2017-12-06 P & R Packet - Laserfiche WebLink

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erosion has contributed to the loss of about 10 mature trees (24"-50' DBH) in the past five years. A sanitary sewer line parallels the lakeshore along this south zone, generally within 116-20' of the eroding shoreline. This sewer main,which is about three to four feet in elevation above the OHWL, is at risk of failure if the lakeshore erosion trend continues. Please note that in the past year the City of Centerville had to implement shoreline stabilization measures to protect the sewer main alignment located immediately south of the project. PROJECT DESIGN Trail Side Park is located on the windward side of Centerville Lake and experiences more than a mile of fetch- On windy days, the shoreline is pounded by waves more than a foot high. The Trail Side Park shoreline also absorbs the wakes from recreational boaters, including waterskiing events held offshore from the Fork. With a goal of long term shoreline stabilization, the Anoka Conservation District proposes Installing riprap (the minimal quantity necessary) and native plantings. North Zone(Approximately 165') -The north zone has a slope that is similar to the shoreline tote no of the project. This north zone design consists of laying type IV gootextile fabric under 12" of riprap(the minimal depth feasible for shoreline protection)that is keyed into the lake bottom. Native willow stakes (similar species to the property to the north)will be installed throughout the riprap area. Low growing native shrubs will be installed in a six foot wide zone above the riprap that is currently mowed. South Zone(Approximately 185')•The south zone is heavily used for community events during the summer months(water skiing shows, fireworks viewing, etc.). Thus, a secondary goal in this zone is to maintain the lake view and access docks seasonally installed in this area. Therefore,the south zone design consists of laying type IV geotextile fabric under 12"of damp (the minimal depth feasible for shoreline protection)that is keyed into the lake bottom. About 550 low-growing native plants{forts and grasses)will be interplanted in a six foot wide zone upslope, of the riprap that is currently mowed. PROJECT BENEFITS Water Quality Stabilization of the Trail Side Park shoreline will provide reductions In total suspended solids, total phosphorus, and other nutrients entering Centerville Lake. As part of the Rice Creek Chain of Lakes system,the water quality benefits will also have downstream benefits to the Chain of Lakes and Rice Creek. Existing Infrastructure Protection Shoreline stabilization will provide protection for the sanitary sewer line within the park, a regional bike path, and Main St. Recreational Use Shoreline stabilization within Trail Side Park will provide continued access to Centerville Lake for community events and general recreational use by the public. ESTIMATED POLLUTANT REDUCTIONS Pollutant reductions were estimated using the Wisconsin NFACS Litrect volume method in conjunction with BWSR's pollution reduction calculator for stream and ditch erosion. Erosion severity along the shoreline was classified as'severe' because the bank is predominantly bare, with exposed tree roots Page 2 of 4