HomeMy WebLinkAbout2015-01-07 PACKET 04.G.
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 ..................................................................................................................................... 10
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 .............................................................................................. 27
13. Water Use ....................................................................................................................................... 27
14. Water-related Land Use Management Districts ............................................................................. 27
15. Water surface use ........................................................................................................................... 28
16. Erosion and sedimentation ............................................................................................................. 28
17. Water Quality-stormwater runoff ................................................................................................... 28
18. Water Quality-Wastewater ............................................................................................................. 28
19. Geologic hazards and soil conditions ............................................................................................. 30
20. Solid wastes; hazardous wastes; storage tanks ............................................................................... 31
21. Traffic ............................................................................................................................................. 32
22. Vehicle-related air emissions ......................................................................................................... 32
23. Stationary source air emissions ...................................................................................................... 34
24. Dust, odors, noise ........................................................................................................................... 34
25. Sensitive resources ......................................................................................................................... 37
26. Adverse visual impacts ................................................................................................................... 40
27. Compatibility with Plans ................................................................................................................ 40
28. Impact on infrastructure and public services .................................................................................. 40
29. Cumulative impacts ........................................................................................................................ 41
30. Other potential environmental impacts .......................................................................................... 41
31. Summary of Issues ......................................................................................................................... 41
Mitigation Initiatives
32. .................................................................................................................... 42
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-Natural Resource Inventory
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
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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 27.42014 Roadway
Figure 27.32014 Stormsewer Management Map
Table 6.1 - Development Scenario Future Land Use Acreages ............................................................. 13
Table 7.1 - Project Magnitude Data - 20 Year Residential Growth .......................................................... 15
Table 7.2 - Project Magnitude Data - 20 Year Commercial Growth ........................................................ 15
Table 8.1 - Permits and Regulatory Review/Approvals ............................................................................. 16
Table 9.1 - Existing Land Use .................................................................................................................... 17
Table 10.1 - Current Natural Community Land Cover ............................................................................. 18
Table 11.1 - Open Space/Green Land Uses in the Development Scenario .............................................. 25
Table 18.1 - Summary of Current and Future Residential Waste Generation ........................................ 29
Table 20.1 - Summary of Current and Future Residential Waste Generation ........................................ 31
Table 20.2 - Summary of Current and Future Non-Residential Waste Generation ................................ 31
Table 22.1 - Top Ten Intersections Twin Cities CO Maintenance Area .................................................. 33
Table 22.2 - Future (2020) Average Daily Traffic ........................................ Error! Bookmark not defined.
Table 24.1 - Noise Analysis Instrumentation Summary ........................................................................... 35
Table 24.2 - Nighttime Noise Monitoring Summary ................................................................................. 35
Table 24.3 - Peak Hour Traffic Volumes .................................................................................................. 36
Table 24.4 - Distance to Contours ............................................................................................................. 37
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
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
Cottage Grove East Ravine AUAR
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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
development scenarios, an inventory of environmental and cultural resources, a
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
an Environmental Assessment Worksheet (EAW) or Environmental Impact Statement (EIS) which simply looks at a
ts and does not attempt to outline mitigation initiatives.
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
ning initiative
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.
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
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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 continuation of
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.
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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
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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
and close the intersection of CSAH 20 (Military Road) and CSAH 19 (Keats Avenue)
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, and was subsequently
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 Stormsewer 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 ( Stantec)
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
Cottage Grove East Ravine AUAR
space and trailway improvements. The higher density resulting from the decreased lot sizes are
January 2015 ~ Update Document
consistent with regional growth policies.
Page 10
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 summer of 2004. The develo
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 Cottagview area node in the
south near Highway 10/61 is more oriented toward larger scale community commercial uses
type commercial uses with intensive parking needs. 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.
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.
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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 of 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 currently under construction, and is
anticipated for completion in the spring of 2015. These roadway projects were analyzed in
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the original AUAR and adopted comprehensive plan. Portions of the 70 street realignment
were incorporated into the South Washing
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.
th
As a component of the 70 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.
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
Page 12
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
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
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residential subdivisions recently approved along 70 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.
A major 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.
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
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
Page 13
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.
Washington Count
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.
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
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
Page 14
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.
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
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
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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
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
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
Page 16
Type of Permit/review or Regulatory Citation
Unit of Government approval (as may be noted)
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.
Table 9.1 - Existing Land Use
There have been no changes in the information reported in Table 9.1.
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
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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.
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
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Land Classification Existing Acres Land Classification Existing Acres
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
shift the ratios of the different land classifications identified in ta
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
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.
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
Page 19
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 Michaels
Pointe which is adjacent to a deep, open water marsh which 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
is a MnDNR public water. The portion that is a MnDNR public water starts just north of 80 th 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.
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.
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
Page 20
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),
ghtshade (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.
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
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
Page 21
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).
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.
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,
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.
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January 2015 ~ Update Document
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The rest of the Neighborhood 1 (south) consists of farm/agriculture land.
The 23.5 acre Wal-Mart 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 Wal-Mart 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
s Tree Preservation Ordinance for this project. The City
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
Walmart. This fee was placed in
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 Furber House and
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 Government center and the New Cottage Grove City Hall, and the
th
realignment of 70 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.
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.
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
Page 23
No areas of grassland/shrubland were disturbed beyond the areas identified as
development area within the original approved East Ravine Master Plan. Areas developed
develop
as residential will have lawn and landscaping areas established as they.
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 area 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.
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 Civic Campus.
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
Page 24
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
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.
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
Page 25
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 Blanding
(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).
habitats to complete their life cycle. 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.
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.
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January 2015 ~ Update Document
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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.
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.
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January 2015 ~ Update Document
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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.
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
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January 2015 ~ Update Document
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Metropolitan Council and the Comprehensive Sewer Policy Plan (CSPP) for the Metropolitan Waste Control
Commission (MWCC). anitary
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
No new on-site systems are proposed to serve the East Ravine area.
The information in this table remains unchanged.
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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
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
ions, and is to be used as 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.
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.
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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
The statements in this section remain unchanged.
Table 20.2 - Summary of Current and Future Non-Residential Waste Generation
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January 2015 ~ Update Document
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* 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 tableremainsunchanged.
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
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
22.
recommended in these studies were completed 2013. Any significant additional commercial
V
EHI
growth in this neighborhood will require phase II of the traffic improvements identified.
-
CLE
RELATED
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 set
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.
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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
th
3 TH 252 at 85 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
7 TH 7 at Williston Road 54,900
3 MPCA Monitored Locations
8 University and Lexington Avenue 59,700
th
9 TH 252 at 66 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
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January 2015 ~ Update Document
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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
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
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
Page 34
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
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
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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
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
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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
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 Number 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
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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.
Old Cottage Grove is in the NW part of the City and extends roughly from 70 th Street (CSAH 22) south along Lamar
th
Ave, including side streets, to 77. 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
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 distri
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.
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
Page 38
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
Prime or unique farmland
It is not anticipated that existing farmlands will be protected through special programs, deed restrictions, conservation
project area will be developed over time.
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.
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
Page 39
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.
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.
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
Page 40
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.
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.
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
Page 41
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.
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.
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
Page 42
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.
The Military Ro
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
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
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.
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
Page 43
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
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.
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:
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
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
Page 44
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
ate 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.
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
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
the AUAR. Tracking of this development will b
final plat process the developer will submit electronic plats consistent with city development requirements in a
intain an ongoing inventory
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:
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
Page 45
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.
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.
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
Page 46
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Cottage Grove East Ravine AUAR
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Cottage Grove East Ravine AUAR
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Cottage Grove East Ravine AUAR
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Cottage Grove East Ravine AUAR
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Cottage Grove East Ravine AUAR
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Cottage Grove East Ravine AUAR
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East Ravine AUAR -2015 Update
City of Cottage Grove
Figure 21.2
2014 Daily Traffic Count Map
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
Page 64
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
Page 65
East Ravine AUAR -2015 Update
City of Cottage Grove
Figure 27.1
2030 land Use Plan
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
Page 66
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
Page 67
East Ravine AUAR -2015 Update
City of Cottage Grove
Figure 27.3
Upper Ravine District Development Update Detail
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
Page 68
East Ravine AUAR -2015 Update
City of Cottage Grove
Figure 27.4
2014 Roadway Functional Classification Map
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
Page 69
East Ravine AUAR -2015 Update
City of Cottage Grove
To be inserted prior to publishing with EQB
Figure 27.5
2014 Stormwater Management Map
Cottage Grove East Ravine AUAR
January 2015 ~ Update Document
Page 70
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Cottage Grove East Ravine Planning Study: Watermain.
