Low Impact Development and Stormwater Management in Pennsylvania

1. Low Impact Development and Stormwater Management in Pennsylvania II. Stormwater Management in Pennsylvania Robert G. Traver, Ph.D., PE Department of Civil and Environmental EngineeringDirector, Villanova Urban Stormwater Partnership

2. Outline • Definitions • Pa Stormwater Management History • Why the Change? • Current Pa Stormwater Requirements.

3. Development and the Hydrologic Cycle Original from MDE Thanks to MDE

4. Definitions: Objectives of SWM • Protecting Life & lessening Public Health & Safety Risk • Reducing Risk of Monetary Damage to Private / Public Property • Minimize disruption of Community Affairs • Protecting Quality of Surface and Groundwater • Enhancement of the Quality of Life in Urban Areas • ASCE Stormwater Manual of Practice

5. ASCE Code of Ethics • Engineers shall hold paramount the safety, health, and welfare of the public and shall strive to comply with the principles of sustainable development in the performance of their professional duties – (ASCE 2002)

6. Definitions - Flooding • Natural - every 2 years out of channel…. • Multiple Causes • Rains too hard • drainage system inadequate • urbanization increases volume / risk • opposite… drought?

7. “Risk” - Definition • Return Period (T) • Rainfall event equaled or exceeded over a year • T = 1/P x 100 2 year storm ~ 50% (P) • 100 ~~~~~~ 1% • Risk = 1-(1-P)^n

8. Definitions - Floodplain & Stormwater Management • Distinction Between - Large vs. Small Sites? • Both Required by Regulation • Degree? Agency? • Floodplain – River • Stormwater - Watershed • Stormwater - Growing Quality Orientation • Flood Plain - Protection –higher priority • Similarities • Life & Safety • Public Interest Intense - but brief & Infrequent • Coming together! • Similar structural / nonstructural measures • Similar Design Tools - same methods, different orientation • Same System

9. Pa SWM - Historically Based on…….. • Groundwater Rich • Concern over Peak Flows / Flooding (property damage) • Channel Stability (Cost) • “Drainage” • Pics from MDE (except as noted)

10. 1978 – PA ACT 167 • Peak Flows Limited to Preconstruction Levels • All Points Leaving Site • Municipal Implementation

11. 1978 - FOCUS • Peak Flows • Large Storms (100 Yr?) • Individual Sites • “downstream property line” • Detention Basins

12. From old Design Manual

13. Storm Hydrograph Post W/ SWM Post Pre

14. 1978 - RESULTS • Flow Collected and Concentrated • Detention Basins • BIG • Bottom of Site Traver 1978

15. 1978 - Results Post Post w/ SWM basin Lost Infiltration Increased Channel Erosion Flow Pre Time

16. ASCE Journal of Hydraulics • Nov 1979 – “Downstream Effects of Stormwater Management Basins” – Richard McCuen • It is recognized that the urbanization process is responsible for increases in both runoff flow rates and sediment volumes…. The question that has led to much consideration is: Are SWM Basins effectively meeting the intent of stormwater management?”

17. 1983 - ACT 167 REVISED! • Enabled Watershed Planning • plans revised every five years • considers existing trouble areas • usually developed by county • Peak Flows • limited to preconstruction levels • limited by effect on Watershed • Municipal Implementation

18. 1983 - FOCUS • Peak Flows • 2 ~ 100 Year Storms • Watershed Drainage System • Release Rate

19. 1983 - RESULTS • Flow Collected and Concentrated • Bigger Detention Basins • 2 ~ 100 year storms • Release Rate ~ Watershed Location • Owned • Homeowners Associations • Municipal

20. Issues

21. Act 167 Status Dec 1999 - PaDEP

24. EPA Region III Website

25. ASCE Journal of Hydraulics • April 1980 – “Stormwater Detention in Developing Watersheds” – C Amandes, P. Bedient • Urban Stormwater runoff has become the major source of stream pollution in many urban areas as point source effluents have been largely controlled through improved treatment. • July 1988 – “Multicriterion Stormwater Management Methods” – R. McCuen & G. Moglen • Both theory and experience indicate that, while detention basins designed to control peak discharge are effective in controlling the peak rates, the basins are ineffective in in controlling the degradatation of erodible channels downstream of the basin.

