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Storm Water Permitting Requirements for Construction Activities

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Storm Water Permitting Requirements for Construction Activities Storm Water Permitting Requirements for Construction Activities John Mathews Storm Water Program Manager Division of Surface Water Why Permit Storm Water? Impacts During Construction • Not an issue until we add rainfall… Impacts During Construction Impacts During Construction • Large amounts of sediment are transported downstream and embed streams. Impacts During Construction • A healthy versus an embedded stream bottom. Post-Construction Impacts • Efficient runoff and pollution delivery Post-Construction Impacts • Stream Erosion (erosion and downcutting) Post-Construction Impacts • Stream Erosion (erosion and downcutting) History of the Construction General Permit (CGP) Increased Sediment Storage; Required Basic Erosion and Skimmers on Sediment Control, Sediment Basins; Very General Post- Allowed Offsite Major Update of Post- Construction, ≥5 Mitigation of Post- Construction acres of disturbance Construction Requirements 1992 2003 2008 2013 2018 ≥ 1 acre; Added Minor Changes Specific Post- construction, Large ≥ 5 and Small (1-5 ac) Sites Authorizes Storm Water Discharge From • Construction activities - clearing, grading, excavating, grubbing and/or filling – that disturb ≥ 1 acres – or will disturb < 1 acre of land but are part of a larger common plan of development or sale that will ultimately disturb ≥ 1 acres • Associated support activities (on-site or contiguous batch plants, borrow pits, & material storage areas) A Statewide Permit • But two watersheds have special conditions (the Big Darby and portions of the Olentangy) • Submittal of the SWP3 • Stream setback • Larger sediment storage and recharge of storm water (Big Darby) Notice of Intent (NOI) Requirements • An NOI is the application for a permit, accessed through https://ebiz.epa.ohio.gov, Ohio’s eBusiness Center site. (You must create an account to use.) Notice of Intent (NOI) Requirements • At eBusiness site, choose Surface Water NPDES Permit Notice of Intent (NOI) Requirements • Create a new permit (Construction) Notice of Intent (NOI) Requirements • Submit NOI form 45 days prior to construction (21 days for special watersheds) • As lots are sold, submit Individual Lot NOI applications 7 days prior to the transfer of ownership • When a parcel within a development is sold… – Is the runoff from the parcel treated by a BMP that detains runoff from multiple parcels? • If so, the Developer remains responsible to maintain BMPs that receive runoff from multiple individual lots Storm Water Pollution Prevention Plans (SWP3) A plan must be fully developed at the time of the NOI submittal. Storm Water Pollution Prevention Plans (SWP3) Submittal Online submittal of SWP3 is requested, but not required (except in Big Darby Creek and portions of the Olentangy River watersheds. Storm Water Pollution Prevention Plans (SWP3) • Plans (SWP3) must be: – Kept on site during normal working hours – Made available within 10 days of written request by • Ohio EPA • Local agency that reviews or approves plans (e.g., SWCD) • Operator of the MS4 system to which site discharges • Permittee may be required to revise their SWP3 if a watershed plan (TMDL) requires more… • Amend within 10 days of written notification by Ohio EPA that the SWP3 is deficient Note: Construction Projects with Older Permit Coverage (4-23-18) Must Reapply • Ohio EPA attempted to notify permittees that a new permit was issued • If construction will not be complete by October 20, 2018, these permittees should have contacted the agency to continue coverage • Old construction general permits (not renewed before October 20, 2018 should have been automatically terminated Non-Numeric Effluent Guidelines Erosion & Sediment Controls • Minimize: – soil and stream erosion – erosion at outlets; downstream channel and streambank erosion by controlling SW discharges – exposed soils – disturbance of steep slopes – sediment discharge by site specific characteristics – soil compaction • Maintain 50 foot buffers around surface waters Non-Numeric Effluent Guidelines Stabilize any disturbed areas that will be idle over 14 days, overwinter or reaches final grade • 50 feet from water of the state – within 2 days • Other areas – within 7 days • Lots being transferred – 7 days prior to transfer New Non-Numeric Effluent Guidelines Dewatering must use appropriate controls, such as: • Running turbid water through a pond or filter bag Pollution Prevention Measures • Vehicle wheel wash water treated in a pond • Minimize exposure of fertilizers, pesticides & detergents and other materials to rainfall • Prevent spills & leaks and have procedures for responding to spills Non-Numeric Effluent Guidelines Prohibited Discharges • Concrete washwater (req. appropriate control) • Construction wastewater or materials • Fuel and oil from vehicle maintenance • Soaps or solvents from vehicle wash water • Surface Outlets • Sediment settling ponds must be dewatered at the surface unless it’s infeasible • Skimmer is commonly used to do this Non-Numeric Effluent Guidelines Surface Outlets • Unless infeasible, sediment settling ponds must be dewatered at the surface (skimmer) Non-Numeric Effluent Guidelines Post-Construction Storm Water Management • Long-term management of quantity and quality Storm Water Pollution Prevention Plan (SWP3) • Plans are key to prevention of problems and good implementation of required practices, since they also representing contractor bidding and budgeting for practices as well as well considered contingencies. • Ohio EPA storm water program website has a checklist available for what belongs in the SWP3. SWP3 Contents • Site map • Site description and calculations • Site controls, drawings and details necessary to construct SWP3 Contents Continued • Controls: – Preservation practices (e.g. vegetative buffer strips, soil, topsoil; phasing construction; tree preservation areas – Erosion controls (e.g. seed, mulch, matting, stable construction entrances…) – Runoff controls (e.g. rock check dams, pipe slope drains, diversions to direct flow away from exposed soils…) – Sediment controls (e.g. basins, traps and sediment barriers) Stream Setbacks or Buffers • Sets aside most frequent water vs. property problem area. And most valuable for stream and water quality Tree Preservation Areas • Mark grading limits & tree preservation areas on site plan. Fencing/signs at drip line of trees to be saved. Sediment & Erosion Controls • Erosion Control BMPs prevent sediment from moving rain and runoff. Are often > 90% effective • Sediment Control BMPs trap sediment once it is moving. Are much less effective (~30 – 80% effective at keeping sediment on sites. Erosion Control BMPs • Establish grass or vegetation • Mulch • Matting or Sod • Ditch Checks • Riprap • Geotextiles Temporary & Permanent Stabilization Mulch Application for Soil Stockpiles Matting Steep Slopes High Velocity Runoff Rock Check Dam Rock Construction Entrances • Prevents mud from tracking Vehicle Access Road and Wheel Washing Sediment Control BMPs Sediment Controls must be installed in 7 days after the initiation of grubbing (construction) activities • Sediment traps • Sediment basins • Silt fence, compost filter socks or compost filter berms • Curb or drop inlet protection • Trench dewatering filter bags Sediment Barriers (E.g. Silt Fence) Trench Dewatering Keep it clean all the way to the stream. Post-Construction Controls • Underground Stormwater Management System Wet Pond With Wetland Bench Bioretention Practice Bioretention Practice Permeable Pavement Post-Construction BMP Requirements Size Best Management Practices (BMPs) to treat the water quality volume using this equation: WQv = Rv · P · A / 12 Where, WQv = water quality volume Rv= 0.05 + 0.9i P = precipitation of 0.9 A = disturbed area or drainage area I = impervious fraction Post-Construction Acceptable BMPs • The permit conditions additional notes options and notes for each practice Post-Construction BMP Requirements Transportation Projects - permittees may utilize Post- Construction BMP standards in ODOT’s Location & Design Manual, Volume as an alternative to the standard list of post-construction practices. For previously developed Areas – The requirement is weighted by the relative increase in imperviousness and allows applicants to different means to handle the post-construction requirements: Post-Construction BMP Requirements Small Construction Activities (>1 < 2 acres) still require post-construction treatment. • If standard practices are shown (in the SWP3) infeasible and the local regulated community (regulated MS4) approves of an alternative practice, then Ohio EPA will accept this practice. Post-Construction BMP Requirements Offsite Mitigation of Post-Construction may be approved by Ohio EPA on a case-by-case basis. This requires: 1. A maintenance agreement, 2. Located in same watershed (HUC-12), 3. Generally a mitigation ratio is 1.5:1. NOTE: What is an MS4 • MS4 (US EPA’s term) stands for municipal separate storm sewer system. These are Ohio’s regulated MS4s. Runoff Reduction Practices Runoff Reduction Practices Water quality volume can be reduced by incorporating runoff reducing practices into the site’s design. • Bioretention • Infiltration basin/trench • Permeable pavement with infiltration • Underground storage with infiltration • Grass swale • Sheet flow to filter strip • Sheet flow to conservation area • Impervious surface disconnection • Rainwater harvesting • Green Roof Post-Construction BMP Requirements Alternative Post-Construction BMPs – Need to have tested effectiveness (to show equivalency to permits
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