Onondaga County Executive Joanne M. Mahoney www.savetherain.us Co-Benefits of Green Infrastructure: An Environmental and Economic Analysis of the Save the Rain Program Zachary Monge, P.E. CH2M Syracuse NYSAWWA/NYWEA Joint Energy Conference November 16, 2016 Co-Authors: Andrew Potts, P.E. – CH2M Tom Rhoads, P.E. – Onondaga County Dept. of Water Environment Protection
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Onondaga County Executive Joanne M. Mahoney
www.savetherain.us
Co-Benefits of Green Infrastructure:An Environmental and Economic Analysis of
the Save the Rain ProgramZachary Monge, P.E.
CH2M Syracuse
NYSAWWA/NYWEA Joint Energy Conference November 16, 2016
Co-Authors:
Andrew Potts, P.E. – CH2M
Tom Rhoads, P.E. – Onondaga County Dept. of Water Environment Protection
Onondaga County Executive Joanne M. Mahoney www.savetherain.us
• 7,660 acres• 6.1 Billion Gallons Total Annual Combined Sewage Generated by the Metro Combined Sewer Service Area
City of Syracuse
Onondaga CreekHarbor Brook
Onondaga Lake
Onondaga County, New York
America’s First Green Infrastructure Consent Order
Onondaga County Executive Joanne M. Mahoney www.savetherain.us
• 1988 – Atlantic States Legal Foundation files lawsuit against County
• 1998 – METRO consent judgment replaced with Amended Consent Judgment (ACJ)
• 2009 ACJ amended to authorize use of Gray and Green infrastructure
enhanced climate change resiliency, etc. • Significant empirical research required
Onondaga County Executive Joanne M. Mahoney www.savetherain.us
Tools and Methods• Tree Benefits
– i-Tree (version 6.09), USDA Forest Service• i-Tree Hydro – Measures effects in tree cover changes in a defined
watershed for water quantity and quality benefits • i-Tree Eco – Measures effects of urban forest tree inventory for air
quality benefits
• SWMM– County’s combined sewer system model is basis for ACJ compliance
• Used to determine stormwater capture and CSO reduction benefit for individual GI projects
• US EPA BenMAP– Used for air quality benefit calculations
Onondaga County Executive Joanne M. Mahoney www.savetherain.us
Tools and Methods
• Monetary Benefits– Reported in 2014 dollars– 40 year return period, 3% discount rate– Calculation method varies per benefit based on readily
available data– Per capita population assumed to remain constant
Onondaga County Executive Joanne M. Mahoney www.savetherain.us
Assumptions• Younger trees provide less benefit than older trees• All benefits based on local climate data available for SYR, NY• 3% tree mortality rate (~40 year lifespan) • GI projects are regularly maintained and operated• GI projects are replaced at end of service life (i.e. porous
pavements)
Onondaga County Executive Joanne M. Mahoney www.savetherain.us
Trees Planted through 2016• Excludes County Street Tree Program• Tree size determined by comparing to USDA Forest
Service database
Onondaga County Executive Joanne M. Mahoney www.savetherain.us
• Reduced wastewater treatment volume– Of 109.7 MG removed by GI, 92.4 MG removed from
sewer through infiltration/evaporation– Reduced WW treatment (39.0 MG) = stormwater
removed – CSO reduction
Onondaga County Executive Joanne M. Mahoney www.savetherain.us
Water Quantity Benefits
• Reduce Potable Water Usage– Cistern projects (Zoo and War Memorial) and rain barrels– Assumed 60% of rain barrels are maintained and operated properly
and EPA estimate of 1,300 gallons stormwater saved per year– Cisterns based on measured savings before/after projects– Total savings = 13.5 MG/yr
Onondaga County Executive Joanne M. Mahoney www.savetherain.us
Water Quality Benefits
• Pollutant load reductions– BOD5, TSS, TP, TN, FC– Selected the lesser of measured values from Onondaga County CSO and US EPA average
– Average cost to treat gallon of WW at County Metro WWTP = $2.30/1,000 gal
• Potable water savings (billed cost) = $33,500– Average City of Syracuse billing rate = $2.50/1,000 gal
• Equivalent avoided gray infrastructure costs = $35M (one time cost)– Without green projects, additional gray projects required– Average cost for completed gray projects = $0.66/gal CSO
reduction
Onondaga County Executive Joanne M. Mahoney www.savetherain.us
Valuation – Annual Savings• Savings from reduced electrical usage from tree cooling
benefits = $400– $0.117/kWh, National Grid 2014 rate
• Savings from reduced natural gas usage = $2,130– $0.71/therm, National Grid 2014 rate
• Air quality savings = $4,530– Based on US EPA BenMAP metrics for air pollutant removal in
relation to human health• Climate Change Savings = $54,745
– Interagency Working Group estimate of $0.043/lb CO2 removed
Onondaga County Executive Joanne M. Mahoney www.savetherain.us
Summary – Annual Benefits
Onondaga County Executive Joanne M. Mahoney www.savetherain.us
Summary• Total Economic Savings = $220,000/yr, $8 million after 40 years• Equivalent avoided gray infrastructure cost = $35 million
– Gray infrastructure also does not provide the economic, environmental, and social benefits provided by green infrastructure
• Improved water quality of Onondaga Lake and its tributaries has spawned development and investment
– Lakeview Amphitheater – Onondaga Creekwalk– Onondaga Lake Loop the Lake Trail– Investment in Armory Square and Inner Harbor
Onondaga County Executive Joanne M. Mahoney www.savetherain.us
Additional Benefits for Future Consideration• Reduced salting demand for porous pavements
– Studies have shown 75% reduction
• Enhanced potential for green job opportunities over life of projects• Enhanced recreation opportunities • Crime reduction• Enhanced property values• Increased air emissions due to construction vehicles (negative benefit)• Economic, social, and environmental benefits related to reduction in peak
storm flows • Derivation of a more detailed analysis for groundwater recharge
Onondaga County Executive Joanne M. Mahoney www.savetherain.us
Contributors• SUNY ESF
– Ted Endreny, Tom Taggart, Chuck Knoll• US Forest Service