands in each class, is presented in Table 4.1.
Table 4.1 Wetland Management Classification
Number of
Management Classification
Wetlands
Stormwater Conveyance 10
Protect 23
Manage I 21
Manage II 15
Filled 9
No Access 1
Lake 3
The wetland management standard categories identified in Table 4.3 include:
Water Quality Protection
j
Water Quantity Protection
j
Buffer Zones
j
Wetland Mitigation
j
The LSCWMO also has developed wetland management standards; at this time these are not based on wetland
functions and values, but rather apply to all wetlands within the jurisdiction of the LSCWMO. The following sections
provide details of each protection strategy developed for wetlands within the City.
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 28
4.3.1 WQ
ATER UALITY
Increased pollutant loads to wetlands, especially nutrients and sediments, are a significant contributing factor to the
degradation of diverse wetland systems. Some provision for water quality treatment before stormwater discharges
into wetlands must be addressed. Since phosphorus is an important nutrient and is related to the removal of other
contaminants, stormwater pretreatment for phosphorus is required for different wetlands depending on what is
necessary to preserve their functional values.
In order to preserve those systems that still possess higher functional values for wildlife habitat and floral
diversity/integrity, a stricter standard based on phosphorus loads is required. As discussed for lakes, wetland can
serve as nutrient sinks, thus loads become important rather that just concentrations. Increased nutrient loading can
affect the plant community of a wetland and therefore a more restrictive total loading standard is needed for Protect
and Manage 1 wetlands. This is importaKQÐPFK@BÐQEBÐTBQI>KAgPÐCRK@QFLK>IÐS>lue is highly dependent on the plant
community quality. Wet detention ponding along with other BMPs can be used to accomplish the pretreatment
requirements of the standards given in Table 4.3.
4.3.2 WQ
ATER UANTITY
The State of Minnesota Stormwater Advisory Group has prepared a technical paper,
, which divides wetland community types into the categories of highly susceptible, moderately susceptible,
slightly susceptible, and least susceptible. This document was used as a guideline for developing protection
standards for each wetland in the city, and for developing overall stormwater susceptibility ranking. A summary of
different community types and their susceptibility to stormwater impacts is provided in Table 4.2.
Table 4.2 k Wetland Community Susceptibility to Stormwater Impacts*
Highly Moderately Slightly Susceptible Least Susceptible
Wetland Types Wetland Types Wetland Types Wetland Types
Sedge Meadow Shrub-carrs Floodplain Forests Gravel Pits
Open Bogs Alder Thickets Fresh (Wet) Meadows Cultivated Hydric Soils
Dredged Material/
Coniferous Bogs Fresh (Wet) Meadows Shallow Marshes
Fill Material Disposal Sites
Calcareous Fens Shallow Marshes Deep Marshes
Low Prairies Deep Marshes
Coniferous Swamps
Lowland Hardwood Swamps
Seasonally Flooded Basins
*Guidance for Evaluating Urban Storm Water and Snowmelt Runoff Impacts to Wetlands (Minnesota Storm Water Advisory
Group, 1997)
4.3.3 B
UFFERS
The wetland standards in Table 4.3 call for the establishment of buffer zones around wetlands. For wetlands
within the SWWD, the Wetland Management Classification provides buffer zone widths designed to preserve the
functions and related values of eachÐ?>PFK Ð4BQI>KAPÐTFQEFKÐQEBÐ)0 4*,ÐOBNRFOBÐ>Ð
gÐ>SBO>DBÐ
gÐJFKFJRJÐ
width) buffer of native vegetation, and must include areaPÐLCÐPQBBMÐPILMBÐÐÐTFQEFKÐ
gÐLCÐQEBÐTBQI>KA ÐÐ
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 29
A buffer of undisturbed vegetation around a wetland can provide a variety of benefits. The buffer can consist of
trees, shrubs, grasses, wildflowers, or a combination of plant forms. Buffers reduce the impacts of surrounding land
uses on wetland functions by stabilizing soil to prevent erosion; filtering solids, nutrients, and other harmful
substances; and moderating water level fluctuations during storms. Buffers also provide essential habitat for feeding,
roosting, breeding and rearing of young birds and animals; and cover for safety, movement and thermal protection
for many species of birds and animals. Buffers can reduce problems related to human activities by blocking noise and
glare from lights, and reducing disturbance. Even a 10-20 foot buffer (depending on the slope steepness) of tall
vegetation can provide some water filtering benefits, but wider buffers will provide additional water quality and
habitat benefits.
Buffers can be planned to tie important upland habitats to wetlands, or connect wetlands and other waters.
Since many animal species require both wetland and upland habitats as part of their life cycles, and also require
opportunities to move to escape predators or find food and cover, buffers should be planned to maximize these
connections. Buffers will be most effective if the landowners around a wetland make a continuous buffer, and
connect desirable wetland and upland habitats.
Cutting vegetation, dumping grass clippings or other debris, and trampling should be avoided in buffer areas. If a
path is desired through the buffer, it should be mown only as wide as necessary for walking, and gently meandered
so that it does not encourage erosion or carry sediments and nutrients from surrounding areas to the wetland.
4.3.4 WM(ASWWDWMP)
ETLAND ITIGATION DAPTED FROM THE
Regardless of wetland classification, loss of wetland area (i.e. impacts) will be mitigated (i.e. replaced) on-site
whenever practical. The project applicant is responsible for demonstrating that on-site mitigation is not technically
feasible or sound by a sequencing analysis. Where on-site replacement is determined unsuitable, replacement of
wetland impacts shall be located within the hydrologic subwatershed; if location within the subwatershed is not
feasible, mitigation should occur within the watershed. Where on-site replacement is not appropriate or possible,
wetland replacements will target areas which exhibit flood prone conditions. Credits will be allowed for mitigating
wetland impacts.
Excavation of a Manage 2 class wetland is not considered an impact for purposes of this WMP, unless that
excavation occurs in a Type 3, 4, or 5 wetland, or results in conversion to a deepwater habitat. However, Minnesota
Rule 7050.0201 subpart 13a protects wetlands from physical alterations to prevent significant adverse impacts to
designated uses as determined by the State. Replacement of wetland impacts on projects by public road authorities
are provided through the State wetland bank, or through a separate wetland bank managed by the Minnesota
Department of Transportation Metro Division. Impacts to wildlife habitat are difficult to quantify, therefore,
mitigation of wildlife impacts will be accomplished through maintaining connectivity to surrounding habitat areas.
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 30
4.4 SUMMARY OF WETLAND MANAGEMENT STANDARDS
Table 4.3 summarizes the management standards that the City will adopt for each wetland management
classification for wetlands within the SWWD.
Table 4.3 k Wetland Management Standards for Wetlands within SWWD
Within a Critical
Criteria Protect Manage I Manage 2 Stormwater Conveyance
Corridor
Water Quality
60% post- 60% post-
Phosphorus Inflow Load Maintain Based on Management
development development
(average annual pounds) predevelopment Classification
load reduction load reduction
Water Quantity
Storm bounce Existing plus
12
ExistingNo limit To be determined
1.0 foot
10-year rainfall (4.2-inch)
Discharge rate (inflow)
12
2-year (2.8-inch) & Existing Existing or less Existing or less To be determined
100-year (6.3-inch) rainfall
Inundation period Existing plus Existing plus
12
ExistingTo be determined
1-year rainfall (2.4-inch) 2 days 7 days
Inundation period Existing plus Existing plus
12
ExistingTo be determined
2-year rainfall (2.8-inch) 14 days 14 days
0 to 1.0 feet 0 to 40 feet
Run-out control elevation
Based on Management
No change above existing above existing
(free flowing) Classification
run out run out
Run-out control elevation Based on SWWD Based on SWWD Based on SWWD Based on Management
(landlocked) Floodplain Map Floodplain Map Floodplain Map Classification
Buffer Width
Based on Management
Wetlands <1 acre 75 feet 50 feet 25 feet
Classification
Based on Management
Wetlands >1 acre 100 feet 75 feet 50 feet
Classification
Impact Mitigation
Based on Management
Area replacement ratio 3:1 2:1 2:1
Classification
Based on Management
Volume replacement ratio 2:1 2:1 2:1
Classification
1
h"UFPQFKDiÐJB>KPÐQEBÐBUFPQFKDÐEVAOLILDF@Ð@LKAFQFLKP Ð&CÐQEBOBÐhave been significant changes in conditions, it means the
conditions which established the current wetland.
2
This standard will be determined at a later time based on a mutual agreement between the City and SWWD.
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 31
For wetlands within the LSCWMO, the City will follow rules of the LSCWMO (provided in Appendix F) that pertain to
wetlands, including:
Support the administration of the Wetland Conservation Act.
j
Overall function and value of wetlands on a site must be maintained.
j
A 30 foot average buffer must be maintained; a 20 foot minimum is required, and buffer averaging may be used
j
QLÐ>@EFBSBÐQEBÐ
gÐ>SBO>DB Ð RCCBOPÐJRPQÐ?BÐBUM>KABAÐQLÐFK@IRABÐPQBBMÐPILMBPÐÐIL@>QBAÐTFQEFKÐ
gÐ
horizontal of the wetland.
Pretreatment of stormwater per the requirements of the General Construction Permit prior to discharging into
j
wetlands.
4.5 PROCEDURES FOR WETLANDS NOT INVENTORIED
Roughly 2/3 of the wetlands within the city were inventoried by the SWWD in 1998. The approximately 42
remaining, non-inventoried wetlands are primarily in the eastern third of the City (Sections 1, 12, 13, 23, 24, 25, 26,
and 34-36). Additional non-inventoried wetlands can also be found in Sections 3, 5, 7, and 19.
To meet Met Council requirements for the 2008 Comprehensive Plan Updates, the city needs to establish a
procedure for completing a function and value assessment of all non-assessed wetlands, either through a complete
inventory of all remaining wetlands or via a phased approach. With a phased approach, the completion of the
wetland function and value assessment process will be driven by development, with the process occurring in
conjunction with development. All future wetland function and value assessments will be done in accordance with
the methods outlined in Minnesota Routine Assessment Method Version 3.1 (MnRAM), or the most current version
at the time of the assessment.
The East Ravine AUAR did not include a wetland assessment, but most of the AUAR project area is within the
SWWD and has been covered in their assessments. Depending on the timeline for expansion into the East Ravine
AUAR area and other undeveloped areas of the city, the City will likely take the approach of assessing the remaining
non-inventoried wetlands in these areas as development activity is occurring. As the assessment of the remaining
non-inventoried wetlands proceeds, the City may want to coordinate with the LSCWMO. The LSCWMO has
jurisdiction over most of the remaining non-inventoried wetlands within the city, and is considering completing an
assessment within the next 3 years.
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 32
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5.1 BACKGROUND
0FK@BÐQEBÐB>OIVÐ
gP ÐQEBOBÐE>PÐ?BBKÐ>Ð@LKPFABO>?IBÐFK@OB>se in the number and rigor of rules and programs at the
state and federal level pertaining to water quality protection of surface and groundwater resources. In addition, the
watershed management organizations that include the City of Cottage Grove within their jurisdiction have also
adopted increasingly stringent control measures to protect water quality. The watershed management organizations
have identified priority surface water resources within their jurisdictions that they believe merit specific levels of
water quality protection. As part of their updated watershed plans, both the SWWD and the LSCWMO have adopted
management standards for designated priority waters in Cottage Grove.
Approximately 20% of the City was developed prior to the onset of more stringent water quality regulations
L@@ROOFKDÐFKÐQEBÐB>OIVÐ
gP Ð1EBPBÐ>OB>PÐLCÐQEBÐ FQV ÐFK@Iuding portions of the Central, East, St. Paul Park, and
Thompson Grove Districts, provide only minimal stormwater ponding facilities, with the focus of these facilities being
primarily flood control, not water quality treatment. The City has developed a list of water quality related system
improvements used to guide the City in retrofitting these older portions of the City. Further discussion about the
water quality improvements list is covered in Section 5.3 of this chapter.
This chapter will identify the priority waters and management standards applying to those waters. This chapter will
also present information on the state and federal programs which most directly affect how the City manages its
water resources to protect water quality.
5.2 RECEIVING WATER CLASSIFICATION
As part of its 2007 Watershed Management Plan, the SWWD adopted a receiving water classification system and
associated management standards. The receiving water within the Cottage Grove portion of the SWWD for which
the SWWD has adopted standards are summarized in Table 5.1.
A detailed explanation of the SWWD Management Classification categories can be found in its plan (SWWD 2007).
The designated beneficial use for each receiving water is based on Minnesota Rule 7050, which classifies virtually all
waters in the state. The designated beneficial use for Class 2B waters is for cool and warm-water fisheries. For Class
2C waters, it is for indigenous fish and associated aquatic communities. Finally, for Class 3B, it is for industrial
consumption. Finally, it should be noted that maximum allowable load information developed by the SWWD is
subject to modification as a result of more detailed studies, such as TMDL analyses.
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 33
Table 5.1 k SWWD Classified Receiving Waters and Management Standards for Cottage Grove
SWWD
City Designated
Lake/River Management Comments
Designation Beneficial Use
Classification
Not on impaired waters list. No
standards due to lack of sufficient data.
Gables Lake GL-P1 Class D Class 2B
Watershed is privately owned and not
expected to develop.
Is listed as an impaired water. Maximum
Ravine Park allowable Total Phosphorus (TP) unit
ER-P5.4 Class B Class 2B
Lake load goal has been established for
watershed by SWWD.
Is listed as an impaired water. SWWD
Mississippi
N/A Class A Class 2C, 3B has not yet established a maximum
River
1
allowable TP unit load goal.
1
According to the adopted 2007 SWWD WMP
In its June 2005 Watershed Management Plan, the LSCWMOÐFABKQFCFBAÐ,g LKKBOgPÐ OBBHÐ>KAÐQEBÐ*FPPFPPFMMFÐ/FSBOÐ
as water resources within the City of Cottage Grove that they consider key surface water features for protection.
The LSCWMO plan does not adopt standards specific to these resources, but has adopted a set of rules that will be
applied everywhere in the watershed to provide for protection of these and other resources. As summarized in
0B@QFLKÐ ÐLCÐQEFPÐMI>KÐ>KAÐMOBPBKQBAÐFKÐQEBÐ,g LKKBOgPÐ0QOB>JÐ>KAÐ)>HBÐ*>K>DBJBKQÐ-I>KÐ)0 4*,Ð
Ð
these provisions include no net increase in phosphorus loads, runoff volumes, or runoff rates above pre-development
conditions for development activities disturbing more than 1 acre of land.
It should be noted that there are currently no treatmentÐ *-gPÐ>PPL@F>QBAÐTFQEÐQEBÐ FQVgPÐ*0ÐPVPQBJÐFKÐQEBÐ
)0 4*,Ð?RQÐQE>QÐ *-gPÐTEF@EÐJBBQÐLOÐBU@BBAÐQEBÐ)0 4*,Ðrules and protection standards will be implemented as
development activities proceed.
5.3 SYSTEM IMPROVEMENTS FOR WATER QUALITY
In 2000, a list of water quality-related system improvements was developed to guide City efforts in this area.
The projects listed as well as estimated costs to implement the projects are presented in Appendix G at the back of
this report. Most of the improvements involve removal of accumulated sediment and expansion of pond wet volumes
to enhance pollutant removal performance of the ponds. In some cases, berms within the ponding areas were
proposed to improve stormwater circulation in the pond with the intent of enhancing performance. The water
quality-related system improvement appendix is adopted by reference for this report, but should be reviewed and
re-evaluated in the context of new regulations, requirements, and priorities that have arisen since it was developed,
including NPDES nondegradation and TMDLs (covered later in this chapter).
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 34
5.4 WATER QUALITY CASH DEDICATION
Greater impervious coverage associated with new development or redevelopment activity places additional burdens
on the storm drainage system by increasing the rate and volume of runoff. This in turn increases the amounts of
pollutants exported from a development site. Existing or expanded storm drainage systems needed to serve the
developed area provide an efficient means of delivering these higher pollutant loads to downstream receiving
waters. Unless these pollutant loads are reduced, downstream receiving waters will be degraded over time as a
result of development.
The City of Cottage Grove recognizes its responsibility to protect priority water resources from adverse impacts due
to increases in land use intensity caused by development and redevelopment activities.
To minimize the impacts of development on Cottage GrovBgPÐMOFLOFQVÐT>QBOÐ?LAFBP ÐABvelopment and redevelopment
activity shall be subject to water quality mitigation requirements as outlined in the policies under Goal #6 in Chapter 3.
Where applicable mitigation requirements are determined infeasible to be fully met on-site, this plan also includes
provisions for collecting water quality cash dedications under certain situations and dedication of the revenue from
such collections to help finance system requirements related to stormwater quality and runoff volume control. The
following is intended to better define under what conditions the City can collect a cash dedication and how it will be
calculated:
1.To the maximum extent practical, the volume control standards presented in this plan should be fully met on-
site. However, infiltration as a volume control measure may be undesirable or impossible because of site
conditions as outlined in Policy 6.2.
2.If the applicant claims that infiltration is not feasible or it is not allowable on-site, the applicant must provide
supporting documentation and follow the Alternative Compliance Sequencing as outlined in Policy 6.2.
3.If the applicant has followed the Alternative Sequencing procedure and the full infiltration requirement
applicable to the site is still not met, the applicant will pay a cash dedication as a last resort for mitigation.
4.The procedure for calculating the appropriate cash dedication amount is as follows:
1EBÐSLIRJBÐLCÐiÐLCÐORKLCCÐCOLJÐQEBÐQLQ>IÐFJMBOSFLRPÐ@LSBO>DBÐLCÐQEBÐPFQBÐTFIIÐ?BÐ@>I@RI>QBA Ð
j
An average depth of temporary ponding of 2 feet will be used to convert the volume of infiltration required
j
to an area required for the theoretical infiltration feature.
The City Council each year will adopt a unit land area price for each type of land use and a unit infiltration
j
feature construction price that will be applied to the area of the hypothetical infiltration feature necessary to
accommodate the runoff volume. The sum of the two components will be the cash dedication for the
project.
To the extent that a percentage of the infiltration volume can be met by the development, the infiltration
j
cash dedication will be based on the shortfall on a pro-rata basis.
5.For-re-development projects, when the total impervious area on the site is increased by any amount, the cash
dedication will be based on the total impervious coverage of the site after re-development. The purpose of this
standard is to discourage net increases in impervious coverage for re-development.
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 35
6.For the year 2008, the recommended rates are as follows:
2
Construction/installation cost: $11/ft
j
Cost per acre for calculated infiltration feature surface for specific land types:
j
Residential $150,000/ac.
o
Schools and Churches $267,900/ac.
o
Industrial $117,600/ac.
o
Commercial $357,200/ac.
o
7.The proceeds from the cash dedication will be ear-marked exclusively to finance water quality and runoff volume
reduction improvements in the City.
8.Example cash dedication amounts based on this procedure are as follows:
Five acre new low-density residential development (20% impervious) - $26,185
j
Five acre new commercial development (75% impervious) - $130,680
j
Five acre new commercial development (75% impervious Ð@>KÐFKCFIQO>QBÐLKIVÐ
iÐLCÐORKLCCÐLKÐQEBÐPFQBÐ
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FKPQB>AÐLCÐiÐLCÐORKLCCÐ
Ð ÐÐ
Two acre commercial re-development project (impervious coverage increased from 75 percent to 80
j
percent) - $52,272
Two acre commercial re-development project, no impervious increase - $0
j
9.The Alternative Sequencing Procedure and cash dedication will be in effect only for those areas outside the
jurisdiction of the LSCWMO (which already has its own sequencing procedure) until such time as the SWWD
develops and adopts a system with which the City must comply.
5.5 TOTAL MAXIMUM DAILY LOADS AND IMPAIRED WATERS
Several waters within the City as well as the Mississippi River adjacent to its southern border are listed on the state
impaired waters list. Known as the 303(d) list from the applicable section of the federal Clean Water Act, these
waters are ones that do not currently meet their designated use due to the impact of a particular pollutant or
stressor. If monitoring and assessment indicate that a waterbody is impaired by one or more pollutants, it is placed
on the list. At some point a strategy would be developed that would lead to attainment of the applicable water
quality standard.
The process of developing this strategy is commonly known as the Total Maximum Daily Load (TMDL) process and
involves the following phases:
1.Assessment and listing
2.TMDL study
3.Implementation plan development and implementation
4.Monitoring of the effectiveness of implementation efforts
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 36
Responsibility for implementing the requirements of the federal Clean Water Act falls to the U.S. Environmental
Protection Agency. In Minnesota, the EPA delegates much of the program responsibility to the state Pollution Control
Agency. Information on the MPCA program can be obtained at the following web address:
http://www.pca.state.mn.us/water/tmdl/index.html. The following is an excerpt from the MPCA website describing
the program and its need:
Table 5.2 lists the 303(d) impaired waters within the City of Cottage Grove and Figure 5.1 shows the location of
these waters in the City.
