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Stormwater GreenHomeNYC August 2008

Presenters: S.W.I.M., NRDC, Sustainable South Bronx, NRDC.

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Stormwater GreenHomeNYC August 2008

  1. 1. Water August 20 Forum Häfele Showroom
  2. 2. S.W.I.M. • Clean Water Act = Fishable and Swimmable • Storm Water Infrastructure Matters • Over 45 members, including Gowanus Dredgers, Nos Quedamos, Cook + Fox, NRDC, Sustainable South Bronx • www.swimmablenyc.info
  3. 3. PROBLEM • CSO = combined sewer overflow • More than 27 billion gallons of untreated stormwater and raw sewage per year • 460 CSOs in NYC
  4. 4. SOLUTION • Green infrastructure, Low Impact Development (LID), Best Management Practice (BMP), Source Control • Interagency BMP Task Force • Citizen Implementation
  5. 5. Natural Resources Defense Council • Larry Levine, Project Attorney • a S.W.I.M. member organization • Local Law 5 – requires a “Sustainable Stormwater Management Plan” for NYC – 1/30/08: Intro 630-A approved unanimously – 2/19/08: Bloomberg signs into law – 10/1/08: First draft due, for public review & comment – 12/1/08: Final Plan DUE
  6. 6. Local Law 5 • Mayor’s Office of Long Term Planning and Sustainability has lead responsibility; quarterly public meetings to solicit input – next meeting anticipated in Oct. • Key Plan Elements: – focus on “green infrastructure” – code revisions for new development and redevelopment – financial and other incentives for retrofitting – design specs for public projects – long-term and interim goals and milestones – public notification of CSO events • Complete progress report due every 2 years
  7. 7. Local Law 5 Example BMPs: • Rain gardens • Downspout disconnection • Green roofs • Enhanced street tree pits and planting strips • Rain barrels • Pervious pavement • Rainwater harvesting • Water conservation; greywater re-use • Stormwater Utility Fee (separated from water rates)
  8. 8. Sustainable South Bronx • Rob Craudereuff • Green Roof Tax Abatement • Passed NYS in June 2008
  9. 9. Rob Crauderueff SUSTAINABLE SOUTH BRONX
  10. 10. USA USA 5% = 25% World’s ? Population
  11. 11. USA USA 5% = 25% World’s World’s Population Incarcerated
  12. 12. •Problems to be addressed: •Unemployment: 25% •Living in POVERTY: 40% •Median Household Income: $20K
  13. 13. Bronx Ecological Stewardship Training
  14. 14. Source: Columbia University Urban Planning Studio, 2006 Instructors: J. Rosenthal & K. Bakewell
  15. 15. Green Roof Tax Abatement • $4.50/s.f. up to $100,000 • 3 year maintenance plan • Agreement for City to inspect • Applications:1/1/09? - 3/15/13
  16. 16. Green Roof Tax Abatement • At least 50% of the roof, green roof defined as: – Roof Membrane – Root Barrier – Insulation – Drainage – Growth Medium (3 inches or irrigation or certified) – Vegetation (80% covered)
  17. 17. EDAW • Timothy Terway • Urban Design Meets Urban Ecology • Interdisciplinary Practice: Different Disciplines engaged in Studying Systems
  18. 18. How do we make this…. function like this?
  19. 19. Green Stormwater Infrastructure: What is it? • Integrated, landscape-based approach to sustainable development • Set of strategies to maintain existing natural systems, hydrology, ecology • Flexible approach based on a toolkit of simple techniques
  20. 20. Stormwater Complimentary Goals Goals • Water quality improvement • Wildlife habitat – Filter pollutants and • Greening cities, contaminants aesthetics • Recreation and open • Water conservation space • Peak flow control • Environmental education & stewardship • Volume reduction • Shading / heat island reduction
  21. 21. The NEW Paradigms – Urban Water Cycle
  22. 22. Landscape Transition SFPUC 2007
  23. 23. What is your primary goal? – Water quality – Aquifer recharge – Combined Sewer Overflow (CSO) reduction – Green streets – Flood reduction
  24. 24. Toolkit • Green Roofs • Cisterns • Downspout Disconnection • Rain Gardens • Bio-Retention • Detention Basins • Constructed Wetlands • Permeable Paving • Stream Daylighting • Urban Forest
  25. 25. Case Studies: • Jordan Cove, CT • 100 acre Urban Regeneration Masterplan (New York Metro)
  26. 26. Stormwater Research: Jordan Cove • Was Designed to Determine Water Quantity/Quality Benefits of BMP’s • Monitoring took place over 10 years
  27. 27. • More info: www.jordancove.uconn.edu
  28. 28. Findings Activity Traditional ($) BMP ($) Cul-de-sac bioretention 1,275 2,183 Driveway (asphalt)/lot 2,800 -- Driveway (paver)/lot -- 7,896 Erosion & sediment 322 625 control/lot 1. To implement BMPs on 100% of the lots in the BMP portion of the subdivision - goal met. Plantings 500 650 2. To maintain post-development peak runoff rate and volume at levels equal to predevelopment rates. – volume and peak rate goal met Planning and design/lot 401 808 3. To maintain post-development loading of TSS at levels equal to predevelopment rates – goal not met. Road and curb 23,494 102,500 4. To retain sediment onsite during construction. – goal not met. 5. To reduce nitrogen export by 65% - goal met. Rain gardens/lot 0 575 6. To reduce bacterial export by 85%. – goal not met. Stormwater collection 7,770 3,600 7. To reduce phosphorus export by 40%. – goal met. 36,562 118,837
  29. 29. EDAW
  30. 30. • Soils Can you infiltrate on • Depth to groundwater site? • Liquefaction dangers • Underground utilities • Slope • Contamination
  31. 31. Using the Toolkit Tools that require infiltration: – Rain gardens – Pervious Pavement Tools that do not require infiltration: – Cisterns – Eco-roofs (or roof gardens) – Bioretention planters – Urban forest – Stormwater wetland – Detention basin
  32. 32. Gauging Impact of Tools
  33. 33. Functions of Tools Runoff Rainwater Landscaping Infiltration Conveyance WQ Minimization Capture Treatment Permeable Pavement O x x Bioretention x x O x O Bioswales x x O O Stormwater x x O x x Planters Green O x x Roofs Wetlands O x O Turf x x O x x Replacement Infiltration x O x Devices O Main function Source: Dan Medina, CH2MHill x Secondary Function
  34. 34. General Rule of Thumbs • Sizing: 4% of catchment • Vegetation: Native vegetation, drought tolerant, medium to tall stem height • Filter Media: Sandy Loam, < 5% fines (clays) • Pretreatment: Always incorporate pretreatment separated from system till catchment built out and veg. established 2/3 Veg Height 80%ile compliance in summer months Inundation tolerance
  35. 35. BMP Sizing Factor Summary Under-Drain or Infiltration: IMP Sizing Factors Flow- Group D: 0.05 Through Planter Vegetated/ Group A: Grassy 0.10 to 0.14 Swale Group D: 0.07 to 0.115 Group A – low runoff potential (<10% clay) Group D – high runoff potential (>40% clay) Bioretention Group A: 0.13 Basin Group D: 0.06 • Source: NRCS
  36. 36. Next Month’s Forum: International Green Building Showcase September 17 Location TBA

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