10-03-07-JOINT PC/CC - Laserfiche WebLink

Home Browse Search

Rule C: Storm -Water Management Plans I Rice Creek Watershed District Page 2 of 4 Management Plans. (i) Outfall structures within wetlands and public waters and public waters wetlands must incorporate a stilling - basin, surge -basin, energy dissipater, placement of ungrouted natural rock riprap or other devices to minimize disturbance and erosion of natural shoreline and bed resulting from stormwater discharges. (�) All new residential, commercial, industrial and other habitable or non -habitable structures must be constructed so that the lowest floor elevations are a minimum of two feet above the critical event 100 -year high water elevation and are one foot above the overflow elevation of nearby surface waterbodies wetlands and stormwater basins. Within landlocked basins, lowest floor elevations must be at least one foot above the surveyed basin overflow elevation. (k) Development resulting in the creation of impervious surfaces must explicitly address use of best management practices (BMPs) to first limit the loss of pervious area; and second, to infiltrate runoff which does occur from impervious areas to the extent feasible considering site-specific conditions. BMPs include the use of vegetated swales, pond outlets perched above groundwater levels, use of infiltration systems, roof drainage to pervious areas, minimum of twenty percent pervious surface, use of depressed/casual storage areas, and minimization of the number and width of parking stalls and use of deep-rooted native vegetation, and narrower "rural section" roads. The goal of these BMPs is to incorporate practices into the design which are capable of infiltrating the impervious surface runoff from the Mpls-St.Paul median storm (0.34 inches) in seventy-two hours. Infiltration volume will be calculated using the appropriate hydrologic soil group classification and saturated infiltration rate from the table below. Hydrologic Infiltration Soil Group Rate Soil Textures A 0.50 in/hr sand, loamy sand, or sandy loam B 0.25 in/hr silt loam or loam C 0.10 in/hr sandy clay loam D 0.03 in/hrclay loam, silty clay loam, silty clay, or clay Source: Urban Hydrology for Small Watersheds, SCS, June 1986. Infiltration area will be limited to the horizontal areas subject to prolonged wetting. Areas of permanent pools tend to lose infiltration capacity over time and will not be accepted as an infiltration practice. a (1) Landlocked basins may be provided with outlets only if they: o (1) Retain a hydrologic regime which complies with District Wetland Alteration Rule F. o (2) Provide sufficient dead storage volume to retain back-to-back 100 -year, twenty -four-hour rainfalls and runoff. o (3) Do not create adverse downstream flooding or water duality conditions as a result of increased discharge rate or volume, or other factors. (m) All stormwater management structures and facilities must be properly maintained in perpetuity to assure that they continue to function as originally designed. This maintenance responsibility must be assumed either by the municipalitya€TMs accepting the required easements dedicated to stormwater management purposes, or by the applicant executing and recording a maintenance agreement acceptable to the District. 4. Required Exhibits. The following exhibits must accompany the permit application. One set, full size; two sets, reduced to maximum size of I 1 "x 17". H . (a) Property lines and delineation of lands under ownership of the applicant. http://www.ricecreekwd.com/rules/rcwd/c 11/1"312(006