26. What do we design for?

27. The “old” way- directly connected • Runoff • Speed -- Increased • Peak Flows -- Increased • Volume -- Increased • No Chance to Infiltrate • No Pollutant Filtration • Infiltration -- Decreased • Baseflow -- Decreased • Groundwater Recharge -- Decreased • Runoff Quality -- Decreased • Stream Bank Erosion -- Increased Roof Street Driveway Post Inlet Culvert

28. Pa Comprehensive Stormwater Policy • Protect and maintain stream uses/water quality; • Protect, maintain and sustain water quantity; and • Integrate federal stormwater management requirements. “NPDES – II” • Best Management Practice (BMP) approach to stormwater management that emphasizes groundwater recharge and the reduction of impacts from discharges to surface water. PaDEP Aug 2002

29. Comprehensive Stormwater Management ProgramPa SW Mgt SymposiumVillanova UniversityOctober 16,2003 Durla Lathia, P.E. Bureau of Watershed Management Pa DEP The following slides are excerpts from a presentation Durla Lathia PaDEP Presentation – Pa SWM Symposium Oct 2003

30. DEP’s Initiative For Public Input for New Directions • 15 Water Forums held in 2001 • Public Identified Stormwater Management as a Consistent Issue, and Wanted a Comprehensive Implementation of Various Water Management Programs PaDEP Presentation – Pa SWM Symposium Oct 2003

31. Pennsylvania’s Comprehensive Stormwater Management Policy September 2002 www.dep.state.pa.us Direct Link to “Stormwater” GOAL: “…..to improve and sustain ground and surface water quality and quantity …… PaDEP Presentation – Pa SWM Symposium Oct 2003

32. Comprehensive SW Policy Under what authority was the policy issued? • Antidegradation Requirements • Section 93.4a • Existing In-Stream Water Uses and the Level of Water Quality Necessary to Protect the Existing Uses Shall Be Maintained and Protected • The Water Quality of High Quality & Exceptional Value Waters Shall Be Maintained & Protected PaDEP Presentation – Pa SWM Symposium Oct 2003

33. Implementation Goals To successfully implement the Comprehensive Stormwater Management Policy the goals must: • Be reasonably attainable • Target and prioritize major obstacles • Be effectively implemented utilizing existing resources PaDEP Presentation – Pa SWM Symposium Oct 2003

34. Comprehensive Stormwater Management Approach • Integration of Planning, Technical and Regulatory Programs • Financial Incentives • Provide Necessary Technical Tools and Support – BMP Tech Manual PaDEP Presentation – Pa SWM Symposium Oct 2003

35. ACT 167 Planning Program COMPREHENSIVE SW POLICY NPDES Phase II MS4 Permits NPDES Construction Permits Special Protection Waters PaDEP Presentation – Pa SWM Symposium Oct 2003

36. NPDES Construction Permits • Permits require protection of uses and maintenance of water quality • E/S Control Plan to minimize pollutants from earth disturbance activities. • Post Construction SW Mgt. Plan • Permits now emphasize requirement for PCSM Plans • Identification, Assurance for Operation and Maintenance of BMPs • Preparedness, Prevention, Contingency Plan PaDEP Presentation – Pa SWM Symposium Oct 2003

37. PCSM PLANS Must Accompany Permit Application Identifiy BMP’s BMP’s MUST be Designed and Constructed in accordance with: DEP Approved Act 167 SW Plan with Water Quality Requirements, if a Plan Exist, Existing MS4 Municipal Ordinance, IF No Act 167 SW Plan, A 2-Year - 24 Hour Runoff Volume Difference Management (Post - Pre Development Conditions), If neither Act 167 nor MS4 Municipal Ordinance exists. A Long Term Maintenance of BMP’s is Required PaDEP Presentation – Pa SWM Symposium Oct 2003

