Stormwater Management: Making Sure Green Is Green
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Transcript of Stormwater Management: Making Sure Green Is Green
West Chester, PA 19382West Chester, PA 19382Cape May, NJ 08204Cape May, NJ 08204
Cahill AssociatesCahill AssociatesEnvironmental ConsultantsEnvironmental Consultants
Stormwater Management: Stormwater Management: Making Sure Green Is Green Making Sure Green Is Green
Critical Link between Critical Link between Land and Water:Land and Water:
Two Sides of the Same CoinTwo Sides of the Same Coin
What happens on the land….
…has everything to do with what happens in and to the water.
Jersey City Reservoir, Morris County
Components of Sustainability Components of Sustainability Water-Related:Water-Related:
• Comprehensive StormwaterComprehensive Stormwater ManagementManagement• Recycled WastewaterRecycled Wastewater• Water Conserving Water UseWater Conserving Water Use• Just for StartersJust for Starters
The Problem - From Smart The Problem - From Smart Growth…Growth…
““The only thing new in the world is the The only thing new in the world is the history we’ve forgotten….” history we’ve forgotten….” Harry TrumanHarry Truman
Sustainability…Sustainability…
• Relates to private residential subdivision and retail and office and industrial centers….
• Also relates to public facilities like schools and parks and recreational facilities and roads….
This could be a new park next to you!
Stormwater Impacts of Conventional Stormwater Impacts of Conventional Development (including Parks and Development (including Parks and
Rec!)Rec!)
• 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
……not to mention other impacts of not to mention other impacts of conventional development conventional development practices…practices…
Habitat Loss/BiodiversityHabitat Loss/BiodiversityWetlands/Floodplains/Other Wetlands/Floodplains/Other
AreasAreasSoils/Special Geologic FeaturesSoils/Special Geologic FeaturesAir Quality/MicroclimateAir Quality/MicroclimateNoiseNoiseHistorical/ArchaeologicalHistorical/ArchaeologicalAesthetics/ScenicAesthetics/ScenicQuality of LifeQuality of LifePublic HealthPublic Health
BalancinBalancing the g the Water Water CycleCycle
Annual Hydrologic CycleAnnual Hydrologic CycleFor an Average YearFor an Average Year
Altered Hydrologic CycleAltered Hydrologic Cycle
InfiltrationInfiltrationInfiltration
Surface RunoffSurface RunoffSurface Runoff
Conventional Development Conventional Development Water Cycle Impacts:Water Cycle Impacts:
• Increased Peak Runoff Rate• Increased Runoff Volumes• Decreased Infiltration• Decreased Groundwater Recharge• Decreased Stream Baseflow• Decreased Evapotranspiration• Temperature
All of which translate into many more related hydrologic, ecologic, other impacts.
Conventional (Detention) Conventional (Detention) Stormwater ManagementStormwater Management
• Controls Peak Rate of Runoff to Predevelopment Conditions
• Fails to Control Volume of Runoff
• Fails to Control Nonpoint Pollutant/Temperature Loadings
We all live downstream….We all live downstream….We haven’t understood the We haven’t understood the
basic hydrology of stream and basic hydrology of stream and river systems.river systems.
Average Annual Rainfall Volume that Occurs by Storm Magnitude for Harrisburg, PA
(PA State Climatological Office, 1926 – 2003)
Average Annual Rainfall Volume that Occurs by Storm Magnitude for Harrisburg, PA(PA State Climatological Office, 1926 - 2003)
1%1%
6%
27%
65%
4" +
3" - 4"
2" - 3"
1" - 2"
0.1" - 1"
0.1” - 1”
Stormwater management has Stormwater management has focused only on the largest focused only on the largest
storms…we haven’t paid storms…we haven’t paid attention to annual water attention to annual water balance and the reality of balance and the reality of
smaller storms.smaller storms.