Table 5.2 k 303(d) List of Impaired Waters within the City of Cottage Grove
Year TMDL
City Ponding Assessment
Water Body First Affected Use Pollutant or Stressor start/
Designation Unit ID #
Listed complete
Unnamed Creek N/A 2002 07010206-517 Aquatic life Fish Bioassessments 2010/2014
Aquatic Nutrient/Eutrophication
Ravine Park Lake ER-P5.4 2006 82-0087-00 2015/2019
recreation Biological Indicators
Aquatic
1
1998 07010206-509 Mercury water column 1999/2011
consumption
Mississippi River Aquatic
1,2
1998 07010206-509 Mercury FCA 1999/2011
(Rock Island RR bridge N/A consumption
to Lock and Dam #2)
Aquatic
2
2002 07010206-509 PCB FCA 2002/2015
consumption
1998 07010206-509 Aquatic life Turbidity 2008/2011
1
A state-wide mercury TMDL study was approved in 2008
2
FCA stands for Fish Consumption Advisory and is thus not an independent pollutant or stressor. Source: MPCA
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 37
Figure 5.1 k Impaired Waters
The absence of a waterbody from the 303(d) list does not necessarily mean the waterbody is meeting its designated
uses. It may be that it has either not been sampled or there is not enough data to make an impairment
determination. Additionally, where mercury is identified as a stressor, the TMDL approach will be regional in nature
as mercury is most commonly an air-borne pollutant.
It is notable that as part of the Lower Minnesota River dissolved oxygen TMDL, the MPCA in their August 2005
implementation plan draft is planning to mandate that municipalities with MS4 permits in that drainage reduce by
30% the load of phosphorus in their urban stormwater runoff. While this does not affect the City of Cottage Grove
directly (since it is not within the Minnesota River basin), the City could be dramatically affected if similar approaches
CLOÐ1*!)gPÐ>OBÐFJMIBJBKQBAÐQLÐMOLQB@QÐALTKPQOB>JÐOBPLROces of the Mississippi River, such as Lake Pepin.
For impaired waters whose watersheds extend into adjacent communities, the City may request the appropriate
jurisdictional WMO to take the lead (with the City participating as needed) or to co-facilitate the completion and
FJMIBJBKQ>QFLKÐLCÐQEBÐ1*!) Ð#LOÐ1*!)gPÐQE>QÐE>SBÐOBDFLKal implications and potentially major implications for
Cottage Grove (e.g., any of the Mississippi River TMDLs), the City will cooperate with lead agencies. Part of this
involvement will be aimed at assuring due acknowledgement and consideration is granted the City for its past efforts
to control urban nonpoint source inputs to the impaired water.
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 38
5.6 NPDES MS4 PERMIT PROGRAM
In 2003, the Minnesota Pollution Control Agency required the City to submit an NPDES Permit Application to
minimize the discharge of stormwater runoff pollutants >KAÐ>RQELOFWBÐPQLOJT>QBOÐAFP@E>ODBÐCOLJÐQEBÐ FQVgPÐ
Municipal Separate Storm Sewer System.
The MPCA also required the City to prepare and submit a Stormwater Pollution Prevention Program (SWPPP).
The SWPPP identifies a combination of stormwater Best Management Practices (BMPs), including education,
maintenance, control techniques, system design and engineering methods, and such other practices, both existing
and planned, determined appropriate to meet the NPDES Permit requirements.
The Cottage Grove SWPPP includes 37 BMPs in the following categories or Minimum Control Measures:
1.Public Education and Outreach
2.Public Participation and Involvement
3.Illicit Discharge Detection and Elimination
4.Construction Site Runoff Control
5.Post-Construction Runoff Control
6.Pollution Prevention/Good Housekeeping
Each year of the 5-year permit cycle, the City must conduct an Annual Public Meeting and submit an Annual Report
to the MPCA which summarizes:
1.The status of compliance with Permit conditions;
2.Assessment of the appropriateness of the BMPs;
3.Progress towards achieving the measurable goals for each of the minimum control measures;
4.Stormwater activities planned for the next reporting cycle;
5.A change in any BMP or measurable goals for any of the minimum control measures; and
6.A notice that the City is relying on another entity to satisfy some of the Permit obligations (if applicable).
The BMPs listed in the SWPPP are a legally enforceable part of the Permit. The City must complete the tasks and
milestones to remain authorized to discharge stormwater into waters of the state.
5.6.1 N
ONDEGRADATION
Appendix D of the revised MS4 permit addresses nondegradation requirements for stormwater management.
This aspect of the permit imposes additional requirements on thirty MS4 permittees to complete a nondegradation
report before revising their SWPPP. The City of Cottage Grove is one of the thirty cities identified by MPCA to which
these requirements apply. The following is a list of the submittal components of the overall nondegradation review,
as required by the MPCA:
Loading assessment
j
Nondegradation report
j
Proposed SWPPP modifications to address nondegradation
j
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 39
Public and local water authority comments on the proposed SWPPP modifications to address nondegradation,
j
with a record of decision on the comments
Application to modify the permit
j
Based on the MS4 permit adopted by the MPCA in February 2006, the City of Cottage Grove submitted its
nondegradation plan along with any modifications to its SWPPP to the MPCA for review and approval on
February 1, 2008.
5.7 RECOMMENDATIONS
Following are recommendations related to this chapter of the SWMP:
1.Adopt the classification scheme and management standards outlined above for Gables Lake, Ravine Park Lake
and the Mississippi River as identified in the adopted 2007 Watershed Management Plan by the SWWD.
2.Re-evaluate/update the list of water quality-related system improvements developed in 2000 and included in
Appendix G in light of changes in regulatory emphasis and management priorities. Complete the re-
evaluation/update within one year of date of adoption of this plan by the City Council.
3.Adopt the water quality cash dedication calculation methodology outlined in this chapter, and review and - as
necessary - adopt unit costs each year for land dedication, outlet appurtenance, and excavation as a basis for
calculating the total water quality cash dedication when it is applied.
4.+LQBÐQEBÐFABKQFCF@>QFLKÐLCÐ,g LKKBOgPÐ OBBHÐ>KAÐQEBÐ*FPPFssippi River as high priority waters by the Lower St.
Croix Watershed Management Organization and comply with applicable LSCWMO requirements and state
requirements to provide an adequate level of protection to these resources.
5.Cooperate with state and local entities as needed to ABSBILMÐ>KAÐFJMIBJBKQÐ1*!)gPÐfor listed impaired waters
within the City.
6.Plan for implementation of the nondegradation plan and revisions to the SWPPP once review and approval of
the plan is completed by the MPCA.
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 40
"(38Ð.%Ð".33 &$Ð&1.5$ÐmÐ241% "$Ð6 3$1Ð, - &$,$-3Ð/+ -Ð
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6.1 TECHNICAL BACKGROUND
Stormwater facilities are an essential part of the development of any municipality. As an area develops from rural
uses to urban uses, culverts and drainage ways that were adequate for rural runoff become overloaded, causing
flooding that frequently results in property damage.
The primary functions of an urban storJT>QBOÐPVPQBJÐ>OBÐQLÐMOLQB@QÐQEBÐNR>IFQVÐLCÐ>Ð@LJJRKFQVgPÐT>QBOÐOBPLRO@BPÐ
and to reduce economic loss and inconvenience due to the periodic flooding of streets, buildings and low-lying
areas. The desirable economic endpoint is reached when the cost of environmental impacts and damage attributable
to storm flooding plus the cost of surface water facilities reaches a minimum. Economy is not the only consideration,
since well-designed surface water facilities also improve aesthetics, wildlife habitat, and recreational opportunities.
If a planned program of storm drainage construction is established and implemented in the early development stages
of a drainage basin, the most economical stormwater system will be achieved. The substantial cost of duplication
and waste arising from storm sewer construction or reconstruction after an area is developed can also be avoided.
Trunk storm sewers and ponding areas can then be incorporatBAÐFKQLÐ>ÐABSBILMBOgPÐMI>KÐ>PÐOBNRFOBA Ð*>MÐÐ>QÐQEBÐ
BKAÐLCÐQEFPÐOBMLOQÐFABKQFCFBPÐQEBÐ FQVgPÐBUFPQFKDÐQORKHÐC>@Flities, as well as proposed facilities to act as a guide as
development occurs.
6.1.1 DS
ESIGN TORM
Stormwater runoff is defined as that portion of precipitation which flows over the ground surface during, and for a
short time after, a storm. The quantity of runoff is dependent on the following:
Intensity of the storm event
j
Amount of antecedent rainfall
j
Length of storm
j
Type of surface upon which the rain falls
j
Slope of the ground surface
j
The intensity of a storm is described by the amount of rainfall that occurs over a given time interval. Storms are
typically characterized by their return frequency. A return frequency designates the average time span during which a
single storm of a specific magnitude is expected to recur. Thus, the degree of protection afforded by storm sewer
facilities is determined by selecting a return frequency for analysis.
The following return frequencies are required by the Cottage Grove SWMP for sizing trunk facilities:
5-year Rational Method for storm sewer design
j
100-year, 6.3-inch 24-hour (Type II distribution) event for overland drainage and pond storage design
j
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 41
As development occurs in Cottage Grove, actual storm sewer design should be a 5-year minimum recurrence for
lateral, or local, systems in residential and commercial areas. This implies that no street, parking lot, or backyard
ponding would occur for the 5-year design event. Trunk facilities should be analyzed and designed to accommodate
the 100-year ponded discharges plus 5-year rational flows from areas that enter the trunk to be carried to the next
storage area downstream.
The excess runoff caused by storms greater than the 5-year will be accommodated by transient street ponding and
overland emergency overflow (EOF) routes. The City requires that these EOF routes be identified on the grading plan,
in accordance with Policy 2.2. During the City development review process, the City will ensure that these EOF routes
provide the necessary protection to proposed properties within the development and downstream properties.
In general, complete protection against large, infrequent storms with return intervals greater than 100 years is only
justified for important flood control projects. For most developing areas like Cottage Grove, the cost of constructing
a large capacity storm drainage system (for events greater than the 100-year) is much greater than the amount of
property damage that would result from flooding caused by a larger than 100-year event occurring in a system
designed for the 100-year event.
6.1.2 HDP
YDROLOGIC ESIGN ARAMETERS
Table 6.1 provides Natural Resources Conservation Service (NRCS) Curve Number (CN) values and runoff coefficients
used in the SWMP to quantify runoff from future land uses. As noted earlier, the predominant Hydrologic Soil Group
(HSG) within the study area is HSG A to HSG B. The CN values in Table 6.1 reflect HSG B, with average soil moisture
conditions (Antecedent Moisture Condition II).
Table 6.1 k Runoff Coefficients and Curve Numbers Assumed for Future Land Use
Runoff Coefficient C
Land Use Type CN Value
5-Year
Bluff/Ravine 0.14 55-58
Public/Open Space 0.17 61
Rural Residential 0.23 66
Low Density Residential 0.38 75
Medium Density Residential 0.59 85
High Density Residential 0.66 88
Commercial/Industrial 0.71 90
Ponds 1.0 100
Special As required by the City Engineer
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 42
For the areas within the City containing primarily HSG A soils, the CN values within Table 6.1 for certain land use
types (Bluff/Ravine, Park/Open Space, Rural Residential and ROW) may be lowered to reflect soils with a higher
infiltration rate. However, it is assumed that the pervious surfaces for more urban land use types (Urban Residential
and Commercial/Industrial) containing primarily HSG A will actually generate runoff depths similar to that of HSG B
soils, due to factors such as:
Compaction of the soil surface layer during construction
j
Placement of topsoil and sod to retain soil moisture and promote healthy turf establishment
j
Efficiently graded lots, limiting the amount of runoff allowed to pool on the landscape and infiltrate.
j
The CN values presented in Table 6.1 should be adjusted for site specific conditions based on the site percent
impervious surface, as necessary. Generally, these calculations should assume a CN value of 61 for site pervious
areas. In addition, the SWWD watershed management plan requires a maximum pre-development non-urban land
use value of 62 be used. Additional information regarding recommended hydrologic design parameters can be
found in both the SWWD Standards Manual and the LSCWMO Rules (see Appendix F).
In addition to identifying the land use type for a specified area, the determination of the amount of runoff generated
from that area also requires the estimate of a time of concentration. The time of concentration is the time required
for the runoff from a storm to become established and for the flow from the most remote point (in time, not
distance) of the drainage area to reach the design point. The time of concentration will vary with the type of surface
receiving rainfall and the slope of the surface. Generally, a time of concentration no less than 10 minutes should be
used for the design of stormwater systems.
6.1.3 CSDP
ONVEYANCE YSTEM ESIGN ARAMETERS
The following standards apply to all new conveyance system designs:
The capacity of a storm sewer is dependent on the pipe slope, pipe diameter, and roughness of the inner surface
j
of the pipe. Computations for storm sewer capacity have been based on Manning's equation. For the purposes
LCÐPQLOJÐPBTBOÐABPFDK Ð>Ð*>KKFKDgPÐOLRDEKBPPÐ@LBCCF@FBKQÐKÐLCÐ
ÐPELRIAÐ?BÐRPBAÐCLOÐ@LK@OBQBÐPQLOJÐPBTBOÐ
pipe and 0.024 for corrugated metal pipe. These roughness coefficients take into account typical losses due to
bends and manholes in the system as well as the roughness of the inner pipe surface.
Proper design of a storm sewer system requires that all sewer lines be provided with access through manholes
j
for maintenance and repair operations. Generally, spacing of manholes should be no greater than 400 feet.
Intervals on larger diameter lines can be increased when the pipes are sufficiently large for a person to physically
enter the storm sewer pipe for maintenance operations. Regardless of sewer size, manholes should normally be
provided at all junction points and at points of abrupt alignment or grade changes.
The design of multiple low points on streets is desirable to reduce catch basin bypass and distribute street
j
ponding. For safety reasons, the maximum depth should not exceed two feet at the deepest point, and the
lowest exposed building elevation should be at least one foot above the elevation to which water rises before
overflowing through adjacent overland routes.
Generally, inlets should be placed and located to eliminate overland flow in excess of 400 feet on all streets or a
j
combination of streets and swales. Additionally, inlets should be located such that 3 cubic feet per second (cfs)
is the maximum flow at the inlet for the 5-year design storm.
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 43
Effective energy dissipation devices or stilling basins to prevent stream bank or channel erosion at all
j
stormwater outfalls should be provided. The following recommendations should be kept in mind when
designing an outlet:
Inlet and outlet pipes of stormwater ponds should be extended to the normal water level whenever
o
possible.
Outfalls with velocities of less than 4 feet per second (fps) that project flows downstream into the channel
o
in a direction 30 degrees or less from the normal channel axis generally do not require energy dissipaters or
stilling basins, but do require riprap protection.
Outfalls with velocities between 4 and 6 fps should include a designed riprap energy dissipation outlet.
o
Where outlet velocities exceed 6 fps, the design should be based on the unique site conditions present.
o
Submergence of the outlet or installation of a stilling basin approved by the City is required when excessive
outlet velocities are experienced.
Riprap should be provided at all outlets to an adequate depth below the channel grade and to a height
o
above the outfall or channel bottom. It should be placed over a suitably graded filter material and filter
fabric to ensure that soil particles do not migrate through the riprap and reduce its stability. Riprap should
be placed to a thickness at least 2.5 times the mean rock diameter so as to ensure that it will not be
undermined or rendered ineffective by displacement.
Overland drainage routes where velocities exceed 4 fps should be reviewed and approved by the City.
o
Whenever possible, a minimum slope of 2% should be maintained in unlined open channels and overland
j
drainage routes. Side slopes should be a maximum of 4:1 (horizontal to vertical) with gentler slopes being
desirable. Where space permits slopes should be cut back to match existing grade. In general, the flatter the
channel side slopes and the more meandering the channel alignment, the more natural the channel will appear.
Sanitary sewer manholes that could be subject to temporary inundation, due to their proximity to ponds,
j
channels, or roadway low points, should be equipped with watertight castings. Precautions should be taken
during construction to prevent the entrance of stormwater into the sanitary sewer. When access is required at
all times, sanitary manholes located near ponding areas should be raised above the 100-year high water level.
If access is not required, water tight castings should be installed. Future storm drainage construction should
include provisions for improving the water tightness of nearby sanitary sewer manholes. All newly constructed
sanitary manholes in the vicinity of ponding areas and open channels described in this report should be
waterproof.
6.1.4 PDP
ONDING ESIGN ARAMETERS
0QLOJT>QBOÐMLKAFKDÐ>OB>PÐ>OBÐ>KAÐTFIIÐ@LKQFKRBÐQLÐ?BÐ>KÐBPPBKQF>IÐM>OQÐLCÐ LQQ>DBÐ$OLSBgPÐPQLOJT>QBOÐJ>K>DBJBKQÐ
system. The following standards apply to new detention basin design:
Where feasible, new local and regional stormwater MLKAPÐTFIIÐ?BÐABPFDKBAÐhLCC
IFKBiÐCOLJÐQEBÐRMPQOB>JÐ
j
T>QBOPEBAÐO>QEBOÐQE>KÐhLK
flushing of water quality volume prior to treatment with
treated water from the upstream watershed. The residence time of water within a water quality pond is
important to achieve sedimentation and allow for biological uptake of nutrients between storm events.
Permanent pool volume should be greater than or equal to the volume of runoff from a 2.5-inch rainstorm
j
under full projected watershed development. This value has been derived from design criteria developed under
National Urban Runoff Program (NURP), with a 25% increase in volume to allow for roughly 25 years of
sediment accumulation. In the summer, this sizing rule provides a mean hydraulic residence time of about 15
days.
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 44
To promote settling and provide space for sediment accumulation, the mean depth of the permanent pool
j
(volume/surface area) should be greater than or equal to 4 feet. This constraint may be infeasible for small
ponds (< approx. 2 acre-feet in volume), where mean depths of 3-4 feet may be used.
For safety purposes and to provide suitable habitat for rooted aquatic plants, an aquatic bench at least 10 feet
j
in width and with a slope not steeper than 10 feet horizontal to 1 foot vertical should extend into the pond from
the shoreline at normal water level. Pond slopes below this bench to the bottom of the pond should be no
steeper than 3 feet horizontal to 1 foot vertical.
To provide stability, the side slopes should not be steeper than 4 feet horizontal to 1 foot vertical.
j
Where possible, a 10-foot maintenance bench at a 10:1 slope should be placed beginning 1-foot above the
j
MLKAgPÐLRQIBQÐBIBS>QFLK Ð1EFPÐ?BK@EÐPELRIAÐ?BÐQFBAÐFKQL an access path connecting to a street, parking lot, or
other point of entry for maintenance vehicles.
For ponds within developed areas, not accessible from a residential street, trail, or parking lot, a dedicated 30
j
foot wide easement should be provided to allow the City access to the pond.
To prevent development of thermal stratification, loss of oxygen, and nutrient recycling from bottom sediments,
j
the maximum depth of the permanent pool should be less than or equal to 8 feet.
This SWMP establishes peak flow limits for future regional ponding basins (see Appendix D) with the intention
j
of preserving the integrity of downstream conveyance routes and detention areas, and providing an efficient
conveyance system.
Water quality pond outlet structures should be designed to skim the surface flow up to the 5-year pond high
j
water level. The design velocity of water flowing through the skimmer opening should be no greater than 1.5
fps for the 5-year, 24-hour storm event to prevent suction of bottom sediment or floating debris.
The City encourages stormwater ponding basins to be designed to appear more natural by incorporating
j
aesthetic features such as undulating pond sides, side slope variation, and planting native upland and wetland
seed mixes.
Stormwater ponding in karst-sensitive areas will require additional investigation to assure bedrock stability.
j
Guidance from the watershed authorities will be used to determine karst-sensitive areas. Watershed authority
technical guidance and rules as well as the Minnesota Stormwater Manual and guidance from the Minnesota
Department of Health will be followed in determining the suitability of specific sites for stormwater ponding.
6.2 STORMWATER MODELING OVERVIEW
The study area was modeled assuming ultimate development conditions (see Figure 2.2). The runoff generated from
the various land use types within the SWMP study area follows the rationale presented in the previous section.
Stormwater modeling programs have been developed to estimate rates and volumes of runoff generated by given
land uses and route these flows through conveyance facilities to analyze and design stormwater trunk systems.
This plan incorporates a combination of both HydroC !Ð>KAÐ5-
04**ÐJLABIFKDÐMOLDO>JPÐQLÐ>K>IVWBÐQEBÐ FQVgPÐ
trunk stormwater ponding system. The map in Appendix H identifies the modeling program used to model a
particular subwatershed.
As mentioned above, a portion of the regional ponding system presented in this SWMP uses the HydroCAD
stormwater modeling program. HydroCAD stormwater runoff hydrographs are calculated based on NRCS TR-20
methodology (i.e. calculation of runoff using drainage area, curve number, and time of concentration). HydroCAD
uses the runoff CN to estimate infiltration and other losses. Curve numbers used in HydroCAD modeling are
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 45
presented in Table 6.1. Hydrograph routing through channels and detention basins is performed using the
Simultaneous Routing method within HydroCAD.
The remainder of the regional ponding system presented in this SWMP uses the XP-SWMM stormwater modeling
program. Two methods for calculating runoff hydrographs are used within the SWMP:
The St. Paul Park and north portion of the Thompson-Grove Districts use the NRCS TR-20 methodology
j
(i.e. calculation of runoff using drainage area, curve number, and time of concentration) to generate runoff.
The East Ravine District north of TH 61, modeled by Emmons and Olivier Resources (EOR) as part of the June,
j
2005 Cottage Grove East Ravine Alternative Urban Areawide Review (AUAR), uses the Horton infiltration
method for generating runoff. This method generates runoff from the input of drainage area, percent impervious
area, watershed width and slope, and the Horton runoff parameters.
It should be noted that the SWWD has completed modeling of other parts of the City as well, including the East
Ravine, West Draw, and Central Draw. Coordination between the City and the SWWD will likely be needed to
reconcile any significant discrepancies in input data, etc. during review of the impacts of future projects.
