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Stormwater Management: Making Sure Green Is Green

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  1. Stormwater Management: Making Sure Green Is Green

  2. Critical Link between Land and Water:Two Sides of the Same Coin

  3. What happens on the land….

  4. Jersey City Reservoir, Morris County …has everything to do with what happens in and to the water.

  5. Components of Sustainability Water-Related: • Comprehensive Stormwater • Management • Recycled Wastewater • Water Conserving Water Use • Just for Starters

  6. The Problem - From Smart Growth…

  7. “The only thing new in the world is the history we’ve forgotten….” Harry Truman

  8. Sustainability… • Relates to private residential subdivision and retail and office and industrial centers…. • Also relates to public facilities like schools and parks and recreational facilities and roads….

  9. This could be a new park next to you!

  10. Stormwater Impacts of Conventional Development (including Parks and Rec!) • Not just Increased Flooding! • Increased Runoff Volume • Decreased Evapotranspiration and Groundwater Recharge • Increased Frequency of Runoff Events • Faster Conveyance of Water • Erosion and Stream Channel Changes • Decreased Baseflow • Impacted Aquatic Life • Pollutants and Temperature Impacts

  11. …not to mention other impacts of conventional development practices… Habitat Loss/Biodiversity Wetlands/Floodplains/Other Areas Soils/Special Geologic Features Air Quality/Microclimate Noise Historical/Archaeological Aesthetics/Scenic Quality of Life Public Health

  12. Balancing the Water Cycle

  13. Annual Hydrologic Cycle For an Average Year

  14. Altered Hydrologic Cycle

  15. Infiltration Infiltration Infiltration Surface Runoff Surface Runoff Surface Runoff

  16. Conventional Development Water Cycle Impacts: • Increased Peak Runoff Rate • Increased Runoff Volumes • Decreased Infiltration • Decreased Groundwater Recharge • Decreased Stream Baseflow • Decreased Evapotranspiration • Temperature • All of which translate into many more related hydrologic, ecologic, other impacts.

  17. Conventional (Detention) Stormwater Management • Controls Peak Rate of Runoff to Predevelopment Conditions • Fails to Control Volume of Runoff • Fails to Control Nonpoint Pollutant/Temperature Loadings

  18. We all live downstream….We haven’t understood the basic hydrology of stream and river systems.

  19. Average Annual Rainfall Volume that Occurs by Storm Magnitude for Harrisburg, PA (PA State Climatological Office, 1926 – 2003) 0.1” - 1”

  20. Stormwater management has focused only on the largest storms…we haven’t paid attention to annual water balance and the reality of smaller storms.

  21. Manage Stormwater as a Precious Resource… not a Disposal Problem for Stream Baseflow/Low Flow for Wells and Springs for Wetlands

  22. Nonpoint Source Pollution • Transported by and dissolved in runoff • Petroleum Hydrocarbons • Metals • Nutrients (Phosphorus and Nitrate) • Organic matter • Sediment • Synthetic Organics (pesticides,herbicides)

  23. Impacts on: Stream Morphology Aquatic Habitat Bank Erosion and Undercutting Streambed Scouring

  24. Dry Channels… Eroded Streambanks…

  25. Land Development Impacts on Stream Morphology: • Channel widening, downcutting, scouring • Stream bank erosion • Imbedded substrate with benthic impacts • Loss of pools, riffles

  26. Land Development Impacts on Stream Ecology: • Reduced diversity of aquatic insects • Reduced diversity of fish • Decline of amphibians • Degraded wetlands, riparian zones

  27. Land Development Impacts on Vegetation

  28. Trees: the Perfect BMP

  29. Land Development Impacts on Soil:A Living Foundation Soil Horizons • Layer of Soil Parallel to Surface • Properties a function of climate, landscape setting, parent material, biological activity, and other soil forming processes. • Horizons (A, E, B, C, R, etc) Image Source: University of Texas, 2002

  30. Dramatic increases in soil compaction…

  31. Common Bulk Density Measurements orHow compacted is this soil? Undisturbed Lands: Forests & Woodlands 1.03g/cc Residential Neighborhoods 1.69 to 1.97g/cc CONCRETE 2.2g/cc Golf Courses, Parks, Athletic Fields 1.69 to 1.97g/cc David B. Friedman, District Director -- Ocean County Soil Conservation District Bulk Density is defined as the weight of a unit volume of soil including its pore space (g/cc or grams/cubic centimeter). Water and air are important components of soil and we must frame our soil concepts so that factors affecting water and air dynamics are included. Thus, we are primarily interested in bulk density and pore space as they affect water and aeration status, and root penetration and development.

  32. Effects of Soil Disturbance Adapted from Impact of Soil Disturbance During Construction on Bulk Density and Infiltration in Ocean County, New Jersey (2001) - www.ocscd.org/soil.pdf

  33. Getting Stormwater Right: Structural BMPs Mitigative Non-Structural BMPs Preventive

  34. Site Planning & Design Procedures WATERSHED ANALYSIS SITE ANALYSIS NON-STRUCTURAL BMPs STRUCTURAL BMPs Soil Infiltration-based BMPs Lot Configuration & Clustering Minimum Disturbance, Minimum Maintenance Volume Reduction BMPs Background Factors: Environmental Constraints Site Factors Inventory APPLICANT SUBMISSION Impervious Coverage Runoff Quality BMPs Sensitive Areas Disconnect, Distribute, Decentralize Background Factors: Environmental Opportunities Site Analysis: Constraints vs. Opportunities Restoration BMPs Source Control PRE- SUBMISSION MEETING WATERSHEDANALYSIS SITE ANALYSIS Design Phase 1 PREVENTIVE BMPs Design Phase 2 MITIGATIVE BMPs STORMWATER MANAGEMENT PLAN BUILDING PROGRAM ISSUES STORMWATER CALCULATIONS Township Comprehensive Plan Zoning Guidance SLDO Guidance

  35. Structural Best Management Practices Runoff Volume/Infiltration-Oriented Vegetative and Soil-Based 1.      Rain/recharge gardens/Bioretention 2.      Vegetated filter strips 3.      Vegetated Swales (Bio-infiltration, Dry, Wet) 4.      Porous pavement with infiltration beds 5.      Infiltration basins 6.      Subsurface infiltration beds 7.      Infiltration trenches 8.      French drains/dry wells 9.      Outlet control (level spreaders, etc.) 10.  Retentive grading techniques, berms Runoff Volume/Non-Infiltration-Oriented 11. Vegetated roofs 12. Cisterns/Rain Barrels/Capture Reuse Runoff Quality/Non-Infiltration 13. Constructed wetlands 14. Wet ponds/retention basins 15. Filters 16. Water quality inserts 17. Detention/Extended Detention 18. Special Storage: Parking Lot, Rooftop, etc. Restoration BMPs 19. Riparian Corridor Restoration 20. Revegetation/Reforestation 21. Soils Amendment

  36. One size no longer fits all…