Howard R. Green Company
February 2005
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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
O:\PROJ\819070J\5.0-InfrastructureAssessment\TechMemo-Watermain-020705.doc3
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.
O:\PROJ\819070J\5.0-InfrastructureAssessment\TechMemo-Watermain-020705.doc4
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Cottage Grove East Ravine Planning Study: Sanitary
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Traffic Impacts East Ravine Community. Howard R.
Green Company. June 05
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6+9
M
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
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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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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
Grove
Grove
(
/
10
(
/
61
Anoka
Ramsey
Project
Hennepin
Washington
Area
Legend
_
^
Carver
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
'SXXEKI
+VSZI
+VSZI
10
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
$SSHQGL[²6WRUPZDWHU0DQDJHPHQW5HSRUW
Cottage Grove East Ravine
Emmons and Olivier Resources, Inc., March 2005
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6+9
Stormwater Management
June 14, 2005
Stormwater Management
Introduction/Background...........................................................................................................................................3
Methodology.................................................................................................................................................................5
Hydrologic and Hydraulic Modeling........................................................................................................................5
Assumptions.............................................................................................................................................................7
Precipitation Events..................................................................................................................................................8
Stormwater Quantity..................................................................................................................................................9
Existing drainage......................................................................................................................................................9
Storm Drain Design...................................................................................................................................................11
Stormwater Basin Design..........................................................................................................................................12
Building Elevation..................................................................................................................................................12
Stormwater Management Basins............................................................................................................................13
Sub-Basins Descriptions.........................................................................................................................................18
Groundwater Mounding...........................................................................................................................................20
East Ravine Regional Park.......................................................................................................................................21
Existing conditions.................................................................................................................................................21
Proposed conditions................................................................................................................................................22
Stormwater Quality...................................................................................................................................................22
South Washington Watershed District....................................................................................................................22
MPCA.....................................................................................................................................................................23
Results....................................................................................................................................................................23
Other practices........................................................................................................................................................24
Construction practices............................................................................................................................................25
Maintenance Requirements.....................................................................................................................................25
Construction Cost Analysis.......................................................................................................................................30
Stormwater Management Areas..............................................................................................................................30
Storm drains and culverts.......................................................................................................................................30
East Ravine.............................................................................................................................................................30
Total Construction Cost..........................................................................................................................................30
Phasing.......................................................................................................................................................................31
General....................................................................................................................................................................31
Neighborhood1 - North..........................................................................................................................................31
Neighborhood 2......................................................................................................................................................32
Cottage Grove East Ravine 1
Emmons and Olivier Resources, Inc. DRAFT -- 7/13/2005
Stormwater Management
Neighborhood1 - South..........................................................................................................................................32
Appendix A.................................................................................................................................................................33
Model Hydrology Input Parameters........................................................................................................................33
Appendix B.................................................................................................................................................................34
Stormwater Basin Data...........................................................................................................................................34
Appendix C.................................................................................................................................................................35
High Water Elevation and Lowest Opening Elevations.........................................................................................35
Appendix D.................................................................................................................................................................36
Infiltration Capacities and Drawdown Times.........................................................................................................36
Appendix E.................................................................................................................................................................37
Technical References..............................................................................................................................................37
Appendix F.................................................................................................................................................................39
Design Standard Matrix..........................................................................................................................................39
Cottage Grove East Ravine 2
Emmons and Olivier Resources, Inc. DRAFT -- 7/13/2005
Stormwater Management
I/B
NTRODUCTIONACKGROUND
The current hydrology of the study area is characterized by numerous landlocked depressions,
some of which are relatively shallow and others that are quite deep. 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. This will be accomplished by
retaining 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 and, in some areas, avoidance of discharge of stormwater to surface waters; which
in turn will lessen the overall amount of pollutants reaching downstream water bodies such as
Cottage Grove Ravine Park Lake and the Mississippi River. Ultimately this approach results in
less burden on the environment, improves quality of life issues for residents of the city, and
lessens potential future city costs for treating and/or retrofitting storm water outfalls that would
be necessary from stricter regulations.
Traditionally, construction of impervious surfaces where none exist creates an increase in the
speed and volume that stormwater runs off of the landscape. In the not too distant past, the goal
of an urban drainage system was to rush water away as fast as possible into a receiving stream or
nearby lake or wetland. When it became evident that this was accelerating the degradation of
water bodies, the approach changed to the routing of water into detention ponds. Although many
of these ponds were designed according to EPA’s Nationwide Urban Runoff Program (NURP)
criteria based on 1980s studies, they too have some deficiencies in effective treatment and
management of runoff. NURP ponds could not recharge the groundwater and were not
addressing stream degradation from excess rate and volumes of runoff. These ponds are limited
in their ability to removal all pollutants from the stormwater runoff, creating diminished water
quality in sensitive lakes, rivers and wetlands. Creation of a traditional NURP pond based
stormwater management system for Cottage Grove would necessitate the discharge of new
runoff to the Mississippi River, adding pollutants and volumes of water that are not present
today.
Today, we have learned that there are better ways to treat runoff water which is to let it soak into
the ground as close to its source as possible and mimic the natural hydrology of the system. In
fact, soaking in every drop of precipitation where it falls is a good goal to strive for. This not
only limits the volume and rate of runoff that occurs, it also eliminates the migration of polluting
material that is picked up by runoff as it flows over urban surfaces. In addition, natural
groundwater recharge is preserved. So called “alternative” runoff management practices merely
seek to mimic the way precipitation would behave without human intervention; that is, it
attempts to soak water into the ground as if the land’s surface did not have impervious surfaces.
In this respect, the practices are an alternative to the “collect and concentrate” approaches of the
past. The environmental benefits of this approach include reduced wetland and open space
impacts, potential regulatory credits (suitable for NPDES Phase II, TMDLs, and watershed/local
Cottage Grove East Ravine 3
Emmons and Olivier Resources, Inc. DRAFT -- 7/13/2005
Stormwater Management
stormwater planning), reduced runoff and erosion, closer to natural water infiltration/recharge,
reduced negative upland habitat impact (ex. trees), enhanced public awareness, and the
opportunity for retrofitting into existing developed areas.
The geology within the East Ravine area of the City of Cottage Grove has resulted in closed
basin drainage; that is, stormwater runoff flows to low areas that in most cases do not have
outlets at normal water levels. Under existing conditions, water flows into these existing natural
basins and leaves through a combination of seepage (infiltration) into the ground and
evaporation. The issue facing the City is how to address stormwater management for the East
Ravine project area under developed conditions while preserving the benefits (ecological,
financial, water quality preservation and flood protection) of the closed basin drainage systems.
To take advantage of the good soils and geologic conditions in the city, this study proposes a
stormwater management approach that minimizes connected impervious surfaces, increases flow
path and time over pervious surfaces, and decentralizes treatment (smaller localized treatment as
opposed to large-scale facility development) is appropriate as a first measure of control. Once
these measures have been implemented as standard practice, an approach can be explored for
collection and further treatment of excess water in the numerous existing natural basins. A
carefully planned and engineered approach that combines a number of alternative practices with
infiltration will meet the city’s goal. This infiltration approach would mimic the natural
condition rather than simply collect and dispose the runoff to the Mississippi River.
Requiring developers to implement alternative stormwater management practices would further
reduce the overall volume of water draining to the closed basins, thus preserving the regional
stormwater basins proposed in this report. The best potential for these practices is infiltration of
water close to the location where the precipitation deposits it. Next, protecting the numerous
natural basins that collect water in large events and allow it to infiltrate is important. Infiltrating
this water mimics the natural system that existed prior to development. On-site runoff control
approach tends to be more economical because there is less or no need to build expensive,
artificial storage and conveyance facilities designed for large events. Development can also be
designed to minimize or eliminate curbs, gutters, wide roadways, and the inlets/outlets and pipes
that must accompany all of these features. Rather, this approach is flexible in its application
from use on a lot-by-lot basis to entire portions of a community. In places where water level
fluctuation can cause problems, any mix of alternative and traditional uses is possible.
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
Cottage Grove East Ravine 4
Emmons and Olivier Resources, Inc. DRAFT -- 7/13/2005
Stormwater Management
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 the regional park from the effects of local urbanization.
