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<br />RCWD Alternative Compliance Sequencing Report <br />City of St. Anthony Village PAGE 23 <br />WSB Project No. 1626-53 <br />C. Proposed Water Quality BMPs <br />The City of St. Anthony Village anticipates completing multiple linear construction <br />projects in the near future. Due to the overwhelming presence of Hydrologic Soil <br />Goups C and D throughout the City, there is little opportunity to provide feasible <br />volume reduction BMPs. The City proposes using an equivalence factor to allow <br />for the achievement of volume reduction credits by implementing phosphorous <br />reducing BMPs. Refer to Figure 5 for the location of proposed BMPs. <br /> <br />Possible stormwater management BMPs have been identified to achieve volume <br />reduction credits through the use of equivalent total phosphorus reduction. Using <br />the annual total phosphorous loading rate provided in the Silver Lake TMDL of <br />0.97 pounds of total phosphorus per acre foot of runoff, the equivalent annual <br />volume reduction was estimated. Calculations or procedures to determine water <br />quality benefits of each BMP will be submitted for RCWD staff review and <br />approval prior to construction. These credits will be used to offset the volume <br />reduction requirements resulting from the City’s planned linear reconstruction <br />projects. The following projects are possible improvement options for <br />consideration in the near future: <br /> <br /> 1. Salo Ponds Alum Treatment System (Silver Lake Watershed) <br /> <br />Project Description: <br />This project includes a permanent alum injection system in Salo Park, south <br />of Silver Lake, to remove total phosphorus and total suspended solids and <br />improve the water quality discharged to Silver Lake, which has been <br />classified by the MPCA as impaired due to excess nutrients. <br /> <br />Project Benefit: <br />The existing ponds remove approximately 66% of total phosphorus or 59 <br />pounds annually as shown in the Silver Lake TMDL. The proposed project <br />is anticipated to increase the removal efficiency to 90% of total phosphorus <br />or an additional 21 pounds annually. Using the total phosphorus loading <br />rate from the Silver Lake TMDL (0.97 lbs of TP/AF of runoff), an <br />equivalent annual volume reduction of 943,051 cubic feet is estimated. <br /> <br />A portion of this project may be paid for under RCWD grant funding. If <br />grant funding is used for this project, RCWD has indicated that a portion of <br />the water quality credits may not be used to benefit linear project <br />improvements.