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Home My WebLink About2010-03-03 PACKET 04.F.REQUEST OF CITY COUNCIL ACTION COUNCIL AGENDA MEETING ITEM # DATE 03/03/2010 a •- -" a Engineering ORIGINATING DEPARTMENT Jennifer Levitt STAFF AUTHOR ***************** * * * * * * * * * * * * * * * * * * * * * * * * * * * * * ** COUNCIL ACTION REQUEST Approve and authorize the submittal of the South Washington Watershed District, Coordinated Capital Improvements Program Application. STAFF RECOMMENDATION Recommend the Council approve and authorize the submittal of the South Washington Watershed District, Coordinated Capital Improvements Program Application. ADVISORY COMMISSION ACTION DATE REVIEWED APPROVED DENIED ❑ PLANNING ❑ ❑ ❑ ❑ PUBLIC SAFETY ❑ ❑ ❑ ❑ PUBLIC WORKS ❑ ❑ ❑ ❑ PARKS AND RECREATION ❑ ❑ ❑ ❑ HUMAN SERVICES /RIGHTS ❑ ❑ ❑ ❑ ECONOMIC DEV. AUTHORITY ❑ ❑ ❑ ❑ ❑ ❑ ❑ SUPPORTING DOCUMENTS ❑ MEMO /LETTER: Jennifer Levitt, February 25, 2010. ❑ RESOLUTION: ❑ ORDINANCE: ❑ ENGINEERING RECOMMENDATION: ❑ LEGAL RECOMMENDATION: ❑ OTHER: Coordinated Capital Improvements Program (CCiP) Request for Proposals and Application Cycle. ADMINISTRATORS COMMENTS City Administrator Date * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * COUNCIL ACTION TAKEN: [ ❑ DENIED ❑ OTHER From: Jennifer M. Levitt, P.E., City Engineer Date: February 25, 2010 Re: Approve and Authorize the submittal of the South Washington Watershed District, Coordinated Capital Improvements Program Application Background /Discussion The South Washington Watershed District (SWWD) developed a Coordinated Capital Improvement Program (CCIP) to provide for financial assistance to local units of government for water quality improvements. The grant will cover up to 35% of the total project cost with a maximum of 10% of grant funds applied to engineering and administration. CCIP grants are only available in the South Washington Management Unit. The enclosed application is for the construction of storm water improvements related to the River Acres Pavement Management Area. The project consists of construction of rain gardens on 115 Street and installation of curb and gutter with a storm sewer system on Inman Avenue. The total project cost is $230,355 and the grant request amount is $80,625 which is the maximum amount that can be requested. Recommendation It is recommended to approve and authorize the submittal of the South Washington Watershed District, Coordinated Capital Improvements Program Application. Coordinated Capital ImprovemenV, Program (CCIP) Request for Proposals and Application 2010 Application Return to: South Washington Watershed District 2302 Tower Dr. Woodbury, MN 55125 jloomis @ci.woodbury.mn.us Due by: March 12, 2010 at 4:00 p.m. As a result of developing and implementing its water resource management plan, working with local government units within the watershed on local water plans and capital projects, and carrying out its permitting program, the District is aware of the challenges posed to sound, comprehensive surface water management by existing urban development. Existing development and impervious surface within the watershed constructed at an earlier time may not have applied due attention to minimizing and managing stormwater impacts under pre- existing regulatory conditions. Stormwater management in these areas may be improved through retrofitting and during redevelopment, roadway and sewer projects, space and options often are constrained and measures may be expensive. To facilitate actions to improve stormwater management in existing developed areas, the District administers a Coordinated Capital Improvement Program (CCIP) to provide financial assistance to local land use and public works authorities for water quality improvement projects. The CCIP seeks to: • Facilitate local government units within the District to explore water quality improvement opportunities and incorporate those opportunities into routine infrastructure operation and maintenance projects; • Promote closer collaboration between local units and the District on water quality improvement efforts as an element of capital improvement plans; • Foster stormwater management innovation and create demonstration /education examples; and • Defray local costs in the broader, watershed -wide interest of improving water quality. Applications are now being accepted for 2010 project funding. Grants may be awarded for up to 35% of the total project cost with a maximum of 10% of grant funds applied to engineering and administration. CLIP grants are funded by stormwater utility fees, and therefore are allocated to projects in the SWWD Management Unit where the fees are collected. Up to $300,000 