This report details efforts to create a management strategy for the East Ravine area of Cottage
Grove that utilizes a combination of approaches. The goals of the management strategy are to
ensure responsible, proactive management of stormwater to protect local and regional water
resources while also providing a reasonable level of safety for houses and other structures from
regional flooding. The approaches are:
Construct a city-based stormwater management system (ponds and/ infiltration
d
basins) along parkways and in green spaces that utilizes existing infiltration capacities
of the soils;
Cooperate with the SWWD towards combined Cottage Grove/SWWD stormwater
d
infiltration management areas;
Require developers to include local and on-site infiltration as part of their
d
development plans equivalent to approximately 15% of the runoff of the 5-yr event
which is approximately 0.2” of runoff; and
Provide emergency overflow routes from stormwater management basins in the event
d
that a storm occurs which is greater than the design storm for these basins.
M
ETHODOLOGY
Hydrologic and Hydraulic Modeling
Hydrology and hydraulics were modeled using XP-Software’s XP-SWMM program (version
9.1) to size stormwater basins and connecting conveyance systems. The base XP-SWMM model
was provided by the South Washington Watershed District (SWWD). Most of the input
parameters set by HDR Engineering for the SWWD were maintained in the analysis of future
conditions.
The model skeleton is shown in Figures 1 though 4. All runoff hydrology and hydraulic storage
features (including manholes and ponds) are represented by nodes. A triangle indicates that
stage/storage (pond) information is modeled. Stormwater conveyance (swales, pipes, culverts,
weirs, and natural channels or swales) are represented within the model links.
Neighborhood 1 (North and South) was brought to a more refined level of detail than that of area
within Neighborhood 2. Model input data necessary included the generation of proposed
subwatershed boundaries, area, weighted average percent impervious based on proposed land use
Cottage Grove East Ravine 5
Emmons and Olivier Resources, Inc. DRAFT -- 7/13/2005
Stormwater Management
as shown in Table 1, subwatershed time of concentration (runoff width and slope factors), pond,
and conveyance data. Model hydrologic input data per subwatershed is contained in Appendix
A.
Stormwater basin input parameters are contained in Appendix B.
Cottage Grove East Ravine 6
Emmons and Olivier Resources, Inc. DRAFT -- 7/13/2005
Stormwater Management
Table 1. Impervious Surface for Proposed Land Uses
Land Use % Impervious
Low Density 35
Mid Density 63
High Density 75
Mixed Use - Commercial 90
Parks/Open Space 3
Greenbelt 56
Public 50
Stormwater Treatment
(water surface area) 100
Assumptions
The design and sizing of stormwater conveyance is an iterative process between the landscape
architects, planners, road designers, and water modelers. For this reason, it was necessary to
pick a starting place by making assumptions and iterating from that point forward. The
following assumptions were used for the initial sizing of the Cottage Grove stormwater
management network of swales, ponds, and pipes:
1. For the determination of basin high water elevations (flood event):
No pond infiltration during the event.
d
Ponds begin dry except for the 6.0”/24-hr event or where ponds are located in areas
d
with shallow bedrock or possible high groundwater levels.
About 15% of the 5-yr post development runoff volume is attenuated at the
d
local/neighborhood scale.
2. For design of the local storm sewer piped conveyance system:
5-yr 24-hr (3.6 inch) rainfall event used for sizing.
d
Initial time of concentration equal to 15 minutes.
d
General layout such that street flows are conveyed in stormsewer pipes and lot flows
d
are conveyed through backyard swales.
Runoff computed using Curve Numbers set in Cottage Grove Surface Water
d
Management Plan.
3. For SWWD regional stormwater basin (CD-P86 north and south):
Basin stage/storage determined from existing 2 ft topography
d
Cottage Grove East Ravine 7
Emmons and Olivier Resources, Inc. DRAFT -- 7/13/2005
Stormwater Management
Overflow weir from CD-P86 north to south at 904 ft as shown on proposed grading
d
plan sheet (Wenck Figure No. 1) received from Matt Moore of the SWWD on
3/30/2004.
4. Determination of landscape runoff:
Future/proposed % impervious computed as a weighted average based on land use
d
sketches provided by HKGi.
Estimated % impervious of each land use as shown in Table 1.
d
Landscape initial abstractions (depression storage) and infiltration defined using
d
SWWD average “summer” infiltration as defined by HDR.
5. For determination and application of 15% runoff volume attenuation:
Computed average 15% runoff volume from a 5-yr 24-hr event (3.6 inches) on
d
proposed land use conditions
Modeled 15% runoff attenuation by increasing pervious depression storage by 0.16
d
inches to 0.27 inches, depending on the volume of runoff from the drainage area.
6. For preliminary pond design:
Using CP-2.11 as a prototype and 5:1 minimum side slopes provided conservative
d
area/depth relations as listed below:
Pond area available 8 ft below the MPF = MPF area x 0.30 (30% of MPF)
d
Pond area available 6 ft below the MPF = MPF area x 0.45 (45% of MPF)
d
Pond area available 4 ft below the MPF = MPF area x 0.65 (65% of MPF)
d
Pond area available 2 ft below the MPF = MPF area x 0.80 (80% of MPF)
d
7. For water quality and volume control design:
Assumed pond invert (or water level) 2 feet below the outlet invert.
d
Utilizes 15% volume reduction on-site.
d
8. Woodbury contributions computed assuming existing pre-development conditions (peak
rates) maintained.
9. The SCS Type II storm distribution was assumed appropriate.
Precipitation Events
Typically, stormwater facilities are designed to convey and manage the runoff from defined
rainfall events. The City of Cottage Grove sizes storm drains to convey the runoff from the more
frequent 5-year/24-hour rainfall event. Stormwater basins are sized to hold the runoff from
either a 100-year/24-hour event, or the 100-year/10-day event, whichever is larger. The East
Ravine project area is subject to precipitation requirements by both the City of Cottage Grove
and the South Washington Watershed District, as defined below:
Cottage Grove East Ravine 8
Emmons and Olivier Resources, Inc. DRAFT -- 7/13/2005
Stormwater Management
5-year/24 hour rainfall event
Cottage Grove defines the 5-year event as 3.6” of rainfall in 24-hours. SWWD does not define a
5-year event standard for local storm sewer design.
100-year/24-hour rainfall event
Cottage Grove defines the 100-year event as 6” of rainfall in 24-hours. This value is consistent
with data contained in the 1992 Minnesota Hydrology Guide, prepared by the US Department of
Agriculture, Soil Conservation Service.
The SWWD has opted to utilize rainfall data from the Midwest Climate Center (Huff and
Angels’ 1992 Bulletin 71), which defines the 100-year event for the southeast Metro area as 6.3”
in 24-hours. The SWWD further defines a larger 24-hour event that represents the upper limit of
a 100-year event for the purpose of testing the adequacy of the 2-foot freeboard between the high
water level of the basins and the lowest opening floor elevation of adjacent structures. This
event is 7.8” in 24-hours.
100-year/10-day runoff and rainfall events
The Cottage Grove Surface Water Management Plan requires an analysis of a 10-day runoff
event equal to 7.2” of runoff. Cottage Grove Public Works staff advised that this analysis has
not been imposed on recent developments. Therefore, this event was not analyzed for the East
Ravine project area.
The SWWD defines the 10-day 100-year event as 9.3 inches of rainfall. The SWWD further
defines a larger event that represents the upper limit of a 100-year event for the purpose of
testing the adequacy of the 2-foot freeboard between the high water level of the basins and the
lowest opening floor elevation of adjacent structures. This event is set at 10.6” rainfall in 10
days.
The SWWD no longer utilizes the 10-day 7.2” runoff event in their design and Cottage Grove
has not been using this event in their review or design.
SQ
TORMWATERUANTITY
Existing drainage
Neighborhoods 1 and 2 are presently closed drainage basin areas of primarily agricultural land
use. The runoff in the land locked areas is fully managed by small swales and depressions. The
area is favorable to infiltration due to the sandy soils and significant depth to groundwater or
bedrock. There are exceptions to this pattern where bedrock does come close to the surface,
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primarily in the western portion of Neighborhood 1 - North and in outcropped knobs within
Neighborhood 2. The northern portion of Neighborhood 1 - South drains east to East Ravine
Regional Park through 6 culverts located across County Road 19 into the East Ravine. The
Cottage View Drive-In sub-area of Neighborhood 1 - South is landlocked without a natural or
constructed outlet. Figure 5 denotes the major drainage basins that currently exist in the East
Ravine area.
The stormwater management goal for this project is to utilize the natural drainage and infiltration
capabilities of the existing land. Stormwater management areas along the parkways 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.
SWWD existing conditions model
Existing conditions were evaluated using an XP-SWMM model created by HDR Engineering for
the South Washington Watershed District (SWWD), created on May 16, 2003. No changes were
made to the background conditions of the model, as described in the section titled Methodology.
