2018-03-14 CC Packet - Laserfiche WebLink

Metadata

Thumbnails

Annotations

RICE CREEK WATERSHED DISTRICT CLEAN WATER GRANT PROGRAM APPLICATION AND CONTRACT GENERAL INFORMATION Contract Number Individual/Group Other Grant Award Amendment Cancelled A18-01 Individual Yes No10 Date: Date: APPLICANT INFORMATION Applicant Phone Email City of Centerville 651-503-1834 GBurmeister@CENTERVILLEMN.com Mailing Address City State Zip 1880 Main Street Centerville MN 55038 CONSERVATION PRACTICE/PROJECT LOCATION Physical Address Municipality Trail Side Park- 7145 Main St. Centerville County Township Range Section %,% Parcel ID Anoka 31 22 23 22 233122220013 Nearest lake,stream or wetland that the proposed practice drains to Approximate distance to nearest waterbody Centerville Lake Adjacent PROJECT INFORMATION Project Description(Attach additional sheets if necessary) The following summarizes the RCWD Water Quality Grant Program application to cost-share the installation of a 328'shoreline stabilization using riprap and native vegetation along the east side of Centerville Lake.This Phase 2 project is a southern continuation of the Phase 1 RCWD Water Quality Grant Program project(A17-08)that is expected to be installed in the spring of 2018.The City of Centerville is hoping to pair this project with Phase 1 in order to capitalize on a favorable bid from Phase 1.The low bidder from Phase 1 has agreed to honor the unit prices for Phase 2. PROJECT DESCRIPTION Trail Side Park Phase 2 is located on two properties along the east side of Centerville Lake,west of Main St.in Centerville(see map to right).Both properties are owned by the City of Centerville.This project includes 328'of actively eroding shoreline.Natural wave action and wakes from boat traffic are the primary causes of erosion.Sediment and nutrients from the eroding shoreline directly enter Centerville Lake,which is part of the Rice Creek Chain of Lakes.Additionally,a sanitary sewer main is at risk of exposure if erosion continues. The 328'project is divided into north and south zones based on a difference in lakeshore bank height.Because the south zone banks are taller,the south zone will require more riprap than the north zone in order to achieve a stable slope. North Zone(Approximately 179')-This zone is characterized by steep shoreline slopes(about 2:1).The crown of the shoreline is about 2.5'above the OHWL and then the topography flattens into about a 20'wide bench.Shoreline erosion has undercut this area,resulting in steep shoreline banks and exposed tree roots.About a dozen small trees(6"-12"DBH)are holding the bank in place,but many of the trees are slumping into the lake.A sanitary sewer line parallels the lakeshore along this north zone,generally within 5'—20'of the eroding shoreline.This sewer main is at risk of failure if the lakeshore erosion trend continues.An emergency repair was recently completed where the sanitary sewer line was already exposed because of the lakeshore erosion.Riprap was installed along 16 linear feet of shoreline in the north zone of Phase 2 South Zone(Approximately 149')—The south zone is characterized by steep shoreline banks(about 2:1).The crown of the shoreline is generally 3'—4'above the OHWL and then the topography flattens into about a 10'wide bench.Shoreline erosion has undercut this level area,resulting in 3'—4'high shoreline banks.A sanitary sewer line parallels the lakeshore along this south zone,generally within 5'—10'of the eroding shoreline.This sewer main is at risk of failure if the lakeshore erosion trend continues. PROJECT DESIGN Trail Side Park Phase 2 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 Phase 2 shoreline also absorbs the wakes from recreational boaters,including waterskiing events held offshore from the park.With a goal of long term shoreline stabilization,the Anoka Conservation District proposes installing riprap(the minimal quantity necessary)and native shrubs. North Zone(Approximately 179')-The north zone design consists of laying type IV geotextile fabric under 12 inches of riprap(the minimal depth feasible for shoreline protection)that is keyed into the lake bottom.On average,the riprap will be 6'wide and will be installed to the crown of the lakeshore bank.Low growing native shrubs,such as redosier dogwood,will be installed in clusters above the riprap in areas that are not on top of the sanitary sewer main. South Zone(Approximately 149')—The south zone design consists of laying type IV geotextile fabric under 12 inches of riprap(the minimal depth feasible for shoreline protection)that is keyed into the lake bottom.On average,the riprap will be 8'wide and will be installed to the crown of the lakeshore bank.Low growing native shrubs,such as redosier dogwood,will be installed in clusters above the riprap in areas that are not on top of the sanitary sewer main. Please note minor regrading of the bank was considered in this zone zone in an attempt to limit the maximum elevation of the riprap.However,the proximity of the sanitary sewer line to the top of the bank and the desire to preserve existing trees made the regrading infeasible. PROJECT BENEFITS Water Quality Stabilization of the Trail Side Park Phase 2 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 that is at risk of near-term failure if shoreland erosion continues. 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 NRCS Direct 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 and fallen trees(see site pictures at end of memorandum).Based on this determination,the lateral recession rate was estimated to be 0.3 ft/yr,which is on the men of tha severe'range(0.3-0.5 ft/yr).Assuming sandy soils,the estimated soil loss from this 328'stretch of bank with an average 3'eroding face is approximately 16.2 tons per year.This results in an estimated 13.8 pounds of total phosphorus contributed to Centerville Lake and downstream waterbodies annually.Stabilization of the bank will result in 100 percent reductions in these estimated pollutant loads. 2016 C-S application contract.pdf P�,a1ge 1 of 3 2/05/2016