Subwatershed Restoration Plan, Franklin, MA Julie Wood Senior Scientist Charles River Watershed Association 190 Park Road, Weston, MA 02493 781-788-0007 [email protected]www.charlesriver.org New England Interstate Water Pollution Control Commission 23rd Annual Nonpoint Source Pollution Conference May 15, 2012
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Fletcher field asphalt swale, 2010 Fletcher field vegetated swale, 2011
Fletcher Field Construction, 2011
Rain garden, with overflow at existing
catch basin, 2011
Reaching the target phosphorus reduction was an iterative process
Scenario 0: Best Professional Judgment Plan
Prioritize sites
Design treatment for most obvious
sites
Assess progress toward reduction goal
Consider more sites for
treatment
Scenario 2: Optimized Plan
Treatment systems sized by optimization algorithm
Optimization restraints: Minimize cost
Meet phosphorus reduction
Treatment system size allowed to vary (no upper or lower bounds set)
Treatment system type and location not allowed to vary
Proposed Drainage Area Retrofits by Scenario
S0
Plan S0 Plan S2
Phosphorous Removal by Drainage Area Plan S0 Plan S2
Drainage Area Retrofit Treatment Systems
Preliminary Cost Comparison:
Cost Per Pound of TP Removed
$0.00
$5,000.00
$10,000.00
$15,000.00
$20,000.00
$25,000.00
$30,000.00
$35,000.00
CRWA S0 CRWA S2 EPA S1 EPA S2 EPA S3
Scenario
Do
llars
($)
$/lb TP removed
Preliminary Cost Comparison
Cost Per Impervious Acre Treated
$0.00
$5,000.00
$10,000.00
$15,000.00
$20,000.00
$25,000.00
$30,000.00
CRWA S0 CRWA S2 EPA S1 EPA S2 EPA S3
Scenario
Do
llar
($)
$/impervious acre
Summary: Lessons Learned
Planning and Design Process
Site visits are vital
Detailed stormwater
infrastructure mapping is
very important
Not all treatment systems
are appropriate at all sites
Summary: Lessons Learned
Model Optimization
Model optimization can save you money!
Treat the first flush
Infiltration is the most cost effective strategy
Treating large volumes at one site may be cost effective but does not solve the whole problem
Summary: Lessons Learned
Design Results
Achieving the TMDL is possible but will require planning, time, and resources
Least expensive strategy may not be the most desirable strategy
Watershed or subwatershed level planning allows implementation to occur opportunistically while providing assurance that an overall goal is being achieved