Act 167 Stormwater Management Plan Update Report April 28, 2008
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Act 167 Stormwater Management Plan Update Report Act 167 Stormwater Management Plan Update Girtys Runs, Pine Creek, Squaw Run and Deer Creek Watersheds Allegheny County, Pennsylvania Prepared for the North Hills Council of Governments Prepared by Art Gazdik, P.E. April 28, 2008 4/28/2008 Table of Contents Allegheny County Council Resolution Number 57-07-RE dated 12/18/2007 Acknowledgement Section Page 1.0 Introduction 1 1 1.1 Project Overview 1 1.2 Act 167 Phase I Findings 2 1.3 Scope of Work 2 2.0 Act 167 Stormwater Management Planning for the Girtys 4 Run, Pine Creek, Squaw Run & Deer Creek Watersheds 2.1 Original Act 167 Planning 4 3.0 Watersheds Characteristics 6 3.1 Study Area 6 3.2 Impervious Cover 7 3.3 Pine Creek 8 A. Project Location and Physical Description 8 B. Land Cover 9 C. Water Quality 11 3.4 Girtys Run 14 A. Project Location and Physical Description 14 B. Land Cover 14 C. Water Quality 16 3.5 Deer Creek 17 A. Project Location and Physical Description 17 B. Land Cover 17 C. Water Quality 19 3.6 Squaw Run 21 A. Project Location and Physical Description 21 B. Land Cover 21 C. Water Quality 22 4.0 The Need For Stormwater Management 24 4.1 Impacts of Development and Stormwater Runoff 24 4.2 Addressing Stormwater Impacts 32 5.0 Unified Stormwater Management Criteria and 33 Calculation Methods 5.1 Summary of Multi-State Stormwater Management Approaches 33 5.2 Description of Stormwater Sizing Criteria 35 A. Water Quality - Treatment of First Flush Volume 35 B. Recharge Volume (Infiltrated Volume) 37 C. Credits for the Use of Nonstructural BMPs 38 D. Channel Protection Volume (CPv) 43 i 4/28/2008 Page 6.0 Review of Existing SWM and Land Development Ordinances 45 6.1 Stormwater Management Ordinances 45 A. Adoption & Use of Stormwater Management Ordinances 45 B. Conformance with Existing Act 167 Release Rate 45 Percentage Requirements C. Design Storms 46 D. No Harm Evaluation 47 6.2 Stormwater Management Ordinance Review Matrices 47 General Findings A. General Comments 48 B. Design Storm Criteria 48 C. Release Rates 49 D. Rainfall Rates & Method of Design 49 E. Other Considerations 50 F. SWM Review Recommendations and Conclusions 51 6.3 Review of Subdivision, Zoning & Grading Ordinances 52 A. Site Planning Model Development Principles 52 B. PennDOT Liquid Fuels Requirements 55 C. Subdivision Ordinance Review Matrices General Findings 55 D. Subdivision Ordinance Review Matrices General Comments 61 E. Zoning Ordinance Review Matrices - General Comments 62 and Recommendations F. Grading Ordinance Review Matrices General Comments 67 G. Grading Ordinance Review Recommendations and 71 Conclusions H. Stream Buffers 73 7.0 Priorities for Implementation of the Plan 81 7.1 Adoption of the Plan Amendment 81 7.2 Publishing of Final Plan Documents 82 7.3 Municipal Implementation of Ordinance Requirements 82 7.4 Maintenance of Plan Documents 82 8.0 Review and Adoption Procedures 84 9.0 MS4 Compliance 87 9.1 Municipal Separate Storm Sewer Systems (MS4s) 87 9.2 A Multi - Municipal Watershed Approach 90 9.3 Act 167 - Storm Water Management Act & MS4 Compliance 91 ii 4/28/2008 10.0 Draft Act 167 Stormwater Ordinance and Ordinance Appendices (The Following is the Table of Contents for the Draft Act 167 Stormwater Ordinance) Section Page 1.0 Purpose 3 2.0 General Provisions 5 2.1 Statutory Authority 5 2.2 Applicability 5 2.3 Exemptions 6 2.4 General Requirements 9 2.5 Repealer 11 2.6 Severability 12 2.7 Compatibility with Other Ordinance Requirements 12 2.8 Permit Requirements by Other Government Entities 12 2.9 E&S Requirements during Regulated Earth Disturbance Activities 12 2.10 Prohibited Discharges and Connections 13 2.11 Enforcement and Penalties 14 3.0 Stormwater Management Plan 16 4.0 Permanent Stormwater Management Design Standard 18 4.1 Design Goals, Principles and Standards 18 4.1.1 Design Goals 18 4.1.2 General Principles 18 4.1.3 Minimum Performance Criteria (New developments & redevelopments) 20 4.2 Stormwater Runoff Calculation Criteria 23 4.3 Standards for Stormwater Management Practices 27 4.3.1 Extended Detention, Water Quality Volume, Infiltration & Nonstructural BMP Credits Criteria 28 4.3.1 A. Runoff Volume 28 4.3.1 B. Water Quality Volume 28 4.3.1 C. Infiltration Volume 29 4.3.1 D. Credits for the Use of Nonstructural BMPs 30 4.3.2 Stormwater Infiltration Practices 34 4.3.3 Open Vegetated Channels 37 4.3.4 Retention Basins 38 4.3.5 Detention Basins 41 4.3.6 Conveyance Systems 43 4.4 Landscaping of Stormwater Management Practices 45 4.5 Stream Buffer Requirements 47 5.0 Operation and Maintenance Responsibilities 49 5.1 General Responsibilities 49 5.2 Ownership and Maintenance 50 5.3 Operation and Maintenance Plan 52 5.4 Operation and Maintenance Agreement 52 5.5 Special Stormwater Facility Maintenance Fund 53 6.0 Plan Submission, Review and Review Fees 54 7.0 Definitions 57 Draft Ordinance Appendices A Release Rate Percentage Tables & Information A1 iii 4/28/2008 B Non-Structural Stormwater Management Practices B1 C Operations and