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in the permitting process should excavation need to take place. The permanent pool storage volume that is needed to meet MPCA recommendations was calculated for Silver View Fond using the impervious area and the direct drainage area of the pond. First, the direct drainage area for the pond was identified by performing a field watershed delineation, Next, the impervious area within (lie drainage area was determined by digitizing impervious area as seen in aerial photographs of the watershed. These values were then used to compute the MPCA recommended design volume for Silver View Pond. 2.8 Stormwater Pond Wetland Evaluation If wetland areas are disturbed or altered during pond construction or expansion, wetland permitting and possibly wetland mitigation are required. Therefore, the Silver View Pond area was evaluated to determine its potential to be considered a historic wetland. The area was compared to the National Wetland Inventory (NWI) wetland maps, hydric soils maps, and topographic maps. The wetland type was determined. The pond was also checked to determine if it is listed in the MnDNR Public Waters Inventory. 2.9 Stormwater Pond Sediment Coring No sediment coring was completed as a pan of this analysis; however, corings should be completed prior to any pond improvements and the total project cost estimate revisited once a sediment analysis has been performed. Sediment samples should be analyzed for a list of baseline parameters established by the MPCA. Based on the most recent MPCA guidance, "Managing Dredged Materials in the State of Minnesota (December 2011 )," sediment samples from urban stormwater ponds must be analyzed for copper, arsenic, and polycyclic aromatic hydrocarbons (PAHs). The historic land use within the drainage area of a stormwater pond should also be reviewed to help determine the reasonable likelihood of other pollutants being present in the sediment. The level of chemical contaminants dictates the disposal method for the excavated sediment. The disposal method required far the sediment is a major factor in determining the cost of sediment removal. The number of sediment cares recommended in the MPCA's guidelines is primarily based on the volume of material to be excavated, if any sediment maintenance is performed. including localized removal at inlets. sediment cores should be obtained to determine the constituents of sediment material. The number of cores needed would be based on the expected sediment removal volume. If the entire volume of accumulated sediment in Silver View Pond were to be removed, at least five cores would be recommended. For planning purposes. it is recommended that the city allocate $4,000 per sediment core to cover the field collection. laboratory testing and reporting costs. This cost estimate is based €'. Mpls'1 MN 62'+F`_'1091 Silver Vine Pond A+srss[nenl Works ilex kepirl tiih'er VICM Pond .hssessntenf-F'inal.d;wx