in CCIP funds will be allocated to projects in the South Washington Management Unit for 2010 funding. Anticipated funding for 2011 projects is also $300,000, allocated to the South Washington Management Unit. Funding for projects in the East Mississippi or Lower St. Croix Management Units may be available in the 2011 application cycle. E All municipalities and county agencies proposing projects within the South Washington Management Unit of the SWWD are eligible. � r The SWWD Technical Advisory Committee will review applications and submit a recommendation to the SWWD Board of Managers. Applications will also be evaluated by SWWD staff based on overall water quality benefit and water quality benefit to cost for Board consideration. Proposed redevelopment projects will be considered based on their total water quality benefit while proposed new development projects will be considered based on the benefit provided in addition to meeting minimum SWWD standards. Grant allocations will be decided by the SWWD Board of Managers and announced following the May Board meeting. The Board may choose to deny all applications. All grants will be awarded contingent on approval following SWWD development review. Project designs must meet all SWWD standards and follow guidance provided in the SWWD standards manual. Development review applications for CLIP funded projects must include a maintenance plan for SWWD review. Grantees will be required to enter into an agreement with SWWD. Payment will be made following completion of the project and submission of final report to consist of as built plans and itemized invoice detailing total project costs. Questions Contact John Loomis at 651/714 -3714 or jloomis @ci.woodbury.mn.us Applicant Information LGU: City of Cottage Grove LGU Representative: Jennifer Levitt, PE Address: 8635 West Point Douglas Rd City: Cottage Grove State: MN Zip Code: 55016 Phone: 651.458.2890 Email: ilevitt @cottage- grove.org Project Location Project Location: 113th Avenue S and Inman Avenue S, Cottage Grove. MN (see attached location map) Watershed Management Unit: South Washington Primary Waterbody Affected: Mississippi River Project Description Purpose /Need The existing drainage along 113 Avenue So, from 113 Street Ct to Inman Avenue So, consists of over- land drainage due to the absence of ditches and storm sewer. The drainage primarily conveys a low point located at 8246 113 Street So. Once storm water reaches this location it pools up to the crown of the roadway. During larger storm events, the water overtops the crown & then runs a course down the driveway of opposite residence on the south side of the street as it conveys over the existing bluff. This existing drainage scenario is causing several issues. The water that pools up on the north side of the street is remaining on the existing pavement for several days causing a safety issue along with rapid deterioration of the bituminous pavement. The City of Cottage Grove has already had to patch the bituminous in this location due to this deterioration. Also, during the larger storm events the water conveys down the driveway of the residence on the south side of the road which is causing erosion on the bluff located in the rear yard. Goals It is proposed that a series of rain gardens or functioning depressions be created along the sides of 113 Street So starting at the existing low point and uphill as necessary to reduce runoff volume, prevent ponding on the existing bituminous roadway, and reduce the magnitude and frequency of erosive concentrated flows over the existing bluff. Benefits /Measurable Results (e.g. estimated pollutant reductions, reduced flooding risk, etc.) It is estimated that the proposed rain garden improvements will provide a load reduction of approximately 2.6 Ibs TP /year which is 88% of the estimated current load. The proposed rain garden improvements are also estimated to provide a volume reduction of approximately 88% for the drainage area. Please refer to the attached documentation for supporting calculations of the estimated benefits. � t Purpose /Need The existing grade of Inman Avenue So. is very steep as it works its way down the existing bluff to 115 Street So. Currently storm water runoff conveys down Inman Avenue So. to an existing set of catch basins located at the bottom of Inman Avenue So. where it meets 115 Street So. Due to the absence of curb along Inman Avenue So, runoff is causing erosion along the edges of the roadway that conveys to 3 , the existing catch basins located at the end of Inman Avenue So. as it makes its way to the Mississippi River. The erosion is also causing gravel to be washed out onto the bituminous