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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 $121,000. Table 8 summarizes the BMP pollutant reduction <br />and cost-effectiveness. <br />Table 8. Forebay Improvements Treatment Level and Cost -Effectiveness. <br />BMP <br />TSS <br />TSS <br />TSS <br />TIP <br />TIP <br />TIP <br />Cost - <br />Inflow, <br />Outflow, <br />Reduction, <br />Inflow, <br />Outflow, <br />Reduction, <br />Effectiveness, <br />Ib/yr <br />Ib/yr <br />Ib/yr <br />Ib/yr <br />Ib/yr <br />Ib/yr <br />$/Ib TP/yr <br />Forebay <br />6,051.90 <br />6,299.90 <br />752.0 <br />47.90 <br />44.10 <br />5.80 <br />$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 <br />TSS Inflow, <br />TSS Outflow, <br />TSS <br />Cost- <br />Ib/yr <br />Ib/yr <br />Reduction, <br />Effectiveness, $/Ib <br />Ib/yr <br />TSS/yr <br />Sump Structure <br />12,656.00 <br />12,352.30 <br />303.74 <br />$150 <br />Improvements <br />Bioretention Features Along 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 />