Other background information was taken from technical reports listed in Appendix E.
Design Standards
The City of Cottage Grove, South Washington Watershed District (SWWD) and the Minnesota
Pollution Control Agency (MPCA) have defined standards for management of stormwater
runoff. Specific standards, for such items as storm drain design, flood protection and infiltration
basin design. Appendix F contains a matrix comparing the design standards used to size the
recommended stormwater management facilities. The storm sewer system was designed using
standards set by the City of Cottage Grove, where pipe conveyance was sized based on a 5-yr 24-
hr rainfall event.
Woodbury flows
The northern edge of Neighborhood 1 - North between Military Road and the western boundary
of the East Ravine project area receives overland drainage from Woodbury. Presently this area
of Woodbury is undeveloped, with the current land use primarily agricultural. Woodbury’s long-
term plan forecasts development of this area to occur after 2020. The existing condition model
was used to determine the flow rates from Woodbury to be accommodated by the proposed
Cottage Grove drainage systems. Capacity for runoff from Woodbury in both the storm drains
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and stormwater management basins should be limited to not exceed existing conditions. Special
consideration must be made to accommodate this runoff in the period between completion of the
Cottage Grove and Woodbury drainage networks. Further discussion is contained in the section
titled Phasing.
Future Drainage Basins
Existing runoff drainage basins were overlaid onto the land use plan created by HKGi. Sub-
catchment areas tributary to each designated stormwater management area were defined
assuming that the future grading plan will generally follow the topography of the existing land.
Storm drains for Neighborhood 1 - North and Neighborhood 1 - South were aligned to convey
the street runoff and yard drainage to a downstream stormwater basin. Proposed sub-catchment
areas and drainage links are noted in Figure 6.
Stormwater Management Basin Configuration
Basins and corresponding sub-catchment areas were numbered following the numerical system
established in the existing conditions drainage model prepared by the SWWD. Sub-catchment
drainage areas tributary to each stormwater management basin were measured and input into the
XP-SWMM model. Basin area was defined by the area of the basin at the lowest contour. Initial
basin outlet elevation was set at 2’ above the basin floor. Outlet structures were sized to keep the
maximum water bounce during a 100-year event equal to or less than 8 feet in depth. Pond High
Water Level (HWL) was based on critical the 100-yr 24-hr precipitation event.
SDD
TORMRAINESIGN
As required by the Cottage Grove Surface Water Management Plan, dated November, 1997, all
storm drains and culverts were sized to convey the peak runoff from a 5-year rainfall event (3.6”
in 24-hours). A unit flow for each land use type was computed using HydroCAD version 7.0.
HydroCAD version 7.0 was used to create a SCS Type II hydrograph for each land use using the
following input parameters:
100-acre catchment
d
Curve numbers from Table 2
d
15 minute Time of Concentration
d
Peak flows from the hydrograph were used to compute a runoff rate per acre (in cubic feet per
second). The per acre unit flows were applied to the sub-catchment tributary to each storm drain
to determine the flows through each segment. Storm drain alignments followed street alignments
wherever feasible. Drainage swales noted on the land use plan are reserved for yard drainage
and would not receive much street runoff. These localized swales are set to overflow into the
street drains. In some areas, the topography requires that the storm drains follow the same
alignment as the yard swales. For these areas, a 40’ utility easement would need to be reserved
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for construction and maintenance of the storm drain. Exploring the use of overland flow
corridors, potentially as internal pathways during final design may be appropriate in some areas.
Storm drain and culvert alignments are shown in Figure 7.
Table 2: Runoff Curve Number Values by Land Use Type
Land Use Type CN Value
Open, Parks 58
Rural Residential 66
Low Density Single Family 72
Residential
Medium Density Single Family 78
Residential
High Density Single Family 84
Residential
Commercial, Industrial 92
Open Water 99
Special As required
Storm drains in the westerly half of Neighborhood 1 North were extended to convey the runoff
from Woodbury. These storm drains were sized to convey the existing runoff that is generated
by a 5-year rain event. Flows exceeding the 5-year event would use overland routes as they do in
the neighborhoods. Future development in Woodbury which would increase both the rate and
volume of runoff contributed to the Cottage Grove drainage system would need to implement
practices and structures to limit the maximum rate of discharge to existing runoff rates.
Infiltration basins where necessary, are linked by culverts sized to convey the excess runoff
during a 100-year event.
SBD
TORMWATERASINESIGN
Building Elevation
According to the requirements of by both the City of Cottage Grove and the South Washington
Watershed District, the lowest opening and exposed building wall elevation of structures should
be set at 2 feet above the high water elevation from a 100-year event. As described above, the
100-year event is defined differently by these agencies. Therefore, to ensure compatibility with
the future SWWD regional system and to meet Cottage Grove requirements, the high water
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elevation was computed for the events used by both entities and the highest was used to set the
lowest opening elevation for each stormwater basin.
Cottage Grove Public Works staff requested that additional safeguards be incorporated into the
analysis that determines the lowest floor elevation. Infiltration basins are assumed to not
infiltrate, plus the base elevation of the basin is set at the outlet elevation and not at the bottom of
the dry basin, except for regional infiltration basins.
The following scenarios were used to compute the high water elevation:
1. 6”/24-hour rainfall event, without infiltration, starting with water at outlet invert
2. 6.3”/24-hour rainfall event, without infiltration, starting dry
3. 9.3”/10-day rainfall event, without infiltration, starting dry
Two foot freeboard was added to the critical high water elevation, and the following events were
run to determine if the runoff would be fully contained below the freeboard elevation. If the high
water elevation of these events was higher than the freeboard elevation, then the higher of the
two was used to set the lowest opening/ exposed building elevation.
1. 7.8”/24-hour rainfall event, without infiltration, starting dry
2. 10.6”/10-day rainfall event, without infiltration, starting dry
Appendix C contains the results of this analysis. The critical high water elevation for each basin
is highlighted. The recommended low floor opening elevation would be set at 2 feet above the
critical high water elevation for each basin. One exception was made to the 2 foot freeboard for
basin CP-2.15, which is the emergency overflow of high water in Shepard’s Woods Pond. At the
request of Cottage Grove Public Works staff, the lowest floor opening elevation for this basin
was set above the emergency overflow culvert, which was slightly higher.
Stormwater Management Basins
Stormwater Ponds
Half of the stormwater basins within the Neighborhood 1 - North drainage basin CP-2 (also
described as Shepard’s Wood Pond) are assumed here to function as stormwater ponds to be
conservative. Geologic mapping of the area shows that bedrock is near the surface for
stormwater basins CP-2.4 and CP-2.5. These basins are considered wet for all events and do not
infiltrate under any conditions. Basins CP-2.10, CP-2.12, CP-2.14, CP-2.15, and CP-2.16 are
considered wet due to their proximity to Shepard’s Wood Pond. For the models that allow
infiltration, these basins are utilize to infiltrate out the sides of the basin at a slow rate when the
pond elevation rises above the normal water level. The next stage of design for these basins
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should involve detailed geologic soil borings to determine the exact elevation of bedrock and
groundwater for all stormwater basins in CP-2. It is possible, however, that the bedrock and
especially the groundwater will be lower than assumed here. If soil borings prove that these
stormwater ponds are not near the local groundwater or bedrock elevation, then these basins
could be redesigned as infiltration basins. In either case, it is recommended that soil
investigations be conducted as part of the next stage of design. As currently modeled, the more
conservative assumption of these basins not infiltrating has been used to ensure a conservative
design,.
Features of stormwater ponds include a permanent pool below the outlet, an outlet structure that
controls the rate of runoff during a 100-year storm event to pre-development rates, a 10 foot
wide vegetated shelf surrounding the entire basin, and, in the areas near bedrock used as a
drinking water aquifer, a clay liner. A native vegetation buffer is recommended for the area
above the normal water level. It is also recommended that all ponds be constructed with a multi-
stage outlet that allows drawdown of water levels in the fall. Increasing pond storage capacity in
winter allows retention of snowmelt, which will provide detention above the ice layer and allow
slow release of spring snowmelt which likely is high in chlorides from winter road salt usage.
Constructed Infiltration Basins
All stormwater basins, not designated to be ponds, and which are adjacent to parkways or
otherwise in the upper reaches of the major drainage areas are assumed to be constructed basins.