6.3 SYSTEM ANALYSIS AND RECOMMENDATIONS
6.3.1 G
ENERAL
The system descriptions and recommendations provided in this section address stormwater issues on a regional
scale, including regional stormwater ponding and conveyance. Description of and recommendation for addressing
local stormwater issues will not be included in the SWMP. Local stormwater issues are typically dealt with on an
operation and maintenance level by City staff, or are addressed as specific elements in the design and construction
of public improvement projects.
The City of Cottage Grove was divided into 13 major drainage districts, as shown on Map 1. The major drainage
districts were designated as shown in Table 6.2.
Table 6.2 k Major Drainage Districts Abbreviations
Major Drainage District Abbreviation
Central C
East Draw ED
East Ravine ER
Gables Lake GL
Grey Cloud Island GCI
Langdon L
Lower St. Croix LSC
St. Paul Park SPP
Seeger Creek SC
South S
Southwest SW
Thompson Grove TG
West Draw WD
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 46
Each major drainage district was subdivided into minor drainage districts. A few of the minor drainage districts are
further subdivided into sub-districts. Each minor district is identified by the abbreviation of the major district in which
it is located, followed by the letter A (for area) and the number of the minor drainage district. An additional number
is added for sub-districts within a minor drainage district to differentiate it from the other sub-districts. The areas of
all subdistricts are presented in Appendix B and their boundaries are shown on Map 1.
1EBÐ FQVÐLCÐ LQQ>DBÐ$OLSBgPÐQORKHÐPQLOJÐPBTBOÐPVPQBJÐFPÐMOesented on Map 1 and the characteristics of the proposed
trunk pipe design characteristics are summarized in Appendix C of the SWMP.
Ponding areas are identified in the same manner as the subdistricts, but rather than using the letter A (for area),
ponds are designated with the letter P. Pond data, including tributary area, storage volume, normal and high water
levels, peak outflow rate, and pond area, are presented in Appendix D. The storage volume and outflow rate of a
pond are attributes that are important to preserve in order to successfully maintain the integrity of the storm
drainage system.
The costs associated with the proposed trunk stormwater management system are summarized in Appendix E of the
SWMP.
Following are sections summarizing the important issues and findings for each district.
6.3.2 CD
ENTRAL ISTRICT
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The Central District is located in the north-central portion of Cottage Grove primarily north of 80 Street,
encompassing approximately 1,140 acres. This district is fully developed consisting primarily of low density
residential development with one small pocket of medium density located in the northwest corner of the district.
Eight existing regional stormwater ponds serve this district, ultimately discharging out of pond C-P8 located in Pine
th
Tree Pond Park south of 80 Street. The regional ponding system within the Central District has operated according
to design, with no known flooding being reported to the City.
6.3.3 EDD
AST RAW ISTRICT
The East Draw District incorporates approximately 1,080 acres of drainage area and is located between the Central
and East Ravine Districts, as shown on Map 1. Currently fully developed, the East Draw District encompasses the
extents of current development in the northeastern portion of the City. Development within the East Draw District is
primarily low density residential, with a few small pockets of medium density residential. Grey Cloud Elementary
School, Cottage Grove Junior High School, and Kingston Park are all located in the north-central portion of the East
Draw District.
Ten existing regional stormwater ponds serve this district, ultimately discharging out of pond ED-P10 located in
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Woodridge Park immediately north of 90 Street and east of Jamaica Avenue. Pond ED-P10 also receives the
discharge from the Central District via pond C-P8. The stormwater system within the East Draw District utilizes
constructed berms or roadway embankments within steep draws to provide regional ponding opportunities in a
number of locations, including ED-P4, ED-P5, ED-P6, ED-P8, and ED-P9. The regional ponding system within the East
Draw District has operated according to design, with no known flooding being reported to the City.
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 47
6.3.4 ERD
AST AVINE ISTRICT
The East Ravine District incorporates approximately 5,650 acres or roughly 25% of the City of Cottage Grove.
1EFPÐAFPQOF@QÐBUQBKAPÐCOLJÐQEBÐ FQVgPÐ?Lrder with Woodbury to the Mississippi River. The majority of the district north
of TH 61 is undeveloped, including the Cottage Grove Ravine Regional Park and existing agricultural land use. Small
pockets of existing Low Density and Rural Residential development can be found around the perimeter of the district.
The majority of the district south of TH 61 is owned by 3M. The existing 3M Cottage Grove Center is located in the
southern portion of the 3M property, with the remaining areas currently undeveloped. To provide Cottage Grove
with a complete SWMP incorporating the entire City, a regional stormwater system has been identified within the
3M property, based on an assumed curve number of 85 for all future development on 3M property. Future
discussions with representatives from 3M will be necessary to further analyze and refine the regional system on 3M
property to more fully meet the needs of the City and 3M.
In addition to the direct drainage area from the City of Cottage Grove, approximately 14,500 acres from the City of
Woodbury will ultimately be routed into the East Ravine District via the Bailey Lake lift station. Discharge from the
Bailey Lake lift station is routed into two basins owned and maintained by the SWWD (identified by the SWWD as
CD-P85 and CD-P86). Regional stormwater basin ER-P2 incorporates the southern portion of CD-P86. The ultimate
discharge rate from the Bailey Lake lift station, as it is routed through CD-P85 into ER-P2 (CD-P86) is included in the
regional stormwater design of the East Ravine. The City of Cottage Grove assumes that the SWWD will provide an
outlet for ER-P2 (CD-P86) with the capacity to handle a peak lift station discharge from Bailey Lake of roughly 150
cfs, as previously discussed. The City assumes that this pipe will be financed by the SWWD.
The regional stormwater system for this district builds off of the stormwater ponding layout proposed in the AUAR
for the East Ravine. The AUAR document identifies an entire stormwater system of interconnected basins and natural
drainage-ways designed to promote infiltration and protect downstream key water resources. From the design
proposed in the AUAR, a number of key ponding basins within the AUAR study area have been incorporated into the
regional stormwater system for the East Ravine District.
As development occurs within the East Ravine District, the regional stormwater system identified in this SWMP
should be implemented. Specific regional stormwater management items are included below:
Additional costs have been included in the SWMP for the restoration of the existing major conveyance ravines
j
within the district, including those portions of ravines within the Cottage Grove Ravine Park and 3M property.
The City should coordinate with the SWWD on the installation of the discharge pipe out of ER-P2 (CD-P86) as
j
development occurs within the East Ravine to avoid having to retrofit this pipe into an existing development.
Pond ER-P3 is an existing land locked basin. A gravity piped outlet for this basin is identified in this SWMP.
j
It is recommended that this ultimate pipe be constructed as development adjacent to this basin proceeds.
Pond ER-P4 is an existing land locked basin, maintaining a water surface elevation roughly 40 feet below the
j
overland overflow for this basin by the combination of evaporation and infiltration. This SWMP proposes a 20
cfs lift station outlet to ultimately drain pond ER-P4. However, until gradually rising water levels in this basin
begin to threaten adjacent structures or roadways, the proposed lift station may be unnecessary. The SWWD
currently monitors the water surface elevation of this basin periodically to determine if water levels are gradually
rising.
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 48
6.3.5 GLD
ABLES AKE ISTRICT
The Gables Lake District is located in the northeast corner of the City and is approximately 1,460 acres in size, with
over 50% of this total area draining from the City of Woodbury. This district is largely undeveloped, with the majority
of the land use within the district either agricultural or ravine/bluff areas surrounding Gables Lake (basin GL-P1).
Future development of this district within Cottage Grove will include a mix of low density and rural residential land
uses, along with the eastern portion of the district identified as urban reserve on the 2030 land use map.
Gables Lake is an existing land-locked depression, with the lowest existing overland overflow for this depression
approximately 50 feet above the assumed water surface elevation of 852.0. The lake appears to maintain a fairly
constant water level by the combination of evaporation and infiltration.
This SWMP proposes a 10 cfs lift station outlet to ultimately drain Gables Lake. However, steep slopes (<18%)
surround Gables Lake, making development below the 900 contour elevation unlikely. For this reason, a future lift
station outlet will likely not be necessary to protect adjacent structures, but rather could be desired to maintain the
existing physical characteristics of Gables Lake. It is recommended that the City monitor the water surface elevation
of Gables Lake as development occurs within this district to determine if a lift station is necessary.
6.3.6 GCID
REY LOUD SLAND ISTRICT
The Grey Cloud Island District is located in the southwest corner of the City and is approximately 1,360 acres in size,
with all but about 90 acres of this area located within the City of Cottage Grove. The current land use on the island
is primarily mining of the available aggregate resources, but also includes some existing rural residential properties
around the perimeter of the island. The City identifies Grey Cloud Island as urban reserve on the 2030 land use map.
The City will be developing a master plan for the island in advance of opening the area for development. The City is
committed to working with future development entities to ensure that development proceeds in a way that preserves
the natural resources of Grey Cloud Island.
No regional stormwater improvements have been identified in the Grey Cloud Island District at this time. A more
detailed study to identify whether regional stormwater facilities will be necessary will be completed with the
forthcoming master plan.
6.3.7 LD
ANGDON ISTRICT
The Langdon District is approximately 1,250 acres in size with the portion of the district north of TH 61 fully
developed and the portion of the district south of TH 61 largely undeveloped. The district receives flows directly from
the Thompson Grove, Central, and East Draw Districts, discharging directly to the Mississippi River.
The majority of the undeveloped area within the district is owned by 3M, with only a small portion of this area
currently developed as part of the 3M Cottage Grove Center. To provide Cottage Grove with a complete SWMP
incorporating the entire City, a regional stormwater system has been identified within the 3M property, based on an
assumed curve number of 85 for all future development on 3M property. Future discussions with representatives
from 3M will be necessary to further analyze and refine the regional system on 3M property to more fully meet the
needs of the City and 3M.
As development has continued in the Langdon District north of TH 61, a number of on-site private stormwater ponds
have been constructed. The primary function of these ponds is to provide water quality treatment for the properties
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 49
they serve. These on-site ponds provide some rate control, but are not considered part of the regional stormwater
system because they are privately owned and maintained.
Development of the regional stormwater system within the Langdon District should continue as recommended in this
SWMP, unless otherwise revised based on cooperation between the City of Cottage Grove and 3M. Specific regional
stormwater design recommendations are included below:
A large portion of the development north of TH 61 within the Langdon District is routed to pond L-P3 via an
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BUFPQFKDÐiÐMFMB ÐTFQEÐQEBÐJ>GLOFQVÐLCÐQEFPÐ>OB>ÐI>@HFKDÐPQLOJT>QBOÐNR>IFQVÐQOB>QJBKQ Ð1EBÐiÐMFMBÐAFP@E>ODBPÐ
directly into the existing MnDNR protected wetland. The SWMP recommends that additional flood storage and
water quality volume be provided east of the existing wetland area. It is also recommended that the existing
iÐMFMBÐ?BÐOBOLRQBAÐFKQLÐQEBÐBUM>KPFLKÐMLKAÐ>OB>ÐQLÐbypass the existing wetland to improve the water quality
characteristics of the discharge to this wetland.
The SWMP design of L-P3 is based on correspondence between 3M and the City establishing a peak 100-year
j
discharge rate of 370 cfs from pond L-P3, while maintaining a 100-year HWL of roughly 770. Based on the
preliminary analysis completed as part of this SWMP, pond L-P3 can meet these established criteria by providing
additional flood storage and modifyFKDÐQEBÐBUFPQFKDÐgUgÐ?LUÐ@RISBOQÐoutlet. A more detailed pond grading
design will be necessary to more accurately estimate the volume of additional flood storage available.
So as to not significantly impact the existing ravine downstream of L-P3 with the increase in runoff volume due
j
to providing an outlet for TG-P19 (particularly for the small frequent storm events), additional rate control within
ponds L-P3 and L-P4 for the 2-year storm event is recommended. The SWMP proposes the use of weirs
structures as part of the pond outlets to reduce the 2-year discharge rates from the ponds. Additional efforts to
stabilize and protect the existing drainage-way are also recommended. Costs associated with improvements to
the existing drainage way are included in Appendix E of the SWMP.
6.3.8 LS.CD
OWER T ROIX ISTRICT
The Lower St. Croix District is approximately 1,350 acres in size and is located in the northeast corner of the City of
Cottage Grove. This district is largely undeveloped, presently used for agricultRO>IÐMROMLPBP Ð1EBÐ FQVgPÐ
ÐI>KAÐRPBÐ
plan identifies this district as primarily urban reserve land use, with a few small pockets of rural residential land use
along the western border of the district. The City will be developing a master plan for this district in advance of
opening the area for development.
Drainage within the district generally proceeds from the southern and northern portions of the district to minor
district LSC-A3, identified as the upstream confluence ofÐ,g LKKBOgPÐ OBBH ÐAO>FKFKDÐQLÐQEBÐI>KA
IL@HBAÐ,g LKKBOgPÐ
Lake. This district is almost entirely located within the jurisdictional boundary of the Lower St. Croix Watershed
Management Organization and is the only district within the City to not drain south and discharge to the Mississippi
River.
No regional stormwater improvements have been identified in the Lower St. Croix District at this time. A more
detailed study to identify whether regional stormwater facilities will be necessary will be completed with the
forthcoming master plan.
6.3.9 S.PPD
T AUL ARK ISTRICT
The St. Paul Park District is located along the west side of Cottage Grove. This district is approximately 640 acres in
size and straddles TH 61, as the highway enters Cottage Grove. The topography within the district varies from
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 50
moderately steep to fairly steep slopes, with ground elevations ranging from 1,000 feet in the north to 780 in the
south. The St. Paul Park district is approximately 60% developed. The portion of the district north of TH 61 consists
mainly of rural residential development, with a small pocket of low density residential and commercial property
within SPP-A7. The portion of the district south of TH 61 is fully developed, including primarily low density residential
development and a small strip of commercial along Hadley Avenue.
In addition to Cottage Grove drainage, this district also incorporates approximately 180 acres of primarily low density
residential drainage area from the northeast corner of St. Paul Park. Runoff from within this district is directed to an
existing wetland area (basin SPP-P9) bordered to the north and south by TH 61 and Canadian Pacific (CP) Railroad
line. Currently, the existing wetland area (DNR Protected Water #82-75W) drains to the northwest, within a CP
Railroad ditch.
Pond characteristics based on a rough design of the Gateway pond (SPP-P9) are presented in Appendix D. These
improvements focus mainly on the maximization of flood storage in this area and the installation of a lift station
outlet. This rough design assumes that modifications to SPP-P8 are performed to more efficiently utilize available
flood storage within this pond. This design also assumes that the 100-year discharge rate from pond SPP-P9 is a
combination of the 10 cfs lift station to TG-P4 and overflow to the northwest. The ultimate design of pond SPP-P9
will include input from a number of different parties, including:
City of Cottage Grove
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City of St. Paul Park
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CP Rail
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Minnesota MnDNR
j
MnDOT
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Specific regional stormwater design recommendations are included below:
Existing ravine erosion issues are present downstream of future ponds SPP-P1 and SPP-P2. In addition to the
j
construction of these ponds to reduce peak rates to the ravine, restoration of the ravine channel is also
recommended. Additional costs for channel restoration are included in the SWMP.
Working with the City of St. Paul Park, further analysis to determine how to provide additional flood storage
j
within minor district SPP-A8 to help alleviate downstream HWL and discharge rate issues within SPP-P9 is
recommended.
Further discussions regarding the ultimate design of SPP-P9 with the parties listed above is recommended. The
j
ultimate design of pond SPP-P9 requires that additional ponding be provided adjacent to the existing wetland.
The ultimate design must take into account the constraints within which the ponding needs to be provided,
namely:
The additional excavated flood storage required must be provided outside the existing wetland.
o
Additional flood storage cannot be provided more than roughly 1 foot below the MnDNR established
o
Ordinary High Water Level (OHW) foOÐQEFPÐBUFPQFKDÐTBQI>KAÐLCÐ
g Ð
The future SPP-P9 100-year HWL must provide adequate freeboard to the CP Railway track elevation of
o
roughly 780.4.
The existing ponding system includes approximately 180 acres of drainage area from the City of St. Paul
o
Park.
Discharge no more than 10 cfs to pond TG-P4 via a future lift station.
o
Reduce the existing 100-year peak discharge to the northwest within St. Paul Park.
o
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 51
It should be noted that the SWWD has listed high water and inter-community flow issues for this area in their 2007
WMP and has expressed an interest in participating in the implementation of improvements to resolve the problems.
6.3.10 SCD
EEGER REEK ISTRICT
The Seeger Creek District encompasses the 3,830 acre drainage area for Seeger Creek, located in the far
southeastern corner of the City of Cottage Grove. Seeger Creek is identified as a MnDNR protected water and a
direct tributary to the Mississippi River. Of the 3,830 acre drainage area to Seeger Creek, approximately 1,580 acres
is located outside of the City of Cottage Grove, in the adjacent Denmark Township to the east.
For the portion of the Seeger Creek District within the City of Cottage Grove, the current land use plan identifies the
northern portion of this district as urban reserve, with the remainder of the district identified as rural residential and
a small pocket of commercial land use adjacent to TH 61. Existing development within the district is primarily limited
to minor district SC-A9, including rural residential and commercial development south of TH 61.
Four future regional ponding locations have been identified within the district. The primary means of stormwater
conveyance will be existing drainageways with stormwater rate control being provided where feasible, such as at
road crossings. A more detailed study to identify whether the proposed regional stormwater facilities will be
adequate to support the type of development identified in a future master plan for this area will be necessary.
Specific regional stormwater design recommendations are included below:
Geologic investigation will be necessary prior to the siting of the regional ponding facilities in the District, due to
j
the presence of potential karst features.
SC-P8 is located at the top of a steep ravine slope discharging to the Mississippi River. The pond is designed
j
to provide stormwater treatment to all of the future rural residential area within the district south of TH 61.
By providing rate control for minor district SC-A8 and piping the flows down the steep slope to the base of the
ravine, the pond is designed to minimize potential erosion within this ravine due to development. Further
analysis to determine the condition of the existing ravine is recommended to determine where the outlet for SC-
P8 should discharge.
The proposed regional ponds will meet applicable watershed authority rules and regulations.
6.3.11 SD
OUTH ISTRICT
The South District along the southern border of Cottage Grove is approximately 1,620 acres in size. The South
District is primarily undeveloped at this time, although some rural residential development exists in the south-central
portion of the district. The topography within the district varies from fairly flat areas in the northern portions of the
district to steep slopes and ravines adjacent to the Mississippi River.
The general drainage pattern within the South District is from West to East and then South to the Mississippi River.
This drainage pattern is consistent with the proposed trunk stormwater system for this district eventually draining to
an existing ravine that drains under the railroad tracks to the Mississippi River. One 24-inch pipe under the tracks is
currently operating and as the area upstream developed, a second 24-inch will need to be provided for sufficient
capacity.
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 52
The far eastern portion of the South District is owned by 3M. To provide Cottage Grove with a complete SWMP
incorporating the entire City, a regional stormwater system has been identified within the 3M property, based on an
assumed curve number of 85 for all future development on 3M property. Future discussions with representatives
from 3M will be necessary to further analyze and refine the regional system on 3M property to more fully meet the
needs of the City and 3M.
Minor district S-A2 and the western portion of S-A11 are owned by the MnDNR and are being preserved as the Grey
Cloud Dunes Scientific and Natural Area. This SWMP assumes that the portions of the South District within this
Scientific and Natural Area will not be developed. No regional stormwater improvements are recommended within
these minor districts. Pond S-P2 is an existing low area adjacent to the railroad embankment overflowing out an
BUFPQFKDÐ
gUÐgÐ?LUÐ@RISBOQ Ð
6.3.12 SD
OUTHWEST ISTRICT
The Southwest District is located in the southwest corner of the City of Cottage Grove and is roughly 1,110 acres in
size. This district is largely undeveloped, with future development identified as a mix between low density residential,
medium density residential, and urban reserve.
The majority of the existing land use in this area is agricultural, with some existing rural residential properties along
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the river. Other important land use features within the distOF@QÐFK@IRABÐQEBÐ >FIBVgPÐ+ROPBOVÐPFQB ÐIL@>QBAÐKLOQEÐLCÐ
rd
Street (minor districts SW-A12, A13, A14) and the Mississippi Dunes golf course, located south of 103 Street (minor
districts SW-A17, A18, A19). The natural drainage pattern within the Southwest District flows from north to south,
but there is minimal runoff from the undeveloped areas because of many land-locked depressions and sandy soils.
>FIBVgPÐ+ROPBOVÐE>PÐ@LKPQOR@QBAÐQEOBBÐPQLOJT>QBOÐMLKAPÐ04
- Ð- Ð-ÐQE>QÐAFP@E>ODBÐLRQÐ>ÐiÐMFMBÐQLÐ>KÐ
rd
existing depression adjacent to 103 Street (pond SW-P16). A piped outlet for the existing depression was provided
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Street Improvements project, alleviating existing drainage issues at this depression area.
as part of the 103
1LÐJBBQÐQEBÐ FQVgPÐCILLAÐMOLQB@QFLKÐ>KAÐMI>KKFKDÐDL>IP Ð >FIBVgPÐ+ROPBOVÐKBBAPÐQLÐMOLSFABÐadditional rate control and
flood storage volume on their property. It is recommended QE>QÐQEBÐ >FIBVgPÐ+ROPBOVÐMLKAFKDÐPVPQBJÐ?BÐFJMOLSBAÐQLÐ
meet City rate control standards, such that the 100-year discharge rate from SW-P14 does not exceed the rate
specified for this basin in Appendix D. Additional rate control can be provided by a combination of outlet
modifications to better utilize available flood storage and additional flood storage within existing ponds.
