Balancing Wetland Preservation and Stormwater Management: a case study


Published on

Presented at 2013 joint scientific meeting of the Society of Wetland Scientists South Atlantic Chapter, Florida Association of Environmental Soil Scientists, and Southwest Chapter of the Florida Association of Environmental Professionals - Wetland Resources and Regulations in a Changing World: What Have We Learned?

Published in: Education, Technology
  • Be the first to comment

  • Be the first to like this

No Downloads
Total views
On SlideShare
From Embeds
Number of Embeds
Embeds 0
No embeds

No notes for slide
  • {"6":"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.\n"}
  • Balancing Wetland Preservation and Stormwater Management: a case study

    1. 1. Presentation for SW SSAC/ FAESS/ FAEP 2013 SW Joint Conference in Tampa, Florida Balancing Nonpoint Source Water Quality Management with Wetland And Stream Preservation On A Watershed Basis: A Case Study (or How Did We Get Here?) October 8, 2013 Andrew T. Der & Associates, LLC Environmental Consulting 1000 Fell Street | Baltimore, MD 21231 1.410.491.2808 |
    2. 2. Habitat Avoidance Insufficient = New Construction SW criteria M Surface water resources • State nontidal waters and wetlands including 100 year floodplain and water quality criteria • State tidal waters and wetlands • Federally regulated waters of the United States Stormwater (nonpoint source pollution) • State stormwater management regulations – includes delegated point and nonpoint source federal criteria • State and local erosion and sediment control criteria • Special state tidal water criteria
    3. 3. Classification of State W aters • 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
    4. 4. State W ater Quality Standards Numerical • Dissolved Oxygen, Temperature, pH, Turbidity, Fecal Coliform, Toxics Narrative •...Protection of Aquatic Life ...Fishable ...Swimmable...Includes EPA AntiDegradation Policy (ADP): “...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...”
    5. 5. W is a Best Management hat Practice (BMP)? BMPs are policies, practices, procedures, or structures implemented to mitigate the adverse environmental effects on surface water quality resulting from activities. BMPs are categorized as structural or nonstructural. • Early Planning/ Avoidance • Low Impact Development (LID), 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
    6. 6. Hierarchy of Engineered Practices Smaller Volumes Most compatible with ESD atsource and/or pretreatment quality control Larger Volumes When preferred is Insufficient for quantity and quality • Infiltration – trench/basin • Stormwater Ponds – wet pond – wet ED pond – dry ED pond (for cold water w/ pre-treatment) – multiple pond system • Filtering – sand filter/bioretention • Hydrodynamic Devices – Curb & gutter vortex/filter basin • “Newer” Technology – pervious surfaces/green roofs • Stormwater Wetlands – shallow marsh – ED shallow wetland – pond/wetland systems
    7. 7. Location of Project Area
    8. 8. Location of Project Area
    9. 9. W atershed and Initial Development at Low Point
    10. 10. Initial Permit Review • Higher Quality Use I-P Water • Purpose and Need • Avoidance and Minimization of Waters of the U. S. from Roads, Utilities, and Other Disturbances • Nonpoint Source Pollution Management: Quality • Stormwater Management (SWM): Quantity • Coordination with Local Authorities, NGOs, and Stakeholders • How to Address ADP and SWM
    11. 11. Apply Hierarchy of SW M Preferences to Site Character • Vegetative buffers, disconnects, open section pavement • Infiltration Practices if Soils Allow • Bioretention, Swales, Wetland Filtering • Retention or Extended Detention Pond with Wetlands (to include quantity management)
    12. 12. Proposed Site-specific Mitigation and BMP’s • Stream/wetland impacts limited to necessary roads/utilities • In-stream SWM in marginal/poor areas only • Minimum stream buffer of 100‘ (30.5 meters) • Wetland mitigation and replanting in cropped riparian buffer areas • “First flush” stormwater quality management in uplands • Infiltration/filtration where feasible (permeable soils and depth) • Primary quantity stormwater management in “horseshoe” pond • Water pooling areas planted with wetland vegetation
    13. 13. BMPs and Mitigation – Forest and W etlands
    14. 14. BMPs and Mitigation - Maximize W etland Treatment with Site
    15. 15. BMPs and Mitigation - Pond and W etlands
    16. 16. BMPs and Mitigation – Impact Avoidance and W etland Filtration
    17. 17. BMPs and Mitigation - Sensitive Resources
    18. 18. BMPs and Mitigation - Transition Habitat
    19. 19. BMPs and Mitigation - SW & M Landscaping
    20. 20. BMPs and Mitigation – SW and M Landscaping
    21. 21. BMPs and Mitigation – Urban Areas
    22. 22. BMPs and Mitigation – Urban Areas
    23. 23. BMPs and Mitigation – Urban Areas
    24. 24. BMPs and Mitigation - Stream Stabilization and Restoration • Can be effective watershed sediment control practice • Can be local approval requirement • Can be a traded credit • Can be out-of-kind wetland mitigation
    25. 25. Public Involvement • Public Notice • Waters may have Use III or IV (higher quality trout water) potential • Temperature and ponds potential concern • EPA Antidegradation Policy may apply • Implemented stream Rapid Bioassessment • Findings - no Use III or IV standards but higher quality Use I
    26. 26. Additional Mitigation and W ater Quality Management Practices • Water Quality Monitoring Plan • Stream Reach Temperature Model and Percent Contribution of “QED” 2, 10 year event to Stream Flow • Maximum 20% Diversion Base Flow • Shade Planting of SW Conveyance and Management Areas •Toe Drain Pipes Under Embankment Fill
    27. 27. Stream and W ater Quality Monitoring Can be used for MS4 Compliance Can be used for state DNR studies Preconstruction, construction and postconstruction Macroinvertebrate studies (more common examples are WWTP & mining requirements) Chemistry Geomorphology Groundwater
    28. 28. Primary Monitoring Component
    29. 29. Historic Bioassessment Data Rapid Bioassessment Metric Comparisons to Pre-Construction Scores ST6 ST10 Year ST2 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.
    30. 30. Historic Dissolved Oxygen Data 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. 1998 1999 Use I Min. D.O. 14 12 10 mg/l 8 6 4 2 0 1992 1993 1994 1995 1996 1997 Year 2000 2001 2002
    31. 31. Historic Temperature Data Piney Branch Instream Peak Tem peratures Stations 2, 6 and 10 ST. 2 ST. 6 ST. 10 1997 1998 35 Temperature (oC) 30 25 20 15 10 5 0 1992 1993 1994 1995 1996 Year 1999 2000 2001 2002
    32. 32. Lessons Learned • Basis for “how we do it now” • Basis for groundbreaking county Special Protection Area legislation • Basis for local, state, federal coordinating committees and public processes • Basis for initial findings for Municipal NPDES Compliance