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SECTION 5 <br /> 5.5.3.Water Quality Policies <br /> 1. By complying with Volume Control Policy 1, it is anticipated that there will be a <br /> net reduction from pre-project conditions of total phosphorus and total suspended <br /> solids as required by the NPDES General Permit. <br /> 2. If infiltration cannot be used to achieve Volume Control Policy 1, the stormwater <br /> plan will need to comply with stormwater management requirements outlined in <br /> the NPDES construction permit for infiltration/filtration, wet sedimentation basin, <br /> or regional ponds. Refer to the MPCA website for more information related to the <br /> Construction <br /> Permit. http://www.pca.state.mn.us/index.php/water/water-types-and-pro ram <br /> ormwater/construction-stormwater/index.html <br /> 3. For redevelopment, any stormwater BMPs that are eliminated as a result of the <br /> project shall be replaced with new BMPs having similar stormwater treatment <br /> capabilities. <br /> 5.5.4.Exceptions/Mitigation Policies <br /> 1. Infiltration techniques shall be prohibited where the infiltration structural <br /> stormwater BMP will receive discharges from, or be constructed in areas: <br /> i. Where industrial facilities are not authorize to infiltrate industrial <br /> stormwater under an NPDES/SDS Industrial Stormwater Permit; <br /> ii. Where vehicle fueling or maintenance occur, <br /> iii. With less than three feet of separation from the bottom of the infiltration <br /> system to the elevation of the seasonally saturated soils or top of bedrock; <br /> iv. Where high levels of contaminants in soil or groundwater will be <br /> mobilized by infiltrating stormwater. <br /> 2. Infiltration techniques to achieve post-construction stormwater management <br /> requirements shall be restricted without higher engineering review, sufficient to <br /> provide a functioning treatment system and prevent adverse impacts to <br /> groundwater, when the infiltration structural stormwater BMP will be constructed <br /> in areas: <br /> i. With predominately Hydrologic Soil Group C or D (clay) soils; <br /> ii. Within 1,000 feet up-gradient, or 100 feet down-gradient of active karst <br /> features; <br /> iii. Within a Drinking Water Supply Management Area (DWSMA) as defined <br /> in Minn. R. 4720.5 100, subp. 13. <br /> iv. Where soil infiltration rates are more than 8.3 inches per hour. <br /> 3. For linear projects where the lack of right-of-way precludes the installation of <br /> Surface Water Management Plan <br /> City of Elk River Section 5 <br /> WSB Project No.1992-030 Page-3 <br />