6.3.13 TGD
HOMPSON ROVE ISTRICT
The Thompson Grove District is approximately 2,360 acres in size and is located in the west-central portion of
Cottage Grove. This district also receives drainage from both the West Draw and St. Paul Park Districts. Land use
within the Thompson Grove District varies from existing commercial and residential development in the north to both
existing and future industrial development in the south within the Cottage Grove Industrial Park. Hamlet Park is
located in the center of this district.
Proceeding south from the West Draw District, the terrain within the Thompson Grove District is considerably more
flat and broad. As runoff drains through the district from the Hamlet Park ponding system (TG-P4) about 2.5 miles to
the southeast, the grade only drops about 15 feet or an average slope of 0.11%. The lack of grade across the
Thompson Grove District coupled with the significant flow rates to be conveyed required the construction of a riprap
flume to provide stormwater conveyance. Currently, this flume extends from the Hamlet Park Pond system, through
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 53
the industrial park, ending at Jamaica Avenue. The City intends to install this box culvert under Jamaica Avenue
within the next 5 years.
The commercial and residential areas in the northern portions of the district were nearly fully constructed by the early
gP Ð QÐQE>QÐQFJB ÐQEBÐ LQQ>DBÐ$OLSBÐPQLOJT>QBOÐJ>K>DBment philosophy was to collect and route stormwater to
the Mississippi River in the most efficient manner possible. This management philosophy is evident in the design of
those portions of the Thompson Grove District that developed first, namely minor districts TG-A1 to TG-A4. These
minor districts show very few ponding areas, but rather rely on large diameter storm sewer pipe to convey
stormwater to Hamlet Park pond. From Hamlet Park pond a high capacity concrete flume was proposed to extend
from Hamlet Park pond to the far south east corner of the district, ultimately routing a 100-year peak flow of1,200
cfs to the downstream Langdon District.
The City has since changed their stormwater management philosophy within the Thompson Grove District due to
both the cost and regulatory implications of the previous design. As a part of this change, the City agreed to limit the
discharge rate from the Thompson Grove District at Jamaica Avenue to the 3M property (L-P3) to roughly 300 cfs. As
a result, revisions to the stormwater system within the Thompson Grove District were first proposed back in the year
2000. These year 2000 revisions were primarily associated with the then partially developed Cottage Grove Industrial
Park area. Although the concept of a drainage flume from the existing Hamlet Park pond remained, numerous
regional ponding locations were identified within the industrial park to reduce peak discharge rates to the flume,
thus reducing the required capacity of the flume and ultimately meeting the maximum discharge rate to the 3M
property.
This SWMP also includes all of the phases of the Hamlet Park Pond Improvements project, which is currently in the
final phase of construction. These improvements included removing conveyance restrictions within the existing
%>JIBQÐ->OHÐ-LKAÐQLÐOBAR@BÐ%4)PÐMBOÐ*K!,1gPÐAFOB@QFSBÐ>nd providing additional flood storage downstream in the
expansion pond. Ultimately, the Hamlet Park Pond Improvements project provides a significant flood control and
aesthetic benefit to the City.
6.3.14 WDD
EST RAW ISTRICT
The West Draw District is located in the northwest corner of Cottage Grove, consisting of approximately 1,450 acres
within Cottage Grove. The land use within the district reflects predominantly low density residential development,
with smaller pockets of mixed medium and high density residential development in the southern portion of the
district. The majority of the new residential development within the City of Cottage Grove within the last 10 years
has occurred within the West Draw District. Currently, this district is approximately 80% developed.
The stormwater infrastructure within the West Draw E>PÐMOL@BBABAÐ>@@LOAFKDÐQLÐQEBÐ FQVgPÐÐ04*-Ð>KAÐ
subsequent drainage studies. The 1984 SWMP set forth a framework for utilizing the topography within the West
Draw District to provide regional ponding locations to both protect existing natural conveyance features within the
district and reduce discharge rates to deal with existing downstream pipe capacity issues at TH 61.
Topography within the district ranges from rolling to fairly steep slopes. Land surface elevations range from about
1,000 feet in the northern portion of the district to about 750 feet in the southern portion. The West Draw
stormwater system utilizes the existing terrain to provide both opportunities for stormwater ponding within existing
depression areas, as well as providing stormwater conveyance via existing ravines. Runoff from the majority of the
th
district is ultimately routed to three large ponds (WD-P15.3), located on either side of 70 Street. These ponds act as
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 54
one pond discharging to the Hardwood Avenue storm sewer system draining to Hamlet Park pond south of Trunk
Highway 61, and ultimately through the Thompson Grove and Langdon Districts to the Mississippi River.
The West Draw extends from the northwest corner of Cottage Grove to TH 61 and the Hamlet Park area,
incorporating approximately 1,450 acres of drainage area within the City. An additional 620 acres of drainage area
from the City of Woodbury drains overland through the West Draw into Cottage Grove.
In addition to the overland drainage area, the 1979 Woodbury Stormwater Plan proposed that 850 acres draining to
a land locked basin just north of the Cottage Grove/Woodbury border be pumped into Cottage Grove via a lift
station. Currently, flows are pumped to an existing land-locked basin on the border of Woodbury and Cottage Grove,
but are pumped no further.
An XP-SWMM model of the 620 acres draining overland into the City has been developed by HDR Engineering,
identifying a discharge rate of 25 cfs from Woodbury to Cottage Grove. This model is a modified existing conditions
model, providing additional flood storage and rate control within the existing system to restrict the discharge rate
into Cottage Grove from 200 cfs to 25 cfs (per 4/8/05 memo from HDR Engineering to the SWWD). As the City of
Woodbury develops an ultimate conditions model for the 620 acres draining overland to Cottage Grove (with a
maximum 100-year discharge of 25 cfs), the impact of the additional runoff volume (above the volume associated
with the 25 cfs) must be identified so as to not negatively impact the existing Cottage Grove trunk system.
The hydrograph associated with the 25 cfs discharge rate COLJÐQEBÐ%!/ÐJLABIÐFPÐFK@LOMLO>QBAÐFKQLÐQEBÐ FQVgPÐ
ultimate development SWMP HydroCAD model of the West Draw. According to this ultimate development model,
ponds WD-P15.3 cannot maintain 2 feet of freeboard to existing adjacent low openings without further restriction of
the 25 cfs from Woodbury. The cost for oversizing the Cottage Grove trunk system to further reduce the flows from
Woodbury and maintain the necessary freeboard within ponds WD-P15.3 should be borne by the City of Woodbury.
Minor district WD-A7 receives an existing conditions 100-year peak runoff rate of approximately 200 cfs from the
620 acres of drainage area from Woodbury (per the HDR model). Conveyance within the existing West Draw
stormwater system to handle this existing peak rate is being provided via the existingMnDNR waterway, crossing
thth
under 65 Street and discharging into pond WD-P15.3. The City replaced an 84-inch CMP culvert crossing under 65
Street, which was in poor condition, with a 36-inch RCP MFMBÐ>KAÐ>Ð
gÐUÐ
gÐ/ -Ð?LUÐ@RISBOQ Ð2KABOÐQEBÐBUFPQFKDÐ
condition, the proposed 36-inch pipe will convey the flows from the majority of the smaller storm events, while the
gÐUÐ
gÐ?LUÐ@RISBOQÐTFIIÐMOLSFABÐ@LKSBV>K@BÐ@>M>@FQVÐAROing major storm events, as necessary. Ultimately, the 36-
th
FK@EÐMFMBÐTFIIÐ@LKSBVÐ>IIÐCILTPÐ>KAÐQEBÐ
gÐUÐ
gÐbox culvert will be used as a trail crossing under 65 Street as part
of a larger regional trail system.
6.4 HIGH PRIORITY STORMWATER QUANTITY RECOMMENDATIONS
Following are the highest priority recommendations related to this chapter of the SWMP:
1.Coordinate with the SWWD to design and install the SWWD outlet pipe for pond ER-P2.
2.Work with all parties involved including the City of Cottage Grove, MnDOT, MnDNR, City of St. Paul Park,
SWWD, and Canadian Pacific Railroad to determine an acceptable design and identify and pursue a joint
funding strategy for these Gateway Pond (SPP-P9) improvements that reflects the proportionate contribution to
the problem among the parties.
3.Construct the box culvert under Jamaica Avenue and conveyance route to basin L-P3.
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 55
"(38Ð.%Ð".33 &$Ð&1.5$ÐmÐ241% "$Ð6 3$1Ð, - &$,$-3Ð/+ -Ð
0B@QFLKÐÐkÐ&JMIBJBKQ>QFLKÐ
7.1 GENERAL
This SWMP provides a plan for expaKAFKDÐ>KAÐJ>K>DFKDÐQEBÐ FQVgPÐPROC>@BÐT>ter system, and protecting key water
resources in the City. The real measure of success of the SWMP will be in its implementation. Implementation of the
SWMP covers a number of aspects, including:
Administering regulations and programs
j
Managing surface water as redevelopment and new development occur
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Implementing a public education program regarding stormwater management
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Operating and maintaining the surface water system
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Constructing prioritized capital improvements
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Financing projects and programs
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System improvement projects and activities
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Providing a process for future amendments to the SWMP
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7.2 REGULATORY ADMINISTRATIVE RESPONSIBILITIES
&QÐE>PÐ?BBKÐQEBÐ FQVgPÐBUMBOFBK@BÐQE>QÐ?LQEÐQEBÐ0LRQh Washington Watershed District and the Lower St. Croix
Watershed Management Organization have made an effort to encourage cities within their jurisdiction to adopt local
SWMPs and assume the regulatory responsibility for stormwater management and other related issues. The City
assumes that with the adoption of this SWMP, the primary regulatory responsibility will rest with the City. The City
expects that close coordination between the local WMOs will continue as development proceeds in Cottage Grove.
7.2.1 ESC
ROSION AND EDIMENT ONTROL
In 2006, the City was required to submit an NPDES MS4 Stormsewer Permit to the MPCA to authorize discharge
COLJÐQEBÐ@FQVgPÐPQLOJÐPBTBOÐPVPQBJ Ð PÐM>OQÐLCÐQEBÐpermit requirements, the City is responsible to:
1.Develop an ordinance or other regulatory mechanism to require erosion and sediment controls, as well as
sanctions to ensure compliance, to the extent allowable under law.
2.Requirements for construction site operators to control waste, such as discarded building materials, concrete
truck washout, chemicals, litter, and sanitary waste at the construction site that may cause adverse impacts to
water quality.
3.Develop requirements for construction site operators to implement appropriate erosion and sediment control
best management practices.
4.Establish procedures for site plan review which incorporate consideration of potential water quality impacts.
5.Establish procedures for receipt and consideration of reports of noncompliance or other information on
construction related issues submitted by the public.
6.Establish procedures for site inspection and enforcement of control measures.
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 56
Currently, the City is taking a proactive approach to erosion and sediment control inspection and enforcement. Each
development within the city is inspected on a weekly basis for compliance with the existing stormwater management
ordinance. Also, the City is in the process of revising thBÐ@ROOBKQÐBOLPFLKÐ>KAÐPBAFJBKQÐ@LKQOLIÐMOLDO>J Ð1EBÐ FQVgPÐ
program will reflect the additional minimum best management practices as outlined in the NPDES permit.
7.2.2 PFPP
RELIMINARY AND INAL LATTING ROCESS
The City has established and fully implemented both a preliminary and final platting process. The preliminary platting
process is outlined as follows:
1.Filing and Review of Application
2.Submission of Application to Planning Commission
3.Report of Planning Commission
4.Council Action, Approval or Denial
The final platting process is outlined as follows:
1.Filing of Application
2.Review of Application
3.Standard Form and Content Review
4.Certification and Financial Guarantee for Improvement Completion
5.Council Action, Approval or Denial
6.Recording (if approved)
7.Plat print to City Clerk/Treasurer
8.Record Plans
7.2.3 FO
LOODPLAIN RDINANCE
The City has a current Floodplain Management Ordinance. This ordinance states that the City is fully responsible for
floodplain regulation within the City.
7.2.4 SO
HORELAND RDINANCE
The City does not have a shoreland ordinaK@BÐ>QÐQEFPÐQFJB Ð&QÐFPÐQEBÐ FQVgPÐABPFOBÐQLÐAO>CQÐ>ÐPELOBI>KAÐLOAFK>K@BÐFKÐQEBÐ
near future.
7.3 EDUCATION
7.3.1 G
ENERAL
Education plays an important role in any effort to implement a stormwater management program like the one
outlined in this SWMP. The objectives of an education effort vary, depending on the target audience. In general, the
target audience for this education program is City staff, City residents, and the development community. The
following sections describe why education of each of these groups is important and presents educational methods
for each that the City is or may begin using.
City of Cottage Grove Project No: 48-05-214
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7.3.2 CS
ITY TAFF
City staff has a wide range of responsibilities for implementing this plan. These include:
Implementing street sweeping and spill containment cleanup programs.
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Maintaining stormwater pond performance and system operability.
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Planning for and management of projects to achieve specified levels of pollutant removal performance, wetland
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protection, etc.
Carrying out grounds maintenance of City-owned lands/facilities in a way that sets a good example for
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residents.
Utilizing BMPs in application of ice control material.
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Application of Best Management Practice policies and regulations to new and redevelopment projects.
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Develop and effective administration of an erosion and sediment control program.
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Planning and delivering education programs.
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Working out cooperative arrangements with regulatory and non-regulatory organizations to achieve SWMP
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objectives.
Assisting the City Council in the application of the SWMP policies.
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Because these responsibilities involve many different levels of City staff, City staff members trained to have a basic
understanding of the SWMP, including:
A description of the major stormwater management issues (including known stormwater management problem
j
areas, stormwater management expectations for new and redevelopment projects, incorporation of stormwater
mitigation into capital improvement projects, and regulatory jurisdictions).
The objectives of the SWMP and the general approach outlined in the SWMP for resolution of these issues.
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The responsibilities of the different work units in implementing the SWMP.
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The information the SWMP provides.
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This information is disseminated in presentations at staff meetings, coverage in internal newsletters, and issuance of
internal memos.
7.3.3 CR
ITY ESIDENTS
In order to obtain the necessary political and economic support for successful SWMP implementation, it is vital to
inform City residents about basic stormwater management and water quality concepts, policies and
recommendations in the SWMP, and the progress of stormwater management efforts.
This information is presented to the public through the City newsletter, press releases to local papers, and at public
meetings as appropriate. Periodic updates on the progress of SWMP implementation and information on specific
improvement projects is also provided to the public. Again, the City newsletter and press releases to local papers are
good methods by which this information is disseminated.
Education projects focused on stormwater quality have received increasing attention and interest from the public
over the last decade. Specific education projects that have been used successfully in Cottage Grove, or are being
considered by the City include the following:
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 58
Catch basin stenciling/door hanger distribution. The objective of this activity is to provide recognition of the direct
connection between the City storm drainage system and J>KVÐLCÐQEBÐ@LJJRKFQVgPÐ@OBBHPÐ>KAÐTBQI>KAP Ð1EBÐALLOÐ
hangers further explain this connection and why it is important to keep vegetative material, fertilizer, pet litter, and
chemicals off hard surfaces and out of the storm drainage system. Scout troops often participate in catch basin
stenciling.
Web Site. The existing City web site currently includes many volunteer opportunities related to minimizing the effects
of stormwater runoff and also raises awareness of the individual practices which can be taken to help minimize
runoff contamination and nutrient loading.
Lawn soil testing. This activity involves the collection and analysis of soil samples from lawns throughout the City to
determine whether additional phosphorus in fertilizer is needed for good turf growth. The results would be helpful in
determining to what degree low and no-phosphorus fertilizer use should be promoted in the City.
Metro-area phosphorus fertilizer ban. Effective January 1, 2004, Minnesota state law banned application of fertilizer
containing phosphate to lawns with some exceptions, such as, where a recent soil test has shown the lawn soil is
deficient in phosphorus. State law also requires clean-up of any fertilizer spread or spilled on paved surfaces. The
City will promote awareness of this law in public education efforts.
Brochures. There are numerous excellent brochures available that could easily be customized for the City.
Distribution could be accomplished through direct mailings, as a fold-in to the City newsletter, a door-to-door
distribution by volunteers, etc.
Annual Stormwater Public Meeting. Each year, the City conducts an annual stormwater public meeting as required
by the NPDES Phase II MS4 Permit. For each meeting, City staff provides residents with a brief description of the
stormwater impacts of municipal runoff and identify the actions taken by the City. Time is available during the
meeting to allow residents the opportunity to comment LKÐQEBÐ>ABNR>@VÐLCÐQEBÐ FQVgPÐPQLOJT>QBOÐMOLDO>JÐ>KAÐ
provide any helpful comments for future management.
The City will join efforts with one or both watershed management organizations to develop and execute educational
activities in order to increase the cost-efficiency of the program, avoid duplication of effort, and ensure delivery of
consistent messages across the City.
7.3.4 DC
EVELOPMENT OMMUNITY
The SWMP is designed to provide the official policy direction that City staff and the City Council desire to guide
stormwater mitigation for new and redevelopment projects. The information about mitigation requirements will be
disseminated to developers and their consulting engineers as early as possible in the development review process.
In this way, developers will know what is expected of them and can consider the requirements in their initial
assessments of the site as well as incorporate the necessary BMPs in any subsequent designs.
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 59
Much of the necessary information will be disseminated to the developers in an information packet in the
development submittal information they receive from the City. The information packet will contain:
Information on the regulatory administrative responsibilities for developments within the major watersheds
j
covering the City.
Information regarding stormwater mitigation requirements.
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Any information on areas of the City where special regulations may apply because of the existence of overlay
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districts.
While dissemination of the information above through an information packet is valuable, there is no substitute for a
meeting between key City staff and the developer as early as possible in the review process. This helps define
expectations for submittals, clarify regulatory compliance issues, and provide additional detailed guidance.
Developers are encouraged to do this as soon as possible after they have reviewed the written information cited
above and thought about how it applies to their site.
7.4 OPERATION AND MAINTENANCE
7.4.1 SB
TORMWATER ASINS
Stormwater basins represent a sizable investment in the City's drainage system. General maintenance of these
facilities helps ensure proper performance and reduces the need for major repairs. Periodic inspections are performed
to identify possible problems in and around the basin. Inspection and maintenance cover the following:
Basin outlets
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Basin inlets
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Side slopes
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Illicit dumping and discharges
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Sediment buildup
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A key issue with stormwater basins is ensuring that the outlets perform at design capacity. Inspection (minimum
20% of outlets per year) and maintenance of basin outlets address the following:
The area around outlets is kept free and clear of debris, litter, and heavy vegetation.
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Trash guards are installed and maintained over all outlets to prevent clogging of the downstream storm sewer.
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Trash guards are inspected at least once a year, typically in the spring, to remove debris that may clog the
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outlet. Problem areas are addressed more frequently, as required.
Emergency overflow outlets are provided for all ponds when possible. These are kept clear of debris, equipment,
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and other materials and properly protected against erosion.
Inspection and maintenance of basin inlets address the following:
Inlets are inspected for erosion.
j
Where erosion occurs near an inlet, energy dissipaters or riprap are installed.
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Inlets are inspected for sediment deposits, which can form at the inlets due to poor erosion practices upstream.
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City of Cottage Grove Project No: 48-05-214
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Where sediment deposits occur, these are removed to ensure design capacities of storm sewers entering the
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basin are maintained.
Inspection and maintenance of basin side slopes address the following:
Side slopes are kept well-vegetated to prevent erosion and sediment deposition into the basin. Severe erosion
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along side slopes can reduce the quality of water discharging from the basin and require dredging of sediments
from the basin.
Noxious weeds are periodically removed from around basins.
j
Some basins in highly developed areas require mowing. If mowing is performed, a buffer strip of 20 feet or more
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adjacent to the normal water level is typically maintained. This provides filtration of runoff and protects wildlife
habitat.
Inspection and maintenance of illicit dumping and discharges into basins address the following:
Basins are periodically inspected for evidence of illicit dumping or discharges.
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The most common of these is dumping of yard waste into the basin.
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Where found, illicit material is removed, and signs are posted as needed prohibiting the dumping of yard waste.
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Water surfaces are inspected for oil sheens. These can be present where waste motor oil is dumped into
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upstream storm sewers.
Skimmer structures are installed as needed at outlet structures to prevent oil spills and other floatable material
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from being carried downstream.
Skimmer structures are periodically inspected for damage, particularly from freeze-thaw cycles.
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As part of the NPDES Phase II Stormwater Pollution Prevention Program, the City is implementing a local spill
containment cleanup plan. Additional information regarding QEBÐ FQVgPÐPMFIIÐ@LKQ>FKJBKQÐMI>KÐ@>KÐ?BÐCLRKAÐFKÐQEBÐ
SWPPP.
Inspection and maintenance of sediment buildup in basins address the following:
Basins are inspected to determine if sediment buildup is causing significant loss of storage capacity from design
j
levels. Excessive sediment buildup significantly reduces the stormwater treatment efficiency of water quality
ponds.
Sediment removal is performed where excessive sediment buildup has occurred.
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As a general guideline, ponds require dredging every 15 to 20 years.