WELL
STREAM
AQUIFER
BEDROCK
SOIL
Green Valleys Association
Cahill AssociatesEnvironmental Consultants
Manage Stormwater as a Manage Stormwater as a Precious Resource… not a Precious Resource… not a Disposal ProblemDisposal Problem
for Stream Baseflow/Low Flowfor Stream Baseflow/Low Flowfor Wells and Springsfor Wells and Springsfor Wetlandsfor Wetlands
Nonpoint Source PollutionNonpoint Source Pollution
• Transported by and dissolved in runoff• Petroleum Hydrocarbons• Metals• Nutrients (Phosphorus and Nitrate)• Organic matter• Sediment• Synthetic Organics (pesticides,herbicides)
Impacts on:Impacts on:
Stream MorphologyStream MorphologyAquatic HabitatAquatic HabitatBank Erosion and UndercuttingBank Erosion and UndercuttingStreambed ScouringStreambed Scouring
Dry Channels…
Eroded Streambanks…
Land Development Impacts on Stream Morphology:
• Channel widening, downcutting, scouring
• Stream bank erosion
• Imbedded substrate with benthic impacts
• Loss of pools, riffles
Land Development Impacts on Stream Ecology:
• Reduced diversity of aquatic insects
• Reduced diversity of fish
• Decline of amphibians
• Degraded wetlands, riparian zones
Land Development Impacts on Land Development Impacts on VegetationVegetation
Trees:Trees:the Perfect the Perfect BMPBMP
Land Development Impacts on Soil:Land Development Impacts on Soil:A Living FoundationA Living Foundation
Soil Horizons• Layer of Soil Parallel
to Surface• Properties a function
of climate, landscape setting, parent material, biological activity, and other soil forming processes.
• Horizons (A, E, B, C, R, etc)
Image Source: University of Texas, 2002
Dramatic increases in soil compaction…
Common Bulk Density Measurements orCommon Bulk Density Measurements orHow compacted is this soil?How compacted is this soil?
David B. Friedman, District Director -- Ocean County Soil Conservation District
Golf Courses, Parks, Athletic Fields1.69 to 1.97g/cc
Undisturbed Lands:Forests & Woodlands
1.03g/cc
CONCRETE2.2g/cc
ResidentialNeighborhoods
1.69 to 1.97g/cc
Bulk Density is defined as the weight of a unit volume of soil including its pore space (g/cc or grams/cubic centimeter). Water and air are important components of soil and we must frame our soil concepts so that factors affecting water and air dynamics are included. Thus, we are primarily interested in bulk density and pore space as they affect water and aeration status, and root penetration and development.
Effects of Soil DisturbanceEffects of Soil Disturbance
Measurements of Sampled Soil within 20 inches of surfaceSITE Bulk Density (g/cm³) Permeability (in/hr)
Woods 1.42 15Pasture 1.47 9.9
Single House 1.67 7.1Subdivision Lawn 1 1.79 0.14
Garage Lawn 1.82 0.04Cleared Woods 1.83 0.13
Subdivision Lawn 2 2.03 0.03Althletic Field 1.95 0.01
CONCRETE 2.2 - 2.4 0
Adapted from Impact of Soil Disturbance During Construction on Bulk Density and Infiltration in Ocean County, New Jersey (2001) - www.ocscd.org/soil.pdf
Getting Stormwater Right:Getting Stormwater Right:
Structural BMPs Structural BMPs MitigativeMitigative
Non-Structural BMPsNon-Structural BMPsPreventivePreventive
Site Planning & Design ProceduresSite Planning & Design Procedures
STORMWATER CALCULATIONS
STORMWATERMANAGEMENT
PLAN
Zoning Guidanc
e
SLDO Guidance
Township Comprehensive
Plan
Minimum Disturbance, Minimum Maintenance
Lot Configuration & Clustering
Impervious Coverage
Disconnect, Distribute, Decentralize
Source Control
SITE ANALYSIS NON-STRUCTURAL BMPsSTRUCTURAL BMPs
Site Analysis: Constraints vs. Opportunities
BackgroundFactors:
EnvironmentalConstraints
BackgroundFactors:
EnvironmentalOpportunities
WATERSHED ANALYSIS
BUILDING PROGRAM
ISSUES
PRE-SUBMISSION
MEETING
APPLICANTSUBMISSION
Design Phase 2MITIGATIVE
BMPs
RestorationBMPs
