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Pennsylvania Stormwater Best Pennsylvania Stormwater Best Management Practices ManualManagement Practices Manual
In cooperation with:
Presented by the
Pennsylvania Department of Environmental ProtectionBureau of Watershed Protection
Stormwater Oversight Committee
Villanova Urban Stormwater Partnership
Cahill AssociatesEnvironmental Consultants
http://www.dep.state.pa.us
Stormwater information (manual revisions, meetings, training, etc.) will be posted on the DEP Stormwater page• DEP Keyword:
“stormwater”• General information• Stormwater Oversight
committee
Draft Stormwater Best Management Practices Manual
• Cover and Table of Contents • Section 1 - Introduction and Purpose of BMP Manual • Section 2 - Stormwater and PA's Natural Systems • Section 3 - Stormwater Management Principles, Goals, and a Management Model• Section 4 - Comprehensive Stormwater Management: Integrating Site Design,
Non-Structural, and Structural BMP's• Section 5 - Comprehensive Stormwater Management: Non-Structural BMP's • Section 6 - Comprehensive Stormwater Management: Structural BMP's • Section 7 - Stormwater Management for Special Areas• Section 8 - Stormwater Calculations and Methodology• Section 9 - Case Studies Innovative Stormwater Management Approaches and
Practices
• Appendix A - Water Quality • Appendix B - Pennsylvania Native Plant List• Appendix C - Soil Infiltration Testing, System Design
and Construction Guidelines• Appendix D - Case Study with Stormwater Calculations
Chapter 1Chapter 1Introduction & PurposeIntroduction & Purpose
• To improve stormwater management throughout Pennsylvania.
• Emphasis on water quality and water resources.
• Describes management methods and practices that can prevent, reduce, and mitigate the impacts of stormwater.
Stormwater ManagementStormwater Management
• Relationship Land Use and Water• Integrated Approach• Manage Stormwater:
• Volume• Water Quality• Peak Rate• Groundwater Recharge• Stream Impacts
COMPREHENSIVESW
POLICY
BMP TechnicalManual
Construction NPDESPermits
NPDESPhase II
MS4 Permits
ACT 167PlanningProgram
Chapter 2 Chapter 2 Stormwater and PennsylvaniaStormwater and Pennsylvania’’s Natural Systemss Natural Systems
• Hydrologic Cycle.• Pennsylvania Rainfall: Avg. 36” to 44”.• Impacts of Development and Impervious Surfaces.• Water and Environmental Quality.• Pennsylvania Watersheds, Soils, Geology.
Stormwater ImpactsStormwater Impacts• Increased Runoff Volume• Compacted Soils• Erosion and Stream
Channel Changes• Decreased Base-flow• Pollutants and
Temperature Impacts
• Decreased Evapo-transpiration and Groundwater Recharge
• Increased Frequency of Runoff Events
• Faster Conveyance of Water• Impacted Aquatic Life
WELL
STREAM
AQUIFER
BEDROCK
SOILWATER TABLE (DEVELOPED CONDITIONS)
Green Valleys Association
Cahill AssociatesEnvironmental Consultants
Chapter 3 Stormwater Management
Principles and Goals
Recommended Site Control Guidance:• Comprehensive – Watershed; Hydrology.• Effective – Prevents impacts.• Equitable – New and re-development.• Flexible – Variable conditions; Creative.
Ten Principles for Stormwater Ten Principles for Stormwater ManagementManagement
Prevent stormwater impacts first.Mitigate second.Manage stormwater as a resource.Maintain water cycle balance-quality and quantity.Integrate stormwater in the initial site design.Preserve and utilize natural systems-soil, vegetation.Manage stormwater close to the source.Disconnect/Decentralize/Distribute.Slow it down, don’t speed it up.Do as much with as little as possible.
Site Control GuidanceSite Control GuidanceVolume CG-1
Do not increase runoff volume, pre-development to post-development, for up to the 2-year frequency, 24-hour duration rainfall. **
Volume CG-2Capture and remove runoff generated by 1.5 inches of rainfall with infiltration of the runoff from the initial 0.5 inches of rainfall.
Extended Detention (CG-2 only)
Provide 24-hour extended detention of the 1-year frequency, 24-hour duration rainfall.
