12.03 - Marshall Street Area Storm Drainage Study

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November 24,2004 Page 2 Pequot Lakes-Engineering Services Proposal for Marshall Street area Storm Drainage Study 5. Define the existing drainage area tributary to this existing low spot on the contour map. This task does include one site visit during which adjustments to the drainage area will be made by 'eye' (no elevation survey). 6. Calculate an estimated volume of runoff from this existing low spot's existing tributary drainage area. We will estimate an ultimate build-out in this area (basically residential in nature)to use in calculating impervious surface area. 7. We will compare the volume of runoff(from Step 6) versus the volume available in the existing low spot(from Step 4)to determine the approximate water level or elevation. For this step, we will assume no infiltration (frozen ground, for example). This is generally the most conservative approach since some amount of infiltration will usually occur over time. 8. We have included some time to review, in a general nature, the possibility of other adjacent tributary areas being possibly directed to this existing low spot. However, we did not include enough time to do detailed calculations for these adjacent tributary areas. If requested by the City, we could perform these calculations at our billing rates included herein. This study does not include delineation of wetlands. There are various rules prohibiting direct discharge of storm drainage into wetlands—a sedimentation basin is first required before overflowing into a wetland. This study also does not include soil borings. We anticipate tasks such as laying out sedimentation basins and obtaining soil borings would most likely be included in a preliminary design phase if the City wanted to proceed with purchasing property. The effort associated with this study could be in the$4,000 range, depending on the ultimate drainage area involved (Step 8). The scope and effort for a design phase and a construction phase would need to be reviewed after the completion of this study. Considering new Council members coming in,WSN will complete this study by the February 2005 City Council meeting, with periodic updates prior to this time. If you are in agreement with our proposed scope of services, please sign below and return one copy of this letter to us as our authorization to proceed. We appreciate the opportunity to continue to serve the City of Pequot Lakes. Sincerely, Timothy M. Houle, P.E. CADocuments and Settings\Administrator\Local Settings\Temporary Internet Files\OLKB\Pequot Lakes-Marshall Street drainage study.doc