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Balancing Wetland Protection with Stormwater Management - a Case Study
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  • The stormwater treatment practices presented in this slide show fall into five major categories: stormwater ponds, stormwater wetlands, infiltration practices, filtering practices, and open channels. Within each category, there are several design variations.

Balancing Wetland Protection with Stormwater Management - a Case Study Presentation Transcript

  • 1. Balancing Wetland Regulationwith Stormwater Management:A Case Study.Mid-Atlantic Wetlands - CLE InternationalNovember 7, 2008, Baltimore, MDAndrew T. DerAssociate and Director of Environmental SciencesLoiederman Soltesz Associates, Inc.2 Research PlaceRockville, MD 20850Telephone 301 948 2750Email ader@LSAssociates.netWeb site www.LSAssociates.net Current Issues in Stormwater Regulation in Maryland | April 22, 2005
  • 2. Effects of Stormwater • Hydrology • Geomorphology • Habitat • Water Quality Current Issues in Stormwater Regulation in Maryland | April 22, 2005
  • 3. Current Issues in Stormwater Regulation in Maryland | April 22, 2005
  • 4. What Happens Runoff from 1” Rain Event Current Issues in Stormwater Regulation in Maryland | April 22, 2005
  • 5. Hydrology• Increase in flow and velocities• Increase in flooding• Increase in frequency• Increase in bankfull flows Current Issues in Stormwater Regulation in Maryland | April 22, 2005
  • 6. Geomorphology• Stream Widening• Channel Instability• Erosion Current Issues in Stormwater Regulation in Maryland | April 22, 2005
  • 7. Habitat• Fish Barriers• Loss of Substrate• Loss of Riparian Zone• Loss of Micro-topography Current Issues in Stormwater Regulation in Maryland | April 22, 2005
  • 8. Water Quality• Sediments - Channel erosion can be the primary sediment source!• Nutrients - Maintained vegetated areas• Temperature - Warm pavements and pond pools• Other - Oils, Greases, heavy metals, toxics Current Issues in Stormwater Regulation in Maryland | April 22, 2005
  • 9. Instability Current Issues in Stormwater Regulation in Maryland | April 22, 2005
  • 10. Instability Current Issues in Stormwater Regulation in Maryland | April 22, 2005
  • 11. Water Resource Regulatory Processes Applicable to Development Streams and Wetlands• Nontidal Wetlands: Jurisdictional Areas per 1987 Corps Manual and 25 Buffer• Tidal Wetlands: Tidally Influenced Open (navigable) Water and Their Wetlands• Streams: Activities Which Alter Flow, Current or Cross-section of Streams & 100 Year Floodplain• §404 Corps Nontidal and Tidal Waters: All waters, no Floodplain• §401 State Water Quality Certification Current Issues in Stormwater Regulation in Maryland | April 22, 2005
  • 12. Water Resource RegulatoryProcesses Applicable toDevelopment Stormwater • NPDES Phase I and II • Most construction permitted under NPDES State GP • Stormwater Management Regulations – determined by State and locality – New Maryland 2007 Stormwater Managemetn Act • Erosion and Sediment Control Regulations • Coastal Zone Management Act • Chesapeake Bay Critical Area Law • Special County requirements Current Issues in Stormwater Regulation in Maryland | April 22, 2005
  • 13. Classification ofMaryland’s Waters• Use I & I-P: Water Contact Recreation and Protection of Aquatic Life• Use II: Shellfish Harvesting Waters• Use III & III-P: Natural Trout Waters• Use IV & IV-P: Recreational Trout Waters Current Issues in Stormwater Regulation in Maryland | April 22, 2005
  • 14. Maryland’s Water QualityStandards• Numerical: Dissolved Oxygen, Temperature, pH, Turbidity, Fecal Coliform, Toxics• Narrative: ...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...” Current Issues in Stormwater Regulation in Maryland | April 22, 2005
  • 15. What is a Best ManagementPractice (BMP)?• Early Planning• Low Impact Development – “LID-like” or Better Site Design• Impervious limitations• Sheet flow management – open section pavement• Local stream buffers and setbacks• Devices Most significant factor affecting performance is construction and maintenance Current Issues in Stormwater Regulation in Maryland | April 22, 2005
  • 16. Common EngineeredPracticesSmaller Volumes Larger VolumesMost compatible with ESD When preferred isgoals of 2007 SWM Act – Insufficient Central LocationsAt Source & Pretreatment For Quantity and QualityQuality Control Only Control• Infiltration • Stormwater Ponds – trench/basin – wet pond – wet ED pond• Filtering – dry ED pond (for cold – sand filter/bioretention water w/ pre-treatment – multiple pond system• Hydrodynamic Devices • Stormwater Wetlands – shallow marsh• “New” Technology – ED shallow wetland – pervious surfaces/green – pond/wetland system roofs Current Issues in Stormwater Regulation in Maryland | April 22, 2005
  • 17. Montgomery County Current Issues in Stormwater Regulation in Maryland | April 22, 2005
  • 18. Piney Branch Watershed Current Issues in Stormwater Regulation in Maryland | April 22, 2005
  • 19. Initial “Template” Developmentat Lowest Point Current Issues in Stormwater Regulation in Maryland | April 22, 2005