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7.4.2 SMSCB
UMP ANHOLES AND UMP ATCH ASINS
Sump manholes and sump catch basins are included in storm sewer systems to collect sediments before they are
transported to downstream waterbodies. These structures keep sediments from degrading downstream waterbodies.
Once sediments are transported to a lake or pond, they become much more expensive to remove.
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 61
Sediments originate primarily from road sanding operations, although construction activity and erosion can also
contribute. Since these structures are designed to collect these sediments, they are routinely cleaned to provide
capacity for future sedimentation. Suction vacuum equipment is typically used.
7.4.3 SSIS
TORM EWER NLET TRUCTURES
To fully utilize storm sewer capacity, inlet structures are kept operational in order to get runoff into the system. All
efforts are made to keep catch basins and inlet flared ends free of debris and sediments so as not to restrict inflow
and cause flood damage. Leaf and lawn litter are the most frequent cause of inlet obstructions. On a routine basis,
City staff visually inspects inlet structures to ensure they are operational.
7.4.4 OC
PEN HANNELS
Overland flow routes constitute an important part of the surface water system. Open channels are typically vegetated
and occasionally lined with more substantial materials. The lined channels typically require little or no maintenance.
Vegetated channels are periodically inspected and maintained, as high flows can create erosion within the channel.
Eroded channels can contribute to water quality problems in downstream waterbodies as the soil is continually
swept away. If not maintained, the erosion of open channels would accelerate and the repair would become
increasingly more costly.
7.4.5 PS
IPING YSTEM
The storm sewer system constitutes a multimillion-dollar investment for the City. The City performs a comprehensive
maintenance program to maximize the life of the facilities and optimize capital expenditures. The following periodic
inspection and maintenance procedures are followed:
Catch basin and manhole castings are inspected and are cleaned and replaced as necessary.
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Catch basin and manhole rings are inspected and are replaced and/or regrouted as necessary.
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Catch basin and manhole structures are inspected and are repaired or replaced as needed.
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Pipe inverts, benches, steps (verifying integrity for safety), and walls are checked.
o
Cracked, deteriorated, and spalled areas are grouted, patched, or replaced.
o
Storm sewer piping is inspected either manually or by television to assess pipe condition. Items looked for
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include root damage, deteriorated joints, leaky joints, excessive spalling, and sediment buildup. The piping
system is programmed for cleaning, repair, or replacement as needed to ensure the integrity of the system.
7.4.6 D-IP
ECING RACTICES
Minnesota receives approximately 54 inches of snow during a typical year. This requires a large amount of de-icing
chemicals (primarily salt) to be applied to roads and sidewalks each winter. Estimates indicate that 80 percent of the
environmental damage caused from de-icing chemicals is a result of inadequate storage of the material (MPCA
1989). Improper storage as well as overuse of salt increases the risk of high chloride concentrations in runoff and
groundwater. High chloride concentrations can be toxic to fish, wildlife, and vegetation. The following procedures
are used for storing de-icing chemicals in the City:
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 62
Stockpiles of de-icing materials are covered by a permanent structure and placed on impervious surfaces.
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Road de-icing stockpiles are not located near municipal well areas or in other sensitive groundwater areas.
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Runoff from stockpiles is not allowed to flow directly into streams or wetlands where environmental damage
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can occur.
7.4.7 SS
TREET WEEPING
0QOBBQÐPTBBMFKDÐFPÐ>KÐFKQBDO>IÐM>OQÐLCÐQEBÐ FQVgPÐBCCB@QFSe surface water management system. It greatly reduces the
volume of sediments that have to be cleaned out of sump structures and downstream waterbodies. The City has a
hPQOBBQÐPTBBMFKDÐMLIF@ViÐQE>QÐFK@IRABPÐQTLÐPTBBMFKDÐLMBO>QFLns in a year. Spring sweeping begins in either late
March or early April after the risk of later snowfall has passed. Fall sweeping commences in mid-August and is
typically completed by Labor Day weekend. Stormwater quality areas are swept on a priority basis throughout the
year.
7.4.8 LC
ITTER ONTROL
Through City programs such as adopt-a-street and adopt-a-park, the City provides opportunities for volunteers to
?B>RQFCVÐQEBÐ FQVgPÐMR?IF@ÐOBPLRO@BP Ð->OQF@FM>KQPÐ>OBÐ>PHBAÐto coordinate a spring and fall clean up efforts to ensure
that City resources are visually attractive to its users throughout the year.
7.4.9 VCBMP
OLUME ONTROL S
The City will follow the guidance provided in the Minnesota Stormwater Manual regarding the operation and
maintenance considerations for volume control BMPs owned and maintained by the City. The City also requires a
detailed operation and maintenance plan for privately owned volume control BMPs be provided.
7.5 TRUNK SURFACE WATER SYSTEM COSTS
The proposed surface water system in the City is presented in Map 1. Surface water facilities will be constructed in
conjunction with new development, redevelopment and street construction. One of the basic objectives of this report
was to determine the cost of completing the City of Cottage Groves surface water system and at the same time
determine trunk area costs that will ensure availability of sufficient funds for the required construction.
The cost estimates presented in this report are based on 2008 construction costs and can be related to the value of
the Engineering News Record (ENR) Index for Construction Costs of approximately 8,126 (April 2008). Future
changes in this index are expected to fairly accurately describe cost changes in the proposed facilities. During interim
periods between full evaluation of projected costs, capital recovery procedures can be related to this index. A
detailed breakdown of the trunk surface water system cost estimates is presented in Appendix E. The cost estimates
are for construction, legal, engineering, and administrative costs.
For this SWMP, the estimated cost to complete the remaining proposed stormwater system cost is $44,373,500. This
estimated cost includes the cost of the proposed conveyance system (including costs for stream and ravine
restoration projects), regional pond construction costs, and some land acquisition costs. This total system cost will be
C>@QLOBAÐFKQLÐQEBÐ FQVgPÐ>KKR>IÐ>OB>Ð@E>ODBÐO>QBÐRMA>QB Ð
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 63
7.6 FINANCING
Several methods of financing the proposed projects and programs in this SWMP are available. Some of these are as
follows:
Area charges: These are fees charged to urban developments on an area (cost per acre) basis. The area charges
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for the land use types more dense than single family residential are higher because these land uses have a
higher percentage of impervious surface and thus generate more runoff. The City currently collects area charges
from new development and redevelopment within the City. The existing area charge rates were developed by a
previous study and have been updated by the City on a regular basis.
Special assessments: Assessments against benefiting or responsible properties can be used to finance surface
j
water improvements.
Stormwater utility: This is a fee charged to existing properties based on an estimate of runoff generated and
j
AFP@E>ODBAÐQLÐQEBÐ FQVgPÐPVPQBJ Ð1EBÐ FQVÐE>PÐOB@BKQIVÐestablished a stormwater utility that has been generating
revenue to fund the operation and maintenance of the FQVgPÐQORKHÐPQLOJT>QBOÐPVPQBJ Ð ROOBKQIV ÐQEBÐ FQVÐ
charges approximately $25 per quarter per household, with more dense non-residential land uses paying a
higher rate. The stormwater utility rate is based on a reviBTÐ>KAÐFKPMB@QFLKÐLCÐQEBÐ FQVgPÐBUFPQFKDÐQORKHÐPVPQBJ Ð
with updates to the rates occurring on a regular basis.
Grants: Though subject to budgetary constraints, a number of state and other grant programs are available for
j
surface water management.
7.7 AMENDMENT PROCEDURES
The SWMP is intended to extend through the year 2018. For the plan to remain dynamic, an avenue must be
available to implement new information, ideas, methods, standards, management practices and any other changes
that may affect the intent and/or results of the SWMP. The amendment procedure for the SWMP is presented below:
Written request for plan amendment is submitted to City staff. The request shall outline the need for the amendment
as well as additional materials that the City will need to consider before making its decision.
A decision is made as to the validity of the request. Three options exist: 1) reject the amendment, 2) accept the
amendment as a minor issue, with minor issues collectively added to the plan at a later date, or 3) accept the
amendment as a major issue, with major issues requiring an immediate amendment. In acting on an amendment
request, City staff shall recommend to City Council whether or not a public hearing is warranted.
The amendment and the need for a public hearing shall be considered at a regular or special Council meeting.
Staff recommendations should be considered before decisions on appropriate action(s) are made.
This step allows for public input based on public interest. Council shall determine when the public hearing should
occur in the process. Based on the public hearing, the City Council could approve the amendment.
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 64
All proposed amendments must be reviewed by the watershed management organizations prior to final adoption of
the amendments.
Final action on an amendment, following approval by the watershed management organizations, is City Council
adoption. However, prior to the adoption, an additional public hearing could be held to review the plan changes and
notify the appropriate stakeholders.
7.8 ANNUAL REPORT TO COUNCIL
A brief annual report will be made by City staff summarizing development changes, capital improvements, and other
water management-related issues that have occurred over the past year. The review will also include an update on
available funding sources for water resource issues. Grant programs are especially important to review since they
may change annually. These changes do not necessarily require individual amendments. The report can, however,
st
be considered when the plan is brought up to date. The annual report should be completed by July 1 to allow
implementation items to be considered in the normal budget process.
1EBÐ FQVgPÐ04*-ÐTFIIÐOBJ>FKÐFKÐBCCB@QÐQEOLRDEÐ
Ð1EBÐ FQV will then review the SWMP for consistency with current
water resource management methods. At that time, all annual reports and past amendments will be added to the
document. Depending on the significance of changes, a new printing of the SWMP may be appropriate.
7.9 SYSTEM IMPROVEMENT PROJECTS AND ACTIVITIES
>PBAÐLKÐQEBÐ>PPBPPJBKQÐLCÐQEBÐ FQVgPÐ@ROOBKQÐPQLOJT>QBO management program, a prioritized list of system
improvement projects and activities has been identified. The system improvements identified range from those being
driven by regulatory requirements, to others driven more ?VÐQEBÐCRK@QFLK>IFQVÐLCÐQEBÐ FQVgPÐOBDFLK>IÐPQLOJT>QBOÐ
management system. Table 7.1 presents a summary of recommended high and medium priority stormwater and
water resource management projects and activities. The budget amounts included in this table should be considered
planning-level cost estimates, with more specific cost estimates to be determined as the project or activity
approaches.
For capital improvement projects, the City will continue to rely on its very detailed 5-year capital improvement
planning process to schedule and plan for funding these projects. This planning process is updated annually by City
staff and reviewed and approved annually by the City Council. The items listed in Table 7.1 will be used as a
reference for particular projects and activities specific to stormwater and water resources management to be
included in the capital improvement planning process.
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 65
Table 7.1 k High and Moderate Priority System Improvement Projects and Activities
Project Description Estimated Cost Priority Comments
FQVgPÐ+LKABDO>A>QFLKÐ/BSFBTÐT>PÐPR?JFQQBAÐ
NPDES MS4 Cost of effort unclear
and is undergoing MPCA review. City will need
Nondegradation Finalize Nondegradation Review until MPCA comments High
to respond to comments from MPCA. Scope of
Review are known
comments unclear.
Review and comment on new WMO
ÐkÐ
Ð
Evaluate WMO On-going. SWWD standards manual as well as
standards, rules, and guidance for City staff and City
standards, rules, and High other changes in standards and rules likely in
documents as necessary to address Attorney/Consulting
guidance documents future for both watershed authorities.
concerns regarding City compliance assistance
Develop spill response $8,000 - $15,000 for
Establish plan to comply with Complete within 1 year of adoption of this
plan for karst-sensitive City staff time and High
LSCWMO plan requirement. SWMP by City Council
areas within LSCWMO consulting assistance
Continue to work with local WMOs
Coordinate education $1,000 -$5,000/yr. in This is expected to be an on-going activity
and the Washington County shared High
efforts City staff time throughout the term of this Plan
water resources educator program
Develop ordinance or other
$15,000 - $25,000
regulatory mechanism to establish
for City staff time and
Erosion and Sediment consistent procedures for site plan Complete within 1 year of adoption of this
City High
control review, inspection, and enforcement, SWMP by City Council
Attorney/consulting
OBNRFOBÐ"0 Ð *-gPÐLKÐ@LKPQOR@QFLKÐ
assistance
sites, control waste and debris.
$15,000 - $25,000
for City staff time and Complete within 2 years of adoption of this
Shoreland ordinance Develop a shoreland ordinance Moderate
City Attorney SWMP by City Council
assistance
Coordinate with the SWWD to
East Ravine Regional Financed by the
design and install the SWWD outlet High
Outlet SWWD
for pond ER-P2 (CD-P86)
Work with MnDOT, MnDNR, City of St. Paul
Gateway Pond (SPP-Implement the necessary
$1,500,000 Moderate Park, SWWD, and Canadian Pacific Railroad to
P9) Improvements improvements to the Gateway Pond
develop a joint funding strategy.
Construct a quality treatment pond
Thompson Grove water adjacent to the Hamlet Park Pond Other water quality BMPs should also be
$1,300,000 Moderate
quality pond system to provide treatment for some investigated
of the tributary residential area
&KPQ>IIÐgUgÐ?LUÐ@RISBOQÐRKABOÐ
Jamaica Avenue box Cost estimate includes box culvert and channel
Jamaica Ave and provide stabilized $200,000 Moderate
culvert stabilization to L-P3
conveyance to L-P3
Update the water quality system
Update long-term improvements costs CIP from 2000 $5,000 - $10,000 for
Complete within one year of adoption of this
system improvements QLÐOBCIB@QÐKBTÐMOFLOFQFBPÐFKÐQEBÐ FQVgPÐCity staff time and High
SWMP by City Council
for water quality plan, such as volume control and consulting time
nondegradation
If completed by city,
Assessment is required prior to development.
cost includes city staff High for
Complete Wetland Work with the appropriate Watershed organizations may complete at little
time plus up to $350 areas likely
Assessment for non-watershed organization to inventory or no cost to the City. Another low cost
- $700+ per wetland to develop
assessed wetlands and classify wetlands within the City alternative would be for City to wait until
if City hires consultant within 2-3
within the city. that have not yet been assessed. development is proposed and have developer
to complete ahead of years.
conduct assessment.
time.
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 66
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8.1 SUMMARY
The Cottage Grove Surface Water Management Plan will address the current needs of the City regarding stormwater
management. It will serve as a guide to managing the surface water system and protecting key water resources
within the City. The surface water system is shown on Map 1. The following issues have been incorporated into this
SWMP:
1.Description of the physical environment and context for surface water management in Cottage Grove
2.Up-to-date goals and policies of the City as well as agency requirements affecting surface water management
3.General layout and a description of the system
4.Regulatory responsibilities
5.Guidelines for surface water management as redevelopment occurs
6.Public education
7.Operation and maintenance of the surface water system
8.Implementation items
8.2 RECOMMENDATIONS
The following actions are recommended to implement this SWMP:
1.Proceed with implementation items
2. LKQFKRBÐLMBO>QFKDÐ>KAÐJ>FKQ>FKFKDÐQEBÐ FQVgPÐPROCace water system in accordance with this SWMP
3.Continue a public education program to inform citizens about water resource management and protection
4.Establish standard review procedures to ensure that all new development/redevelopment is in compliance with
QEBÐ FQVgPÐDL>IPÐ>KAÐMLIF@FBPÐ>PÐTBIIÐ>PÐ>DBK@VÐOBNRFOBJBKQPÐ
5.Continue cooperating with the watershed management organizations in the City to regulate, manage, and
protect water resources
6.Adopt and implement amendments to the SWMP as warranted by future standards or regulations
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 67
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Lower St. Croix Watershed Management Organization, 2005.
Watershed Management Plan (Written by Emmons and Olivier Resources).
Lower St. Croix Watershed Management Organization, 2007.
,g LKKBOgPÐ0QB>JÐ>KAÐ)>HBÐ*>K>DBJBKQÐ-I>KÐTritten by Emmons and Olivier Resources).
Metropolitan Council, 2001. Minnesota Urban Small Sites BMP Manual.
Stormwater Best Management Practices for Cold Climate.
Minnesota Stormwater Advisory Group, 1997.
Guidance for Evaluation of Urban Stormwater and Snowmelt Runoff Impacts to Wetlands.
South Washington Watershed District (SWWD), 2007.
Watershed Management Plan (written by Houston Engineering, Inc.).
South Washington Watershed District (SWWD), 2007.
South Washington Watershed District Standards Manual Volume 1 (Draft).
State of Minnesota, 2005. The Minnesota Stormwater Manual.
1984 Surface Water Management Plan for Cottage Grove.
1979 Woodbury Stormwater Plan.
2005 Cottage Grove East Ravine AUAR (Prepared by Emmons and Olivier Resources).
April 8, 2005, memo from HDR Engineering to the SWWD, regarding the West Draw stormwater modeling.
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 68
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Acre-Foot: Volume of water that would cover an acre of land to a depth of one foot (43,560 cubic feet).
Bedrock: KVÐPLIFAÐOL@HÐBUMLPBAÐ>QÐQEBÐB>OQEgPÐPROC>@BÐLOÐ@LSBOBd by unconsolidated material such as till, gravel, or
sand.
Best Management Practices (BMPs): Activities or structural improvements that help reduce the quantity and improve
the quality of stormwater runoff. BMPs include treatment requirements, operating procedures, and practices to
control site runoff, spillage or leaks, sludge or waste disposal, or drainage from raw material storage.
Bluegreen algae: A type of algae whose population often increases dramatically at high nutrient concentrations in
lakes. They can form objectionable surface scums, cause taste and odor problems, and secrete toxins poisonous to
warm-blooded animals.
Bounce: The difference in elevation between the normal water elevation and the peak water elevation of a pond for
a given size runoff event.
Buffer strip: A band of un-maintained, preferably native, vegetation left along the edge of a stream, lake or wetland
to filter runoff and/or stabilize the shoreline.
Clean Water Act (Water Quality Act): (formerly the Federal Water Pollution Control Act or Federal Water Pollution
Control Act Amendments of 1972). Public law 92-500; 33 U.S.C. 1251 et seq.; legislation which provides statutory
authority for the NPDES program. Also know as the Federal Water Pollution Control Act.
Conveyance: The process of water moving from one place to another.
Cubic feet per second (cfs): A unit of flow rate.
Degradation: A decrease in quality.
Detention Pond: A pond designed to catch and temporarily store runoff before discharging the water downstream.
The volume of the pool of standing water in the pond is important in determining how effective the pond will be in
treating the incoming stormwater.
Discharge: The volume of water (and suspended sediment if surface water) that passes a given location within a
given period of time.
Discretionary MS4: A small MS4 who is required to comply with the NPDES Phase II permit due to the permitting
agency (MPCA) designated criteria.
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 69
Dissolved Oxygen (D.O.): Oxygen that is dissolved in water. Fish and other water organisms need oxygen for
respiration to survive. Depletion of oxygen from water can occur as a result of chemical and biological processes,
including decomposition of organic matter.
Ecosystem: A community represented by interaction among animals, plants, and microorganisms, and the physical,
biological and chemical environment in which they live.
Empirical: Based on experiment and observation; used to describe water quality models which are developed from
measured data.
Erosion: When land is diminished or worn away due to wind, water, or glacial ice. Often the eroded debris (silt or
sediment) becomes a pollutant via stormwater runoff. Erosion occurs naturally but can be intensified by land clearing
activities such as farming, development, road building, and timber harvesting.
Eutrophication: A natural process caused by the gradual accumulation of nutrients and consequent increased
biological production, and resulting in the slow filling in of a basin with accumulated sediments, silt, and organic
J>QQBO Ð*>KgPÐ>@QFSFQFBPÐ@>KÐFK@OB>PBÐQEe rate at which eutrophication occurs.
Feet per second (fps): A unit of flow velocity.
Flood Storage Volume: The volume of water that can be stored beQTBBKÐ>ÐMLKAgPÐKLOJ>IÐT>QBOÐIBSBIÐ>KAÐFQPÐEFDEÐ
water level. The size of the flood storage volume strongly influences the performance of the pond for floodwater
management and rate control.
Excavation: The process of removing earth, stone, or other materials from land.
General Permit: A permit issued under the NPDES program to cover a certain class or category of stormwater
discharges whose operations, emissions, discharges, or facilities are the same or substantially similar. These permits
reduce the administrative burden of permitting stormwater discharges.
Grading: The cutting and/or filling of the land surface to a desired slope or elevation.
High Water Level (HWL): The peak water surface elevation in a ponding area as a result of a specific runoff event.
Once the peak is reached, the pond water elevation eventually returns to its normal (standing) water level.
Hydrology: The science and study of water in nature, including its circulation, distribution, and its interaction with
the environment.
Impervious Surface: A surface that is impermeable to the downward seepage of water; e.g., pavement and roof
tops.
Karst-sensitive area: Areas consisting of less than 50 feet of soil cover to fractured bedrock, and the first bedrock
encountered is either unconsolidated St. Peter Sandstone or the soluble Prairie du Chein group.
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 70
Loading: The amount of a pollutant or other substance delivered to a lake, usually expressed as a weight per unit
time (i.e. pounds per year). The loading of a given constituent to a receiving water is a function of the volume of
incoming water and the concentration of the constituent in the incoming water.
Model: A mathematical representation of an event or process.
Mitigation: Actions taken to reduce an impact. Water quality mitigation measures can be non-structural (such as
street sweeping, regulation of fertilizer use, and creation/protection of natural buffers to filter runoff) or structural
(such as installation of detention basins). Properly designed detention basins are among the most effective and
reliable measures for mitigating the water quality impacts of urban developments.
