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January 26,2024 <br /> Don Peterson <br /> Page 17 of 21 <br /> Reference: Water Quality Assessment of Silver View Pond,Mounds View,MN <br /> Total cost of the improvement is estimated at$121,000. Table 8 summarizes the BMP pollutant reduction <br /> and cost-effectiveness. <br /> Table 8. Forebay Improvements Treatment Level and Cost-Effectiveness. <br /> BMP TSS TSS TSS TP TP TP Cost- <br /> Inflow, Outflow, Reduction, Inflow, Outflow, Reduction, Effectiveness, <br /> lb/yr lb/yr lb/yr lb/yr lb/yr lb/yr $/lb TP/yr <br /> Forebay 6,051.90 6,299.90 752.0 47.90 44.10 5.80 $20,900 <br /> Improvements <br /> Sump Structures on Lake Court Drive: Improvements in the subwatershed north of the pond are limited due <br /> to grade and available space. For this reason, the proposed improvements are replacing the downstream <br /> catch basins in the street with sump structures and installing SAFL Baffles and Snout skimmers or equal. <br /> SHASM modeling was used to find a representative removal rate for a 4-foot diameter and 4-foot depth <br /> sump with a SAFL baffle. The existing loadings of the P8 modeling were used and the SHSAM removal <br /> rates applied to the existing loadings to determine the TSS reduction per year. <br /> Total cost of the improvement is estimated at$46,000.Table 9 summarizes the BMP pollutant reduction <br /> and cost-effectiveness. These structures are not designed to remove TP, so cost-effectiveness is based on <br /> TSS removal. <br /> Table 9. Sump Structures Treatment Level and Cost-Effectiveness. <br /> BMP TSS Inflow, TSS Outflow, TSS Cost- <br /> lb/yr lb/yr Reduction, Effectiveness,$/lb <br /> lb/yr TSS/yr <br /> Sump Structure 12,656.00 12,352.30 303.74 $150 <br /> Improvements <br /> Bioretention Features Alone Apartment Parking Lot: Two linear bioretention features are proposed north of <br /> the H2 Flats apartments parking lots, as shown in Figure 9. Each will capture runoff from the apartment site <br /> and provide filtration/infiltration prior to discharge into the pond. Due to the flat terrain and high <br /> groundwater, the features are relatively shallow(1'), with flat draintile lines discharging directly at the pond <br /> normal water level. <br /> Design with community in mind <br />