Ordinance No. 131 Consolidated Land Use Ordinance

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2. Regional ponds are required to be constructed and operational prior to constructing imperviousness within the contributing drainage area. 10. Wet sedimentation basins and practices shall include at least 1-foot of freeboard from the top of facility for the 100-year event. 11. Infiltration and filtration facilities shall: 1. Select the design infiltration based on the least permeable soil horizon within the first five (5) feet below the bottom elevation of the proposed facility. Site -specific infiltration measurements completed by a licensed professional (as described in the Minnesota Stormwater Manual, November 2005, and as amended) may be used in place of the values in the Minnesota Stormwater Manual, and as approved by the City; 2. Include a diversion or other method within the construction documents to keep construction site sediment from entering an infiltration and/or filtration system prior to final stabilization of the entire contributing drainage area; and 3. Include provisions within the construction documents that will prohibit construction equipment from compacting the soils where infiltration and/or filtration practices are proposed. 12. To the maximum extent practicable, volume control shall be fully met onsite (Section 22.2.2.2). Site conditions may make infiltration infeasible. The applicant must make soil corrections and/or investigate other locations on the site for feasible infiltration locations. Infiltration practices are not allowed in the following areas: 1. Areas that receive runoff from vehicle fueling and maintenance areas, regardless of the amount of reconstructed impervious surface; 2. Areas where there are high levels of contaminants in soil or groundwater; 3. Areas where soil infiltration rates are more than 8.3 inches per hour, unless soils are amended; 4. Areas with less than 3 feet of separation distance from the bottom of the infiltration system to the elevation of the seasonally saturated soils or the top of bedrock; 5. Areas of predominately hydrologic soil group D (clay) soils; 6. Areas in an Emergency Response Area (ERA) within a Drinking Water Supply Management Area (DWSMA) as defined in Minn. R. 4720.5100, Subp. 13, classified as: 1. High or very high vulnerability as defined by the Minnesota Department of Health; or 2. Moderate vulnerability unless the permittee performs or approves a higher level of engineering review sufficient to provide a functioning treatment system and to prevent adverse impacts to groundwater; 7. Areas outside of an ERA within a DWSMA classified as high or very high vulnerability unless the permittee performs or approves a higher level of engineering review sufficient to provide a functioning treatment system and to prevent adverse impacts to groundwater; 8. Areas within 1,000 feet up -gradient or 100 feet down gradient of known active karst features; 9. Areas that receive runoff from the following industrial facilities not authorized to infiltrate stormwater under the NPDES stormwater permit for industrial activities: automobile salvage yards; scrap recycling and waste recycling facilities; hazardous waste treatment, storage, or disposal facilities; or air transportation facilities that conduct deicing activities; or 10. Areas within 50 feet of a septic tank or drain field. If the applicant claims that infiltration is not feasible or allowed onsite, the applicant must provide supporting documentation and follow Section 2, Subsection 4. Updated January 2025 — Gem Lake Consolidated Land Use Ordinance No. 131 112