Agenda - Council Work Session - 02/23/2021

Home

Hydrologic Soil Group Soil Textures clay loam, sandy clay, silty clay Clay, clay loam, silty Corresponding Unified Soil Classification D CL - Lean clay or lean clay with sand or gravel or gravelly lean clay CH - Fat clay or fat clay with sand or gravel or gravelly fat clay OH - Organic clay or organic clay with sand or gravel or gravelly organic clay MH - Elastic silt or elastic silt with sand or gravel StDU;C;:MilineStormw-a-t-e-r""""Viii-iii7 'thirty guidance manuals and many reviewed by the MPCA when it compiled the recommended infiltration rates. Sites Where Infiltration is Infeasible or a 3)ro Infiltration Rate (in/hr) mnu er stormwater rererences were 0.06 The LRRWMO recognizes that infiltration may be infeasible or inappropriate in some instances, and will review these on a case -by -case basis. Reasons that infiltration may be infeasible or inappropriate include: • Physical limitations including soils, high water table, and available space limitations in the case of redevelopment. • Projects within a Drinking Water Supply Management Area (DWSMA). Refer to MN Department of Health guidance entitled "Evaluating Proposed Stormwater Infiltration Projects in Vulnerable Wellhead Protection Areas" (http://www.health.state.mn.us/divsieh/water/swp/stormwater.pdf) to determine if infiltration techniques are appropriate. • Storm water discharges from potential stormwater hotspots, such as fueling stations, vehicle service or washing areas, vehicle fleet storage areas, auto recycling or salvage, stockpiled snow from salted roadways, construction site inputs, manufacturing sites, public works storage areas, facilities that generate or store hazardous waste materials, and others as determined by the community or watershed management organization. • Utility locations. Contaminated soils. • Others as determined by the LRRWMO. In these scenarios, permittees must treat the required volume through the following techniques, in order of preference: 1. On site infiltration of the entire, or a portion of, the required volume. 2. On site filtration or off site infiltration within the LRRWMO. Excess volume reduction on any project may be banked for use on another off site project. The excess volume reduction bank will be administered by the LRRWMO. 3. Other non -volume control treatment on site. Comprehensive Watershed Management Plan Lower Rum River Watershed Management Organization October 2111 (lhitovisoll 041)1 1 8 E-7