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7550 MERIDIAN CIR N, SUITE 120 | MAPLE GROVE, MN 55369 PAGE 6 OF 8 <br />Table 3.Calculation of Estimated Land Value Change <br />Item Value <br />Area of Parcels Adjacent to RCD 4 65.9 Acres <br />Existing ROW Area 6.45 Acres <br />Reduced ROW Area 1.7 Acres <br />Total EMV (Per Ramsey County parcel data)$29,026,800 <br />Per Acre EMV (based on non-ROW land) $488,255 <br />Decrease in ROW Area (acres)4.75 <br />Increase in EMV based on reduced ROW $2,319,214 <br />EMV of remaining ROW area $830,034 <br />UPSTREAM FLOODPLAIN REDUCTION <br />Under existing conditions, the unnamed detention pond upstream of County Road C floods to an <br />elevation of 917.22 (NAVD 88) <br />3 during a 100-year storm event. This flood elevation corresponds to <br />an flooded area of 5.05 acres, which inundates both residential lots and road ROW. The proposed <br />project lowers this flooding elevation to 916.94 (NAVD 88), which corresponds to an area of 4.86 <br />acres, or a 0.19-acre decrease. The benefit of the flood reduction goes beyond the decrease in <br />floodplain, as more frequent rainfall events will also have reduced peak elevations. <br />One method to determine the value of the upstream flood reduction provided by the proposed project <br />is to determine the cost of an alternative project required to achieve a similar level of flood reduction. <br />The alternative project consists of excavating next to the pond to create additional storage within the <br />basin. Using the District Wide Modeling Program (DWMP), we determined that creating <br />approximately 3 acre-feet of additional storage achieves a similar reduction in flooding to the <br />proposed project.Table 4 displays a cost estimate for the alternative project. <br />4 <br />Table 4.Cost Estimate for the Alternative Project (Pond Excavation) <br />Item Unit Unit <br />cost Quantity Cost <br />Mobilization LS $15,000 1 $15,000 <br />Common Excavation and Haul-Off CY $10 5,000 $50,000 <br />Erosion Control and Seeding LS $15,000 1 $15,000 <br />Construction Cost $80,000 <br />Contingency (25%) $20,000 <br />Engineering (20%)$16,000 <br />Total Cost $116,000 <br />3 All elevations reported in this memo are NAVD 88, unless otherwise specified <br />4 Assumed that no maintenance costs over a 100-year period to maintain the additional flood storage.