Stream Conservation/ Stream Channel
Protection
Flood Protection: 1- through 100-Year
Storms, Site by SiteCumulative Flood
Protection as Needed through Act 167
Planning
Groundwater Quality
Surface Water Quality - reduction of 85%
particulate-associated NPS; reduction of 50%
solute loads Temperature
** Existing (pre-development) non-forested pervious areas must be considered meadow or its equivalent.
Groundwater/ Water Table/ Stream Base
Flow & Stream Conservation/
Stream Channel Protection
* These guidelines are recommended for use in watersheds throughout Pennsylvania. Guidelines may be further modified in Special Stormwater Management Areas and other zones where different stormwater guidelines for quantity and quality control are warrant
Peak Rate (CG-1 and CG-2)
Do not increase peak rate of runoff for larger storms (1-, 2-, 10-, 25-, 100-year storms at minimum), pre-development to post-development; as necessary, provide additional peak rate control for largest storms through the Act 167 planning.
Water Quality (CG-1 and CG-2)
A reduction of 85% of particulate-associated pollutants (as represented by TSS), including 85% of Total Phosphorus. In addition, removal or prevention of 50% of solutes (as represented by NO3-N) is required. BMPs shall not result in a temperature increase of 3 degrees Farenheit.
Control Guidance 1Control Guidance 1Do not increase the post development total runoff discharge volume for up to the 2 year storm.Flood protection peak rates held to existing levels for the 1 – 100 year storm.
Notes: Existing condition is defined as those that occurred predevelopment, i.e. the current land cover (including impervious area). Existing non-forested pervious areas are classified as meadow or its equivalent.
Control Guidance 2Control Guidance 2Base flow
Infiltrate runoff from the first 1/2 ” of rainfall. Calculated as 0.5” x impervious area.
Water QualityInfiltrate or capture runoff from the next 1” of rainfall.Capture is defined as permanent removal from runoff volume.Volume credits added to promote green practices.
Channel ProtectionControl the 1 year peak discharge to the equivalent flow achieved by 24 hour extended detention of 1 year, 24 hour storm.
Flood ProtectionPeak Rates held to existing levels for the 1 – 100 year storm.
Chapter 4 Chapter 4 Integrating Site DesignIntegrating Site Design
• Comprehensive design process.• Emphasize non-structural BMP value.• Stormwater not an afterthought.
Chapter 5 Chapter 5 NonNon--Structural BMPsStructural BMPs
• Each technique presented as a BMP.• Incentives and values for non-structural BMPs.• Emphasis on preventing/reducing stormwater.
• Soils• Vegetation• Reduced impervious surfaces.
• Natural area conservation.• Small scale structural BMPs.
- Protect sensitive/special value features. - Protect/conserve/enhance utilize riparian areas.- Protect/utilize natural flow pathways in overall
stormwater planning and design.
Protect Sensitive and Special Value Resources
- Cluster uses at each site; build on the smallest area possible.
- Concentrate uses areawide through smart growth practices.
Cluster and Concentrate
- Minimize total disturbed area grading. - Minimize soil compaction in disturbed areas.- Re-vegetate and re-forest disturbed areas, using
native species.
Minimize Disturbance and Minimize Maintenance
- Reduce street imperviousness.- Reduce parking imperviousness..
Reduce Impervious Cover
- Rooftop disconnection.-- Disconnection from storm sewers.Disconnection from storm sewers.
Disconnect/Distribute/Decentralize
Source ControlSource Control
- Street sweeping.
Chapter 6 Chapter 6 Structural BMPsStructural BMPs
• Volume/Peak Rate by Infiltration.• Volume/Peak Rate Reduction BMPs.• Quality/Peak Rate Reduction BMPs.• Restoration. • Other.
Structural BMPs Structural BMPs Volume/Peak Rate by InfiltrationVolume/Peak Rate by Infiltration• Porous Pavement• Infiltration Basin• Infiltration Trench• Dry Well / Seepage Pit• Rain Garden/Bioretention• Vegetated Swale• Constructed Filter• Infiltration Bed• Vegetated Filter Strip• Berm
Volume/Peak Rate Reduction BMPs
• Vegetated Roof
• Rooftop Runoff Capture & Reuse
Runoff Quality/Peak Rate BMPsRunoff Quality/Peak Rate BMPs
• Constructed Wetland
• Wet Pond / Retention Basin
• Dry Extended Detention Basin
• Water Quality Filter
Restoration BMPs
• Landscape Restoration
• Riparian Buffer Restoration
• Soils Amendment & Restoration
Other BMPs
• Level Spreader
• Special Detention Areas Parking Lot, Rooftop
BMP ElementsBMP Elements• One- page Overview • Description and Pictures• AutoCAD Details• Variations• Applications (examples)• Design Considerations• Detailed Stormwater Functions• Construction Sequence• Maintenance Issues• Cost Information• Specifications
10 to 15 pages per BMP
Structural BMPsStructural BMPs• One-page Overview: Snapshot of Key Design/Function Elements• Description, Diagrams, and Pictures
Structural BMPs ContStructural BMPs Cont’’d.d.•Design Considerations•Detailed Functions
Structural BMPs ContStructural BMPs Cont’’d.d.•Maintenance Considerations•Cost Issues•Specifications
Chapter 7 Chapter 7 Stormwater Management for Special Stormwater Management for Special
AreasAreas
• Urban areas.• Mined lands.• Highways and Roads.• Karst areas.• Brownfields.• Source water protection area.
