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BMP Performance Monitoring
Research Field Facility at UNH Tc ~ 19 minutes
Watershed Boundary
Tree Filter
Porous Asphalt
Bioretention Retrofit
UNHSC Research Facility
Parallel Performance
Evaluation
•Each system uniformly sized to treat 1” runoff for 1 acre of impervious area
•WQV=3300 cf
•Qwqv=1 cfs
•Uniform contaminant loading
•Uniform storm event characteristics
•Systems lined for mass balance
•Long term record of hydrology and contaminants
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Hydrodynamic Separator Subsurface Infiltration
Filter Unit
Porous Asphalt Retention Pond Stone Swale
Gravel Wetland Sand Filter Bioretention Unit Tree Filter
Pervious Concrete
Isolator Row
Veg Swale
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Ru
no
ff R
ate
Time
Post-Development
Post-Development Peak Control
Pre-Development
Pre and Post Development Hydrographs
Courtesy Jeff Dennis, ME DEP, and CEI
Same storm < peak, = volume and > duration Same storm < peak and < volume
Storm with large peak and large volume
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Swale Flow and Volume Attenuation
Average Annual Peak Flow Reduction is 48%
Average Annual Lag Time is 19 min
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Porous Asphalt Flow and Volume Attenuation
Average Annual Peak Flow Reduction is 68%
Average Annual Lag Time is 790 min
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Not All BMPs Are Created Equal
– Physical Operations
– Biological Processes
– Chemical Processes
– Hydrologic Operations
Use Unit Operations & Processes (UOPs)
Economic impacts of land use change (increased runoff)
1.) Loss of revenue due to impacts to tourism and natural resources
2) Expenses from stress to municipal infrastructure
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