Runoff Quality BMPs
Volume Reduction
BMPs
Soil Infiltration-
based BMPs
Design Phase 1PREVENTIVE
BMPs
Sensitive Areas
Site Factors Inventory
WATERSHEDANALYSIS
SITE ANALYSIS
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, bermsRunoff Volume/Non-Infiltration-Oriented
11. Vegetated roofs12. Cisterns/Rain Barrels/Capture Reuse
Runoff Quality/Non-Infiltration13. Constructed wetlands14. Wet ponds/retention basins15. Filters16. Water quality inserts17. Detention/Extended Detention
18. Special Storage: Parking Lot, Rooftop, etc.Restoration BMPs
19. Riparian Corridor Restoration
20. Revegetation/Reforestation
21. Soils Amendment
One size no longer fits all…One size no longer fits all…
Structural BMPs Structural BMPs Runoff Volume/Infiltration-Oriented Vegetative and Soil-Based
• Porous Pavement• Infiltration Basin• Infiltration Bed• Infiltration Trench• Rain Garden/Bioretention• Dry Well / Seepage Pit• Constructed Filter• Vegetated Swale• Vegetated Filter Strip• Berm
Pollutant Removal EffectivenessPollutant Removal Effectiveness
POLLUTANT INFILTRATION PRACTICES
Stormwater Wetlands
Stormwater Ponds Wet
Filtering Practices
Water Quality Swales
Stormwater Dry Ponds
Total Phosphorus
70 49 51 59 34 19
Soluble Phosphorus
85 35 66 3 38 -6
Total Nitrogen 51 30 33 38 84 25
Nitrate 82 67 43 -14 31 4
Copper N/A 40 57 49 51 26
Zinc 99 44 66 88 71 26
TSS 95 76 80 86 81 47
Water quality benefits of porous pavement with infiltration from “National Pollutant Removal Performance Database for Stormwater Treatment Practices” Center for Watershed Protection, June 2000 \
Porous Porous PavemePaveme
ntnt
Porous Paving w/ InfiltrationPorous Paving w/ Infiltration
Rams Head Plaza at University of North Rams Head Plaza at University of North CarolinaCarolina
West Chester, PA 19382West Chester, PA 19382Cape May, NJ 08204Cape May, NJ 08204
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DuPont Barley Mills Office DuPont Barley Mills Office ComplexComplex
West Chester, PA 19382West Chester, PA 19382Cape May, NJ 08204Cape May, NJ 08204
Cahill AssociatesCahill AssociatesEnvironmental ConsultantsEnvironmental Consultants
• Precipitation is carried from roof by roof drains to storage beds.• Stormwater runoff from impervious and lawn areas is carried to storage
beds.• Precipitation that falls on porous paving enters storage beds directly• Stone beds with 40% void space store water. Continuously perforated
pipes distribute stormwater from impervious surfaces evenly throughout the beds.
• Stormwater exfiltrates from storage beds into soil, recharging groundwater.
Costs of Porous PavementCosts of Porous Pavement
• Generally costs the same or less for the site• Actual asphalt slightly more expensive (special gradation and higher grade binder)• Reduces Piping Infrastructure and Basins • Penn State Berks Campus – 320 spaces 1999
- $3500 / space budgeted for standard pavement
- $2700 actual cost for porous
Swarthmore College
Permeable Patios, Terraces, Permeable Patios, Terraces, CourtyardsCourtyards
Infiltration BasinsInfiltration Basins
Infiltration Basin – Commerce Plaza 1983
Vegetated Infiltration BedsVegetated Infiltration Beds
Distributing Water in Sub-Surface Bed
Penn New School Penn New School 4343rdrd and Locust Streets and Locust Streets
• PaDEP Growing Greener & Philadelphia Water Department
• Porous Pavement Play Yard• Infiltration Bed Beneath Athletic Field• Rain Gardens and Native Vegetation • Environmental Education
Previous impervious parking lot at site
Completed Porous Pavement PlayfieldCompleted Porous Pavement Playfield
Infiltration TrenchesInfiltration Trenches
Rain Gardens / BioretentionRain Gardens / Bioretention
Rainwater can support the landscape and soils, reducing pipes and basins.
