Uploaded byAndrew T. Der & Associates, LLC
Current Issues in Stormwater Management
This document provides an overview of current issues in stormwater management. It discusses how increased stormwater runoff from development can negatively impact water quality and the environment by altering hydrology, increasing erosion, degrading habitats, and reducing water quality. It also reviews regulations around stormwater management, including the National Pollutant Discharge Elimination System (NPDES) permitting process, state and local regulations, and water quality standards. Finally, it discusses best management practices (BMPs) for erosion and sediment control during construction as well as post-construction stormwater management, including low impact development techniques and engineered structural practices.
More Related Content
![1 ksa%20conference%202010%20 %20 mary%20kuo[1]](https://cdn.slidesharecdn.com/ss_thumbnails/1ksa20conference20201020-20mary20kuo1-100515121206-phpapp02-thumbnail.jpg?width=640&height=640&fit=bounds)
Similar to Current Issues in Stormwater Management
Current Issues in Stormwater Management
- 1. Current Issues inStormwater Management Stormwater Management and Water Resources Presentation for Lorman Educational Services Washington, DC March 20, 2014 Andrew T. Der & Associates, LLC Environmental Consulting 1000 Fell Street | Baltimore, MD 21231 1.410.491.2808 | AndrewTDer@comcast.net
- 2. STORMWATER EFFECTS ON WATERQUALITY AND THE ENVIRONMENT
- 3. Why Are WeHere?
- 4.
- 5. Four Categories ofEffects • Hydrology • Geomorphology • Habitat • Water Quality
- 6. Hydrology • Increase inflow and velocities • Increase in flooding • Increase in frequency • Increase in bankfull flows
- 7. Geomorphology • Stream Widening •Channel Instability • Erosion
- 8. Habitat • Fish Barriers •Loss of Substrate • Loss of Riparian Zone • Loss of Micro-topography
- 9. Water Quality • Sediments Channelerosion can be the primary sediment source! • Nutrients Maintained vegetated areas & ag • Temperature Warm pavements and pond pools • Other Oils, Greases, heavy metals, toxics
- 10.
- 11.
- 12.
- 13.
- 14. What is aStream? • Waters of the U. S. • Definition includes tidal navigable water, nontidal navigable water and adjacent headwaters and wetlands adjacent to such waters – but how far up does it go? • Determines extent of Sec 401 (Water Quality Certification), 402 (NPDES) and 404 (Dredge and Fill) components of the Clean Water Act.
- 15. What is animpact? • Impacts are discharges or grading • Discharges can be out of a pipe or placement of material (CWA Sec 402 & 404) • Discharges can be permitted • Individual Permits or General Permits
- 16. Types of StormwaterPermitting • NPDES Phase I and II – U. S. EPA delegated to States by GP – regulates new construction AND existing older stormwater sources – passes through localities – only permit means to retrofit • DoD and federal facility SWM mandates • State/local Stormwater Management Regulations – new construction • State/local Erosion and Sediment Control Regulations – new construction • Other (Wetlands, Flood Plain, etc.) • Both Individual & General NPDES permitting - Most new construction under GP
- 17. NPDES Phase I&II Permitting • 1972 amendments to the Federal Water Pollution Control Act (Clean Water Act) prohibit the discharge of any pollutant to waters of the United States from a point source unless the discharge is authorized by a National Pollutant Discharge Elimination System (NPDES) permit. • Past efforts to address stormwater discharges under the NPDES program have generally been limited to certain industrial categories
- 18. Background • Stormwater outof a pipe was not necessarily a point source discharge • National Urban Runoff Program (NURP) – first meaningful stormwater study showed stormwater impacts • In response to water quality concerns, in 1987, the EPA was required to issue regulations addressing stormwater discharges under the NPDES program
- 19. Phase I • NPDESestablished first regulations in 1990 permit requirements for existing stormwater: 1) existing “medium” and “large” municipal separate storm sewer systems (MS4) – individual permits by State to locality with conditions 2) new construction activity disturbing 5 (changed to 1) acres of land or greater – general permits 3) certain industrial activities • Many continue to operate under Phase I
- 20. MDE Phase IPermit Conditions • Effectively prohibit pollutants in stormwater discharges as necessary to comply with water quality standards • Attain wasteload allocations (WLAs) for approved TMDL • Assess existing programs and ID licit and illicit Sources • Implement SWM and E/S • Hot spots • Trash and litter • Watershed Management and Restoration (often needs its own water and state wetland permit!) • Utilize current collected best management practice (BMP) data to modify and improve programs • Monitoring and mapping • Reduction in impervious surfaces • Fiscal Analysis and Annual Reports