Such basins may need significant grading and other alterations to achieve the shape defined in
this analysis. Since these basins are constructed, it is assumed that the optimum infiltration rates
will be slower than current infiltration rates for the site. Operation of these basins, including
computation of the overflow rates and drawdown times, were based on an infiltration rate of 0.5
inches per hour for ideal outwash soils and 0.2 inches per hour for average till soils (only found
in CP-2). These infiltration rates were applied over the outlet area to convert from inches per
hour to an outflow rate in cubic feet per second.
Features of the constructed infiltration basins include creation of a filter strip and or inlet settling
basin, grading and shaping, installation of inlet and outlet structures, and vegetation appropriate
for infiltration basins.
Natural Infiltration Basins
The larger basins at the furthest most downstream areas of each major drainage area except CP-2
are typically natural infiltration basins. Additional construction is not needed to shape these
basins. Because only minor construction is needed for these sites, it is assumed that the existing
infiltration rates will be preserved. Operation of these basins, including overflow computations
and drawdown rates, were based on an infiltration rate of 0.60 in/hr to 0.75 in/hr, depending on
the water depth (deeper water equates to faster infiltration). These values come from 8 years of
infiltration basin monitoring and analysis in the immediate region. As described in the
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constructed basin section above, special care should be taken during construction to prevent
compaction of the soils and siltation by sediment released by construction activities.
Features of the natural infiltration basins include creation of a filter strip and or inlet settling
basin, installation of inlet and outlet structures where necessary, and minor re-vegetation as
appropriate for infiltration basins.
Monitoring of natural infiltration basins will be necessary to ensure adequate infiltration is
occurring and also to protect and preserve groundwater quality. The monitoring of the natural
infiltration basins should be coordinated with the SWWD, with the City of Cottage Grove
responsible for monitoring of the necessary constructed and natural basins if the SWWD is not
monitoring those basins.
The data collected from the monitoring efforts will be used to document infiltration rates on a
site-by-site basis. The documented infiltration rates will establish a baseline for future operation
and maintenance activities. Accumulated sediment can lower the infiltration rates of basins.
Should the basin infiltration rates fall below a yet to be determined standard, maintenance will
need to be done to restore the infiltration basins’ capacity by removing accumulated fine
sediment loads.
The monitoring effort should not be limited exclusively to infiltration rates, but should also
monitor the water quality entering the infiltration basins. The MPCA and Department of Health
(DOH) have concerns about large-scale infiltration efforts and the impact infiltration could have
on groundwater quality. Groundwater monitoring wells will also be needed, typically three per
basin, at the regional infiltration basins. Monitoring should include water levels through time
(for groundwater mounding) and water quality.
Drawdown times
Drawdown times for the infiltration basins were computed for two purposes. First, the draw
downs for a range of moderate events will allow comparison to actual monitored rates and will
guide future O & M efforts. Second, the basins within the boundary of SWWD CD-P86 (East
Ravine basins CP-3.22, CP-3.9, CP-3.11, CP-3.13, CP-3.18, and CP-3.19) were assessed to
ensure that the majority of the Cottage Grove local runoff is infiltrated before the regional water
pumped from CD-P85 into CD-P86. Local Cottage Grove runoff was redistributed among the
basins to optimize the infiltration drawdown time to ensure that the SWWD drawdown
conditions are met. Predicted drawdown times for each basin are detailed in Appendix F.
Outlets and Emergency Overflows
As described above, the outlet structures have been sized to convey stormwater runoff from
basin to basin during a 100-year precipitation event. The elevation of the outlet for each basin is
set at two feet above the infiltration basin floor for most cases. If not adequately maintained, the
soils may slowly fill with silt and other fine particles typically found in urban stormwater runoff.
Therefore, outlet structures should include a valve or removable weir which will allow for
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drawdown of any permanent pool of water that forms below the normal outlet elevation. This
valve would serve the purpose of draining the basin for maintenance and can recreate storage
capacity in the event that a large storm occurs before maintenance can be performed. Figure 8 is
a possible configuration of such an outlet structure.
Interior basins
As required by the city current standard as shown in the Cottage Grove Surface Water
Management Plan, stormwater basins are sized to allow no greater than an 8 foot water
bounce during a 100-year storm event. Outlets are sized to limit this bounce to a
maximum height less than the 8 foot allowed. Emergency overflows from these basins,
for storm events that create a bounce greater than the predicted maximum bounce, will
overflow onto the street and to the next basin downstream.
Shepard’s Woods Pond
The natural overflow from Shepard Woods Pond, a land-locked basin, is through a low
point easterly of the existing pond. For purposes of emergency overflow to protect future
structures, a culvert was set at this natural low point. Emergency overflow would be
directed to the major drainage basin to the east, CP-3.13. The elevation of this culvert
would be set at an elevation above the high water elevation set for Shepard Woods Pond.
CP-3
Cottage Grove area CP-3 drains through the SWWD site named CD-P86. Infiltration
basin CD-P86 south (CP-3.9, CP-3.11, CP-3.13, CP-3.18, CP-3.19) is of adequate size to
infiltrate all the runoff during a 100-year precipitation event for runoff from Cottage
Grove. The City of Cottage Grove has two options for an emergency overflow: 1) utilize
excess capacity in the existing Cottage Grove storm drainage system located immediately
to the south of CD-P86; or 2) utilize with the SWWD for emergency overflow capacity in
their future regional storm conveyance system. Figure 6 shows the potential emergency
overflow routes.
Option #1 would direct emergency overflow through existing Cottage Grove pond East
Draw #P-811. Since this it is recommended that detailed analysis of the existing system
be conducted to determine if any structural improvements are needed to convey
emergency flows. Option #2 is feasible at such time that the SWWD completes their
regional pipe from CD-P86 to the proposed basin located in Neighborhood #2. Selection
of this option would involve negotiations between the City and the SWWD on issues
such as capacity and cost sharing. This option may result in properties within this major
drainage basin would be subject to an annual stormwater utility charge from the SWWD.
Since this is an emergency overflow situation and not a normal outlet it is recommended
that the City consider proposing a user-fee scenario, which would involve payment to the
SWWD only if, and when, the emergency capacity is utilized.
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Unnamed Basin (CP4-3_1.1)
This natural basin is large enough to fully contain and infiltrate all the runoff from a 100-
year/ event. This analysis assumes that the excess runoff from a greater event will
overflow across an existing natural overflow to Vandeberg Pond (EW1-2a_1). The
SWWD has proposed to incorporate this basin into their regional network, but has not
scheduled acquisition of the property. At some undefined date in the future, the SWWD
plans to construct a pipe that will provide an overflow into the East Ravine Regional
Park. The City of Cottage Grove may opt to utilize this future SWWD outlet for
emergency overflow if the Vandeberg Pond route becomes unfeasible. If this option is
chosen, the Neighborhood #1 North recommendations for cost sharing with SWWD
would also apply to this basin.
CR 19 to East Ravine
NRL2-21, NRL2-22, ERL2-9, ERL2-8, ERL2-4, and ERL2-4A are all basins in
Neighborhood 1 - South that presently drain to the East Ravine Regional Park through
culverts under County Road 19. The outlets from these basins are sized to limit the
maximum water bounce during a 100-year precipitation event to 8 feet or less. Rate
control will allow the peak runoff rates to be less than currently exist. Existing culverts
will be utilized for emergency overflow from these areas. Volume control is important in
these areas to reduce any impacts to the park channel or lake. Park improvements could
be coordinated with SWWD improvement plans.
Cottage View
The Cottage View area of Neighborhood 1 - South is land-locked under existing
conditions. The Cottage Grove Surface Water Management Plan recommends that this
area be drained to an existing wetland south of Highway 61. Appendix C of the Cottage
Grove Stormwater Management Plan, dated June 8, 2000 limits the rate of discharge to
this future storm drain during a 100-year/24-hour event to 8.1 cubic feet per second. This
maximum outlet rate was used to size the infiltration basin proposed in this plan. The
maximum proposed conditions rate of discharge is 8.0 cubic feet per second, meeting the
Cottage Grove requirements.
Other areas
Two areas in the far westerly portion of Neighborhood #1 will overflow into the existing
Cottage Grove storm drainage system. Basin CP-25.1 will drain to a 24” storm drain
proposed for construction in Cottage Grove area West Draw #25. Basin CP-6.7 will
drain to an existing 12” culvert at 70th St. which is part of Cottage Grove area Central
Draw #67. Future ponds proposed in the Cottage Grove Stormwater Management Plan
contain capacity for these two areas of Neighborhood 1 North.
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Sub-Basins Descriptions
Neighborhood 1 North
CP-2.2Outlets through orifice and into drop structure before entering CP-2.3.
CP-2.3Outlets through orifice and into drop structure before entering CP-2.4. It also
receives flow from Woodbury (W1).
