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
Onondaga County Executive
Joanne M. Mahoney
www.savetherain.us
America’s First Green
Infrastructure Consent Order
Onondaga Lake
Onondaga County,
New York
City of Syracuse
• 7,660 acres
• 6.1 Billion Gallons Total Annual
Combined Sewage Generated by the
Metro Combined Sewer Service Area
Onondaga County Executive
Joanne M. Mahoney
Harbor Brook
Onondaga Creek
www.savetherain.us
History
• 1988 – Atlantic States Legal Foundation
files lawsuit against County
Onondaga Lake Facts
• 1998 – METRO consent judgment replaced
with Amended Consent Judgment (ACJ)
Watershed: 285 Square Miles
• 2009 ACJ amended to authorize use of
Gray and Green infrastructure
1 Mile Wide – 4.6 Miles Long
Average Depth: 35 feet
Max Depth: 63 feet
1940 – Swimming Banned
1970 – Fishing Banned
Onondaga County Executive
Joanne M. Mahoney
www.savetherain.us
1998-2008 CSO Abatement Accomplishments
• Developed System Model (SWMM)
• Separated and closed 12 CSOs
• Completed 1 storage facility
(Erie Blvd)
• Constructed 4 Floatables Control
Facilities (HB, Franklin, Teall, Maltbie)
• Completed 2 Regional Treatment Facilities
(Midland, Hiawatha)
• At least 35 projects investing over $350 million
Onondaga County Executive
Joanne M. Mahoney
www.savetherain.us
Fourth Stipulation to the ACJ (2009)
• Agreed to by all parties (State, ASLF, County)
• Authorized use of Gray and Green infrastructure
• Requires Storage Facilities in place of RTFs
• Includes time extension for Construction, and Metro phosphorus
effluent limit
• Balanced program provides additional water quality and
community benefits
– Improve Quality of Life (civic infrastructure investments),
Promote Sustainability (beyond stormwater), Cost Benefit/Efficiency
Onondaga County Executive
Joanne M. Mahoney
www.savetherain.us
Green Infrastructure
Program Summary
2009 - 2018
• 185 projects throughout CSS
• Compliments Gray Program
• Total Gray + Green annual
volume wet weather capture
requirements:
89.5% by Dec 2013
91.4% by 2015
93.0% by 2016
95.0% by Dec 2018
• Extensive monitoring &
reporting required
Onondaga County Executive
Joanne M. Mahoney
Before/After
Nicholas J. Pirro Convention Center
66,000 sq.ft. Green Roof (Completed 2011)
www.savetherain.us
National and Regional Recognition
• US EPA Green Infrastructure
Community Summit
• U.S. Water Prize
• NYS Environmental
Excellence Award
• APWA Environmental Project
of the Year (West Onondaga St.)
• StormWater Solutions Magazine
2013 US Water Prize Ceremony
Top Stormwater Project
Washington DC
(Rosamond Gifford Zoo)
• American Academy of Environmental Engineers Honor Award
(Water Street Gateway )
Onondaga County Executive
Joanne M. Mahoney
www.savetherain.us
Save the185Rain
Project
Map
projects completed and
120,000,000+ gallons of runoff reduction
Onondaga County Executive
Joanne M. Mahoney
www.savetherain.us
Net Environmental Benefit Analysis (NEBA)
• Publicly available document
• Appendix to County’s 2015 Annual
Report:
– http://savetherain.us/annual-report2015/
Onondaga County Executive
Joanne M. Mahoney
www.savetherain.us
Net Environmental Benefit Analysis (NEBA)
• Comprehensive review of 169 constructed Save the
Rain projects through 2014
– Projects grouped into two categories
• Structural – Providing benefits through infiltration and/or storage
• Trees – Including 4 shrubs = 1 tree
– “Easily” Quantifiable Benefits
• Water quantity, water quality, energy, air quality, climate change, etc.
– “Not Easily” Quantifiable Benefits
• Green job creation, crime reduction, increased property values,
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
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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
Water Quantity Benefits
• Reduced stormwater/CSO volume (SWMM)
– 109.7 MG stormwater, 53.4 MG CSO
• 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
concentrations
– Pollutant reduction = CSO reduction volume x pollutant concentration
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BOD5 = 13,000 lb/yr
TSS = 37,100 lb/yr
TP = 200 lb/yr
TN = 1,600 lb/yr
FC = 7,600 x 1012 lb/yr
Onondaga County Executive
Joanne M. Mahoney
www.savetherain.us
Air Quality/Climate Change Benefits
• i-Tree Eco calculates air pollutant removals from trees
• Reduce emissions from reduced wastewater treatment and building
heating/cooling calculated based on EPA metrics
Onondaga County Executive
Joanne M. Mahoney
www.savetherain.us
Air Quality/Climate Change Benefits
• Climate change benefits (CO2)
– Tree sequestration calculated by i-Tree Eco metrics for CO2 for small, medium and large trees
• 0.030, 0.034, 0.58 (lb/m2/yr)
• CO2 sequestration from plant biomass (green roofs, bioretention) = 0.37
lb/m2/yr (MSU, Andresen, 2009)
• Avoided emissions from WW treatment (0.5 lb/kWh electric, 0.14 lb/therm
natural gas, US EPA metrics)
Onondaga County Executive
Joanne M. Mahoney
www.savetherain.us
Valuation – Annual Savings
• Wastewater treatment cost savings = $89,700
– 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
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–
–
–
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
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Onondaga County Executive
Joanne M. Mahoney
www.savetherain.us
Contributors
• SUNY ESF
– Ted Endreny, Tom Taggart, Chuck Knoll
• US Forest Service
– David Nowak, Alison Bodine, Alexis Ellis
Onondaga County Executive
Joanne M. Mahoney
www.savetherain.us
Thank You
Zachary Monge, P.E.
Project Manager
CH2M Syracuse
[email protected]
315-401-7109
Onondaga County Executive
Joanne M. Mahoney
www.savetherain.us