Municipal Separate Storm Sewer System (MS4): A publicly-owned conveyance or system of conveyances that
discharges to waters of the U.S. or waters of the State, and is designed or used for collecting or conveying
stormwater, is not a combined sewer, and is not part of a Publicly-Owned Treatment Works (POTW).
NPDES (National Pollutant Discharge Elimination System): The name of the surface water quality program
authorized by Congress as part of the 1987 Clean Water Act. This is EPA's program to control the discharge of
pollutants to waters of the United States (see 40 CFR 122.2). In Minnesota, the MPCA is the permitting authority
and also controls the discharge of pollutants to the waters of the State.
Normal Water Level (NWL): The elevation of the surface of the standing water pool within a pond or wetland.
Generally, the NWL is the elevation of the bottom of the primary outlet pipe or overland flow channel.
Non-Point Source Pollution: Refers to pollution other than that caused by discharge of pollutants through a pipe
from a closed system to a receiving water. Pollution caused by runoff from farm fields or paved streets are examples
of this non-point pollution.
NURP: Acronym for Nationwide Urban Runoff Program, an EPA program aimed at characterizing the composition
of stormwater runoff and its impacts upon receiving waters as well as assessing Best Management Practices.
The program was undertaken in 28 U.S. cities in the early 1980s.
Nutrient Trap: A type of pond or wetland that is effective at removing nutrients from water.
Parts per billion (ppb): A unit of concentration, sometimes expressed as micrograms per liter (ug/l).
Parts per million (ppm): A unit of concentration, sometimes expressed as milligrams per liter (mg/l).
pH: A measure of the acidic or basic nature of the water; it is defined as the logarithm of the reciprocal of the
hydrogen-ion concentration in moles/liter.
Phosphorus: A nutrient essential to plant growth. Phosphorus is the nutrient most commonly limiting plant growth
in lakes.
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 71
Rate Control: A term that refers to controlling the rate at which water is discharged from a watershed. Rate control
is often accomplished by creating ponds-either by excavation or berming- to temporarily store runoff, then
discharging the stored water at a slower rate to downstream areas. Further reductions in the rate at which water is
released from a pond can be accomplished by reducing the size of the outlet, such as through installation of a wall in
the outlet structure with a hole (orifice) through it.
Residence Time: The amount of time it takes for water flowing into a lake to equal the lake volume. The shorter the
residence time, the more incoming water the lake is receiving relative to its volume.
Stormwater Pollution Prevention Program (SWPPP): A program to describe a process whereby an MS4 thoroughly
evaluates potential pollutant sources and selects and implements appropriate measures designed to prevent or
control the discharge of pollutants in stormwater runoff.
Suspended Solids: Particulate material which floats in or is carried along in water (e.g., algae, soil particles).
Total Maximum Daily Load (TMDL): The maximum amount of pollutants which can be released into a water body
without adversely affecting the water quality.
Total Phosphorus: A measure of all of the different forms of phosphorus in water. Includes phosphorus dissolved in
the water, suspended or incorporated in algae or other organisms.
Watershed: The area of land draining into a specific body of water.
Wetland: Habitats where the soil is saturated or covered with water for part of the year.
Wet Volume: The volume of water in a ponding area that lies between the bottom of the ponding area and the
normal (standing) water level. The size of the wet volume strongly influences the water quality treatment
performance of the ponding area.
City of Cottage Grove Project No: 48-05-214
Surface Water Management Plan Page 72
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Appendix B - Drainage Areas
Central DistrictEast Ravine District
AreaAreaAreaArea
Designation(acres)Designation(acres)
C-A1238ER-A1560
C-A271ER-A2596
C-A342ER-A3609
C-A4112ER-A3013
C-A549ER-A4492
C-A6236ER-A5.113
C-A7315ER-A5.29
C-A862ER-A5.318
Total Area1125ER-A5.41819
ER-A617
East Draw District
ER-A7198
ER-A8135
AreaArea
ER-A9125
Designation(acres)
ER-A1016
ED-A129
ER-A1152
ED-A2.1115
ED-A2.227ER-A12207
ER-A1348
ED-A3.113
ER-A14111
ED-A3.273
ER-A15.124
ED-A4.170
ER-A15.226
ED-A4.245
ER-A1669
ED-A5169
ER-A1764
ED-A6105
ER-A1836
ED-A778
ER-A1970
ED-A8121
ER-A2063
ED-A9.119
ER-A21.120
ED-A9.212
ER-A21.250
ED-A9.33
ER-A2227
ED-A9.44
ER-A238
ED-A10185
Total Area1067ER-A2489
ER-A2514
Gables Lake District
ER-A265
ER-A274
AreaArea
ER-A2813
Designation(acres)
GL-A11469ER-A2921
ER-A3013
Total Area1469
Total Area5642
Appendix B - Drainage Areas
Central DistrictEast Ravine District
Grey Cloud Island DistrictSt. Paul Park District
AreaAreaAreaArea
Designation(acres)Designation(acres)
GCI-A11271SPP-A126
Total Area1271SPP-A223
SPP-A331
Langdon District
SPP-A4.116
SPP-A4.28
AreaArea
SPP-A574
Designation(acres)
L-A137SPP-A651
L-A2138SPP-A746
L-A3597SPP-A8172
L-A4289SPP-A9.159
L-A5205SPP-A9.254
Total Area1266
SPP-1046
SPP-A1131
Lower Saint Croix District
Total Area637
AreaArea
Southwest District
Designation(acres)
LSC-A1527AreaArea
LSC-A2344Designation(acres)
SW-A176
LSC-A3252
SW-A292
LSC-A4225
Total Area1347SW-A336
SW-A495
South District
SW-A575
AreaArea
SW-A641
SW-A745
Designation(acres)
S-A142SW-A864
S-A2209SW-A933
S-A3193SW-A1026
S-A4140SW-A11106
S-A5259SW-A1239
S-A6278SW-A1311
S-A7.135SW-A1448
S-A7.270SW-A1535
S-A7.321SW-A1623
S-A88SW-A1753
S-A987SW-A1816
S-A10202SW-A1911
S-A1180SW-A20184
Total Area1624Total Area1108
Appendix B - Drainage Areas
Central DistrictEast Ravine District
Seeger Creek DistrictWest Draw District
AreaAreaAreaArea
Designation(acres)Designation(acres)
SC-A1687WD-A119
SC-A2538WD-A262
SC-A31294WD-A372
SC-A4174WD-A4.128
SC-A583WD-A4.228
SC-A631WD-A4.327
SC-A7566WD-A4.410
SC-A8162WD-A4.52
SC-A9293WD-A4.611
Total Area3828WD-A4.735
WD-A516
WD-A624
WD-A767
WD-A832
WD-A9.120
Thompson Grove District
WD-A9.213
AreaAreaWD-A9.312
WD-A9.43
Designation(acres)
TG-A1.125WD-A9.532
TG-A1.222WD-A10.118
TG-A1.32WD-A10.225
TG-A1.425WD-A10.314
TG-A243WD-A10.4100
TG-A377WD-A11.18
TG-A41433WD-A11.23
TG-A5.198WD-A11.321
TG-A5.229WD-A1248
TG-A6118WD-A13.128
TG-A719WD-A13.210
TG-A822WD-A13.37
TG-A922WD-A13.416
TG-A1018WD-A13.57
TG-A1110WD-A13.638
TG-A12108WD-A13.75
TG-A13.15WD-A14.143
TG-A13.25WD-A14.23
TG-A13.34WD-A15.123
TG-A14144WD-A15.216
TG-A156WD-A15.312
TG-A1616WD-A15.414
TG-A1748WD-A15.5151
TG-A188WD-A15.674
TG-A1917WD-A15.781
TG-A2023WD-A1644
Total Area2347WD-A1749
WD-A18.126
WD-A18.24
WD-A18.312
WD-A19.124
WD-A19.211
WD-A19.337
Total Area1483
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Appendix C - Proposed Trunk Storm Sewer Data
Ponded DesignConveyance
FromTo
Flow Pipe SizeLength
(in.)(ft.)
(cfs)
East Ravine District
ER-P1ER-P219.0243400
ER-P2ER-P5158.77212200
ER-P3ER-P45.8122300
ER-P4ER-P520.030" FM1760
ER-P8ER-P19607.28'X6' Box100
ER-P9ER-N12.17.9212310
ER-P10ER-N12.11.712150
ER-N12.1ER-P129.6211980
ER-P11ER-P127.0153640
ER-P12ER-P1436.027150
ER-P13ER-P143.612950
ER-P15.1ER-P15.21.912300
ER-P15.2ER-P1958.030110
ER-P17ER-P1813.921740
ER-P18ER-P1916.218750
ER-P19ER-P24651.22-66125
ER-P21.1ER-P21.24.612310
Gables Lake District
GL-P1ER-P410.020" FM1900
Langdon District
L-P4L-N5.1371.810'x5' Box100
St. Paul Park District
SPP-P1SPP-N3.12.912580
SPP-P2SPP-N3.14.112730
SPP-N3.1SPP-P37.018220
SPP-P3SPP-P526.421750
SPP-P7SPP-P9.28.21250
SPP-P9.2TG-P410.024" FM3000
Seeger Creek District
SC-P1SC-N2.1126.42-3660
SC-P2SC-N7.1235.04'x6' Box60
SC-P8SC-N9.119.118575
South District
S-P3S-P416.3271910
S-P4S-P533.7362510
S-P5S-P7.356.9362980
S-P6S-P7.326.424110
S-P7.1S-P7.34.512180
S-P7.2S-P7.37.412330
S-P7.3River93.224150
S-P9S-P107.815250
Southwest District
SW-P1SW-P26.112660
SW-P2SW-P310.921690
SW-P3SW-P616.524370
SW-P4SW-P55.912190
SW-P5SW-P613.5181490
SW-P6SW-P839.5362610
SW-P7SW-P83.4121300
SW-P8SW-P945.836580
SW-P9SW-N10.144.8361620
SW-P10SW-N10.12.68160
SW-N10.1River47.436950
SW-P14SW-N16.14.612120
SW-P15SW-N16.11.5151130
Appendix C - Proposed Trunk Storm Sewer Data
Ponded DesignConveyance
FromTo
Flow Pipe SizeLength
(in.)(ft.)
(cfs)
East Ravine District
Thompson Grove District
TG-P1.1TG-P1.35.412510
TG-P10TG-P197.31250
TG-P11TG-P195.41250
TG-P19TG-P20315.46'x6' Box140
TG-P20L-P3350.08'x5' Box90
West Draw District
WD-P1WD-P21.212380
WD-P2WD-P31.312880
WD-P5WD-P62.112365
WD-P6WD-P83.212800
WD-P7WD-P821.718950
WD-P10.1WD-P10.21.312350
WD-P18.1WD-P18.294.215175
WD-P18.2WD-P19.310.715420
WD-P19.2WD-P19.35.212930
WD-P19.3TG-P49.212190
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Existing (E)
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Existing (E)
Proposed (P)
Existing (E)
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Rules and Regulations of the
Lower St. Croix Watershed
Management Organization
LOWER ST. CROIX WATERSHED
MANAGEMENT ORGANIZATION
651 Hale Avenue North
Oakdale, MN 55128
Tel: 651-770-8448
Fax: 651-770-2552
Adopted February 13, 2008
Effective June 1, 2008
For additional information, please see the LSCWMO website at:
www.denmarktownship.org
Adopted February 13, 2008
FOREWORD
The Lower St. Croix Watershed Management Organization (LSCWMO) was organized on
June 21, 1985, to fulfill the watershed planning and management responsibilities of
Minnesota Statutes section 103B. The LSCWMO is organized under a Joint Powers
Agreement among Denmark Township and the Cities of Afton, Cottage Grove, and
Hastings. The LSCWMO adopted a Watershed Management Plan on June 8, 2005. The
Plan calls for development and implementation of watershed Rules based on standards,
goals, and policies within the Plan.
These Rules follow the suggested formatSURSRVHGE\:DVKLQJWRQ&RXQW\·V
UHSRUW´&RPSDUDWLYH5HYLHZRI:DWHUVKHG'LVWULFW5XOHVDQG5HFRPPHQGDWLRQVIRU
6WDQGDUGL]DWLRQµ
Rulemaking Process
During October 2005, the Board began its rulemaking process. A Steering Committee
was formed to assist the Board with rule development consisting of City and Township
staff which met throughout 2006 and 2007. The LSCWMO solicited official comments
on Draft Rules from each of the LGUs including Cottage Grove, Afton, Denmark
Township and Hastings on July 30, 2007. Comments received were discussed and
revisions were made to the Rules by the Board of Managers at their regular meeting on
October 10, 2007. Comments were then solicited from Washington County,
Washington Conservation District, the Board of Water and Soil Resources, and MN
Department of Transportation on November 6, 2007. A public hearing was conducted
on December 12, 2007. Comments were discussed at the January 9, 2008 Board
meeting and the Rules were revised. This final revision was then officially adopted by
the Board of Managers as the Watershed Rules and Regulations on February 13, 2008.
Authority
The LSCWMO is required by Minnesota Statutes section 103B.231 to create a watershed
management plan. The plan must include a course of implementation and regulatory
controls pursuant to Minnesota Rules 8410.0100, subp. 2 and 8410.0130, and the
LSCWMO plan adopted in June 2005 included development of rules as part of its
implementation plan. These rules were developed pursuant to the plan.
LSCWMO Rules and Regulations 1
Adopted February 13, 2008
Relationship with Municipalities
The LSCWMO recognizes that the control and determination of appropriate land use is
the responsibility of the Local Units of Government (LGUs; i.e. municipalities and
counties). LGUs are responsible for adopting Local Water Plans that implement the
LSCWMO Watershed Plan. After approval of the Local Water Plans by the LSCWMO, the
LGUs have 120 days to begin implementing the plans and 180 days to amend their
official controls. During the interim period between LSCWMO rule adoption and local
government adoption of ordinances and controls, the LSCWMO will work with local
governments to amend their ordinances and other controls to incorporate the LSCWMO
Rules.
The LSCWMO anticipates that the LGUs will be the implementing agencies for these
Rules and will assume responsibility for all permitting under these Rules. The LSCWMO
will provide review and comment to the LGU during the concept or initial planning
stages for activities regulated under these Rules, and will also provide review of and
comment on the construction documents suEPLWWHGDVSDUWRI/*8V·SHUPLWWLQJ
processes. The LSCWMO will conduct its review of such documents within the 60-day
review period within which the LGUs must act on permit applications. (Minnesota
Statute section 15.99.)
7KHVH5XOHVDUHEDVHGRQWKH/6&:02·V:Dtershed Plan policies, objectives, and
actions. The LSCWMO envisions that the incorporation of its Watershed Plan and Rules
into local plans and controls, coupled with a system of project review coordinated
between the LGUs and the LSCWMO will be a critical and substantial part of achieving
WKH/6&:02·VZDWHUVKHGPDQDJHPHQWJRDOVand standards. LGUs may adopt more
restrictive standards. In addition, the LSCWMO recognizes that LGUs have different
authorities and different ways of implementing programs that will necessitate different
language and approaches that vary from those presented in the following Rules.
LSCWMO Rules and Regulations 2
Adopted February 13, 2008
DEFINITIONS
For the purposes of these Rules, unless the context otherwise requires, the following
words and terms shall have the meanings set forth below. References in these Rules to
specific sections of the Minnesota Statutes or Rules include amendments, revisions or
UHFRGLILFDWLRQVRIVXFKVHFWLRQV7KHZRUGV´VKDOOµDQG´PXVWµDUHPDQGDWRU\ WKH
ZRUG´PD\µLVSHUPLVVLYH
Agricultural Activity²7KHXVHRIODQGIRUWKHJURZLQJDQGRUSURGXFWLRQDQG
wholesale distribution of field crops, livestock, and livestock products for the
production of income or own use, including but not limited to the following:
1.Field crops, including but not limited to barley, beans, corn, hay, oats,
potatoes, rye, sorghum, and sunflowers.
2.Livestock, including but not limited to dairy and beef cattle, goats,
sheep, hogs, horses, poultry, game birds and other animals, including
deer, rabbits and mink.
3.Livestock products, including but not limited to milk, butter, cheese,
eggs, meat, fur and honey.
4.Trees, shrubs, bushes, and plants for wholesale distribution.
5.Sod farming.
6.Orchards.
Alteration or Alter²:KHQXVHGLQFRQQHFWLRQZLWKSXEOLFZDWHUVRUZHWODQGVLVDQ\
activity that will change or diminish the course, current or cross-section of public
waters or wetlands.
Applicant²$Q\SHUVRQRUSROLWLFDOVXEGLYLVLRQthat submits an application to a Local
Unit of Government (LGU) under these Rules.
Best Management Practices or BMPs²7HFKQLTXHVSURYHQWREHHIIHFWLYHLQFRQWUROOLQJ
runoff, erosion and sedimentation including those documented in the Minnesota
Construction Site Erosion and Sediment Control Planning Handbook (BWSR, 1988);
Protecting Water Quality in Urban Areas (MPCA, 2000); the Minnesota Urban Small Sites
BMP Manual (Metropolitan Council 2001); Minnesota Stormwater Manual (MPCA, 2005);
and other sources as approved by the LSCWMO: as such documents may be amended,
revised or supplemented.
LSCWMO Rules and Regulations 3
Adopted February 13, 2008
Bioengineering²XVHRIOLYHSODQWLQJVLQFRQVWUXFted features to stabilize streambanks
and shorelines.
Buffer²$QDUHDRIQDWXUDOXQPDLQWDLQHG vegetated ground cover abutting or
surrounding a watercourse, public waters wetland, or wetland.
BWSR²7KH0LQQHVRWD%RDUGRI:DWHUDQG6RLO5HVRXUFHV
Construction Activity²,VDGLVWXUEDQFHWRWKHODQGthat results in a change in the
topography, existing soil cover (both vegetative and non-vegetative), or the existing
soil topography that may result in accelerated storm water runoff, leading to soil
erosion and the movement of sediment into surface waters or drainage systems.
County²:DVKLQJWRQ&RXQW\0LQQHVRWD
Development²7KHFRQVWUXFWLRQRIDQ\SXEOLFimprovement project, infrastructure,
structure, street, or road, or the subdivision of land.
Dewatering²7KHUHPRYDORIZDWHUIRUFRQVWUXFWLRQDFWLYLW\
Drain or Drainage²$Q\PHWKRGIRUUHPRYLQJRUGLverting water from waterbodies,
including excavation of an open ditch, installation of subsurface drainage tile, filling,
diking or pumping.
Easement ²7KHULJKWWRXVHWKHODQGRIDQRWher owner for a specified use. An
easement may be granted for the purpose of constructing and maintaining walkways,
roadways, subsurface sewage treatment systems, utilities, drainage, driveway, and
other uses.
Energy Dissipation²0HWKRGVHPSOR\HGDWSLSHRXWOHWVWRSUHYHQWHURVLRQLQFOXGLQJ
but not limited to concrete aprons, riprap, splash guards, and gabions.
Erosion²7KHZHDULQJDZD\RIWKHJURXQGVXUIDFHDVDUHVXOWRIZLQGIORZLQJZDWHU
ice movement or land disturbing activities.
Excavation²7KHDUWLILFLDOUHPRYDORIVRLORURWKHUHDUWKPDWHULDO
Fill²7KHGHSRVLWRIVRLORURWKHUHDUWKPDWHULDOE\DUWLILFLDOPHDQV
LSCWMO Rules and Regulations 4
Adopted February 13, 2008
Filtration Practice ²$VWRUPZDWHUFRQWUROWKDWFDSWXUHVWHPSRUDULO\VWRUHVDQGURXWHV
stormwater runoff through a filter bed to improve water quality, as described in the
Minnesota Stormwater Manual, 2005, and as amended.
Floodplain²7KHDUHDDGMDFHQWWRDZDWHUERG\that is inundated during a 100-year
flood.
Groundwater Recharge²WKHUHSOHQLVKPHQWRIJURXQGZDWHUVWRUDJHWKURXJKLQILOWUDWLRQ
of surface runoff into subsurface aquifers.
Impervious Surface²$FRQVWUXFWHGKDUGVXUIDFHWKDWHLWKHUSUHYHQWVRUUHWDUGVWKH
entry of water into the soil and causes water to run off the surface in greater quantities
and at an increased rate of flow than prior to development. Examples include rooftops,
sidewalks, patios, driveways, parking lots, storage areas, and concrete, asphalt or
gravel roads. Impervious surfaces must be calculated on a site by site basis.
Infiltration Practice²$VWRUPZDWHUUHWHQWLRQPHWKRGIRUWKHSXUSRVHRIUHGXFLQJWKH
volume of stormwater runoff by transmitting a flow of water into the ground through
the soils, as described in the Minnesota Stormwater Manual, 2005, and as amended.
Infrastructure²7KHV\VWHPRISXEOLFZRUNVIRUDFRXQW\VWDWHRUPXQLFLSDOLW\
including, but not limited to, structures, roads, bridges, culverts, sidewalks;
stormwater management facilities, conveyance systems and pipes; pump stations,
sanitary sewers and interceptors, hydraulic structures, permanent erosion control and
stream bank protection measures, water lines, gas lines, electrical lines and associated
facilities, and phone lines and supporting facilities.
Karst - A topography developed largely by the dissolution of bedrock. Karst
topography is often characterized by features such as springs, sinkholes, solution
valleys, caves, and disappearing streams.
