Stormwater BMPs for Water Quality and Quantity: Making ...Water Quality and Quantity: Making Sure Green is Green Brandywine Conservancy Environmental Management Center. Comprehensive

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



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



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…



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)


---

---

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)


26 ft. (parking on both sides)


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)



---

200

200-1,000

200

200-1,000

(Cohen, 1997; Bucks County Planning Commission, 1980; Center for Watershed Protection, 1998)



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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Stormwater BMPs for Water Quality and Quantity: Making ...Water Quality and Quantity: Making Sure Green is Green Brandywine Conservancy Environmental Management Center. Comprehensive