Flood and Stormwater Mitigation Using Green Infrastructure Kari Mackenbach, Green Initiatives Practice Leader, URS Christine Worley, URS Incorporate Green Infrastructure •What is Green Infrastructure? •How does it relate to stormwater and flood management? •What are the site selection criteria? •What are costs and operation and maintenance concerns? Green Infrastructure • Natural and managed green areas in both urban and rural settings, • Strategic connection of open green areas, • Treating rainwater as a resource and not as trash to be discarded as quickly as possible, • Transforming “grey” infrastructure to green through restoration of watersheds to slow and store water, and • Providing multiple benefits for people. What Else Can Green Infrastructure Do? • Help communities come closer to attaining their requirements (CWA, MS4, NPDES, CSO, Chesapeake Bay TMDL, etc.) • Enhance public perception (sustainable cities) • Leverage State and Federal program dollars (brownfield redevelopment) • Opportunity to “marry” two forms of public work effort (street, sidewalks, stormwater management) Even your home has a big impact on stormwater runoff House Driveway Stormdrain Street + “Green Concrete” Compacted Lawn 8,390 s.f. “impervious” x 1” rain (if infiltrates first ¼” of rain) = 3,880 gallons of runoff 1,500 s.f. house (& patio) x 1” rain = 925 gallons of runoff In a 1” rainfall Potential Runoff: 5,422 gallons 1,000 s.f. driveway x 1” rain = 617 gallons of runoff 2,500 s.f. “impervious” x 1” rain Stormdrain = 1,542 gallons of runoff Street Where can rain soak in? Q - How Do We Protect Our Streams? A - Manage How Stormwater Runs Off the Landscape Photo: Rusty Schmidt Distributing Stormwater Controls Close to Runoff Sources Distributed Stormwater Features Regional Traditional Techniques Green Roof Applications Pervious Infrastructure Rain Gardens & Bio-Infiltration Devices Green Infrastructure in Your Backyard! Local Challenges Local Opportunities CONSTRUCTING GREEN SOLUTIONS ON EVERY STREET RESIDENTAL RETROFIT VISUAL RESIDENTIAL RETROFIT RAINGARDEN RESIDENTIAL RETROFITPERVIOUS PAVERS Green infrastructure does not replace gray infrastructure. Can reduce the capital costs and O & M costs of gray technology. $ $ http://www.coxconcrete.com/products/rcp/index.html $ The Green Behind the “Green” Green Infrastructure Type Installation Costs Operation and Maintenance Life Cycle Costs Rain Gardens $5-7 sq. ft. $12-15 sq. ft. minimal Annual Mulching and Weeding $0.50-2 sq. ft Pervious Pavement $20-35 sq. ft. minimal Fewer repairs, longer overall lifespan, yearly vacuuming/ pressure washing $0.15 sq. ft Green Roof Applications $30 sq. ft. $12-15 sq. ft. great to minimal Conventional roof 1520 yrs, green is double or triple that life cycle, watering needed until established. Rain Barrels $35-75 great No maintenance, reduce water bills Constructed Wetlands $6-20 sq. ft. minimal Replace pretreatment components 3-5 yrs, weed invasive plants $200-500 yr RIGHT-SIZING STRATEGY Downspout Disconnection Infiltration Trenches & Dry Wells High Cost Effectiveness Bio-infiltration Swales Rain Gardens Pervious Pavers Green Roofs Lower Cost Effectiveness Burnsville, MN Paired Study of Residential Street Runoff Control Diagram courtesy of the City of Burnsville, MN from their Burnsville Stormwater Retrofit Study 17 Rain Gardens Installed Burnsville, MN Diagram courtesy of the City of Burnsville, MN from their Burnsville Stormwater Retrofit Study 5.3 acres treated and 7.5 acres controlled Average treated lot < .5 acres Average total rain gardens < 1 acre Neighborhood Application Burnsville, MN Residential Neighborhood AFTER Rain Garden Retrofits Long-Term Monitoring BEFORE Photos Courtesy of Rice Creek Watershed District Burnsville, MN Blue: Control Red: With Rain Gardens Diagram courtesy of the City of Burnsville, MN from their Burnsville Stormwater Retrofit Study Site Specific/Neighborhood Application •Create a “First of its Kind” •Municipal scale rain garden •Educate the public •Design model for rain gardens •Balances security and openness •Low impact/low maintenance •Use innovative design measures FEMA Supported, FEMA Funded. Regional Applications Large Cities Initiatives Opportunities, Incentives & Regulatory Kansas City, MO • Educating the public about water quality, sewer and stormwater concerns • Promoting green solutions • Encouraging funding for required sewer and stormwater improvements Montgomery County, MD RainScapes Program •Provides rebate rewards to property owners for LID practices http://www.montgomerycountymd.gov LOUISVILLE, KY. OVERVIEW • • • Flood Protection Wastewater Treatment Stormwater Management EVALUATION OF GREEN VS. GRAY Develop Case Study Template Cost per Gallon Gallons Removed Long-term Trends Standardize Design Criteria and O&M Standardize Green Modeling Parameters Target Pilot CSO Basins for Right-Sizing CLEAN, GREEN, GROWING COMMUNITY GREEN TOOLS COLLABORATION ON GREEN FIRST CRADA COMMUNITY • 3 Year Effort-potential for up to 10 years • EPA’s involvement in Green Infrastructure validation process • Establish gallons removed compared to gray • Evaluate and establish long term trends • Standardize Design Criteria/O&M • Standardize Modeling Parameters • Other Ancillary Benefits • Partner with University of Louisville US EPA ORD PARTNER • Monitoring Lead • GMP Selection QA/QC MONITORING IN LOUISVILLE CSO 130 RESULTS Existing AAOV Existing # OF / YR 0.84 MGD 9 Option Gray Cost Green Cost Total Cost POST AAOV POST # OF / YR Gray Only $1,077,000 $0 $1,077,000 0.67 MG Green Only (Option 1 – GMPs 0, 10, 11, 13, 21) $0 $129,000 $129,000 0.44 MG 7 Green Only (Option 2 – GMPs 0, 10, 11, 12,13, 14, 17,19, 21 ) $0 $342,000 $342,000 *Pendi ng Final Model Run *Pending Final Model Run 8 Wrap UP Green Infrastructure can: • Be implemented on a site, neighborhood, or regional level • Help manage flooding and stormwater • Protect our streams • Be cost effective • Provide multiple benefits • Help communities meet environmental requirements • Improve public perception Questions? Kari Mackenbach – Kari.Mackenbach@URS.com Christine Worley – Christine.Worley@URS.com