Maintenance Agreement C1 D List of References Cited and Additional Sources of Information D1 E Credits for Use of Nonstructural BMPs Example Calculations E1 F Small Project Standardized SWM Planning Guidance F1 Report Appendices Appendix A Synoptic Precipitation Analysis for the ALCOSAN Service Area Appendix B MS4 PAG – 13 Stormwater Management Program Requirements Appendix C MS4 Public Education Advertisements Appendix D Matrices • Stormwater Management Ordinance Review Matrix • Subdivision Ordinance Review Matrix • Zoning Ordinance Review Matrix • Grading Ordinance Review Matrix Appendix E EPA’s Aquatic Buffer Model Ordinance iv Acknowledgement This project is a multi-municipal effort to “Update” the Act 167 Stormwater Management Plan and Ordinance for the Girtys Run, Pine Creek, Squaw Run and Deer Creek watersheds in Allegheny County, Pennsylvania. There are many significant improvements contained within the new regional Act 167 Stormwater Management Ordinance, such as; ¾ The incorporation of water quality and infiltration standards ¾ Provision of credits for the use of non-structural best management practices, such as; the protection of existing wooded and natural areas, the use of stream buffers, the use of enhanced swales and infiltration practices and for the use of low density development practices ¾ Continued 2, 10, 25 and 100 year storm peak rate reduction requirements ¾ The application of stormwater management requirements to all sites having a disturbed area of greater than 400 square feet ¾ Stormwater management requirements for existing sites that undergo redevelopment ¾ Ordinance requirements may not be waived by the local municipality and must be approved by Allegheny County or its designee ¾ The development of a simplified BMP design method for single residential lots The Update was brought about by the coordinated efforts of the municipalities in these watersheds. The project was initiated and managed by Art Gazdik, P.E., the Ross Township Engineer, who acted as the project’s engineer and project manager. Project funding was provided by the State Of Pennsylvania through Act 167 and by pro-bono contributions from Ross Township, Art Gazdik, the North Hills Council of Governments and the Allegheny County Department of Economic Development The development of the Update was overseen by the Watershed Plan Advisory Committee (WPAC). The WPAC was made up of individuals from local environmental groups, PA DEP, the Allegheny County Conservation District, the Allegheny County Department of Economic Development, the North Hills Council of Governments and municipal managers, planners and engineers. In particular, the contributions of the following individuals who greatly assisted in the development of this important stormwater management effort should be recognized. Bud Schubel Allegheny County Department of Economic Development Wayne Roller North Hill Council of Governments Andy Banfield, P.E. Partridge Venture Engineering Mary A. Moretti Bradford Woods Borough, Manager Mark Weber Bradford Woods Mary Ellen Ramage Etna Borough Manager Bill Gordon, P.E. Fox Chapel Borough Manager Ambrose Rocca Franklin Park Borough Manager W. Christopher Lochner Hampton Township Manager Martin Orban Hampton Township Planner Dan Anderson Indiana Township Manager Dan Slagle, P.E. Indianan Township Engineer Neil D. McFadden Marshall Township Manager Bill Campbell Marshall Township Scot Fodi Middlesex Township Manager Tobias M. Cordek Town of McCandless Manager Bruce Betty Town of McCandless Mark Sabina Town of McCandless Virginia Heller Millvale Borough Manager Bob Robinson, P.E. O’Hara Township Engineer Gary J. Koehler Pine Township Manager John Swinderman Pine Township Dick Hadley Reserve Township Manager Dean E. Bastianini Richland Township Manager Jeff Walzer Richland Township Thomas D. Lavorini Ross Township Manager Art Gazdik, P.E. Ross Township Engineer Timothy Rogers Shaler Township Manager Kevin Creagh, P.E. Shaler Township Engineer Debbie Vita Shaler Township Ron Borczyk Sharpsburg Borough Manager Scott Shoup, P.E. Shoup Engineering Jason Dailey West Deer Township Manager Gary Bogan West Deer Township Kenneth Wolf West View Borough Manager Dave McMillen Montour Run Watershed Association Bill Moul North Area Environmental Council Mary Wilson North Area Environmental Council Jen Novak Pennsylvania Environmental Council Rick Kowalski Allegheny County Conservation District Steve Haubner Atlanta Regional Commission Barry Newman, P.E. PA DEP Bob Scheib, P.E. PA DEP Greg Holish, P.E. PA DEP Ed Ritzer PA DEP It was a pleasure being involved with this effort and it is my hope that the standards contained in our plan will be used by others, within Allegheny County and our region, to reduce the effects of flooding and to improve the quality of our waterways. Art Gazdik, P.E. Ross Township Engineer Act 167 Project Manager [email protected] Section 1.0 Introduction 1.1 Project Overview This project is a multi-municipal effort to “Update” the Act 167 Stormwater Management Plan (SWM) for the Girtys Run, Pine Creek, Squaw Run and Deer Creek watersheds in Allegheny County, Pennsylvania.