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CRWA Pres 20100524
1. Building Blue Project
Spruce Pond Sub-watershed, Franklin
A Practical Example of Pollution Prevention in a
Typical New England Suburban Town.
Charles River Watershed Association
5. Design Parameters
• Reduce phosphorus in stormwater runoff by
43% to comply with expected permit
• Design with no credit given for street
sweeping, fertilizer control or other practices
• Evaluate existing stormwater treatment for
credit and/or retrofit
6. Site 4A - 1: Central Park Terrace/
North Park Street
7. Fletcher Field Infiltration Area
Proposed underground infiltration
chamber to infiltrate 1” storm
INFILTRATION CHAMBER
DRAINAGE AREA 1,096,682 sqft
% IMPERVIOUS 32%
BMP AREA (AB) 14,775 sqft
BMP DEPTH (AD) 3 ft
ACTUAL WQV 30,941 cuft
ACTUAL WQD 1.00 in
9. Peck Street Lot, Fletcher Field
Bioretention area placed within
reorganized parking lot
BIORETENTION- 1” Storm
DRAINAGE AREA 34,474 sqft
% IMPERVIOUS 100%
WQV 2873 cf
DEPTH MEDIA (DF) 2.00 ft
PONDING HEIGHT (2X HF) 9 in
TF (FILTER TIME) 2 days
SURFACE AREA
REQUIRED 1210 sqft
11. Peck Street lot – alternative design in park area
Alternative 2- Bioretention system
placed on field instead of reorganizing
parking lot
BIORETENTION- 0.4” Storm
DRAINAGE AREA 34,474 sqft
% IMPERVIOUS 100%
WQV 1149 cf
DEPTH MEDIA (DF) 2.00 ft
PONDING HEIGHT (2X HF) 9 in
TF (FILTER TIME) 2 days
SURFACE AREA REQUIRED 484 sqft
17. Drainage Areas - Parmenter School
Four Bioretention areas dispersed across
site to treat 1” storm
BIORETENTION - 1" storm
DRAINAGE AREA 93,422.05 sqft
IMPERVIOUS AREA 49,933.31 sqft
PERVIOUS AREA 43,488.74 sqft
WQV 4,107 cf
DEPTH MEDIA (DF) 2.00 ft
PONDING HEIGHT 6 in
TF (FILTER TIME) 2 days
SURFACE AREA
REQUIRED 1826 sqft
21. Site 3G – 2: Cottage St./Union St.
Dispersed bioretention areas treating 1” storm
across sub-drainage areas including:
• Cottage and Union Street on and off ROW
retrofits
• On site retrofits on hardware store site, etc.
• Bump-outs at intersection of Geb & Saxon St.
BIORETENTION - 1" storm
DRAINAGE AREA 340,774.00 sqft
IMPERVIOUS AREA 270,628.70 sqft
PERVIOUS AREA 70,145.30 sqft
WQV 20,882 cf
DEPTH MEDIA (DF) 2.00 ft
PONDING HEIGHT (2X HF) 6 in
TF (FILTER TIME) 2 days
SURFACE AREA
REQUIRED 9,281 sqft
27. Lessons Learned
• Model optimization can save
you money!
• Treat the first flush
• Infiltration is the most cost
effective strategy
• Treating large volumes is cost
effective but may not solve
the whole problem
28. Next Steps for Franklin
• New stormwater permit, expected by end of
2010
– Develop a Phosphorus Control Plan within 5 years
– Implement Phosphorus Control Plan within 10
years
• Install several pilot projects to learn from
experience
29. Special Thanks
• Jeff Nutting, Town Administrator
• Bill Yadisernia, Robert Cantoreggi, Franklin DPW
• James Esterbrook, Franklin GIS Department
• Nick Alfieri, Franklin Conservation Commission
• Beth Dahlstrom, Franklin Planning Department
• Franklin Technical Advisory Committee