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

Home Browse Search

Page 9 of 26 Permit No: MN R10000I an individual permit application. If MPCA's written notification requires a response, failure to respond within the specified timeframe constitutes a permit violation. The SWPPP must factor in any findings of and include any storm water mitigation measures required as the result of any environmental, archeological or other required local, state or federal review conducted for the project. For the purposes of this permit provision, mitigation measures mean avoiding, minimizing, rectifying (e.g., repairing, rehabilitating, restoring), reducing, eliminating or compensating for impacts related to: (1) storm water discharges associated with the project's construction activity; and (2) erosion prevention, sediment control and the permanent storm water management system for the project. 6. The SWPPP must provide additional measures as necessary to assure compliance with surface and ground water standards in Minn. R. chapters 7050 and 7060 in karst areas and to ensure protection of drinking water supply management areas (see Minn. R. 4725.4450). 7. If runoff from the site discharges to an impaired water which has an approved TMDL implementation plan containing requirements for construction storm water discharges, the Permittee must include the following in the SWPPP: a. identify the receiving water and the areas of the site discharging to it; and b. BMPs that are appropriate for the site and sufficient to comply with all applicable requirements of the TMDL implementation plan. B. TEMPORARY SEDIMENT BASINS Where ten (10) or more acres of disturbed soil drain to a common location, a temporary (or permanent) sediment basin must be provided prior to the runoff leaving the construction site or entering surface waters. The Permittee is encouraged, but not required, to install temporary sediment basins where appropriate in areas with steep slopes or highly erodible soils even if less than ten (10) acres drains to one area. The basins must be designed and constructed according to the following requirements: 1. The basins must provide storage below the outlet pipe for a calculated volume of runoff from a 2 year, 24 hour storm from each acre drained to the basin, except that in no case shall the basin provide less than 1800 cubic feet of storage below the outlet pipe from each acre drained to the basin. 2. Where no such calculation has been performed, a temporary (or permanent) sediment basin providing 3,600 cubic feet of storage below the outlet pipe per acre drained to the basin, shall be provided where attainable until final stabilization of the site. Temporary basin outlets must be designed to prevent short-circuiting and the discharge of floating debris. The basin must be designed with the ability to allow complete basin drawdown (e.g., perforated riser pipe wrapped with filter fabric and covered with crushed gravel, pumps or other means, see Part IV.D.) for maintenance activities, and provide a stabilized emergency overflow to prevent failure of pond integrity. Energy dissipation must be provided for the basin outlet (see Part IV.13.4). wq-stnn2-5 I