- 21. Phase II • In1999, new rule automatically covers on a nationwide basis all existing small MS4s located in urbanized areas and new construction activities of 1 acre or more • Most localities already complying • Can authorize industries or facilities • Have more flexible permitting options GP including the NOI process Utilizing existing programs in place Combine with other Phase II Combine with a Phase I
- 22. Six Requirements of PhaseII • Personnel education/outreach • Public involvement/participation • Illicit discharge detection elimination • Construction site stormwater runoff control (E/S) • Post construction stormwater management • Pollution prevention/good housekeeping
- 23. Phase II Canbe Subjective • Monitoring, public outreach and BMPs can be flexible as long as: – Reduces pollutants to the maximum extent practical – Protects water quality – Satisfies CWA – Many existing SWM programs are satisfactory – Newer MS4 permits will be templates
- 24. How Does NPDESAffect New Construction? • Compliance with NPDES Stormwater permits is primarily through BMP implementation • E/S and SWM plans are not the same as NPDES compliance – but can usually serve as compliance with NPDES requirements • However, a good E/S and SWM plan alone does not necessarily assure compliance with all NPDES criteria
- 25. How Does NPDESAffect New Construction? To comply with NPDES General Permit (GP) requirements, submit Notice of Intent NOI if 1 acre or more of disturbance. In addition to customary (“sediment- centric”) E/S plans, compliance can include: • Water quality and sensitive construction techniques for waters with an established Total Maximum Daily Load (TMDL) • If significant sediment discharge, then additional inspection, evaluation and installation of site controls • Control measures that minimize pollutants as necessary to meet applicable water quality standard • Conduct weekly inspections and the next day (changed from next business day) after a rainfall event resulting in runoff • If there is “an excursion” above any applicable water quality standard, modify controls to indicate receiving water is attaining water quality standards • Hot topic - Potential for flocculent or turbidity controls?
- 26. How Does NPDESAffect New Construction? • NPDES Compliance is by NOI and a Stormwater Pollution Prevention Plan (SWPPP) – what is it and when is one required? - Includes E/S and SWM plans (structural) but also includes ESD and nonstructural: other pollutant management considerations (spillage, storage, litter), monitoring records - In MD, not typically required under general permit • Potential vs. Actual Discharges – treated the same?!
- 27. State & LocalSWM Concurrently along with new NPDES compliance, need to comply with following regulations • State Erosion and Sediment Control Law • State Stormwater Management Law Incorporates SWM Manual by reference - Revised by 2007 Maryland Stormwater Management Act – Effective May 2009 Formalizes “LID-like” or Environmental Site Design to “Maximum Extent Practicable” - MEP is met if channel stability and predevelopment groundwater recharge rates are maintained and nonpoint source pollution is minimized…. structural stormwater practices may be used only if determined to be absolutely necessary
- 28. State & LocalSWM Applies via approved local ordinance • In MD, primary MEP standard is to use ESD to reduce post development runoff to levels found in natural, forested conditions – need to treat 1 to 2.6 in rainfall depending on site and design conditions • In Virginia starting July 2014 will require TP oriented management of 1 inch runoff of entire site utilizing their Srormwater BMP Clearinghouse also emphasizing nonstructural disconnections
- 29. Other Permitting Criteria •CWA Section 404 dredge and fill permit U. S. Army Corps of Engineers Waters of the U. S. including wetlands • State Wetland and Waterway Permit Can have special NTW E/S BMP Conditions • State Tidal Wetlands and Waters permits • Coastal Zone Management Act • MD Tier II Waters Criteria • MD Chesapeake Bay Critical Area Law Administered through local zoning and subdivision ordinances for overlay 1,000 feet from shoreline - 10% SWM rule in Intensely Developed Areas • MD State Forest Conservation Law Delegated to localities Requires NRI or FSD which could be first SWM concept under new regulations - silt fences frequently double as tree save fence • VA Chesapeake Bay Preservation Act Through localities Resource protection Areas, Better Site Design
- 30. Water Quality Standardsfor Permitting Criteria • Wetland permitting processes can incorporate CWA Section 401 Water Quality Certification Requirements required when 404 Corps permit required • Numeric and Narrative Water Quality Standards are basis for sensitive waters requirements • Numeric - DO, Temp, pH, Turbidity, fecal coliform, toxics • Narrative – basis of more stringent controls Protection of aquatic life...fishable…swimmable…includes EPA Anti-degradation policy: “…To accomplish the objective of maintaining existing water quality…Nonpoint sources shall achieve all cost effective and reasonable best management practices for nonpoint source control…”