Dry Well / Seepage PitDry Well / Seepage Pit
Vegetated Swales (simple & Vegetated Swales (simple & inexpensive)inexpensive)
Vegetated Swale (Enhanced)Vegetated Swale (Enhanced)
Vegetated Filter Vegetated Filter Strip Strip
Infiltration BermsInfiltration Berms
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, bermsRunoff Volume/Non-Infiltration-Oriented
11. 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 Restoration
20. Revegetation/Reforestation21. Soil Amendment
Vegetated RoofVegetated Roof
Vegetated RooftopsVegetated Rooftops
• Reduce the Volume of Stormwater Runoff (typically 50% or more annually)
• Reduce the Rate of Stormwater Runoff
• Increase the Lifespan of a Conventional Roof Surface by 2 to 3 times
• Reduce heating and cooling costs
• Enhance property values and Aesthetics
Fencing Academy of PhiladelphiaFencing Academy of PhiladelphiaRoofmeadowRoofmeadowTMTM
Before
After
Stuttgart’s “Green Space”Stuttgart’s “Green Space”
Capture / ReuseCapture / Reuse
• Volume Control
• Reduced potable water consumption
• Cost savings
UNC-Chapel UNC-Chapel HillHill
• $1.5 billion construction program, largest in 211-year history of UNC-CH
• Funded in part by biggest higher education bond in U.S.
• Guided by award-winning 2001 Campus Master Plan
• Included an Environmental component which set rigorous goals
UNC-Chapel Hill Campus Master PlanAyers Saint Gross, Architects
Image Source: Andropogon Associates
Rams Head Stormwater System
•40,000 SF Green roof plaza•Cistern•Vegetated swale w/ check dams
•Reinforced-turf fire lane•Storage/infiltration bed under artificial turf athletic field•Re-created ephemeral stream•Water quality inserts•Manages runoff from project area and additional 17 acres
Vegetated Vegetated Roof PlazaRoof Plaza
Unique, non-proprietary system design, including:• 56,000-gallon cistern under pathways• Additional 32,000-gallon water storage zone under
soil to support trees• Visual stormwater connections and overflows• 12 to 24 inches of soil for native trees and
groundcovers• Perforated pipe and Rainstore distribution system
Green Roof Plaza with Cisterns
• Cistern constructed of recycled plastic “Rainstore”
• Overflow to Storage Layer under soil
Bricks being placed above cistern Flood test of cistern area
•56,000 gallon cistern filled by 2.7 inches of rainfall (in one or more storms)•On average, it will fill and empty 9 times per irrigation season•Provides 3 weeks irrigation without replenishment
…And then into an Infiltration Bed beneath an Artificial Turf Athletic Field
Returning Springs
and Stormwater Flow to Daylight
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, bermsRunoff Volume/Non-Infiltration-Oriented
11. 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 Restoration
20. Revegetation/Reforestation21. Soil Amendment
Constructed WetlandsConstructed Wetlands
Wet Pond / Retention BasinWet Pond / Retention Basin
Water Quality Inserts/FiltersWater Quality Inserts/Filters
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, bermsRunoff Volume/Non-Infiltration-Oriented
11. 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. Soil Amendment
Riparian Buffer Restoration and ReforestationRiparian Buffer Restoration and Reforestation
Lawn to Sustainable Meadows
Seeding 1st year
2nd year
3rd year
Landscape RestorationLandscape Restoration
Images courtesy of Rolf Sauer and PartnersImages courtesy of Rolf Sauer and Partners
Landscape Restoration (cont.)Landscape Restoration (cont.)