38. Act 167 Stormwater Planning Program • Incorporates hydrologic and hydraulic Evaluation of a Watershed for Existing and Future Land Use Scenario • Requires County and Municipal participation • Considers Existing Local Regulatory Programs • Recommends Control of Stormwater Runoff from Development Activities • A Recommended Model Ordinance PaDEP Presentation – Pa SWM Symposium Oct 2003

39. NPDES Phase II MS4 Program • “Municipal Separate Storm Sewer System (MS4)” • 20 Urbanized Areas • 929 municipalities, 30 counties, 14 potential municipalities, plus state and federal institutions (PADOT, PTC, prisons, universities) • Permit Requires Implementation of 6 Minimum Control Measures • Public Education • Public Participation & Involvement • Illicit Discharges • Construction • Post-construction • Pollution Prevention/Good Housekeeping PaDEP Presentation – Pa SWM Symposium Oct 2003

40. NPDES II-MS4 Permit • For General Permits, MS4s have Two options: • Follow DEP “SW MGT. PROTOCOL” • “Pre-approved” Tasks • Relaxed deadlines for Multi-municipal Efforts, Working on Watershed Based Approach • Funding Opportunity, if Act 167 Planning is Involved Or • Develop own program • Must get DEP approval • No funding PaDEP Presentation – Pa SWM Symposium Oct 2003

41. Expanded Scope of Act 167 Program • In addition to the requirements of the Section 5(b) of the Act, ALL Minimum Control Measures of the NPDES MS4 Permit requirements may be included in a SW Plan, if Counties and Municipalities wish to do so • Funding is also included for the expanded scope PaDEP Presentation – Pa SWM Symposium Oct 2003

42. Infiltration Groundwater Recharge Special Protection Waters Rate & Volume Control Water Quality Technical Assistance Financial Assistance Act 167 SW Management Planning NPDES Construction Permit NPDES MS4 Permit Tailored Municipal Ordinances PaDEP Presentation – Pa SWM Symposium Oct 2003

43. How Does Act 167 SW Planning Implement Comp SW Policy??? • Recommend Measures and Techniques to Address Stormwater Runoff Impact with a Goal to Mimic Pre-Development Conditions after Development is Completed. • Control Standards for Quantity, Quality,Groundwater Recharge and Stream Protection • NPDES Regulatory Components Included PaDEP Presentation – Pa SWM Symposium Oct 2003

44. Act 167 SW Planning Status • 85 Plans approved for 47 counties • Plans approved after Aug. 2001 contain WQ Components • 777 Municipalities to enact and implement ordinances • 42 additional Plans currently under way (23 Counties, 603 Municipalities): All Plans have WQ Components PaDEP Presentation – Pa SWM Symposium Oct 2003

45. STORMWATER ORDINANCE • MS4 Ordinance(available on DEP Website) • A General SW Ordinance which includes all the components of Stormwater Management. Counties include this ordinance in their SW Plans, subject to watershed specific modifications. Municipalities, not part of a SW Plan, are encouraged to consider adoption PaDEP Presentation – Pa SWM Symposium Oct 2003

46. Pa BMP Technical Manual • Tech Manual to Provide Computational Procedures and Specifications- It will NOT Be a Regulatory Handbook • 18 Month Project • Consultant Has Been Selected • Oversight Committee Members Appointed • First Oversight Committee Meeting Held on October 10, 2003 • DEP Contacts: Dennis Stum/Ken Reisinger PaDEP Presentation – Pa SWM Symposium Oct 2003

47. Stormwater ManagementHow Can We Help ?? Central Office Regional Offices WWW.DEP.STATE.PA.US Direct Link to “Stormwater” PaDEP Presentation – Pa SWM Symposium Oct 2003