CP-2.4 & CP-2.5Located in area with shallow bedrock, zero infiltration modeled under
any scenario. The two ponds equilibrate with each other for larger rainfall events.
CP-2.7This pond receives the Woodbury runoff from watershed W2.
CP-2.8This pond receives the Woodbury runoff from watershed W3.
CP-2.11This pond receives the Woodbury runoff from watershed W4.
CP-2.10, CP-2.12, CP-2.14, CP-2.15 & CP-2.16 These ponds begin wet for all scenarios
because of their proximity to Shepard’s Wood Pond and the possibility that a high water
table is present. Also infiltration basin design requirements include a mandatory 3’
vertical separation from the water table.
CP-2.15Primary outlet west to basin CP-2.16 is the only outlet utilized for 100-yr
events. The emergency overflow east through backyard swales and into CP-3.13 will be
utilized for larger events.
CP-2.17Shepard’s Wood Pond, located in average soil, no infiltration assumed until
water level rises one foot above its NWL, then at 0.2 in/hr out the side of the pond.
CP-3.6Drains into a natural channel which drains into CP-3.9.
CP-3.8This infiltration basin receives all the impervious runoff from this area. It then
flows into the dry CP-3.8b and continues downstream.
CP-3.8b, CP-3.8c & CP-3.8d These basins begin dry and receive no initial runoff, only
that which has passed through the upstream pond (CP-3.8). They eventually drain into a
natural channel which drains into CP-3.9.
CP-3.9 Part of SWWD CD-P86 Large natural basin with almost identical size and shape
to existing; little grading required. Existing berm downstream of the Military Road
culvert is the controlling outlet. SWWD plans propose to create a channel through CP-
th
3.9 to create a water pathway to the proposed outlet at 70 St. Creating this channel will
increase infiltration capacity and have a minor effect on the HWLs.
CP-3.10This basin in some respects, will behave as an extension of CD-P86, while also
serving local drainage needs and treatment.
CP-3.11Part of SWWD CD-P86.Large natural basin with almost identical size and
shape to existing basin, only a small amount of grading required near housing boundary.
CP-3.13Part of SWWD CD-P86
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CP-3.18Part of SWWD CD-P86
CP-3.19Part ofSWWD CD-P86. Currently modeled without an outlet, however at
some future time an outlet will be added by South Washington Watershed District. An
existing 24” culvert from this basin to Cottage Grove pond ED-P3A2 could be utilized as
part of an emergency overflow.
CP-3.21 Runoff from this area naturally drains to SWWD CD-P86. SWWD has
indicated that this basin would not be available for local on-site stormwater management.
Therefore it is assumed that space in this development area must be made available for
onsite infiltration and treatment before overflow to CD-P-86N.
CP-3.22SWWD CP-86. Extremely large, deep basin that only a small amount of
Cottage Grove stormwater will enter. SWWD is preparing plans for temporary overflow
from this area into Gables Lake in Neighborhood 2. In the future, overflow of SWWD
water will be directed into Cottage Grove basin CP-3.9.
CP-25.1Drains east through existing culvert. This culvert could be replaced with a
smaller culvert, or an orifice could be added to lessen flow rates leaving the study area.
City plans for a park may also effect the configuration of this basin.
CP-6.7 Drains south through existing culvert. This culvert could be replaced with a
smaller culvert, or an orifice could be added to lessen flow rates leaving the study area.
The pond volume could also be increased because not all of the green space available was
utilized for the pond.
C-69 Undeveloped area that currently flows south into an existing drainage system.
Since the area is protected by a conservation easement, no change in land use proposed
and no improvements are needed.
Neighborhood 1 South
All ponds in this area meet the MPCA requirement that ½” of runoff from new impervious
surfaces must infiltrate in 48 hours or less. The ponds located in the commercial area in the
southern portion of Neighborhood 1 South (named SP-xx) have infiltration drawdown times that
are slower than what is generally acceptable for infiltration basins for the 2-year precipitation
event. Some additional on site runoff storage is recommended for this commercial region (e.g.
depressed parking lot islands, raingardens, vegetated swales, etc.). It is also recommended that
additional maintenance be scheduled for these infiltration basins.
The east draining ponds (named EP-xx or ERL-xx) and the northern draining ponds (NP-xx) or
NRL-xx) are all infiltration ponds with generally acceptable drawdown times. These areas
contain a number of shallow natural infiltration basins and one large one (ERL-2-5b). The EP or
NP label denotes a constructed basin while the ERL or NRL name represents a natural basin with
no change in storage volume.
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Neighborhood 2
Neighborhood 2 was not taken to the level of detail of Neighborhood 1. Therefore there are
fewer specific comments about basins.
No Cottage Grove stormwater was added to the northernmost basin (GL1-1_1). This basin likely
has sufficient capacity to receive extra stormwater runoff coming from future development likely
to occur to the north.
The land use plan for the areas designated as stormwater basins MR-1 and WR-1 did not set
aside a specific site for stormwater management. The East Ravine Regional Park exists
immediately downstream of this site; and there are not any sites in the park which could be
utilized for stormwater management. Therefore space in these development areas must be made
available for on-site infiltration and treatment.
GM
ROUNDWATEROUNDING
Modeling
Groundwater mounding was analyzed for the infiltration basins in the eastern portion of
Neighborhood 1. These basins are underlain by Superior Lobe outwash consisting of sands,
loamy sands, and gravels approximately 80 feet thick or greater (cf SWWD MW-3 in EOR,
2001). These outwash deposits are underlain by the subcropping St. Peter Sandstone, a fine- to
medium-grained quartz sandstone approximately 50 feet thick with its base at an elevation of
approximately 790 ft MSL (Figure 9). The base of the St. Peter is generally comprised of
siltstones and claystones constituting an aquitard and was considered the base of the aquifer
within which the mounding occurs. The water table in this area is approximately 840 feet MSL
or approximately 60 to 70 feet below the land surface in low areas.
The mounding within the hydrogeologic system was analyzed using HANTAXIS
(GeoHydroCycle, 1991), a transient, analytic model which calculates the groundwater mounding
at a particular time after a finite period of infiltration from a rectangular area on the land surface.
Because the specific hydrogeologic conditions are not known, the expected mounding was
determined for the outwash materials and the St. Peter using hydraulic conductivities of 95 and
11 ft/day, respectively (EOR, 2001)[Note: Bibliographic citation: Emmons & Olivier Resources,
Inc., (November, 2001) Infiltration Management Study, Phase II Report; South Washington
Watershed District.]
Local flows from the Cottage Grove area did not produce mounding under the basins to cause
any limitations to infiltrating the water or limits to adjacent structures. A simplified,
conservative analysis of regional flows from the SWWD overflow were also analyzed.
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For regional/SWWD flows, the model was used to assess the groundwater mounding under a
representative infiltration basin after 30 days’ ponding in CD-P85 and CD-P86N and after 20
days’ ponding for basins south with an average infiltration rate of 1.5 feet per day (0.75
in/hr).The individual predicted groundwater mounding ranged from 3 to 52 feet for the smallest
to largest infiltration basin, respectively. These bounding values correspond to a depth to the
water table mounding of approximately 53 to 8 feet, respectively. Further analysis involved
superpositioning of the mounding for adjacent basins indicated that areas near the south group of
basins (3.9 through 3.19). The compound effects of superimposed mounding could result in
potential problems for adjacent basements. These results, using the conservative infiltration
durations of 20-30 days, indicate that groundwater mounding should be considered in the final
design of regional infiltration areas. Further analysis of mounding is warranted particularly with
the design of the SWWD overflow. The critical event, 100-year hydrographs provided by
SWWD as part of the overflow design indicate water present for approximately 5-15 days,
depending on the basin. Analysis of “wet period” infiltration scenarios is also warranted in
addition to the single events discussed here. This analysis is outside the current scope of the
project, but should be consider as the regional system is designed.
Further analysis is recommended including the reduced duration indicated by SWWD and
extended wet periods. Final results may warrant modification of the basins’ configuration and
size. Also, additional field data collection is needed to determine the potential ground water
mounding effects beneath and surrounding regional infiltration basins including existing ground
water levels, stratigraphy, and hydrogeology.
Monitoring
Monitoring of groundwater mounding will be required for the regional infiltration basins.
Installation of groundwater mounding wells will be coordinated by SWWD and the City of
Cottage Grove.
