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MCM 5 – Post-Construction Runoff Control (DRAFT) YES NO Post-construction stormwater management for that construction activity is in compliance with MCM5.

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Presentation on theme: "MCM 5 – Post-Construction Runoff Control (DRAFT) YES NO Post-construction stormwater management for that construction activity is in compliance with MCM5."— Presentation transcript:

1 MCM 5 – Post-Construction Runoff Control (DRAFT) YES NO Post-construction stormwater management for that construction activity is in compliance with MCM5 and Anti-deg standards. No further action required. Rates and volume of stormwater runoff from each site where construction activity takes place will be equal to or less than pre-development rates and volume of stormwater runoff. Will the construction activity be conducted on land that is described as any of the following? A.A brownfield site B. High Density (> 7 units per acre) C.Vertical Density, (Floor to Area Ratio (FAR) of 2 or > 18 units per acre) D.Mixed use and Transit Oriented Development (within ½ mile of transit) Will rates and volume of stormwater runoff from each site where construction activity is described as A-D, meet 50% of pre- development rates and volume of stormwater runoff. Post const. rates and volume are equal to or less than that of pre-const (existing land use). Mitigation must be conducted that results in rates and volumes of runoff equal to the projects pre-development hydrology within 1) the stormshed, 2) watershed, 3) the MS4 Can mitigation be conducted up-stream and prior to the initiation of the const. project. Anit-deg is satisfied Permittee must conduct a Social and Economic Justification. This will involve the proposal of the least degrading alternative. Mitigation must be conducted that results in rates and volumes of runoff being at least 50% of the project’s pre- development hydrology within 1) the stormshed, 2) watershed, 3) the MS4 "Construction Activity" includes construction activity as defined in 40 C.F.R. pt (b)(14)(x) and small construction activity as defined in 40 C.F.R. pt (b)(15). This includes a disturbance to the land that results in a change in the topography, existing soil cover (both vegetative and non-vegetative), or the existing soil topography that may result in accelerated stormwater runoff, leading to soil erosion and movement of sediment into surface waters or drainage systems. Examples of construction activity may include clearing, grading, filling, and excavating. Construction activity includes the disturbance of less than one acre of total land area that is a part of a larger common plan of development or sale if the larger common plan will ultimately disturb one (1) acre or more. “Pre-Development” means stormwater run-off rates and volume calculated using native soils and vegetation. “Pre-Construction” means land use prior to the beginning of a specific construction activity. “Post-Construction” means land use immediately following a specific construction activity. MCM 5 Limitations Any construction activity resulting in any of the following, is not authorized to use infiltration BMPs to meet the terms and condition of MCM5. NPDES permitted industrial activity prohibited from infiltration, Stormwater discharges from vehicle fuieling and maint. Areas, Discharges from areas 1000ft up-gradient, or 100ft down- gradient of karst features, Discharges from areas with less than 3ft separation distance from bottom of infiltration system to elevation of seasonal high groundwater or top of bedrock, Areas from etc etc etc. Draft Definitions Box 1 Box 3 Box 2 Box 4 Box 8 Box 5 Box 6 Box 10 Box 9 Box 7 Box 11 Box 14 Box 13 Box 15 Box 12


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