Agenda - Planning Commission - 08/07/2014

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Section 117-393 is hereby amended as follows (additions indicated as underline. deletions indicated as strike through): Sec. 117-393. - Mininrar Design Standards 6.0sr ztat uvratcr wet detention facilities. At a minimums these facilities must conform to the most current technology as reflected in the current version of the Minnesota " o'&ition Contra'. Agency's publication, 'Nitecting Water Quality in Areas" and the current requirements found in the same agency's NPDEC rcrmits for c ivrataf associated with construction ac ivitioz. Minimal impact design standards shall be followed to achieve the best stormwater management. The BMPs used should seek to mimic the natural hydrology. utilize pervious areas for stormwater treatment and to infiltrate stormwater runoff from driveways. sidewalks. rooftops. parking lots. and landscaped areas to the maximum extent practical to provide treatment for both water quality and quantity. The Minnesota Stormwater Manual (Stormwater Steering Committee. MN Pollution Control Agency). the Minnesota Urban Small Sites BMP Manual (Metropolitan Council). Local Road Research Board BMP Maintenance Guide. and Protecting Water Quality in Urban Areas (MPCA) are resources that provide guidance in achieving these goals. (a) Implementation. Low Impact Development or Better Site Design techniques are the preferred methods of achieving stormwater management. Mimicking the natural topography and land cover as they exist in the pre -developed condition to meet the standards and reauirements of the City and other regulatory agencies shall be the first consideration. (b) Recommended practices. Practices and methods used to achieve the intent of the above paragraph shall include. but not be limited to. the following: (1) rain gardens (2) green roofs (3) bio-retention practices (4) pervious pavements or pavers (5) plots of native vegetation and/or buffers in place of sod (6) reforestation and revegetation (7) trees and tree box filters (8) reduction of impervious area (9) rain water harvesting (c) Other practices. Other traditional stormwater BMPs may be approved on a site by site basis to achieve the goals of water aualitv and auantitv. and rate control. These practices shall conform to the standards outlined in the resources referenced above. (d) All stormwater runoff shall be pre-treated prior to discharge to any surface water. (e) Maintenance plan. A plan shall be established to maintain all temporary and permanent BMPs in a working and efficient condition. This may include removal of invasive species. sediment. debris. or any other foreign or obstructive obiect or condition that prevents the BMPs from performing as designed. (f) Exemption. The mill and overlay or rehabilitation of a public roadway that does not create additional impervious surfaces: and sidewalk or trail proiects are exempt from these stormwater requirements. These proiects may be subiect to other regulations.