The groundwater monitoring effort should be focused on the natural depression areas, where the
majority of the water volume will be infiltrated. A number of wells should be positioned
adjacent to and at distances up to 2,000 feet from the natural infiltration basins. Groundwater
levels will need to be monitored during dry and wet periods to determine the effect of peak
infiltration events on the groundwater elevation and seasonal ground water fluctuations.
ERRP
ASTAVINEEGIONALARK
Existing conditions
Within the Regional Park is a dry ravine that drains to Ravine Lake. Runoff flows through this
ravine from areas immediately to the north and west of the park. Presently there are no runoff
controls in place. Care should be taken to ensure that increased rates or volumes of post
development runoff do not contribute to erosion in this ravine.
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Proposed conditions
Pre- and post- development runoff volumes were checked to determine if this proposal would
increase flows through East Ravine Regional Park. As a result of this project, flows through the
park will actually decrease after full development. This reduction in flows is caused by the
proposal to construct infiltration basins and severely limit the overflow that drains through the
existing culverts. Therefore no additional improvements or erosion control measures are
necessary for East Ravine Regional Park.
SQ
TORMWATERUALITY
South Washington Watershed District
The South Washington Watershed District (SWWD) currently has an approved Watershed
Management Plan, adopted in 1997, and watershed Rules, adopted in 1999. The Plan and Rules
outline the water quality goals, policies, and requirements for the watershed.
Watershed requirements for water quality are based on the downstream receiving waterbody. In
the East Ravine project area there are 10 identified wetlands classified as SWWD Protect or
Manage 1 category wetlands and 2 lakes, including Gables Lake and East Ravine Regional Park
Lake, which are classified as SWWD Concern lakes. In addition, a portion of the Cottage View
area of Neighborhood 1 South drains to a wetland complex to the west of the project area where
the wetlands are classified as Protect category wetlands. All of the identified wetlands and lakes
have the same water quality standard based on annual total phosphorus loads to the waterbody.
The SWWD requires that developed annual total phosphorus loads not exceed 75% above
predevelopment annual total phosphorus loads for each of the waterbodies. In addition, 50-100
foot buffers are required around each of the wetlands.
Shepard’s Woods Pond is classified as a Protect wetland. Therefore, SWWD rules require that
the post development annual total phosphorus loading must not exceed 75% above the
predevelopment annual total phosphorus loading. All grading and construction should be set
back from this wetland by a minimum of 100 feet.
Watershed Rules, Section IX, describes SWWD watershed water quality standards as follow:
A. Any activity conducted pursuant to a permit must meet the runoff water quality
management standards and criteria set forth in the Plan both for wetlands and
waterbodies.
B. Where runoff from lands that are urban or suburban in character is contributing to
the pollution of the water resources of the District, every effort should be made to
abate the impurities at its source including the use of infiltration practices. Where
this proves to be impractical or impossible, an effective system of filters, ponds,
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or constructed treatment wetlands, where practical, will be constructed and
maintained by the project applicant or the local municipality.
C. Stormwater ponds draining into DNR protected wetlands, District priority
wetlands, or infiltration basins shall incorporate a skimming device capable of
retaining floating liquids and debris. In pond networks, it may be adequate to
provide the skimming device in the most downstream pond as determined by the
District Technical Professional.
D. Stormwater ponds will require long-term maintenance by the pond owner or
designated responsible entity including the following:
1. Field inspection every five years by pond owner to determine functioning
condition. If a pond is not performing to its full design potential, the
owner must return the pond to a good functioning condition.
2. Inlets and outlets will be inspected every two (2) years and as needed
maintenance performed by the pond owner as necessary.
MPCA
On August 1, 2003, the Minnesota Pollution Control Agency issued General Permit MN
R100001, which regulates discharge of stormwater associated with construction activities. This
general permit contains requirements for sizing permanent stormwater management systems that
will affect the design of the stormwater management basins in the East Ravine project area.
Wet sediment basins must be designed with a permanent pool below the outlet pipe, must control
the rate of discharge, must be designed to prevent short-circuiting and must have a stabilized
emergency overflow. All wet sediment basins are designed to contain the required permanent
pool.
The MPCA General Permit states that “infiltration basins must have a reasonable chance of
achieving approximately 80% removal of total suspended solids from a water quality event.”
MPCA presently defines a water quality event as ½“ of runoff from all new impervious surfaces.
Requirements for infiltration basins include rigorous sediment control during construction,
pretreatment device or filtration strip, discharge of water quality volume in 48 hours or less, and
3 foot separation between bottom of basin and seasonal high groundwater table.
Results
The water quality requirements of the MPCA and the SWWD are greatly exceeded for all areas
that are part of the natural infiltration basins. Drainage to Shepard’s Wood Pond could be an
exception due to management class. Runoff from the 100-year precipitation event is fully
infiltrated in the proposed systems. Therefore the minimum requirement of the MPCA of
infiltration of ½” of runoff and the SWWD requirement for a 2-year event are met.
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All water quality basins will be designed to standards set by MPCA. Water quality requirements
of the SWWD will be met by limiting the post development volume of runoff in a 2-year rainfall
event to no greater than 75% above predevelopment volumes. If post development runoff
volumes are equal to or less than predevelopment volumes, then annual total phosphorus loads
limitations will be met. It can be seen in Table 3 that the proposed infiltration basins will
decrease the total volume of runoff to Gables Lake and East Ravine Lake. The pre- vs. post-
runoff volumes to Shepard’s Woods Pond do increase, however they increase by less than the
allowable 75% increase. Therefore, additional on-site infiltration techniques which infiltrate the
runoff from a 2-year precipitation event will be required for the areas tributary to the stormwater
ponds within the Shepard’s Woods Pond drainage area.
Table 3: Pre- and Post- Development Volume Comparison
WaterbodyPre-development Runoff Post-development volume
volume
Gables Lake 9.4 acre-feet 5.3 acre-feet
East Ravine Lake 4.9 acre-feet 4.5 acre-feet
Shepard’s Woods Pond 15.8 acre-feet 19.3 acre-feet
Other practices
As described in the section titled Methods, it was assumed that future developments would
include onsite features that would retain a minimum of 15% of the runoff volume from a 5-year
precipitation event. Techniques to retain this runoff would be determined by the future
developers. Options could include a combination of the following techniques:
Minimized impervious surfaces, such as narrower driveways and streets;
d
Reduced compaction of residential grass areas and reapplication of organic topsoil,
d
which would allow for optimized infiltration;
Directed runoff from rooftops and/or driveways to lawns or raingardens rather than
d
directly to street;
Incorporation of infiltration features, such as rock infiltration trenches, into backyard
d
drainage swales.
Most of the information available today on alternative stormwater best management practices
(BMPs) can be obtained in reference material compiled by the Center for Watershed Protection
the Low Impact Development Center, the U.S. EPA, or various professional trade groups.
Additional information can also be obtained from environmental organizations and occasionally
from local governments that post information on their websites. Since this material is readily
obtainable and summarizes state-of-the-art installations, these web sites and the links they
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provide to other informative sites along with EOR’s experienced-based knowledge of the
practices provide key sources of information for this section.
Specific sources of information for this study and among the best to look for additional
information are:
Low Impact Development Center, Beltsville, Maryland
d
(www.lowimpactdevelopment.org)
Center for Watershed Protection, Ellicott, Maryland (www.cwp.org and
d
www.stormcenter.net)
U.S. Environmental Protection Agency, Office of Water, Washington D.C.
d
(www.epa.gov/owow)
Stormwater Magazine, Santa Barbara, CA (www.stormh2o.com)
d
The Natural Resources Defense Council (NRDC), New York, NY (www.nrdc.org)
d
The Puget Sound Action Team, Olympia, WA (www.psat.wa.gov)
d
Prince George’s County, Maryland (www.goprincegeorgescounty.com)
d
Successful incorporation of practices that result in runoff reductions greater than 15% would
allow resizing of the stormwater management basins recommended in this report and better
protect the regional and natural basins.
Construction practices
Special care must be taken during construction to prevent compaction of the soils and siltation by
sediment released during construction activities. Strict erosion control practices, such as
salvaging of topsoil and re-vegetation of exposed soils should be required for all construction
activities. Temporary sediment basins should be constructed upstream of each designated
infiltration basin to capture the sediment that is captured by the runoff. The infiltration basins
should be fenced to prevent construction equipment from compaction of the underlying soils, and
the final infiltration basin should not be constructed until after the construction sites in the sub-
catchment area are stabilized.
