Erie County Planning Department Act 167 County-Wide Watershed Stormwater Management Plan for Erie County Phase I – Scope of Study July 2008 200 West Kensinger Drive• Cranberry Township, Pennsylvania 16066 • 724.779.4777 [phone] TABLE OF CONTENTS INTRODUCTION ....................................................................................................................................... 1 STORMWATER RUNOFF – ITS PROBLEMS AND ITS SOLUTIONS ...................................................... 1 PENNSYLVANIA STORMWATER MANAGEMENT ACT (ACT 167) .................................................. 1 ACT 167 PLANNING FOR ERIE COUNTY ........................................................................................ 2 BENEFITS OF THE PLAN ................................................................................................................... 2 APPROACH FOR THE DEVELOPMENT OF THE STORMWATER MANAGEMENT PLAN ................. 3 THE NEED FOR A COMPREHENSIVE APPROACH FOR STORMWATER MANAGEMENT ...................................................................................... 4 PREVIOUS PLAN EFFORTS ............................................................................................................... 4 GENERAL COUNTY DESCRIPTION ........................................................................................................... 5 TRANSPORTATION .......................................................................................................................... 5 POLITICAL JURISDICTIONS ............................................................................................................. 5 NATURAL CHARACTERISTICS .................................................................................................................. 6 WATER RESOURCES ........................................................................................................................ 6 CLIMATE .......................................................................................................................................... 8 GEOLOGY ...................................................................................................................................... 9 BEDROCK FORMATIONS ................................................................................................................ 9 SLOPES .......................................................................................................................................... 11 SOILS ............................................................................................................................................. 11 FLOODPLAIN DATA ...................................................................................................................... 13 LAND USE ............................................................................................................................................... 15 EXISTING PATTERNS ...................................................................................................................... 15 GENERAL DEVELOPMENT PATTERNS ........................................................................................... 17 INTEGRATED WATERSHED RESOURCE PLANNING ................................................................................ 18 INTRODUCTION AND PURPOSE ................................................................................................... 18 APPROACH FOR THE DEVELOPMENT OF INTEGRATED WATERSHED RESOURCE PLAN ........... 18 CONSISTENCY AND COORDINATION DISCUSSION ................................................................... 19 EXPANDED FOCUS OF IWRP CONCEPT ...................................................................................... 21 PHASE I PLANNING PROCESS ............................................................................................................... 22 AGREEMENT BETWEEN PADEP AND ERIE COUNTY .................................................................... 22 ENGINEERING CONSULTANT SELECTION .................................................................................... 22 CREATION AND DISTRIBUTION OF A QUESTIONNAIRE FORM .................................................... 22 ESTABLISHMENT OF A WATERSHED PLAN ADVISORY COMMITTEE (WPAC) ............................ 22 WATERSHED PLAN ADVISORY COMMITTEE MEETINGS .............................................................. 24 PHASE I REPORT ..................................................................................................................................... 24 SUBMISSION OF PHASE I REPORT TO PADEP ............................................................................... 24 QUESTIONNAIRE DISCUSSION .............................................................................................................. 25 QUESTIONNAIRE RESULTS ............................................................................................................. 25 PHASE II DISCUSSION ............................................................................................................................ 26 ITEMS TO BE ADDRESSED IN PHASE II ............................................................................................... 26 GENERAL WORK PLAN .......................................................................................................................... 28 PHASE II AGREEMENT......................................................................................................................... 28 CONSULTANT SELECTION.................................................................................................................. 28 QUESTIONNAIRE ................................................................................................................................. 28 WATERSHED PLAN ADVISORY COMMITTEE (WPAC) .................................................................... 28 MUNICIPAL ENGINEERS PARTICIPATION......................................................................................... 29 LEGAL ADVISORY PARTICIPATION................................................................................................... 29 STANDARDS......................................................................................................................................... 29 ROLES OF COUNTY AND CONSULTANT .......................................................................................... 29 WORK SCHEDULE ............................................................................................................................... 30 REFERENCES ........................................................................................................................................... 30 HRG Project Number: 3361.006 Herbert, Rowland & Grubic, Inc. Erie County Phase I Act 167, Stormwater Management Plan LIST OF APPENDICES APPENDIX A – Questionnaire Form APPENDIX B – Questionnaire Summary APPENDIX C – Phase II Scope of Work APPENDIX D – Phase II Cost Proposal APPENDIX E – Phase II Proposed Schedule APPENDIX F – Erie County Map APPENDIX G – Erie County Designated Watersheds Herbert, Rowland & Grubic, Inc. Erie County Phase I Act 167, Stormwater Management Plan INTRODUCTION STORMWATER RUNOFF – ITS PROBLEMS AND ITS SOLUTIONS The water that runs off the land into surface waters during and immediately following a rainfall event is referred to as stormwater. In a watershed undergoing urban expansion, the volume of stormwater resulting from a particular rainfall event increases because of the reduction of pervious land area (i.e., natural land covered by pavement, concrete, or buildings). That is, the alteration of natural land cover and land contours by residential, commercial, industrial, forestry, and farmland uses results in decreased infiltration of rainfall and an increased rate and volume of stormwater runoff. The need for stormwater management in Pennsylvania has been demonstrated repeatedly in the past. As the population of an area increases, land development is inevitable, and the alteration of natural ground surfaces results in decreased infiltration of rainfall. As a result of continued development, the volume and rate of stormwater runoff increases causing environmental impacts including flooding, stream channel erosion and siltation, water quality degradation, and reduced groundwater recharge. Cumulative effects of development in some areas of a watershed can result in flooding of natural watercourses with associated costly property damages. History has shown that individual land development projects are often viewed as separate incidents and not necessarily part of the bigger picture of urbanization. This has also been the case when the individual land development projects are scattered throughout a watershed (within many different municipalities). However, it is now observed and verified that this cumulative nature of individual land surface changes dramatically affects runoff and flooding conditions. This cumulative effect of development in some areas has resulted in flooding of both small and large streams with associated property damages and even causing loss of life. Therefore, given the distributed and cumulative nature of the land alteration process, a comprehensive approach must be taken if a reasonable and practical management and implementation approach or strategy is to be successful. PENNSYLVANIA STORMWATER MANAGEMENT ACT (ACT 167) Recognizing the need to deal with the serious and growing problem of extensive