Soil Amendment / RestorationSoil Amendment / Restoration
Non-Structural Strategies Non-Structural Strategies
aka Low Impact aka Low Impact DevelopmentDevelopment
aka Conservation Designaka Conservation Designaka Green Infrastructureaka Green Infrastructure
Even for Community Parks!Even for Community Parks!
Site Planning & Design ProceduresSite Planning & Design Procedures
STORMWATER CALCULATIONS
STORMWATERMANAGEMENT
PLAN
Zoning Guidanc
e
SLDO Guidance
Township Comprehensive
Plan
Minimum Disturbance, Minimum Maintenance
Lot Configuration & Clustering
Impervious Coverage
Disconnect, Distribute, Decentralize
Source Control
SITE ANALYSIS NON-STRUCTURAL BMPsSTRUCTURAL BMPs
Site Analysis: Constraints vs. Opportunities
BackgroundFactors:
EnvironmentalConstraints
BackgroundFactors:
EnvironmentalOpportunities
WATERSHED ANALYSIS
BUILDING PROGRAM
ISSUES
PRE-SUBMISSION
MEETING
APPLICANTSUBMISSION
Design Phase 2MITIGATIVE
BMPs
RestorationBMPs
Runoff Quality BMPs
Volume Reduction
BMPs
Soil Infiltration-
based BMPs
Design Phase 1PREVENTIVE
BMPs
Sensitive Areas
Site Factors Inventory
WATERSHEDANALYSIS
SITE ANALYSIS
Non-Structural BMP Categories with Specific Non-Structural BMP Categories with Specific Non-Structural BMPsNon-Structural BMPs
1.0 Protect Sensitive and Special Value Resources1.0 Protect Sensitive and Special Value ResourcesBMP 1.1BMP 1.1 Protect sensitive/special value featuresProtect sensitive/special value featuresBMP 1.2BMP 1.2 Protect/conserve/enhance utilize riparian areasProtect/conserve/enhance utilize riparian areasBMP 1.3BMP 1.3 Protect/utilize natural flow pathways in overall Protect/utilize natural flow pathways in overall
stormwater stormwater planning and designplanning and design2.0 Cluster and Concentrate2.0 Cluster and Concentrate
BMP 2.1BMP 2.1 Cluster uses at each site; Build on the smallest Cluster uses at each site; Build on the smallest area possiblearea possible
BMP 2.2BMP 2.2 Concentrate uses areawide through Smart Concentrate uses areawide through Smart Growth practicesGrowth practices3.0 Minimize Disturbance and Minimize Maintenance3.0 Minimize Disturbance and Minimize Maintenance
BMP 3.1BMP 3.1 Minimize total disturbed area – grading Minimize total disturbed area – grading BMP 3.2BMP 3.2 Minimize soil compaction in disturbed areasMinimize soil compaction in disturbed areasBMP 3.3BMP 3.3 Re-vegetate and re-forest disturbed areas, using Re-vegetate and re-forest disturbed areas, using
native speciesnative species4.0 Reduce Impervious Cover4.0 Reduce Impervious Cover
BMP 4.1BMP 4.1 Reduce street imperviousnessReduce street imperviousnessBMP 4.2BMP 4.2 Reduce parking imperviousnessReduce parking imperviousness
5.0 Disconnect/Distribute/Decentralize5.0 Disconnect/Distribute/DecentralizeBMP 5.1BMP 5.1 Rooftop disconnectionRooftop disconnectionBMP 5.2BMP 5.2 Disconnection from storm sewersDisconnection from storm sewers
Non-Structural BMP Categories with Specific Non-Structural BMP Categories with Specific Non-Structural BMP’sNon-Structural BMP’s
1.0 1.0 Protect Sensitive and Special Value Protect Sensitive and Special Value ResourcesResources
BMP 1.1BMP 1.1 Protect sensitive/special value Protect sensitive/special value featuresfeatures
BMP 1.2BMP 1.2 Protect/conserve/enhance utilize Protect/conserve/enhance utilize riparian areasriparian areas