- 31. Even More WaterQuality Initiatives in Progress! • Chesapeake Bay TMDL for N & P – what does this mean for SWM? • Largest most complex TMDL in the country, covering the 64,000 s. m. watershed in six states & DC = Watershed Implementation Plans (WIP) in progress now
- 32. Issues under DeliberationNow • What should be most sound priorities of focus? Sediments, P, O, Flow? • ESD (and LID) versus Smart Growth versus impervious surface criteria? • TMDL model assumptions challenged • Financing TMDL WIPs (rain tax) • TMDL AFG Offset credits vs. existing SWM criteria • Nutrient trading
- 33. Construction Compliance • Usuallyoriented to E/S compliance • Locality primary inspector • State (and occasionally EPA) inspect also for NPDES, E/S and Wetland and Waterways Permit • Corps inspects for Wetland and Waterways Permit
- 34. Newer Compliance Requirements • Usuallyoriented to post-construction assessment • Third party quality control construction monitoring • Specific SWM device maintenance conditions • Post-construction BMP performance can be required
- 35. • Used alsofor MS4 Compliance • Can be state requirement • Preconstruction, construction and post- construction • Macroinvertebrate Studies (from WWTP & mining) • Chemistry • Geomorphology • Groundwater Post-Construction BMP and Water Quality Monitoring
- 36. For Construction Activities- Remember! • Have most current approved plans on site during construction • Diligence over perfection – develop a good relationship with regulatory agencies • Any E/S modifications made after permitting may potentially have other regulated impacts. • Any temporary material storage, staging or heavy equipment in or near flood plain, streams, wetlands, buffers, forest, specimen tree may potentially be a regulated impact • Document all E/S plan changes, rectification measures and spill control measures in log book
- 37. Types of Designsfor Storm Water Control
- 38. What is aBest Management Practice (BMP)? Best Management Practices (BMPs) are policies, practices, procedures, or structures implemented to mitigate the adverse environmental effects on surface water quality resulting from development. BMPs are categorized as structural or non-structural. • Early Planning • Low Impact Development – “LID-like” or Better Site Design or Environmental Site Design • Local stream buffers and setbacks • Minimize or disconnect impervious surfaces sheet flow, open section pavement • Devices Most significant factor affecting performance is construction and maintenance
- 39. Erosion and SedimentControl vs. Stormwater Management E/S • Construction Phase • Sediments are primary criteria • Can be temporary or “permanent” SWM • Post-construction • Manages various pollutants • Permanent
- 40. Common E/S Practices •Silt Fence • Vegetative Stabilization • Stone lined conveyance • Temporary Sediment Basin/Trap • Temporary Use of Permanent Pond or other facility
- 41.
- 42.
- 43.
- 44.
- 45.
- 46.
- 47. Common Compliance Issues Similarfor E/S & SWM Construction Maintenance
- 48. Common SWM Practices •Better/Environmental Site Design • Sheet flow management – prior to and after conveyance • Open section surfaces • Engineered practices
- 49. Common “ESD” Practices •Preserving and protecting natural resources • Conserving natural drainage patterns • Minimizing impervious area • Reducing runoff volume • Using ESD practices to maintain 100 percent of the • Annual predevelopment groundwater recharge volume • Using green roofs, permeable pavement, reinforced turf, • And other alternative surfaces • Limiting soil disturbance, mass grading, and compaction • Clustering development • Any practices approved by the Administration.
- 50. The Best BMP- Work with Forest and Wetland Conservation
- 51. Work with SiteCharacter Before Devices
- 52. When Using EngineeredPractices Smaller Volumes Most compatible with ESD and BSD At Source & Pretreatment Quality Control Only • Infiltration – trench/basin • Filtering – sand filter/bioretention • Hydrodynamic Devices • “New” Technology – pervious surfaces/green roofs Larger Volumes When preferred is Insufficient Central Locations For Quantity and Quality Control • Stormwater Ponds – wet pond – wet ED pond – dry ED pond (for cold water w/ pre-treatment) – multiple pond system • Stormwater Wetlands – shallow marsh – ED shallow wetland – pond/wetland systems
- 53.
- 54.
- 55.
- 56.
- 57.
- 58.
- 59.
- 60.
- 61.
- 62. SWM & AmenityNot Incompatible
- 63. Detention or DryPond
- 64. Enhance & PlantDry Ponds Also
- 65. Stream Stabilization asa BMP • Can be effective watershed sediment control practice • Can be local approval requirement • Can be a traded credit • Can be out-of-kind wetland mitigation
- 66.