  • 20. Initial Wetland andWater Quality Issues• Purpose and Need• Avoidance/Minimization• Roads, Utilities, Embankments• SWM: Quality• SWM: Quantity• Coordinate with County• ADP and Instream SWM Current Issues in Stormwater Regulation in Maryland | April 22, 2005
  • 21. Need to InvestigateHierarchy of SWM Preferences• Infiltration Trenches and Depressions• Bioretention, Swales, Sandfilters, Filtering Marsh• Extended Detention (with Wetland Bottom)• Retention (with Wetland and Forebays) Current Issues in Stormwater Regulation in Maryland | April 22, 2005
  • 22. Watershed Mitigation andBMP’s• Wetland/stream impacts limited to roads/utilities• In-stream SWM in marginal/poor areas• Minimum stream buffer of 100‘• Wetland mitigation in riparian buffer areas• “First flush” SWM in uplands• Infiltration/filtration where feasible• Quantity management in “horseshoe” ponds• Pooling areas planted with wetland vegetation Current Issues in Stormwater Regulation in Maryland | April 22, 2005
  • 23. The Best BMPWork with Forest and Wetland Conservation Current Issues in Stormwater Regulation in Maryland | April 22, 2005
  • 24. Work with SiteCharacter Current Issues in Stormwater Regulation in Maryland | April 22, 2005
  • 25. BMP’s and Mitigation Current Issues in Stormwater Regulation in Maryland | April 22, 2005
  • 26. BMP’s and Mitigation Current Issues in Stormwater Regulation in Maryland | April 22, 2005
  • 27. Sensitive Resources Current Issues in Stormwater Regulation in Maryland | April 22, 2005
  • 28. SWM & AmenityNot Incompatible Current Issues in Stormwater Regulation in Maryland | April 22, 2005
  • 29. Transition Habitat Current Issues in Stormwater Regulation in Maryland | April 22, 2005
  • 30. BioretentionInfiltration Current Issues in Stormwater Regulation in Maryland | April 22, 2005
  • 31. BioretentionInfiltration Current Issues in Stormwater Regulation in Maryland | April 22, 2005
  • 32. Landscaped BioretentionFacility Current Issues in Stormwater Regulation in Maryland | April 22, 2005
  • 33. Hydrodynamic Devices Current Issues in Stormwater Regulation in Maryland | April 22, 2005
  • 34. Stream Stabilization• Can be effective watershed sediment control practice• Can be local approval requirement• Can be a traded credit• Can be out-of-kind wetland mitigation Current Issues in Stormwater Regulation in Maryland | April 22, 2005
  • 35. Get Creative Current Issues in Stormwater Regulation in Maryland | April 22, 2005
  • 36. Public Involvement• Public Notice• Use III or IV Potential• Temperature and Ponds• ADP• RBA• No Use III or IV standards but higher quality Use I Current Issues in Stormwater Regulation in Maryland | April 22, 2005
  • 37. Additional WatershedManagement Practices • Water Quality Monitoring Plan • Stream Reach Temperature Model and Percent Contribution of QED, 2, 10 to Stream Flow • Maximum 20% Diversion Base Flow • Shade Planting of SW Conveyance and Management Areas • Toe Drain Pipes Under Embankment Fill Current Issues in Stormwater Regulation in Maryland | April 22, 2005
  • 38. MonitoringUsed also for MS4 ComplianceCan be State requirementPreconstruction, construction and post-constructionMacroinvertebrate Studies(more common examples are WWTP & mining requirements)ChemistryGeomorphologyGroundwater Current Issues in Stormwater Regulation in Maryland | April 22, 2005
  • 39. Monitoring Current Issues in Stormwater Regulation in Maryland | April 22, 2005
  • 40. Bioassessment Rapid Bioassessment Metric Comparisons to Pre-Construction Scores Year ST2 ST6 ST10 1993 Non Impaired ** Non Impaired ** 1994 Non to Mod. Impaired Non Impaired Non Impaired ** 1995 Non to Mod. Impaired Non to Mod. Impaired Non Impaired 1996 Non to Mod. Impaired Moderately Impaired Non to Mod. Impaired 1997 Non to Mod. Impaired Non to Mod. Impaired Moderately Impaired 1998 Moderately Impaired Non to Mod. Impaired 1999 Moderately Impaired Moderately Impaired Moderately Impaired 2000 Moderately Impaired Non to Mod. Impaired 2001 Non to Severely Impaired Moderately Impaired Non Impaired 2002 Non to Mod. Impaired Mod. to Severely Impaired** Non Impaired value is given to the first (reference) date for comparison purposes; the streams on those dates are not necessarily truly non-impaired. Current Issues in Stormwater Regulation in Maryland | April 22, 2005
  • 41. Dissolved Oxygen Piney Branch Mean Dissolved Oxygen Levels for Stations 2, 6 and 10 ST. 2 Mean D.O. ST. 6 Mean D.O. ST. 10 Mean D.O. Use I Min. D.O. 14 12 10 8 mg/l 6 4 2 0 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 Year Current Issues in Stormwater Regulation in Maryland | April 22, 2005
  • 42. Temperature Piney Branch Instream Peak Tem pe ratures Stations 2, 6 and 10 ST. 2 ST. 6 ST. 10 35 30 25Temperature (oC) 20 15 10 5 0 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 Year Current Issues in Stormwater Regulation in Maryland | April 22, 2005
  • 43. State/County WatershedInitiatives • Biological Monitoring Workgroup • County Special Protection Area Legislation • Biosensitive Stream Crossing Committee • Interagency Wetlands Coordinating Committee • Findings input to Municipal NPDES Compliance Current Issues in Stormwater Regulation in Maryland | April 22, 2005