Stormwater BMPs for Water Quality and Quantity: Making ...Water Quality and Quantity: Making Sure...
Transcript of Stormwater BMPs for Water Quality and Quantity: Making ...Water Quality and Quantity: Making Sure...
StormwaterStormwater BMPsBMPs for for
Water Quality and Quantity:Water Quality and Quantity:
Making Sure Green is GreenMaking Sure Green is Green
Brandywine ConservancyBrandywine Conservancy
Environmental Management CenterEnvironmental Management Center
Comprehensive Comprehensive StormwaterStormwater Management (LID)Management (LID)
--Water QualityWater Quality
--Peak RatePeak Rate
--Volume and HydrologyVolume and Hydrology
--TemperatureTemperature
“…everything is connected to everything else…”“…everything is connected to everything else…”
In the midst of….In the midst of….
• PADEP Changing MS4 Requirements
• PADEP Changing Chapter 102
• Possible PADEP Changing the BMP Manual
• EPA New Stormwater Requirements
• EPA New Requirements for Chesapeake Bay
…what’s a municipality to do?
Some Basics:Some Basics:
Penn’s Woods…Land and WaterPenn’s Woods…Land and Water
Two Sides of the Same CoinTwo Sides of the Same Coin
Imbalancing Natural Systems….
Some Impacts of Conventional Some Impacts of Conventional
(Unsustainable) Development(Unsustainable) Development
• Not just Increased Flooding!
• Increased Runoff Volume
• Decreased Evapotranspiration and Groundwater Recharge
• Increased Frequency of Runoff Events
• Faster Conveyance of Water
• Erosion and Stream Channel Changes
• Decreased Baseflow
• Impacted Aquatic Life
• Pollutants and Temperature Impacts
We all live downstream….We all live downstream….
We haven’t understood the basic We haven’t understood the basic
hydrology of stream and river hydrology of stream and river
systems.systems.
WELL
STREAM
AQUIFER
BEDROCK
SOILWATER TABLE (DEVELOPED CONDITIONS)
Green Valleys Association
Cahill AssociatesEnvironmental Consultants
Land Development Impacts on Stream Morphology:
• Major changes to bankfull flow
• Channel widening, downcutting/undercutting, streambed scouring
• Stream bank erosion
• Imbedded substrate with benthic/other aquatic impacts
• Loss of pools, riffles, aquatic habitat
Manage Stormwater as a Valuable Manage Stormwater as a Valuable
Resource… not a Disposal Problem. Resource… not a Disposal Problem.
Volume Control Is Critical….Volume Control Is Critical….
to Minimize Downstream Floodingto Minimize Downstream Flooding
to Support Stream Baseflow/Low Flowto Support Stream Baseflow/Low Flow
to Support Wells and Springsto Support Wells and Springs
to Support Wetlandsto Support Wetlands
to Minimize Nonpoint Pollutant Loadingsto Minimize Nonpoint Pollutant Loadings
to Minimize Stream Morphological Impactsto Minimize Stream Morphological Impacts
A Word on Vegetation….A Word on Vegetation….
Trees as the only Trees as the only BestBest MP…MP…
Impacting Essential Impacting Essential
Living Soil:Living Soil:
Common Bulk Density MeasurementsCommon Bulk Density Measurements
Concrete
2.2 g/cc
Golf Courses; Parks; Athletic Fields
1.69 to 1.97 g/cc
Residential Neighborhoods
1.69 to 1.97 g/cc
Undisturbed Lands
Forests & Woodlands
1.03 g/cc
David B. Friedman, District Director Ocean County Soil Conservation District
Solutions:Solutions:
Best Management PracticesBest Management Practices
Sustainable Sustainable StormwaterStormwater
Management (aka LID or Green Management (aka LID or Green
Infrastructure):Infrastructure):
NonNon--Structural Approaches Structural Approaches
PreventivePreventive
Structural Practices Structural Practices
MitigativeMitigative
Preventive NonPreventive Non--Structural BMP Categories Structural BMP Categories (LID)(LID)
Protect Sensitive and Special Value Resources from Watershed to Protect Sensitive and Special Value Resources from Watershed to Site Site BMPBMP Protect sensitive/special value featuresProtect sensitive/special value features
BMP BMP Protect/conserve/enhance riparian areasProtect/conserve/enhance riparian areas
BMP BMP Protect/conserve natural flow pathwaysProtect/conserve natural flow pathways
Cluster and ConcentrateCluster and ConcentrateBMPBMP Cluster uses at each site; build on smallest area possibleCluster uses at each site; build on smallest area possible
BMP BMP Concentrate uses areawide through Smart Growth Concentrate uses areawide through Smart Growth
Minimize Disturbance and Minimize MaintenanceMinimize Disturbance and Minimize MaintenanceBMP BMP Minimize total disturbed area Minimize total disturbed area –– grading grading
BMP BMP Minimize soil compaction in disturbed areasMinimize soil compaction in disturbed areas
BMP BMP ReRe--vegetate and revegetate and re--forest disturbed areas (natives)forest disturbed areas (natives)
Reduce Impervious CoverReduce Impervious CoverBMP BMP Reduce street imperviousnessReduce street imperviousness
BMP BMP Reduce parking imperviousnessReduce parking imperviousness
Disconnect/Distribute/DecentralizeDisconnect/Distribute/DecentralizeBMP BMP Rooftop disconnectionRooftop disconnection
BMP BMP Disconnection from storm sewersDisconnection from storm sewers
Preventive NonPreventive Non--Structural BMP Structural BMP
Categories with Specific Categories with Specific BMPsBMPs::