.DUVW,QYHVWLJDWLRQ$UHD²Areas identified in the LSCWMO Karst Feature Inventory and
Management Plan (2007) where possible Karst features may be present. These areas
include features such as tree clusters in open active agricultural land, areas that appear
to have terminated swales, and depressional lows.
.DUVW6HQVLWLYH$UHD²Areas consisting of less than 50 feet of soil cover to fractured
bedrock, and the first bedrock encountered is either unconsolidated St. Peter
Sandstone or the soluble dolomitic Prairie du Chien group.
LSCWMO Rules and Regulations 5
Adopted February 13, 2008
Land Disturbing Activity²$Q\FKDQJHRIWKHODQGVXUIDFHWRLQFOXGHUHPRYLQJ
vegetative cover, excavation, fill, grading, stockpiling soil, and the construction of any
structure that may cause or contribute to erosion or the movement of sediment into
water bodies. The use of land for new and continuing agricultural activities shall not
constitute a land disturbing activity under these Rules.
Landlocked Basin²$EDVLQWKDWLVRQHDFUHRUPRUHLQVL]HDWWKHRYHUIORZHOHYDWLRQ
and does not have a natural outlet at or below the existing 100-year flood elevation.
Local Government Unit (LGU) - Any city or township wholly or partly within the Lower
St. Croix Watershed Management Organization.
²7KHORZHVWJUDGHHOHYDWLRQDGMDFHQWWRDVWUXFWXUH
Low Opening
Mining²7KHH[WUDFWLRQRIVDQGJUDYHOURFNEODFNGLUWSHDWVRLODQGRWKHUPDWHULDO
from the land surface and the removal thereof from the site.
MPCA ²7KH0LQQHVRWD3ROOXWLRQ&RQWURO$JHQF\
MPCA General Construction Permit - General Permit Authorization to Discharge Storm
Water Associated With Construction Activity Under the National Pollutant Discharge
Elimination System/State Disposal System Permit Program Permit MN R100001 (NPDES
General Construction Permit) issued by the Minnesota Pollutant Control Agency,
August 1, 2003, and as amended.
Municipality²$Q\FLW\RUWRZQVKLSZKROO\RUSDUWO\ZLWKLQWKH/RZHU6W&URL[
Watershed Management Organization.
Nonpoint Source²1XWULHQWDQGSROOXWLRQVRXUFHVQRWGLVFKDUJHGIURPDVLQJOHSRLQW
e.g. runoff from agricultural fields, feedlots or urban landscapes.
Owner²$Q\LQGLYLGXDOILUPDVVRFLDWLRQSDUWnership, corporation, trust or any other
legal entity having proprietary interest in the land.
Parcel²$SDUFHORIODQGGHVLJQDWHGE\SODWPHWHVDQGERXQGVUHJLVWHUHGODQGVXUYH\
auditors subdivision or other accepted means and separated from other parcels or
portions by its designation.
Person²$Q\LQGLYLGXDOWUXVWHHSDUWQHUVKLp, unincorporated association, limited
liability company or corporation.
LSCWMO Rules and Regulations 6
Adopted February 13, 2008
Political Subdivision²´3ROLWLFDOVXEGLYLVLRQµPHDQVDFRXQW\FLW\WRZQVFKRROGLVWULFW
or other local government jurisdiction to which the state provides state aids or on
which the state imposes state mandates.
3UHGHYHORSPHQW&RQGLWLRQ²The land use on a site that exists immediately prior to a
proposed alteration. Under pre-development conditions, the following Runoff Curve
Numbers must be used for all agricultural land-uses unless site specific replacements
are agreed upon by the LSCWMO. All other pre-development Runoff Curve Numbers
must reference the Minnesota Hydrology Guide.
Allowable Runoff Curve Numbers for Agricultural Land-use
Hydrologic Soil
A B C D
Group
Runoff Curve number 39 61 74 80
Based on Minnesota Hydrology Guide for Pasture
Public Health and General Welfare²$UHGHILQHGLQ0LQQHVRWD6WDWXWHV6HFWLRQ
103D.011, Subdivisions 23 and 24.
Public Waters²$Q\ZDWHUVDVGHILQHGLQ0Lnnesota Statutes, section 103G.005,
subdivision 15.
Public Waters Wetlands ´3XEOLFZDWHUVZHWODQGµPHDQVDOOW\SHVDQGZHWODQGV
as defined in United States Fish and Wildlife Service Circular No. 39 (1971 edition), not
included within the definition of public waters, that are ten or more acres in size in
unincorporated areas or 2-1/2 or more acres in incorporated areas.
Redevelopment²7KHUHEXLOGLQJUHSDLURUDOWHUDWLRQRIDVWUXFWXUHODQGVXUIDFHURDG
or street, or facility.
Retention²7KHSUHYHQWLRQRIGLUHFWGLVFKDUJe of stormwater runoff into receiving
water; examples include systems which discharge through percolation, exfiltration,
and evaporation processes and which generally have residence times less than three
days.
Runoff²5DLQIDOOVQRZPHOWRULUULJDWLRQZDter flowing over the ground surface.
LSCWMO Rules and Regulations 7
Adopted February 13, 2008
Sediment²7KHVROLGPLQHUDORURUJDQLFPDWHULDOWKDWLVLQVXVSHQVLRQLVEHLQJ
transported, or has been moved from its original location by erosion and has been
deposited at another location.
Sedimentation²7KHSURFHVVRUDFWLRQRIGHSRVLWLQJVHGLPHQW
Shoreland District²6KRUHODQGDUHDVUHJXODWHGE\DORFDOPXQLFLSDORUFRXQW\6KRUHODQG
Ordinance, or by Minnesota Statues 103F. Generally Shoreland District consists of land
located within a floodplain, within 1,000 feet of the OHW of a public water or public
waters wetland, or within 300 feet of a stream or river.
Sinkhole- A depression in the earth's surface caused by dissolving of underlying
bedrock. Drainage is provided through underground channels which may be enlarged
by dissolution or the collapse of a cavern roof.
Soil Treatment System - A system where sewage effluent is treated and disposed of
into the soil by percolation and filtration, and includes trenches, seepage beds,
drainfields, at-grade systems, and mound systems.
Stabilized²([SRVHGVRLOLVFRQVLGHUHGWREHVWabilized when it has been adequately
covered through temporary measures (e.g. mulch, staked sod, riprap, erosion control
blanket, or other material that prevents erosion from occurring), or permanent
vegetation has been established over 70% of the surface.
Stormwater Facility²$Q\IDFLOLW\LQFOXGLQJUHWHQWLRn and detention ponds, wetlands,
reservoirs, impoundments, infiltration practices, filtration practices, conveyance
systems, and connecting infrastructure that are constructed for or serve the purpose of
stormwater management.
Storm Water Pollution Prevention Plan (SWPPP) - A site-specific, written document that:
identifies potential sources of stormwater pollution at the construction site; describes
practices to reduce pollutants in stormwater discharges from the construction site; and
identifies procedures the operator will implement to comply with the terms and
conditions of a construction general permit.
Structure²$Q\WKLQJPDQXIDFWXUHGFRQVWUXFWHGRU erected which is normally attached
to or positioned on land, including portable structures, earthen structures, water and
storage systems, drainage facilities and parking lots.
LSCWMO Rules and Regulations 8
Adopted February 13, 2008
Subdivision²7KHVHSDUDWLRQRIDQDUHDSDUFHORUWUDFWRIODQGXQGHUVLQJOHRZQHUVKLS
into two or more parcels, tracts, or lots.
Subsurface Sewage Treatment System - A sewage treatment system, or part thereof,
serving a dwelling, or other establishment, or group thereof, and using sewage tanks
followed by soil treatment and disposal or using advanced treatment devices that
discharge below final grade. Subsurface sewage treatment system includes holding
tanks and privies.
Subwatershed²DSRUWLRQRIODQG contributing runoff to a particular point of discharge.
Surface Water²$OOVWUHDPVODNHVSRQGVPDUVKHVZHWODQGVUHVHUYRLUVVSULQJULYHUV
drainage systems, waterways, watercourses, and irrigation systems whether natural or
artificial, public or private.
Ultimate conditions²WKHSK\VLFDOWRSRJUDSKLFDQGhydrologic characteristics of a
subwatershed upon completion of the maximum level of expected development.
WCD²7KH:DVKLQJWRQ&RQVHUYDWLRQ'LVWULFW
Waterbody All surface waters, watercourses and wetlands as defined in these Rules.
Watercourse²$Q\QDWXUDORULPSURYHGVWUHDPULYHUFUHHNGLWFKFKDQQHOFXOYHUW
drain, gully, ravine, swale or wash in which waters flow continuously or intermittently
in a definite direction.
Waters of the State²$OOVWUHDPODNHVSRQGVZHWODQGVZDWHUFRXUVHVZDWHUZD\V
wells, springs, reservoirs, aquifers, irrigation systems, drainage systems and all other
bodies or accumulations of water, surface or underground, natural or artificial, public
or private, which are contained within, flow through, or border upon the state or any
portion thereof. Streams include both intermittent and perennial.
²$UHJLRQGUDLQLQJWRDVSHFLILFZDWHUFRXUVHRUZDWHUEDVLQ
Watershed
Wellhead Protection Plan²$GRFXPHQWWKDWSURYLGHVIRUWKHSURWHFWLRQRIDSXEOLF
water supply, submitted to the Minnesota Department of Health, is implemented by the
public water supplier, and complies with: A) the wellhead protection elements specified
in the 1986 amendments to the Federal Safe Drinking Water Act, United States Code,
title 42, chapter 6A, subchapter XII, part C, section 300h-7 (1986 and as subsequently
amended); and B) Minnesota Rules parts 4720.5200 to 4720.5290.
LSCWMO Rules and Regulations 9
Adopted February 13, 2008
Wetland²$Q\ZHWODQGDVGHILQHGLQ0LQQHVRWD Statutes, section 103G.005, subdivision
19.
Wetland Conservation Act or WCA²7KH0LQQHVRWD:HWODQG&RQVHUYDWLRQ$FWRI
as amended.
1.0Administrative Procedures
1.1Policy Statement
It is the policy of the LSCWMO to limit the duplication of effort, minimize the
expense incurred by the LSCWMO, the LGU and applicant, and provide timely
review of activities regulated under these Rules.
1.2Regulated Activities
Subject to an exception, the requirements of these Rules apply to:
a.Land disturbing activities that trigger an LGU grading permit
(including re-development projects), which disturb, remove, or cover
surface vegetation or other surfaces of one (1) acre or more;
b.All projects that create a new impervious surface area of 6,000 square
feet or more including road, bikeway, sidewalk or other linear
impervious surface;
c.Any land disturbing activity or proposed impervious surface which
requires an LGU, state, county or federal permit within a shoreland
district, floodplain, or within the waters of the State, all shoreland and
streambank improvements, and stream or ravine crossings;
d.All subdivisions, plats, and development of four or more lots.
1.3Exceptions
a.These Rules do not apply to annually cultivated land.
b.These Rules do not apply to construction on an individual lot within a
residential subdivision reviewed by the LSCWMO and approved by the
LGU, provided the activities comply with the original development
plan.
c.These Rules will be modified for redevelopment projects where less
than 50 percent of the total site area (including road right-of-way)
LSCWMO Rules and Regulations 10
Adopted February 13, 2008
will be disturbed. In these cases, these Rules will only apply to the
disturbed area of the site.
d.Linear projects (roads, bike paths, trails, etc.) that do not disturb more
than 1 acre of land, do not affect stream crossings, and do not
increase imperviousness, such as mill and overlay road reclamations
or road blacktopping, are exempt from these Rules.
e.Road shoulder improvement projects are exempt from these Rules
when less than two feet of impervious surface on either edge of the
existing roadway is added; the project is at least 50 feet from a Water
of the State; and there is no disturbance to a Water of the State or
natural resources. For the purpose of this exception only, roadside
ditches are not considered a Water of the State.
1.4Required Exhibits
The following items, including nine 11-inch by 17-inch, one full size as
applicable, and electronic PDFs as applicable, and certified by a professional
engineer registered in the State of Minnesota, registered land surveyor, or other
appropriate professional, shall be submitted to the LSCWMO [by the LGU].
a.Names and contact information for proposed project, owner, and
engineer.
b.Location map
c.Plat drawing including buffer boundaries identified as conservation
easements, when required by the LGU.
d.Grading plan/mapping exhibits
1.Property lines and delineation of lands under ownership of the
applicant;
2.Two-foot topography showing existing and proposed conditions
and pre-development and post-development subwatersheds,
including areas necessary to determine downstream analysis for
the proposed stormwater management facilities;
3.([LVWLQJDQGSURSRVHGVWRUPZDWHUIDFLOLWLHV·ORFDWLRQ V
DOLJQPHQW
and elevation;
4.Minimum low opening elevations for each lot;
5.Delineation and elevation of the OHWL of each public water on site
and bankful levels for streams and corresponding buffers and
setbacks;
LSCWMO Rules and Regulations 11
Adopted February 13, 2008
6.Delineation of the existing and proposed 100-year water
elevations on-site;
7.Wetland delineation and buffer boundaries, as applicable.
8.Drainage easements covering land adjacent to ponding areas,
wetlands, and waterways up to the 100-year flood levels and
covering all ditches and storm sewers when required by the LGU.
Access easements to these drainage easements and to other
stormwater management facilities shall also be shown when
required by the LGU;
9.Such other information that is necessary to determine compliance
with these Rules.
e.Hydrologic/hydraulic and water quality design exhibits
1.Stormwater runoff rate analysis for the 2-, 10-, and 100- year
critical events under pre- and post-development conditions
including a map of each modeled subwatershed and supporting
model documentation.
2.Stormwater runoff volume calculations including delineation of
impervious areas used in calculations or references.
3.Description and calculations for any proposed stormwater volume
credits.
4.Geotechnical investigations including soil maps, borings, site-
specific recommendations, and any additional information
necessary to support the proposed stormwater management
design
f.Erosion and sediment control exhibits.
1.Erosion and sediment control plan including delineation of
slopes greater than or equal to 12%.
2.Copy of the Storm Water Pollution Prevention Plan (SWPPP)
ZKLFKFRQIRUPVWRWKH03&$·VGeneral Construction Permit.
7KH6:333PXVWFRQIRUPWRWKHUHTXLUHPHQWVIRU´6SHFLDO
:DWHUVµZKHQDSSOLFDEOH
g.Construction plans for all proposed stormwater management facilities.
h.All necessary construction specifications and details and sequence of
construction.
i.Proof of National Pollutant Discharge Elimination System (NPDES)
permit coverage for qualifying projects.
j.Maintenance plan and schedule for the stormwater management
facilities.
LSCWMO Rules and Regulations 12
Adopted February 13, 2008
k.Spill Prevention Plan, if applicable, including the location and detailed
design of any spill and leak collection systems for the purpose of
containing accidentally released hazardous or toxic materials.
l.Landscaping/vegetative plan for buffers, if applicable, including
maintenance plan for the buffer.
m.Wetland delineation report, if applicable.
2.0Stormwater Management
2.1Policy Statement
It is the policy of the LSCWMO to:
a.Require each development or Land Disturbing Activity to manage its
stormwater effectively, on-site, although the LSCWMO will consider
off-site stormwater management when it is proven that on-site
stormwater management will not work due to technical problems with
the site or if on-site stormwater management reduces the ability of
the property to be useable.
b.Assure that property owners control the rate and volume of
stormwater runoff originating from their property so that surface
water and groundwater quantity and quality is protected or improved,
soil erosion is minimized, flooding potential is reduced and thermal
impacts are minimized.
c.Maximize groundwater recharge as a means of maintaining drinking
water supplies, preserving base flows in streams, and limiting
discharges of stormwater to downstream receiving waters.
d.Protect and improve key natural resources within the watershed to
prevent the loss or degradation of fish and wildlife habitat.
2.2Regulation
a.Rate Control
The proposed activity will not increase the peak stormwater runoff rate
from the site, under pre-development conditions, for anything less than a
24-hour precipitation event with a return frequency of 2-, 10- and 100-
years (equivalent to 2.8, 4.2, and 6.0 inches, respectively). The applicant
PXVWFRPSO\ZLWKWKHUHTXLUHPHQWVRIWKH03&$·V*HQHUDO&RQVWUXFWLRQ
Stormwater Permit.
LSCWMO Rules and Regulations 13
Adopted February 13, 2008
b.Volume Control
Stormwater runoff volume retention shall be achieved onsite in the
amount equivalent to the runoff generated from one inch of runoff over
the impervious surfaces of the development or as specified under Rule
8.0. Volume control credits can be used to control up to one-half (0.5)
inch of runoff as described under Rule 2.5.
c.Water Quality
Stormwater management must comply with the requirements of the
03&$·V*HQHUDO&RQVWUXFWLRQ6WRUPZDWer Permit. No direct (untreated)
discharges of stormwater to natural or improved waterbodies are allowed.
d.Waste Disposal to Waters
Stormwater management must not result in the discharge of any
regulated substance, hazardous or biological waste, or petroleum
product, whether treated or untreated, to an infiltration practice that may
have a deleterious effect upon the groundwater, unless the discharge is
in compliance with Federal, State and local regulations.
2.3Criteria
a.Stormwater facilities must provide:
1.An identified overflow spillway and downstream route
sufficiently stabilized to convey a 100-year critical storm event;
2.Pond outlets designed to prevent short circuiting of the flow
from pond inputs to the outlet;
3.A maximum depth of 10 feet;
4.An outlet skimmer to prevent migration of floatables and oils
for the 2-year event; and
5.Access for future maintenance.
b.Stormwater facilities proposed in Karst sensitive areas must comply
with Rule 9.0.
c.Regional ponds and practices can be used to provide for stormwater
management based on the following criteria:
Regional ponds are required to be designed based on ultimate
conditions for the contributing subwatershed.
LSCWMO Rules and Regulations 14
Adopted February 13, 2008
Regional ponds are required to be constructed and operational
prior to constructing imperviousness within the contributing
drainage area.
d.Design of all best management practices will be consistent with the
Minnesota Stormwater Manual, November 2005, and as amended and
the MPCA General Construction Permit, 2003, and as amended.
e.When using infiltration for volume control, infiltration volumes and
facility sizes shall be calculated using the appropriate hydrological soil
group classification and infiltration rate, and shall be capable of
infiltrating the required volume within 48 hours or as specified in the
MPCA General Construction Permit.
f.In evaluating the infiltration capacity of a constructed BMP under
post-development conditions, the infiltration rates in the following
table shall be used. Select the design infiltration based on the least
permeable soil horizon within the first five feet below the bottom
elevation of the proposed infiltration facility. Documented site-
specific infiltration measurements completed by a licensed
professional as described in the Minnesota Stormwater Manual,
November 2005, and as amended may be used in place of the values
in the following table, and as approved by the LSCWMO.
LSCWMO Rules and Regulations 15
Adopted February 13, 2008
Infiltration Rates for the Design of Constructed Infiltration Practices (MPCA, 2005)
Infiltration
Hydrologic
Soil Textures Corresponding Unified Soil Classification Rate
Soil Group
[inches/hour]
GW - Well-graded gravel or well-graded gravel
with sand
1.6
Gravel, sand, GP²3RRUO\JUDGHGJUDYHORUSRRUO\JUDGHG
sandy gravel, gravel with sand
A silty gravel,
GM - Silty gravel or silty gravel with sand
loamy sand,
SW - Well-graded sand or well-graded sand
sandy loam
with gravel 0.8
SP²3RRUO\JUDGHGVDQGRUSRRUO\JUDGHGVDQG
with gravel
SM - Silty sand or silty sand with gravel 0.6
ML²6LOW
B Loam, silt loam
0.3
OL ²2UJDQLFVLOWRURUJDQLFVLOWZLWKVDQGRU
gravel or gravelly organic silt
GC²&OD\H\JUDYHORUFOD\H\JUDYHOZLWKVDQG
C Sandy clay loam 0.2
SC²&OD\H\VDQGRUFOD\H\VDQGZLWKJUDYHO
CL²/HDQFOD\RUOHDQFOay with sand or gravel
or gravelly lean clay
Clay, clay loam, CH²)DWFOD\RUIDWFOD\ZLWKVDQGRUJUDYHORU
silty clay loam, gravelly fat clay Infiltration
D
sandy clay, silty OH²2UJDQLFFOD\RURUJDnic clay with sand or not feasible
clay gravel or gravelly organic clay
MH²(ODVWLFVLOWRUHODVWLFVLOWZLWKVDQGRU
gravel
g.All stormwater retention practices designed to meet the volume
control regulation must provide pretreatment of stormwater runoff
prior to infiltrating into the groundwater system or discharging
downstream. Pretreatment methods must comply with the Minnesota
Stormwater Manual, 2005, and as amended, for the proposed
practice. All highly recommended and recommended design criteria
must be met.
h.To the maximum extent practicable, the volume control rule shall be
fully met onsite. Site conditions may make infiltration undesirable or
impossible. The applicant must make soil corrections and/or
investigate other locations on the site for feasible infiltration
locations. Infiltration practices are not allowed:
LSCWMO Rules and Regulations 16
Adopted February 13, 2008
1.For runoff from fueling and vehicle maintenance areas;
2.Within HSG D type soils;
3.Within 100 feet of a private well or within the emergency
response zone for a wellhead protection area (1-year time of
travel);
4.Within 50 feet of a septic tank or drain field;
5.On areas with less than 3 feet vertical separation from the
bottom of the infiltration system to the elevation of seasonal
high groundwater or top of bedrock; or
6.Within 300 feet of an identified sink hole or other Karst feature.
