Storm Water Pollution Prevention Plan (SWPPP) - the City of Lompoc!
Storm Water Pollution Prevention Plan (SWPPP) - the City of Lompoc!
Storm Water Pollution Prevention Plan (SWPPP) - the City of Lompoc!
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OrderXIII. POST-CONSTRUCTION STANDARDSA. All dischargers shall comply with <strong>the</strong> following run<strong>of</strong>f reductionrequirements unless <strong>the</strong>y are located within an area subject to postconstructionstandards <strong>of</strong> an active Phase I or II municipal separate stormsewer system (MS4) permit that has an approved <strong>Storm</strong> <strong>Water</strong>Management <strong>Plan</strong>.1. This provision shall take effect three years from <strong>the</strong> adoption date <strong>of</strong>this permit, or later at <strong>the</strong> discretion <strong>of</strong> <strong>the</strong> Executive Officer <strong>of</strong> <strong>the</strong>Regional Board.2. The discharger shall demonstrate compliance with <strong>the</strong> requirements <strong>of</strong>this section by submitting with <strong>the</strong>ir NOI a map and worksheets inaccordance with <strong>the</strong> instructions in Appendix 2. The discharger shalluse non-structural controls unless <strong>the</strong> discharger demonstrates thatnon-structural controls are infeasible or that structural controls willproduce greater reduction in water quality impacts.3. The discharger shall, through <strong>the</strong> use <strong>of</strong> non-structural and structuralmeasures as described in Appendix 2, replicate <strong>the</strong> pre-project waterbalance (for this permit, defined as <strong>the</strong> volume <strong>of</strong> rainfall that ends upas run<strong>of</strong>f) for <strong>the</strong> smallest storms up to <strong>the</strong> 85 th percentile storm event(or <strong>the</strong> smallest storm event that generates run<strong>of</strong>f, whichever is larger).Dischargers shall inform Regional <strong>Water</strong> Board staff at least 30 daysprior to <strong>the</strong> use <strong>of</strong> any structural control measure used to comply withthis requirement. Volume that cannot be addressed using nonstructuralpractices shall be captured in structural practices andapproved by <strong>the</strong> Regional <strong>Water</strong> Board. When seeking RegionalBoard approval for <strong>the</strong> use <strong>of</strong> structural practices, dischargers shalldocument <strong>the</strong> infeasibility <strong>of</strong> using non-structural practices on <strong>the</strong>project site, or document that <strong>the</strong>re will be fewer water quality impactsthrough <strong>the</strong> use <strong>of</strong> structural practices.4. For sites whose disturbed area exceeds two acres, <strong>the</strong> discharger shallpreserve <strong>the</strong> pre-construction drainage density (miles <strong>of</strong> stream lengthper square mile <strong>of</strong> drainage area) for all drainage areas within <strong>the</strong> areaserving a first order stream 14 or larger stream and ensure that postprojecttime <strong>of</strong> run<strong>of</strong>f concentration is equal or greater than pre-projecttime <strong>of</strong> concentration.14 A first order stream is defined as a stream with no tributaries.2009-0009-DWQ 36 September 02, 2009
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