Green Roofs and Green Infrastructure

1. Green Roofs and Green Infrastructure High-Performance Building Week June 16, 2010

2. Environmental Benefits of Green Roofs, Green Infrastructure, and Low-Impact Development: • Control stormwater runoff • Improve water quality • Conserve water • Reduce urban heat island effect • Store carbon • Improve air quality • Reduce building energy use • Create biohabitat

3. Impervious Surface and Water Quality • Natural landscapes clean and filter water, slow and reduce runoff • Traditional development increases impervious surfaces • In the U.S., impervious surfaces are increasing 3% annually • Result: Urban and suburban stormwater runoff is the #1 cause of pollution in urban watersheds Sources: Urban Green Space: Effects on Water and Climate, Regina E. Bonsignore, University of Minnesota, 2003; Stream Corridor Restoration: Principles, Processes, and Practices, Federal Interagency Stream Restoration Working Group, 1998.

4. Impervious Surface and Water Quality • Water quality begins to degrade when impervious cover exceeds 10% • Water quality becomes “poor” when impervious cover exceeds 25% • D.C. – 46 % impervious • NYC – over 90% impervious • Stormwater concerns: • Pollutant load • Water temperature • Speed and quantity causes erosion and streambed scouring Sources: Urban Green Space: Effects on Water and Climate, Regina E. Bonsignore, University of Minnesota, 2003; Stream Corridor Restoration: Principles, Processes, and Practices, Federal Interagency Stream Restoration Working Group, 1998.

5. Water Quality: Combined Sewer Outflows • Heavy storms = release of untreated sewage and runoff into watersheds. • Nationwide, CSOs affect 772 cities, 40 million people • Scope of problem in D.C. — 2.5 billion gallons of untreated wastewater and precipitation released annually • In some parts of D.C., one-tenth inch of rain triggers CSOs • Cost of fixing problem in D.C. -- $2.6 billion Sources: U.S. Environmental Protection Agency; D.C. Water and Sewer Authority

6. Water Quality: Combined Sewer Outflows • CSOs are #1 cause of beach closures around urban areas

7. Impervious Surface and Flooding • As development increases, so does the amount and speed of stream flow • As stream flow speeds increase, so does flooding Source: U.S. Geological Survey

8. Houston 2001: Tropical Storm Allison • $6.5 billion (‘08 USD) in damages • 41 deaths • 70,000 homes flooded

9. Traditional Development = Urban Heat Island • = Increased air pollution and related health problems • = Increased carbon footprint -- higher temperatures require more energy for cooling Test Sources: U.S. Environmental Protection Agency; Paul R. Baumann, Department of Geography, SUNY Oneonta April 15, 2004

10. Roofs are 15-25% of surface area in cities Image Courtesy of Michael Van Valkenburgh Associates, Inc. & ASLA ASLA: Pre-Green Roof

12. ASLA Green Roof

13. ASLA Green Roof Results • Retains 100 % of a one-inch rainfall and over 77 % of total annual rainfall • Reduces the amount of nitrogen entering the watershed • Building energy use reduced by 10 % in winter months • Temperature as much as 43.5 cooler in the summer

14. 25% reduction in stormwater leaving site • Bioretention planters filter and clean water

16. LEED platinum • Integrated stormwater and wastewater system Sidwell Friends School, D.C. Image courtesy of Andropogon

17. Biofilterstreat building wastewater for reuse • Uses constructed wetlands, rain gardens, bioswales, biofiltration and habitat pools

19. 120 acre residential redevelopment • Returns clean water to an urban salmon-bearing stream Sustainable Housing Community: High Point Seattle, Washington Photo courtesy of Mithun

20. Rain gardens, pervious pavements, 22,000 linear feet of bioswales • Native plants and rich vegetation • Controls water flow for 100-year storm events Photo courtesy of Mithun

21. Incorporates “Complete Streets” • Handles 100-year storm rainfalls Photo courtesy of Mithun

22. Retail district “green street” • Retains 100% of rainfall from a 100-year storm • Channels water from street into stormwater planters SW 12th Avenue, Portland, OR Photo courtesy of Kevin Robert Perry, ASLA

24. Residential “green street” NE Siskiyou, Portland, OR Photo courtesy of Kevin Robert Perry, ASLA

25. Photo courtesy of Kevin Robert Perry, ASLA

26. Photo courtesy of Kevin Robert Perry, ASLA

27. Turned derelict riverfront into 23 acres of park land • Mitigated erosion • Enhanced flood control Buffalo Bayou Promenade, Houston, TX Photo courtesy SWA Group

28. Reduces air temperature • Provides recreation opportunities • Creates biohabitat Buffalo Bayou Promenade, Houston, TX Photo courtesy SWA Group

29. Important Legislation • HR 4202 The Green Infrastructure for Clean Water Act of 2009 • Provides grants to states, localities, and other qualified entities for plan, design and implementation of green infrastructure projects that would mitigate stormwater runoff and address other water quality and quantity issues

30. HR 4202 • Recommends changes to local ordinances, permitting processes, and zoning regulation to encourage the use of Green Infrastructure solutions • Establishes a Green Infrastructure program at EPA to promote the use of green infrastructure • Creates up to 5 Green Infrastructure centers of excellence to conduct research and develop best management practices

31. Questions? Roxanne Blackwell rblackwell@asla.org 202.216.2334 Kevin O’Hara kohara@asla.org 202.216.2370