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Presenters: S.W.I.M., NRDC, Sustainable South Bronx, NRDC.
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Water
August 20 Forum
Häfele Showroom
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
PROBLEM
• CSO = combined sewer overflow
• More than 27 billion gallons of untreated stormwater and raw sewage per year
• 460 CSOs in NYC
SOLUTION• Green infrastructure, Low
Impact Development (LID), Best Management Practice (BMP), Source Control
• Interagency BMP Task Force
• Citizen Implementation
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
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
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)
Sustainable South Bronx
• Rob Craudereuff
• Green Roof Tax Abatement
• Passed NYS in June 2008
Rob CrauderueffSUSTAINABLE SOUTH BRONX
USA USA= 5% 25%
World’sPopulation ?
USA USA= 5% 25%
World’sPopulation
World’sIncarcerated
•Unemployment: 25%•Living in POVERTY: 40%
•Median Household Income: $20K
•Problems to be addressed:
Bronx Ecological Stewardship Training
Source: Columbia University Urban Planning Studio, 2006 Instructors: J. Rosenthal & K. Bakewell
Green Roof Tax Abatement
• $4.50/s.f. up to $100,000
• 3 year maintenance plan
• Agreement for City to inspect
• Applications:1/1/09? - 3/15/13
Green Roof Tax Abatement
• At least 50% of the roof, green roof defined as:– Roof Membrane– Root Barrier– Insulation– Drainage– Growth Medium (3 inches or irrigation or certified)
– Vegetation (80% covered)
EDAW
• Timothy Terway
• Urban Design Meets Urban Ecology
• Interdisciplinary Practice: Different Disciplines engaged in Studying Systems
How do we make this…. function like this?
Green Stormwater Infrastructure: What is it?
• Integrated, landscape-based approach to sustainable development
• Set of strategies to maintain existing natural systems, hydrology, ecology
• Flexible approach based on a toolkit of simple techniques
Stormwater Goals
• Water quality improvement– Filter pollutants and
contaminants• Water conservation• Peak flow control • Volume reduction
Complimentary Goals
• Wildlife habitat• Greening cities,
aesthetics• Recreation and open
space• Environmental education
& stewardship• Shading / heat island
reduction
The NEW Paradigms – Urban Water Cycle
Landscape Transition
SFPUC 2007
What is your primary goal?
– Water quality– Aquifer recharge– Combined Sewer Overflow (CSO) reduction– Green streets– Flood reduction
Toolkit
• Green Roofs• Cisterns• Downspout Disconnection• Rain Gardens• Bio-Retention• Detention Basins• Constructed Wetlands• Permeable Paving• Stream Daylighting• Urban Forest
Case Studies:
• Jordan Cove, CT
• 100 acre Urban Regeneration Masterplan (New York Metro)
Stormwater Research: Jordan Cove
• Was Designed to Determine Water Quantity/Quality Benefits of BMP’s
• Monitoring took place over 10 years
• More info: www.jordancove.uconn.edu
FindingsActivity Traditional ($) BMP ($)
Cul-de-sac bioretention1,275 2,183
Driveway (asphalt)/lot 2,800 --
Driveway (paver)/lot -- 7,896
Erosion & sediment control/lot
322 625
Plantings 500 650
Planning and design/lot 401 808
Road and curb 23,494 102,500
Rain gardens/lot 0 575
Stormwater collection 7,770 3,600
36,562 118,837
1. To implement BMPs on 100% of the lots in the BMP portion of the subdivision - goal met.
2. To maintain post-development peak runoff rate and volume at levels equal to predevelopment rates. – volume and peak rate goal met
3. To maintain post-development loading of TSS at levels equal to predevelopment rates – goal not met.
4. To retain sediment onsite during construction. – goal not met.
5. To reduce nitrogen export by 65% - goal met.
6. To reduce bacterial export by 85%. – goal not met.
7. To reduce phosphorus export by 40%. – goal met.
EDAW
Can you infiltrate on site?
• Soils• Depth to groundwater• Liquefaction dangers• Underground utilities• Slope• Contamination
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
Using the Toolkit
Gauging Impact of Tools
Functions of ToolsRunoff Minimization
Rainwater Capture
Landscaping Infiltration Conveyance WQ Treatment
Permeable Pavement O x x
Bioretention x x O x O
Bioswales x x O O
Stormwater Planters
x x O x x
Green Roofs
O x x
Wetlands O x O
Turf Replacement x x O x x
Infiltration Devices
x O x
Source: Dan Medina, CH2MHillO Main function
x Secondary Function
• 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
Inundation tolerance
2/3 Veg Height
80%ile compliance in summer months
General Rule of Thumbs
BMP Sizing Factor Summary
IMP Sizing Factors
Flow-Through Planter
Group D: 0.05
Vegetated/Grassy Swale
Group A: 0.10 to 0.14
Group D: 0.07 to 0.115
Bioretention Basin
Group A: 0.13Group D: 0.06
Under-Drain or Infiltration:
• Source: NRCS
Group A – low runoff potential (<10% clay)Group D – high runoff potential (>40% clay)
Next Month’s Forum:
International Green Building Showcase
September 17
Location TBA