roadway surface causing the likelihood of a vehicle to skid and lose control down the steep grade which has become a safety concern of the City. Goals It is proposed that curb be installed down Inman Avenue So. as necessary to keep storm water from causing erosion along the steep grade by confining runoff to the roadway. It is also proposed to extend storm sewer & install catch basins uphill from the existing catch basins at the bottom of Inman Avenue to aid in getting storm water off of the roadway surface as it travels down the steep grade and before it over -tops the curb. Benefits /Measurable Results (e.g. estimated pollutant reductions, reduced flooding risk, etc.) Eliminating the erosion along Inman Avenue So. will benefit water quality of the runoff by reducing the amount of sediment being introduced as it conveys down the bluff to the Mississippi River. Another benefit will be the elimination of erosion washing onto the roadway surface increasing safety as it reduces the likelihood of a vehicle to skid and lose control. Project Budget Total Project Cost: $230,355 CCIP Funding Requested (maximum of 35% of total project cost): $80,625 * A combined maximum of 10% of grant funds may be applied to engineering and administration costs. i certify to the best of my knowledge that the information included in this application is true, complete, and accurate Signature 4 Simplified Pollutant Loading Estimate L = (P)(R Where: L = Load of a pollutant in pounds per year P = Rainfall depth per year (inches) Rv = Runoff coefficient C = Flow- weighted mean concentration of the pollutant (total phosphorus) in urban runoff (mg /1) = 0.30 mg /lb A = Area of the development site (acres) L = (32 in) (0.40) 0.30 m (3.9 ac) (0 = 3.01b �P Y Simplified Load. Reduction Estimate LR = (L)(BMPRE)(DA Served)(RO Treated) Where: LR = Annual total phosphorus load removed by the proposed BMP (lbs /yr) L = Load of a pollutant in pounds per year (lbs /yr) BMPRE = BMP removal efficiency for total phosphorus DA Served = Fraction of the drainage area served by the BMP RO Treated = Fraction of the annual runoff treated Com arative BMP Phosphorus Removal Per ormonce BMP Group BMP Design Variation Average TP Removal Rate Maximum TP Removal Rate Average Soluble P Removal Rate Bioretention Underdrain 50% 65% 60% Infiltration 100% 100% 100% Filtration Sand Filter 50% 55% 0% Dry Swale 0% 55% 0% Wet Swale 0% 40% 0% Infiltration Infiltration Trench 100% 100% 100% Infiltration Basin 100% 100% 1 100% Stormwater Wet Pond 50% 75% 70% Ponds Multiple Pond 60% 75% 75% Stormwater Shallow Wetland 40% 55% 50% Wetlands PondNdetland 1 55% 75% 65% Source: Minnesota Stormwater Manual, MPCA (2008) a 0.20 is a regional constant and unit conversion factor 'The C factor can be customized if good local water quality data exist or if an adjustment in the 0.30 mg /l term is needed. Assuming the BMPs are designed based on the 90% capture rule in which 90% of the annual cumulative precipitation depth is treated. Based on a rainfall frequency analysis from the Minneapolis /St. Paul Airport for the period of 1971 through 2000 the rainfall depth associated with the 90 percentile is 1.05 inches. It is important to note that 1.05 inches of the precipitation depth of an individual storm which is in excess of 1.05 inches (the 90th percentile event) will still be managed by the BMP to some degree. For example, the total precipitation that was recorded at the Minneapolis /St. Paul airport over the past 30 years (not including snow records) totals 633 inches. The sum of all rainfall up to 1.05 inches, plus 1.05 inches of each precipitation event in excess of 1.05 inches totals 556 inches of precipitation. In total, 88% of the cumulative depth of rainfall (556 1633) that occurred over the period of record used to assemble this data would be managed by a BMP sized to treat 1.05 inches. (Source: Minnesota Stormwater Manual, Appendix J, Issue Paper 8) LR = ( 3.0 lbsTP (1.00)(1.00)(0.88) = 2.6 yr yr ) yr Simplified Volume Reduction Estimate VRE - ' ( h + df d (Af)(t) f Where: VRE = Volume reduction (ft i = Infiltration rate (ft /day) hf = Average height of water above filter bed(ft) dr = Filter bed depth (ft) Af = Surface area of the filter bed (ft t = Drain time (days)d VRE = 2 day ( 5 f t ft f t \ (3125 ft ( 2 days) = 15000 ft Based on an estimated volume reduction capacity of 15000 ft the equivalent depth of runoff over the 3.9 acre drainage area which will be handled by the proposed BMPs is 1.05 inches. As previously explained, rainfall totals up to and including 1.05 inch events account for approximately 88% of the annual cumulative rainfall. 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