Concentrate and ClusterConcentrate and ClusterBMP Concentrate uses areawide BMP Concentrate uses areawide
through Smart Growth through Smart Growth
practicespractices
BMP Cluster uses at each site; build BMP Cluster uses at each site; build
on the smallest area possibleon the smallest area possible
Preventive NonPreventive Non--Structural BMP Structural BMP
Categories with Specific Categories with Specific BMPsBMPs::
Protect Sensitive and Special Value Resources Protect Sensitive and Special Value Resources Watershed to SiteWatershed to Site
BMP Protect sensitive/special value BMP Protect sensitive/special value
featuresfeatures
BMP Protect/conserve/enhance utilize BMP Protect/conserve/enhance utilize
riparian areasriparian areas
BMPBMP Protect/utilize natural flow Protect/utilize natural flow
pathways in overall stormwater pathways in overall stormwater
planning and designplanning and design
Preventive NonPreventive Non--Structural BMP Structural BMP
Categories with Specific Categories with Specific BMPsBMPs::
Minimize Disturbance/Minimize MaintenanceMinimize Disturbance/Minimize MaintenanceBMP Minimize total disturbed area BMP Minimize total disturbed area ––
grading grading
BMP Minimize soil compaction in BMP Minimize soil compaction in
disturbed areasdisturbed areas
BMP BMP ReRe--vegetate and revegetate and re--forest forest
disturbed areas, using native disturbed areas, using native
speciesspecies
Minimize soil compaction…Minimize soil compaction…
Preventive NonPreventive Non--Structural BMP Structural BMP
Categories with Specific Categories with Specific BMPsBMPs::
Reduce Impervious CoverReduce Impervious CoverBMP Reduce street imperviousnessBMP Reduce street imperviousness
BMP Reduce parking imperviousnessBMP Reduce parking imperviousness
Table 1: Narrow Residential Street Widths
Jurisdiction Residential Street Pavement Width
Maximum Daily Traffic (trips/day)
State of New Jersey 20 ft. (no parking)
28 ft. (parking on one side)
0-3,500
0-3,500
State of Delaware 12 ft. (alley)
21 ft. (parking on one side)
---
---
Howard County, Maryland 24 ft. (parking not regulated) 1,000
Charles County, Maryland 24 ft. (parking not regulated) ---
Morgantown, West Virginia 22 ft. (parking on one side) ---
Boulder, Colorado 20 ft.
20 ft. (no parking)
22 ft. (parking on one side)
26 ft. (parking on both sides)
26 ft. (parking on one side)
150
350-1,000
350
350
500-1,000
Bucks County, Pennsylvania 12 ft (alley)
16-18 ft. (no parking)
20-22 ft. (no parking)
26 ft. (parking on one side)
28 ft. (parking on one side)
---
200
200-1,000
200
200-1,000
(Cohen, 1997; Bucks County Planning Commission, 1980; Center for Watershed Protection, 1998)
Preventive NonPreventive Non--Structural BMP Structural BMP
Categories with Specific Categories with Specific BMPsBMPs::
Maximize preventive source controlsMaximize preventive source controlsBMP Trash/debris collectionBMP Trash/debris collection
BMP Street sweeping, spillsBMP Street sweeping, spills
BMP Fertilization regulationsBMP Fertilization regulations
OthersOthers
Mitigative Structural Best Management Practices
Runoff Volume/Infiltration-Oriented Vegetative and Soil-Based
1. Rain/recharge gardens/Bioretention2. Vegetated filter strips3. Vegetated Swales (Bio-infiltration, Dry, Wet)4. Porous pavement with infiltration beds5. Infiltration basins6. Subsurface infiltration beds7. Infiltration trenches8. French drains/dry wells9. Outlet control (level spreaders, etc.)10. Retentive grading techniques, berms
Runoff Volume/Non-Infiltration-Oriented11. Vegetated roofs12. Cisterns/Rain Barrels/Capture Reuse
Runoff Quality/Non-Infiltration13. Constructed wetlands14. Wet ponds/retention basins15. Filters16. Water quality inserts17. Detention/Extended Detention18. Special Storage: Parking Lot, Rooftop, etc.
Restoration BMPs19. Riparian Corridor Restoration20. Revegetation/Reforestation21. Soils Amendment
Porous Porous
PavementPavement
West Chester, PA 19382West Chester, PA 19382
Cape May, NJ 08204Cape May, NJ 08204
www.thcahill.comwww.thcahill.com
Cahill AssociatesCahill AssociatesEnvironmental ConsultantsEnvironmental Consultants
DuPont Barley Mills Office ComplexDuPont Barley Mills Office Complex
West Chester, PA 19382West Chester, PA 19382
Cape May, NJ 08204Cape May, NJ 08204
www.thcahill.comwww.thcahill.com
Cahill AssociatesCahill AssociatesEnvironmental ConsultantsEnvironmental Consultants
Penn State University ParkPorous Concrete Sidewalks
Villanova UniversityPorous Concrete Plaza
Infiltration Beneath Standard WalkwaysInfiltration Beneath Standard Walkways
Rain Gardens / BioretentionRain Gardens / Bioretention
Rainwater can support the landscape and soils, reducing pipes and basins.
Vegetated Infiltration BedsVegetated Infiltration Beds
Distributing Water to Prevent Sinkhole and Flooding Problems
……27 years of infiltrating over 27 years of infiltrating over limestone!limestone!
Infiltration Basin – Commerce Plaza 1983
Infiltration Infiltration
TrenchesTrenches
• Reduced Disturbance
Infiltration BermsInfiltration Berms
• Simple construction along contour
• Capture runoff behind shallow berm
• Allow runoff to infiltrate
• Very little disturbance
Vegetated SwaleVegetated Swale
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