BMP 1.3BMP 1.3 Protect/utilize natural flow Protect/utilize natural flow pathways in overall pathways in overall
stormwater stormwater planning and planning and designdesign
Non-Structural BMP Categories with Non-Structural BMP Categories with Specific Non-Structural BMPsSpecific Non-Structural BMPs
2.0 Cluster and Concentrate2.0 Cluster and Concentrate
BMP 2.1BMP 2.1 Cluster uses at each site; Cluster uses at each site; build build on the smallest area on the smallest area possiblepossible
BMP 2.2BMP 2.2 Concentrate uses areawide Concentrate uses areawide through Smart Growth through Smart Growth
practicespractices
Cost Comparison:Cost Comparison:Chapel RunChapel Run
Conventional DevelopmentConventional Development$2,460,200$2,460,200Conservation Design-ParkwayConservation Design-Parkway $ $ 888,735888,735
Non-Structural BMP Categories with Specific Non-Structural BMP Categories with Specific Non-Structural BMPsNon-Structural BMPs
3.0 3.0 Minimize Disturbance and Minimize Minimize Disturbance and Minimize MaintenanceMaintenance
BMP 3.1BMP 3.1 Minimize total disturbed area – Minimize total disturbed area – grading grading
BMP 3.2BMP 3.2 Minimize soil compaction in Minimize soil compaction in disturbed areasdisturbed areas
BMP 3.3BMP 3.3 Re-vegetate and re-forest Re-vegetate and re-forest disturbed areas, using disturbed areas, using
native native speciesspecies
Non-Structural BMP Categories with Non-Structural BMP Categories with Specific Non-Structural BMPsSpecific Non-Structural BMPs
4.0 Reduce Impervious Cover4.0 Reduce Impervious Cover
BMP 4.1BMP 4.1 Reduce street Reduce street imperviousnessimperviousness
BMP 4.2BMP 4.2 Reduce parking Reduce parking imperviousnessimperviousness
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)
Non-Structural BMP Categories with Non-Structural BMP Categories with Specific Non-Structural BMPs:Specific Non-Structural BMPs:
5.0 Disconnect/Distribute/Decentralize5.0 Disconnect/Distribute/Decentralize
BMP 5.1BMP 5.1 Rooftop disconnectionRooftop disconnectionBMP 5.2BMP 5.2 Disconnection from storm Disconnection from storm
sewerssewers
Top Ten Stormwater Top Ten Stormwater Management Principles:Management Principles:
-Prevent first, -Prevent first, -Mitigate second. -Mitigate second. -Manage as a resource – not a waste!-Manage as a resource – not a waste!-Maintain water cycle balance, pre- to post.-Maintain water cycle balance, pre- to post.-Integrate early into site design process.-Integrate early into site design process.-Protect/utilize natural systems (soil, -Protect/utilize natural systems (soil, vegetation).vegetation).-Manage as close to the source as possible.-Manage as close to the source as possible.-Disconnect. Decentralize. Distribute.-Disconnect. Decentralize. Distribute.-Slow it down – don’t speed it up.-Slow it down – don’t speed it up.-Achieve multiple objectives; do as much with -Achieve multiple objectives; do as much with asas little as possible. little as possible.
System Balance….System Balance….
“…everything is “…everything is connected to everything connected to everything
else….”else….”
West Chester, PA 19382West Chester, PA 19382Cape May, NJ 08204Cape May, NJ 08204
Cahill AssociatesCahill AssociatesEnvironmental ConsultantsEnvironmental Consultants
Stormwater Management: Stormwater Management: Making Sure Green is GreenMaking Sure Green is Green