If the applicant claims that infiltration is not feasible or allowed
onsite, the applicant must provide supporting documentation and
follow Rule 2.4.
2.4Alternative Compliance Sequencing
For sites where infiltration practices are determined infeasible as described in
Rule 2.3h, the following Alternative Compliance Sequencing steps shall be taken
in the order shown:
a.Use of alternative volume control practices as described in the
Minnesota Stormwater Manual, 2005, and as amended, sized
according to Rule 2.2b.
b.Use of on-site filtration practices and biofiltration using an
impermeable liner and under drain, sized to filter a volume of runoff
according to Rule 2.2b.
c.Use of off-site volume control practices sized according to Rule 2.2b.
Off-site volume control practices can be used to provide for
stormwater management based on the following criteria:
Off-site practices shall be constructed within the same drainage
area or subwatershed as the project site.
Off-site practices are required to be constructed and operational
prior to constructing imperviousness within the contributing
drainage area.
d.Use of wet sediment basins sized per the standard described within
the MPCA General Construction Permit, 2003, and as amended.
LSCWMO Rules and Regulations 17
Adopted February 13, 2008
2.5Volume Control Credits
a.Volume control credits will be awarded as described in the Minnesota
Stormwater Manual, 2005, and as amended.
b.Volume control credits must be determined based on the methods
outlined within Chapter 11 of the Minnesota Stormwater Manual,
2005, and as amended, for the Adjusted Water Quality Volume.
1.The water quality volume (V) shall be calculated by
wq
multiplying 1 inch of runoff over the proposed impervious
surface.
greater than ½ inch of
2.Applied credits cannot exceed a V
wq
runoff over the proposed impervious area.
3.All recommended and highly recommended conditions must be
met.
4.For Drainage to Stream, Wetland, or Shoreland Buffer Credits,
the credits will apply to areas outside of the minimum buffer
requirement as prescribed within these Rules.
5.Grass Channel Credits can be applied to the roadway portion of
the proposed site when grass channels have been designed
with water quality adaptations such as water quality berms.
2.6Maintenance and Easement
a.Stormwater management easements shall be provided by the
applicant for (1) access for facility inspections and maintenance and
(2) preservation of stormwater runoff conveyance, infiltration, and
detention areas and facilities, including the overflow route.
b.Land used by stormwater management facilities shall be preserved by
dedication and/or perpetual easement to the LGU, when required by
the LGU. These easements shall cover those portions of the property
which are adjacent to the facility and which lie below the 100- year
flood elevation.
c.A maintenance agreement shall be recorded with the County as part
of the LGU development approval process. Minimum requirements for
the maintenance agreement include:
A list of the responsible party(s) (LGU and facility
owner/manager)
Contact information
LSCWMO Rules and Regulations 18
Adopted February 13, 2008
A formalized maintenance schedule, with scheduled
activities
$´)DLOXUHWR3HUIRUPµSURYLVLRQOD\LQJRXWUHPHGLDODFWLRQV
if the responsible party does not perform as expected
Maintenance debris handling plans
Emergency response (environmental, spill, safety)
d.Maintenance is required for all stormwater practices constructed in
compliance with these Rules. Each LGU will conduct periodic
inspection of stormwater practices. A minimum of 20% of all
stormwater facilities shall be inspected annually by the LGU. LGUs
must provide to the LSCWMO annual inspection reports detailing
inspection activities and proof of maintenance where required.
e.When land used by stormwater management facilities is public land or
public right-of-way, easements under this section will not be
required, and a written agreement between the LGU and applicant may
be executed in lieu of the recorded maintenance agreement.
3.0Erosion Control
3.1Policy Statement
It is the policy of the LSCWMO to require erosion control for land development
activities to prevent the degradation of resources and the loss or damage of
property due to erosion and sedimentation.
3.2Regulation
The proposed activity will not result in an increase in sediment off the site
during construction and post-construction activities and be in conformance with
the MPCA General Construction Permit, and as amended.
3.3Criteria
a.Erosion and sediment control plans must comply with the MPCA
General Construction Permit, as amended.
b.Erosion and sediment control plans for sites disturbing slopes greater
than 12 percent (12%) require:
1.Erosion control measures installed at 75 foot intervals along
slopes.
LSCWMO Rules and Regulations 19
Adopted February 13, 2008
2.Protection with temporary or permanent erosion control within
seven (7) days.
c.The applicant is required to remove temporary erosion control
measures after the site is permanently stabilized. Any areas that are
disturbed by the removal of temporary erosion control measures must
be stabilized in accordance with the approved Stormwater Pollution
Prevention Plan.
d.All construction related sediment must be removed from ponding
areas after the site is permanently stabilized.
3.4Exception
The erosion control measures described in Rule 3.0 are not required for land
that is regularly used for agricultural activity, provided that a grass or natural
vegetation buffer zone extending sixteen (16) feet or the width of an applicable
shore impact zone, whichever is wider, is maintained along any waterbody or
wetland and no fertilizer is used in the zone. In addition, mowing or grazing
within the buffer zone is prohibited.
4.0Lake, Stream and Wetland Buffers/Management
4.1Policy Statement
Natural vegetation bordering the bed and banks of lakes, streams, and wetlands
serves a critical role in maintaining the ecologic functions and societal values of
these resources. The LSCWMO seeks to preserve, maintain or establish
adequate buffers in riparian areas and minimize disturbance within them.
4.2Regulation
The LSCWMO adopts the provisions of the Wetland Conservation Act and
accompanying rules of the Minnesota Board of Water and Soil Resources. A 30
foot average buffer zone of native vegetation must be provided around all
wetlands, natural and manmade, and natural surface waters including lakes and
stream channels or as defined in the Watershed Management Plan.
4.3Criteria
a.The LSCWMO has adopted the provisions of the Wetland Conservation
Act of 1991 and accompanying rules of the Minnesota Board of Water
LSCWMO Rules and Regulations 20
Adopted February 13, 2008
and Soil Resources (Minnesota Rules Chapter 8420, as amended). The
LSCWMO intends that LGUs administer the Wetland Conservation Act,
unless a particular city or township has elected not to assume that
role in its jurisdictional area. In these cases, the LSCWMO will serve as
the LGU for administration.
b.Replacement wetlands shall be located within the WMO boundary,
unless the LSCWMO approves otherwise.
c.Buffer averaging may be used provided that the minimum buffer width
is not less than 20 feet or the width of the Washington County
Shoreland Management Ordinance shore impact zone, whichever is
greater, measured from the ordinary high water level of lakes,
bankfull level of streams or delineated boundary of wetlands and
apply whether or not the lake, stream, or wetland is on the same
parcel as a proposed development.
d.The vegetative buffer must be expanded to include steep slopes,
defined as lands having average slopes over 12 percent, as measured
over a horizontal distance of 50 feet or more.
e.The following activities are prohibited in buffer areas:
1.Creating impervious cover;
2.Excavating or placing fill or debris;
3.Altering vegetation including mowing or grazing, except for
vegetative enhancements, removal of trees for disease control,
removal of invasive exotic species for revegetation, or as
needed to assure the safety associated with adjacent trails and
roadways; as approved by the LSCWMO;
4.Applying phosphorus-containing fertilizers; and
5.Locating roads, utilities or drainage fields, except for the
purpose of a crossing of the associated lake, stream, or
wetland.
f.Stormwater facilities shall not be located within the buffer unless no
other feasible alternative exists.
4.4Exception
a.Use and maintenance of an unimproved access strip through the
buffer, not more than 20 feet in width, for recreational access to the
lake, stream, or wetland.
b.Streambank stabilization or lakeshore erosion control projects.
LSCWMO Rules and Regulations 21
Adopted February 13, 2008
c.Cases where narrower buffer strips may be necessary to allow a
reasonable use of the parcel, as defined by the LSCWMO, and where,
in combination with other best management practices, equivalent
water quality treatment performance is provided.
5.0Shoreline and Streambank Alteration
5.1Policy Statement
Intact, vegetated and stable shorelines and streambanks provide valuable
functions to the associated water resource including prevention of erosion,
reinforcement of soils through root structure, trapping of nutrients and
sediments, and provision of fish and wildlife habitat. The LSCWMO promotes
the preservation and enhancement of the ecological integrity and natural
appearance of shorelines and streambanks with the intent of preventing
erosion. When alteration is necessary, the LSCWMO encourages bioengineering,
landscaping and preservation of natural vegetation practices.
5.2Regulation
Shoreline or streambank improvement or alteration partially or wholly below the
ordinary high water mark of a lake or wetland or bankful height of a stream
shall not result in detrimental effects to the lake, wetland, or stream.
5.3Criteria
a.The use of bioengineering is encouraged as an alternative to
traditional engineered stabilization techniques for its cost advantage,
aesthetic superiority and ecological integrity. Bioengineering
techniques should be used to the extent possible.
b.Retaining walls are to be used only when there is no adequate
stabilization alternative.
6.0Stream and Lake Crossing
6.1Policy Statement
The LSCWMO discourages the use of beds and banks of streams and lakes for
the placement of roads, driveways, and utilities. It is the policy of the LSCWMO
to regulate crossings of watercourses for driveways, roads, and utilities to
LSCWMO Rules and Regulations 22
Adopted February 13, 2008
maintain stream stability, conveyance capacity, and the ability to transport,
without adverse effect, the flows and detritus of its watershed.
6.2Regulation
The portion of a road, highway, utility, or associated structure that crosses the
bed or bank of any waterbody shall not be installed, modified, or replaced
without first demonstrating a public benefit and ensuring that the crossing will
retain adequate hydraulic capacity and navigational capacity if applicable,
preserve wildlife passage along each bank, not adversely affect water quality,
and represent the "minimal impact" solution to a specific need with respect to all
other reasonable alternatives. Projects must follow the DNR manual Best
Practices for Meeting DNR General Public Waters Work Permit GP 2004-0001,
when applicable.
6.3Criteria
a.$QDO\VLVLVUHTXLUHGGHPRQVWUDWLQJWKHVWUHDP·VSK\VLFDO
characteristics and the effect of the project on hydraulic capacity and
water quality.
b.Construction must be timed to take advantage of seasons with no or
low stream flow.
c.Construction must be timed to avoid spawning seasons if applicable.
d.Sizing and placement of stream crossings
1.5HJDUGOHVVRIWKHVWUHDP·VZLdth to depth ratio (bankfull
width/mean depth), minimum culvert width shall match or
exceed stream bankfull width (water surface width at discharge
associated with the 1.5-year return period). Combined width
of multiple culverts is satisfactory.
2.Culvert length shall extend beyond side slope toe.
3.Slope of culvert shall match stream thalweg slope.
4.Culverts shall be buried 1/6 of their height.
th
5.When using multiple culverts, offset culvert inverts. Use the
fewest and largest multiples possible. A minimum vertical
separation of 1foot is required between the lowest placed
culvert and multiples.
6.Alignment of culvert shall match stream alignment.
LSCWMO Rules and Regulations 23
Adopted February 13, 2008
7.0Floodplain and Drainage Alteration
7.1Policy Statement
It is the policy of the LSCWMO to regulate alterations within the floodplain and
drainageways within the watershed to provide flood protection to natural
resources, permanent structures and private lands.
7.2Regulation
Alteration to or filling land below the 100-year flood elevation of any wetland,
public water or landlocked subwatershed shall be subject to the following
regulations and shall be completed in accordance with a state-approved
floodplain management ordinance:
a.No filling is allowed within the 100-year floodplain without 1:1
mitigation.
b.The lowest opening of proposed structures must be a minimum of
two feet above the 100-year high water level of nearby surface waters
or one foot above the emergency overflow elevation, whichever is
greater, unless specified in Rule 8.0.
7.3Criteria
a.Ultimate conditions must be used to determine the flood elevation.
b.No person shall install a culvert, drainage tile, or other artificial means
to remove or drain surface water or an obstruction to the natural flow
of waters without demonstrating that there is no adverse impact on
upstream or downstream landowners or water quality, habitat or
fisheries.
8.0Landlocked Basins
8.1Policy Statement
Landlocked basins provide a unique stormwater challenge within the LSCWMO.
It is the policy of the LSCWMO to protect property owners from flooding within
landlocked basins and minimize the capital expenditure associated with large
flood mitigation projects and basin outlets.
LSCWMO Rules and Regulations 24
Adopted February 13, 2008
8.2Regulation
a.The proposed land-altering activity will not increase the stormwater
runoff volume from the site, under pre-development conditions, for
anything less than a 24-hour precipitation event with a return
frequency of 10-years (equivalent to 4.2 inches).
b.Minimum low openings within areas draining to landlocked basins
must be two feet above the natural overflow elevation of the
landlocked basin.
c.Outlets from landlocked basins are not allowed unless subwatershed
planning which results in no negative impacts to downstream
resources has been approved by the LSCWMO.
9.0Groundwater Management
9.1Policy Statement
Groundwater in the LSCWMO provides drinking water, sustains unique
groundwater dependent natural resources, and maintains the base flow and
thermal stability of watershed streams. Large areas of karst terrain are present
within the LSCWMO which are highly susceptible to groundwater contamination.
It is the policy of the LSCWMO to maintain groundwater recharge and protect
groundwater from contamination. The LSCWMO also supports the Washington
County Groundwater Plan, 2003.
9.2Regulation
Alterations to the land or water in a way that could be determined as
detrimental to groundwater resources are not allowed. Certain types of ponding
may not be suitable in Karst sensitive areas when data indicate lack of bedrock
stability or there is insufficient soil layering between pond bottom and bedrock
surface. Surface runoff may not be directed to identified sink holes.
9.3Criteria
a.Groundwater recharge is required, where feasible, as specified under
Rule 2.0. and Rule 8.0.
b.Karst sensitivity analysis is required for stormwater ponds located in a
Karst sensitive area. The investigation must be consistent with
LSCWMO Rules and Regulations 25
Adopted February 13, 2008
Appendix C of the LSCWMO Karst Feature Inventory and Management
Plan (2007). At a minimum, the following are required:
1.Investigation of subsurface material to identify depth to water
table and bedrock and first bedrock unit if less than 50 feet to
bedrock.
2.Identification of sinkholes and/or other closed depressions on
the site, using a backhoe or other excavation techniques when
necessary to characterize the feature.
c.Karst Investigation Areas are identified in the LSCWMO Karst Feature
Inventory and Management Plan (2007). Applications proposing work
on parcels where these features are present will need to investigate
these locations. The investigation must be consistent with the
LSCWMO Karst Feature Inventory and Management Plan (2007).
10.0Water Appropriations
10.1Policy Statement
An understanding of the groundwater and the surface-groundwater interactions
in the LSCWMO is needed for the effective management of surface water
resources and protection of groundwater dependent resources. Definition of
the potential scope and effects of water appropriations is necessary to ensure
proper stewardship of the system as a wholH,WLVWKH/6&:02·VLQWHQWWREH
informed of the proposed appropriation of surface or groundwater in or near
the watershed. It is also the policy of the LSCWMO to carefully evaluate the
potential impacts of public or private infrastructure (including private and
municipal groundwater appropriations) and interference of flows on
groundwater recharge, transmission and discharge.
10.2Regulation
a.In all cases of appropriation of surface or groundwater requiring a
Department of Natural Resources permit in or near the LSCWMO, a
copy of the permit application and information on the location of the
discharge/withdrawal must be filed with the LSCWMO for their review.
b.The effect of the proposed appropriation must be defined for
consideration by the LSCWMO.
LSCWMO Rules and Regulations 26
Adopted February 13, 2008
11.0Greenways and Open Space
11.1Policy Statement
Greenways and open space provide a mechanism for preserving hydrologic
corridors, providing flood protection, and safeguarding groundwater resource
areas. The LSCWMO supports the Department of Natural Resources Metro
Greenways Program goals. Greenways and open space protection will be
considered when evaluating applications for alterations to wetlands, buffer
areas, floodplains, shoreland areas and for water crossings.
12.0Fees
12.1Policy Statement
It is a policy of the LSCWMO to charge the development site /owner a fee to
cover the cost of review, inspection, and administration as incurred by the
LSCWMO. These costs will be based on actual incurred costs and will be billed
through the LGU to the applicant. Governmental units are exempt from paying
fees.
13.0Sureties and Performance Bonds
13.1Policy Statement
It is the policy of the LSCWMO to assure compliance with these Rules where
necessary by requiring a bond or other surety that is conditioned on adequate
performance of the authorized activities and compliance with these Rules. The
bond or surety will be held by the LGU. Governmental units are exempt from
providing sureties and performance bonds.
14.0Variances
14.1Policy Statement
It is the policy of the LSCWMO to be informed of all variances to these Rules
being considered by a LGU. The LSCWMO will cooperate with and provide input
to the LGU when variances from these Rules are being considered. Variances
may be necessary when the LGU finds that due to unique physical conditions of
the land or waters involved, undue hardship may result from strict compliance.
Undue hardship may be found if the property in question cannot be put to a
LSCWMO Rules and Regulations 27
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GABLES LAKE
DISTRICT
FROM WOODBURY (CD-P85)
WD-P9.1
12"
WD-P1
WD-P9.2
WD-P5
WD-P2
WD-P4.3
WD-P6
WD-P4.4
WD-P10.1
WD-P10.2
12"
12"
WD-P7
WD-P9.312"
WD-P4.5
WD-P4.2GL-P1
EAST RAVINE(GABLES LAKE)
WD-P3
ER-P1
WD-P10.3
(SHEPARDS WOODS POND)
12"
DISTRICT
18"
WD-P4.1
WD-P8
20" FM
WEST DRAW
WD-P10.4
WD-P11.1WD-P11.3
WD-P13.2
WD-P13.1 DISTRICT
WD-P11.2
WD-P13.3
WD-P12
SPP-P1
SPP-P2ER-P2 (CD-P86)
24"
WD-P13.4
12"
12"
WD-P13.5
SPP-P4.1
SPP-N3.1 CENTRAL
C-P1
18"
SPP-P3
DISTRICT
SPP-P4.2
WD-P13.7
WD-P15.1
72"
WD-P13.6
ED-P1
WD-P15.3
21"
SPP-P5
C-P2
WD-P14.1
WD-P15.2
LOWER ST. CROIX
ED-P2
WD-P17
C-P3
ED-P3
C-P6
WD-P16
DISTRICT
SPP-P6
WD-P19.1
ER-P3
C-P5
C-P4
SPP-P8
ST. PAUL PARK WD-P19.2
72"
EAST DRAW
DISTRICT
12"
12"
DISTRICT
PROP
15"
WD-P18.1
LIFT STA
WD-P18.2
ED-P5
WD-P19.3
SPP-P9.2
15"
ER-P4
12"
24" FM
SPP-P9.1WD-P18.3
TG-P1.1
ER-P5.1
12"
C-P7
SPP-P7
12"ER-P5.2
TG-P1.3
TG-P1.2
TG-P1.4
ER-P5.3
ED-P4
30" FM
TG-P2
C-P8
TG-P3
ED-P8
ED-P6
72"
ED-P7
ED-P9.1
ED-P9.2
ED-P10
ED-P9.3
ED-P9.4
TG-P4
24"
TG-P4.1
(HAMLET PARK POND)
SW-P1
12"
LANGDON
SW-P2
L-P2
THOMPSON GROVE
DISTRICT
21"
DISTRICT
SW-P4
12"
SW-P3
TG-P5.1
24"
24"SW-P5
SW-P6
TG-P5.2
L-P1
36"
TG-P15
TG-P14
SW-P7
12"12"
SW-P9
TG-P19
TG-P11
TG-P10
TG-P16
36"
12"
ER-P9
TG-P96'x8' BOX
18"
TG-P20
SW-P11
8'x5' BOX
SW-P8
TG-P8
ER-P5.4
TG-P18
(RAVINE PARK LAKE)
36"TG-P12
TG-P17
ER-P11
L-P3
SW-N10.1
21"
SW-P10
8"
TG-P7
SC-P1
2-36"
12"
36"
SW-P13
ER-N12.1
15"ER-P10
12"
15"
SW-P14
SW-P15
SW-P16
21"
12"
ER-P7
SW-N16.1
SW-N16.2
15"
ER-P6
SW-P19
SW-N19.1
SW-P18
ER-P12
S-P4
SW-P17
S-P3
ER-P13
27"
SOUTH
12"
27"
DISTRICT
SEEGER CREEK
SOUTHWEST
ER-P16
S-P2
L-P4
ER-P8
36"ER-P14 DISTRICT
DISTRICT
10'x5' BOX
10'x7' BOX
ER-P15.1
ER-P15.2
ER-P18
12"18"
S-P5
21"ER-P17
S-P6
SC-P2
30"
36"
ER-P19
24"
4'x6' BOX
2-66"
ER-P21.1
S-P7.2
S-P9ER-P20
12"ER-P21.2
12"
15"
S-P7.1
GREY CLOUD
ER-P30
ER-P22
L-P5
ER-P29
12"
S-P8
ISLAND DISTRICT
S-P7.3
ER-P27ER-P23
ER-P28
ER-P25
24"
ER-P24
SC-P7
S-P10
ER-P26
SC-P8
18"
LEGEND
CITY OF COTTAGE GROVE
SURFACE WATER MANAGEMENT PLAN
SURFACE WATER SYSTEM MAP
MAP 1
April 2008
I:\48\48GEN\Storm Water\Stormwater Management Maps\2007\Management Map\48strm-map_final.dwg
South Washington Watershed District (SWWD) Plan:
To access the plan, go to: http://www.swwdmn.org/about-swwd/watershed-plan/