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HomeMy WebLinkAboutContract No. 2013 2494 (/s1 A WSB &Associates.Inc. engineering-planning-environmental•construction 701 Xenia Avenue South Suite 300 Minneapolis,MN 55416 Tel: 763-541 4800 Fax: 763-541-1700 February 27,2013 Mr.Kevin Hansen Public Works Director City of Columbia Heights 636 38th Avenue NE Columbia Heights,MN, 55421-3835 Re: Scope of work to prepare a Jackson Pond Feasibility Study WSB Project No. 01792-070 Mr.Hansen: We are pleased to provide this scope of work to prepare a water quality focused feasibility study for Jackson Pond. Previous Jackson Pond reports focused on the pond's flood control features and only developed minimal water quality aspects to the pond rehabilitation project. This new look will focus on expanding the water quality performance of the project while maintaining the project's flood control performance, as developed in previous analysis. The City prepared a feasibility study in 2008 to improve flood control function at Jackson Pond and has installed storm sewer pipe near University Avenue in preparation for a Jackson Pond project. The feasibility study recommended a project whereby Jackson Pond would be converted to a dry pond,thus increasing available flood storage. A small pump would lower the pond below the current gravity outlet. Water quality modeling determined that the conversion to a dry pond with highly restrictive 1-cfs low stage outlet had little impact on the pond's TSS and TP removal. The purpose of this feasibility study is to consider additional project features that would reduce runoff volume and/or phosphorus discharge to the Mississippi River via this pond. Below we list the tasks necessary to complete the feasibility study. Task 1: Hydrologic and Water Quality Analysis Based on drainage area delineations and land use,we will calculate annual runoff volume,TP, and TSS loading to Jackson Pond and the loading passed from Jackson Pond to the Mississippi River. We will do this for existing conditions and then compare this to existing MWMO Minimum Standards. The preliminary design for Jackson Pond consists of a small "off-peak"dewatering pump. Given this design,there will be a significant amount of annual runoff captured below the gravity outlet. This runoff can be routed to an off-site treatment BMP or to an area where it could be used for irrigation,such as Huset Park. Depending on the types of BMPs considered,we will calculate phosphorus,TSS,and volume load reductions within the Jackson Pond drainage area and the resultant decrease to Mississippi River loadings. St.Cloud• Minneapolis•St.Paul Equal Opportunity Employer wsbeng.com Mr.Kevin Hansen February 27, 2013 Page 2 We will not re-quantify flood control benefits since this was adequately covered in the 2008 feasibility study and conditions on the ground have not significantly changed. We will summarize the results of the previous study in the new feasibility report,however. The report will emphasize that any potential project that frees storage in the Jackson Pond and the Huset Park pond(such as a recycling for irrigation project)would benefit downstream flood-prone areas in Minneapolis. Task 2: Alternatives Discussion We will discuss alternative projects and their potential to provide pollutant reductions to the Mississippi River via Jackson Pond. Alternatives might include water recycling for irrigation, augmenting in-pond extended detention,consideration of upstream BMPs,using structural BMPs or iron enhanced filters in the Jackson Pond area, and searching for more effective downstream BMPs. It is necessary to explore the alternatives so that there is reasonable assurance that the most cost effective project stands out. We will also discuss any impact on habitat and vegetative cover in converting the existing wet pond to a dry pond. Our alternatives discussion will provide descriptive narrative,pollutant reduction calculations, and planning level cost estimates for up to four feasible alternatives. We will also discuss maintenance issues with each alternative and will include ongoing maintenance and operations in a present worth comparison of the four alternatives. Only the recommended alternative will be brought forward to task 3. Task 3: Preliminary Design and Feasibility Report We will develop the recommended design and quantify the water quality benefits based on existing loadings to Jackson Pond. To support our narrative description,we anticipate including an overview map,two plan view sheets showing improvements at Jackson Pond and downstream if the recommended project involves facilities in some other location. We will also provide a detailed excel spreadsheet showing the water balance and pollutant reduction calculations. Permits and approvals are required for this project and we will outline these in the feasibility report. We have already discussed the project with the Minnesota DNR and U.S.Army Corps of Engineers so we have a good understanding how the project fits within their permit processes. Other permits include an MPCA construction permit, and a permit to dispose of contaminated sediments if these are encountered. Task 4: Project Management Project management tasks include a kickoff meeting and one other meeting or council presentation,depending on City and Watershed Staff preferences. We will also be requesting certain files from the City including GIS shape files of land use and drainage areas,storm sewer base mapping,and aerial photographs. Project management tasks also include regular progress updates via email and descriptive and promptly submitted invoices. Mr.Kevin Hansen February 27, 2013 Page 3 We can complete the feasibility study within four weeks of authorization as long as data we request is provided within a couple business days. We propose compensation on an hourly basis not-to-exceed $13,600. I will serve as project manager on the feasibility study. Technical analysis will be conducted by Earth Evans and/or Paul Hudella,with my assistance. If you have any questions about this scope, please call me at 763-231-4876. We have included a signature block for City authorization to proceed. Sincerely, WSB&Associates,Inc. Bob Barth Senior Project Manager I hereby authorize WSB&Associates, Inc. to proceed with the above-referenced work. Signature Dxfe Authorized Representative,City of Columbia Heights s � r g1 �� Printed Name Title