Maintenance Requirements
Formally establishing a City controlled O&M program is essential to effectively implementing
alternative stormwater management. The following steps are adapted from EPA’s recommended
steps to establish such a program:
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1. Establish a regulatory framework (ordinance or regulations) within which to formalize a
cooperative agreement with a homeowner, developer or any other entity, including the
City, that will be maintaining an alternative system;
2. Incorporate maintenance into design and construction specifications, including pre-
treatment;
3. Identify the mechanism for stable, long-term funding (even if it is the homeowner);
4. Formalize a regular inspection schedule, criteria for departing from the schedule (ex. after
a large event or when a problem is evident) and keep a log of inspections;
5. Define triggers for action (ex. 5” of sediment accumulation will trigger action to clean a
forebay);
6. Prevent sediment, debris and litter from moving into and accumulating into the system;
7. Make provisions for monitoring (visual or actual sampling) of treatment criteria;
8. Develop a training and education program, possibly with a certification element;
9. If water is not draining down after 4 to 6 days, remove accumulated fine sediments until
coarse soils are exposed and replant with raingarden vegetation; and
10. Develop an informational booklet for homeowners on need and role of infiltration
raingardens in neighborhoods.
Maintenance Personnel and Staffing
The public works maintenance functions for infiltration basins will include such activities as
maintaining pre-treatment systems, keeping streets clean, monitoring (visually) drainage
functions, and maintaining open space areas. If the City intends to rely heavily on biological
system components (ex. bioretention or raingardens), it should eventually acquire some staff or
train staff with some botanical/ecological background to manage or assist homeowners in
managing those features.
Installation of alternative practices into a commercial, industrial or institutional setting should
include a plan for who will maintain the system. Typically, a landscape firm or division of the
company is charged with grounds maintenance. The responsibilities for maintenance should be
clearly set out in the development-related permits issued by the City. Failure to comply with the
agreement will mean that the City has to undertake the effort and charged back costs to the
property owner, so careful structuring of the agreement is warranted.
The inclusion of alternative management techniques can often be an appealing aspect of a home
site. Asking a homeowner to maintain a simple practice, such as a raingarden, can result in a
commitment by that homeowner to the alternative management philosophy. This should be
treated as an amenity because it usually involves aesthetically pleasing additions to a
neighborhood. Experience in Maplewood, Minnesota has shown that most residents view
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upkeep of these facilities as part of maintaining their property value. However, changing
ownership, poor owner health, lack of interest or many other conditions could mean that
maintenance fails over time. The City again must be prepared to take over or re-negotiate for the
maintenance of properties where maintenance does not otherwise occur.
Finally, maintenance should be an essential component of any alternative design. This must then
be followed-up with adequate training of whoever is charged with the operation and maintenance
of the facility. This is much easier to accomplish with City staff than with homeowners or
commercial land managers. In any case, it should be fully defined before the system is
implemented.
Enforcement
If the City does not chose to be the maintenance provider for all alternative systems installed
within the City, it will need to develop some enforcement provisions defining how it will deal
with owners/operators who are unwilling or unable to correct problems. Good examples of
ordinance or regulations can be reviewed at www.stormcenter.net. Appendix E contains an
example of a Stormwater Management/BMP Facilities Agreement from Albemarle Co., VA.
The City will also need to define how it will financially implement the desired maintenance
practices, keeping in mind that any non-City failure to maintain could mean a responsibility shift
to the City to correct the problem.
Maintenance Checklist
The easiest way to assure that desired maintenance is performed is to develop a formal checklist
of the various activities that need to be performed. The checklist could include the information
contained in Table 4, but in a format that walks the maintenance staff or homeowner who might
be unfamiliar with the system through a prescribed series of routine steps designed to assure
continued effective operation of the system. A checklist not only assures that certain tasks are
completed on a routine basis, it also assures consistency among inspectors and provides a
historic record of maintenance and system performance. It also identifies consistently those
elements causing problems and those elements that need little attention.
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CCA
ONSTRUCTIONOSTNALYSIS
Stormwater Management Areas
Unit prices for stormwater management areas, such as ponds and infiltration basins, were derived
by computing a generic unit price for a typical basin, comprised of the features described in the
section titled Stormwater Management. A cost per acre was applied to the specific pond or basin
size for each area. Land purchase was not included in pond or basin estimates.
Storm drains and culverts
Storm drain and culvert estimates for Neighborhood 1 North and 1 South are more detailed than
for the stormwater basins. Components of the estimate include pipe length, catch basins,
manholes, and flared-end sections. Detailed designs were not created for storm drains or culverts
in Neighborhood #2. Therefore the construction cost estimate was based on a pro-ration between
Neighborhood #1 and #2 based on relative percentage of land use.
East Ravine
The rate of runoff from the future developed areas to the East Ravine Regional Park is at or
below the rates currently draining through the ravine. Therefore, no additional construction
activities are recommended.
Total Construction Cost
Construction cost estimates were prepared using 2004 construction prices. No inflation
adjustments were applied. Projects contained in the Cottage Grove CIP or the Cottage Grove
Surface Water Management Plan is not included in these estimates. Mobilization, erosion
control, engineering fees and a contingency are included in these estimates. Table 5 summarizes
the construction cost for the stormwater management components of the Cottage Grove East
Ravine area.
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Table 5: Construction Cost Estimate
NeighborhoodDrainage Basin Storm Drain Cost Basin/Pond Cost Total Cost
1N CP-2 $2,400,000$4,400,000 $6,800,000
1N CP-3 $4,400,000$2,700,000 $7,100,000
1N CP-6 $200,000$120,000 $320,000
1N CP-25 $100,000$130,000 $230,000
2 All $10,500.000$12,500,000 $23,000,000
1S NP $900,000$450,000 $1,350,000
1S EP $1,100,000$370,000 $1,470,000
1S SP $800,000$1,200,000 $2,000,000
Total $20,400,000$21,870,000 $42,270,000
P
HASING
General
One clear benefit of this proposal to maintain natural basins for stormwater management relates
to phasing of construction. Typically, stormwater management systems of interconnected storm
drains and NURP ponds must be phased such that the most downstream area is constructed first.
Construction phasing for this system of independent drainage basins can be linked to the phasing
needs of the other components of the public infrastructure (sanitary sewer, roads, and/or water
distribution). However, the construction within each drainage basin should start with the
stormwater basins. In most neighborhoods, this would require that the green spaces and
parkways be constructed first. Once the basins are in place and operational, then the storm
drains can be connected to each basin. If it is necessary to break the drainage basins into smaller
phases, then the lowest stormwater basins should be constructed in the early phases, proceeding
to upper stormwater basins in the later phases. Figure 10 outlines the areas of each drainage
basin that should be considered a single phase.
Neighborhood 1 - North
The large infiltration basins in Neighborhood 1 North (CP-3.22, CP-3.9, CP-3.11, CP-3.13, CP-
3.18 and CP-3.19) are proposed to be on land presently owned by the SWWD. The SWWD is
presently working on improvements for basin CP-3.22. Improvements for the remainder of their
land have not yet been scheduled. The City of Cottage Grove should closely coordinate
construction of these basins with the SWWD. The City should also determine which emergency
overflow route from these basins is preferred. If it is preferred that emergency flows should be
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directed through the existing stormwater drainage network, then it should be determined if
improvements in the existing system are necessary before the infiltration basins are constructed.
If it preferred that emergency overflows be directed to the future SWWD pipe, then close
coordination on construction of this pipe is needed before the infiltration basins can be
constructed.
The stormwater system in drainage basin WD-25 will eventually connect to a storm drain and
pond proposed in the Cottage Grove Capital Improvement Program. These downstream facilities
must be in-place before any improvements can be made in this drainage basin.
Neighborhood 2
The SWWD has unscheduled plans to construct a storm drain from Basin CP-3.19 in
Neighborhood 1 North to Basin CP4-3 in Neighborhood 2. Figure 7 also notes a proposed
alignment for the SWWD pipe. The City of Cottage Grove should coordinate construction of
Neighborhood 2 with the SWWD plans to construct this pipe.
Neighborhood 1 - South
The only stormwater system that needs careful timing in Neighborhood 1 South is the area
tributary to Basin WP-23. This basin will drain to future storm drain proposed in the Cottage
Grove Surface Water Management Plan. Once the proposed storm drain is in place, then the
stormwater management system of this basin can be constructed.
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AA
PPENDIX
Model Hydrology Input Parameters
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AB
PPENDIX
Stormwater Basin Data
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AC
PPENDIX
High Water Elevation and Lowest Opening Elevations
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AD
PPENDIX
Infiltration Capacities and Drawdown Times
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AE
PPENDIX
Technical References
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AF
PPENDIX
Design Standard Matrix
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EastRavinePre-Design
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