Urban AreasUrban Areas
Stormwater BMP Challenges in Stormwater BMP Challenges in Urban AreasUrban Areas
1. High imperviousness (50% to 100%).
2. High property values, limited physical space, etc.
3. Compacted soils, contamination.
4. Underground utilities.5. Severely impacted streams;
enclosed/buried in culverts.6. Elimination of the original
floodplain . 7. Direct connection of
impervious surfaces.
8. Combined sewers.9. High levels of trash, debris and
pet waste.10. Stormwater “hot spots” :
industrial areas, vehicle service areas, public works storage areas, dumpsters, etc.
11. Regulations and ordinances that may conflict with current BMP design strategies.
12. Limited economic resources; need to encourage rather than discourage redevelopment.
Highways and RoadsHighways and Roads
Constituent SourceParticulates Pavement wear, vehicles, atmospheric deposition, maintenance activitiesNitrogen, Phosphorus Atmospheric deposition and fertilizer applicationLead Leaded gasoline from auto exhausts and tire wearZinc Tire wear, motor oil and grease
IronAuto body rust, steel highway structures such as bridges and guardrails, and moving engine parts
CopperMetal plating, bearing and bushing wear, moving engine parts, brake lining wear, fungicides and insecticides
Cadmium Tire wear and insecticide applicationChromium Metal plating, moving engine parts, and brake lining wear
NickelDiesel fuel and gasoline, lubricating oil, metal plating, bushing wear, brake lining wear, and asphalt paving
Manganese Moving engine partsCyanide Anti-caking compounds used to keep deicing salts granularSodium, Calcium Chloride Deicing saltsSulphates Roadway beds, fuel, and deicing salts
* From FHWA Stormwater Best Management Practices in an Ultra-Urban Setting
Table 8-1 Constituents and Sources in Highway Runoff *
Highway and Road Stormwater Issues
• High levels total suspended solids. • High levels pollutants.• Use of vegetative, linear BMPs.• Spills.• Deicing. • Temperature.• Physical space constraints.
Chapter 9 Stormwater Calculations and
Methodology
• Guidelines for volume, peak rate, and extended detention calculations.
• Flowcharts.• Worksheets.• Integration of volume and peak rate.
• BMPs provide volume and peak rate control.
Flowchart ExamplesFlowchart Examples
Worksheet ExamplesWorksheet Examples
Peak Rate CalculationsPeak Rate Calculations• ID existing methodologies/limitations• Detailed routing • “Composite” stage-storage-discharge• Adjusted Tc for BMPs – DURMM
Chapter 9 Case Studies
• Built projects around the state.• Locations, information, contacts.• Considering reference to web-site; updates.
Appendices• Appendix A – Water Quality• Appendix B – Pennsylvania Native Plant
List• Appendix C – Soil Infiltration Testing;
Infiltration System Design and Construction Guidelines
• Appendix D – Case Study with Stormwater Calculations
Focus Groups Focus Groups Initial Focus Group
Meetings•January 19 Wilkes-Barre•January 21 Williamsport•January 25 Meadville•January 26 Greensburg•January 27 Harrisburg•January 28 Norristown
Follow-up Focus Group Meetings
•March 2 Meadville •March 3 Greensburg•March 7 Norristown•March 10 Williamsport•March 11 Harrisburg•March 15 Wilkes-Barre
Beyond The Focus GroupsBeyond The Focus Groups• Comments recorded from the second Focus Group
meeting and subsequent written comments.• Comments reviewed with the Stormwater
Management Oversight Committee for discussion• Manual revised.• Public review and comment period.• A final manual will prepared and distributed.• Training.
Stormwater Information Stormwater Information •Stormwater information (manual
revisions, meetings, training, etc.) will be posted on the DEP Stormwater page•www.dep.state.pa.us•Keyword “stormwater”•General information•Stormwater Oversight Committee
