Section I – Introduction
Total Page:16
File Type:pdf, Size:1020Kb
White Deer Watershed Act 167 Stormwater Management Plan June 2003 Prepared by Union County in conjunction with Union County Courthouse The preparation of the White Deer Stormwater Management Plan has been funded in part by a grant from the Pennsylvania Department of Environmental Protection Bureau of Watershed Conservation. WHITE DEER CREEK WATERSHED ACT 167 STORMWATER MANAGEMENT PLAN Prepared by Union County Planning Commission in Conjunction with Herbert, Rowland & Grubic, Inc. June 2003 369 East Park Drive Harrisburg, PA 17111 (717) 564-1121 www.hrg-inc.com ©Herbert, Rowland & Grubic, Inc., 2003 WHITE DEER CREEK WATERSHED ACT 167 STORMWATER MANAGEMENT PLAN JUNE 2003 H:\21\2189\007\rpts\plan\WD_plan.doc Table of Contents: Section 1 – Introduction 1 1.0 Introduction ................................................................................................................................. 1 1.1 Stormwater Runoff – Its Problems and Its Solutions .................................................................. 1 Section 2 – Act 167 Watershed Level Stormwater Management Planning & Implementation 2 2.0 The Pennsylvania Stormwater Management Act, Act 167 .......................................................... 2 2.1 Plan Preparation Strategy ............................................................................................................ 3 Stage A - Data Collection and Analysis ............................................................................................... 4 Stage B - Technical Analysis ............................................................................................................... 5 Stage C – Public/Municipal Participation ............................................................................................ 6 Stage D - Plan Preparation and Implementation .................................................................................. 7 Section 3 - White Deer Creek Watershed Characteristics 9 3.0 General Description ..................................................................................................................... 9 3.1 Political Features ......................................................................................................................... 9 3.2 Natural Features ......................................................................................................................... 10 3.3 Hydrology .................................................................................................................................. 11 3.4 Existing Stormwater Drainage Problem Areas .......................................................................... 11 3.5 Suggested Solutions ................................................................................................................... 12 3.6 Problem Area Remediation approach ........................................................................................ 12 3.7 Significant Obstructions ............................................................................................................ 13 3.8 Designation of Stormwater Hotspots ......................................................................................... 14 Section 4 – Watershed Technical Analysis – Modeling 16 4.0 Hydrologic Model ..................................................................................................................... 16 4.1 Modeling Results & Release Rates ........................................................................................... 16 4.2 Reservoir Modeling ................................................................................................................... 17 Section 5 – Technical Standards and Criteria for Control of Stormwater Runoff 19 5.0 Introduction ............................................................................................................................... 19 5.1 Water Quality Volume (WQv) ................................................................................................... 19 5.2 Recharge Volume Requirements (Rev) ...................................................................................... 22 5.3 Channel Protection Storage Volume Requirements (Cpv) ......................................................... 24 5.4 Overbank and Extreme Event Flood Protection Requirements (Release Rates) ....................... 28 5.5 Design Example: Computing Stormwater Storage Volumes .................................................... 29 Section 6 – Runoff Control Techniques and Their Efficiencies 34 6.0 Acceptable Urban Best Management Practices (BMP) Options ............................................... 34 Section 7 – Municipal Handbook 36 7.0 Introduction - Why Stormwater Matters.................................................................................... 36 7.1 Declining Water Quality ............................................................................................................ 37 7.2 Intent of the Act 167 Plan .......................................................................................................... 37 7.3 Suggested Best Management Practices ..................................................................................... 37 7.4 BMP Maintenance ..................................................................................................................... 38 7.4.1 Overview of BMP Maintenance ............................................................................................ 39 7.4.2 Routine Maintenance Needs.................................................................................................. 40 7.4.3 Nonroutine Maintenance ....................................................................................................... 41 7.4.4 Maintenance Responsibilities ................................................................................................ 43 7.4.5 Estimating Routine Costs ...................................................................................................... 44 7.4.6 Estimating Nonroutine Costs ................................................................................................ 44 7.4.7 Planning Ahead ..................................................................................................................... 44 7.4.8 Access for Maintenance ........................................................................................................ 44 7.4.9 Maintenance Agreements ...................................................................................................... 45 7.5 Effective Site Planning .............................................................................................................. 45 (i) 7.5.1 Some Important Principles of Effective Site Planning .......................................................... 45 7.5.2 Resources for Identifying and Mapping Sensitive Areas ...................................................... 46 7.5.3 Important Functions of Sensitive Areas and How They are Best Protected ......................... 47 7.5.4 Preserving Natural Hydrologic Conditions ........................................................................... 48 7.5.5 Reducing or Disconnecting Impervious Surface Areas ........................................................ 49 7.5.6 Preserving Natural Drainage Features ................................................................................... 50 7.5.7 Protecting Natural Depression Storage Areas ....................................................................... 50 7.6 Site Planning and Land-Use Techniques to Minimize Efforts of Development ....................... 50 7.6.1 Setbacks and Buffers ............................................................................................................. 51 7.6.2 Cluster Development ............................................................................................................. 52 7.6.3 Zoning Restrictions ............................................................................................................... 53 7.6.4 Conservation Easements ....................................................................................................... 53 7.6.5 Development Designed to Fit Site Topography .................................................................... 53 Section 8 – Plan Review Adoption and Updating Procedures 54 8.0 Plan Review and Adoption ........................................................................................................ 54 8.1 Procedure for Updating the Plan ............................................................................................... 55 Section 9 – Priorities for Implementation of Technical Standards and Criteria 57 9.0 Summary of Plan Conclusions and Recommendations ............................................................. 57 Section 10 - Model Act 167 Stormwater Management Ordinance 58 Tables: Table 2.0 - Existing Municipal Ordinance Matrix, White Deer Creek Watershed ....................................... 4 Table 2.1 - White Deer Creek Watershed Plan Advisory Committee (WPAC) ........................................... 6 Table 2.2 - White Deer Creek Watershed Municipal Engineer’s Committee (MEC) .................................. 7 Table 2.3 - White Deer Creek Watershed Legal Advisory Committee (LAC) ............................................. 7 Table 3.0 - Municipalities Lying Within The Watershed ............................................................................