City of Philadelphia Natural Hazard Mitigation Plan Managing Director’s Office May 2012 Office of Emergency Management City of Philadelphia Managing Director’s Office of Emergency Management Natural Hazard Mitigation Plan May 2012 Michael Nutter Mayor Everett Gillison, Esq. Samantha Phillips Chief of Staff Acting Deputy Managing Director Deputy Mayor, Public Safety Emergency Management Table of Contents Page - 1 - City of Philadelphia Natural Hazard Mitigation Plan Managing Director’s Office May 2012 Office of Emergency Management 1. Introduction ................................................................................................................. 4 1.1 Background ........................................................................................................... 4 1.2 Purpose and Scope ............................................................................................... 4 1.2.1 Premise ........................................................................................................... 4 1.2.2 Purpose of the Plan ......................................................................................... 6 1.3 Authority and References ...................................................................................... 6 2. Community Profile: Philadelphia ............................................................................... 10 2.1 Physical Environment .......................................................................................... 10 2.1.1 Geography .................................................................................................... 10 2.1.2 Hydrography and Hydrology .......................................................................... 12 2.1.3 Topography and Geology .............................................................................. 16 2.1.4 Climate .......................................................................................................... 18 2.2 Social Environment .............................................................................................. 21 2.2.1 History ........................................................................................................... 21 2.2.2 Social Characteristics .................................................................................... 22 2.2.3 Economic Characteristics .............................................................................. 27 2.3 The Built Environment ......................................................................................... 31 2.3.1 Neighborhoods and Planning Districts .......................................................... 31 2.3.2 Land Use ....................................................................................................... 33 2.3.3 Housing ......................................................................................................... 35 2.3.4 Population Density ........................................................................................ 36 2.3.5 Population Change ........................................................................................ 38 2.3.6 Infrastructure ................................................................................................. 39 2.3.7 Emergency Services ..................................................................................... 50 2.3.8 Hospitals and Healthcare Facilities ............................................................... 52 2.3.9 Higher Educational Facilities ......................................................................... 53 2.3.10 Cultural Facilities ......................................................................................... 54 3. Planning Process ...................................................................................................... 56 3.1 Planning Process and Participation Summary ..................................................... 56 3.2 Planning Committee ............................................................................................ 56 3.2.1 Participants and Agency Descriptions ........................................................... 57 3.3 Planning Committee Meetings and Documentation ............................................. 58 3.4 Public Meetings ................................................................................................... 60 3.4.1 Meeting Logistics .......................................................................................... 60 3.4.2 Meeting Materials .......................................................................................... 60 3.4.3 Hazard Mitigation Plan Website .................................................................... 61 4. Risk Assessment ....................................................................................................... 62 4.1 Hazard Identification ............................................................................................ 62 4.1.1 Table of Disaster Declarations ...................................................................... 62 4.1.2 Summary of Hazards .................................................................................... 69 4.2 Hazard Profiles and Vulnerability Assessment .................................................... 73 4.2.1 Drought ......................................................................................................... 73 4.2.2 Earthquake .................................................................................................... 89 4.2.3 Extreme Temperatures ............................................................................... 108 Table of Contents Page - 2 - City of Philadelphia Natural Hazard Mitigation Plan Managing Director’s Office May 2012 Office of Emergency Management 4.2.4 Floods ......................................................................................................... 122 4.2.5 Tropical Cyclones – Hurricanes and Tropical Storms ................................. 155 4.2.6 Windstorm and Tornado .............................................................................. 174 4.2.7 Winter Storm ............................................................................................... 191 4.3 Hazard Vulnerability Summary .......................................................................... 204 4.3.1 Methodology ................................................................................................ 204 4.3.2 Hazard Ranking .......................................................................................... 204 4.3.3 Potential Loss Estimates ............................................................................. 209 4.3.4 Future Development and Vulnerability ........................................................ 210 5. Capability Assessment ............................................................................................ 214 5.1 Philadelphia Capability Assessment .................................................................. 214 5.1.1 Conducting the Capability Assessment ....................................................... 214 5.1.2 Capability Assessment Findings ................................................................. 214 6. Mitigation Strategy ................................................................................................... 224 6.1 Introduction ........................................................................................................ 224 6.1.1 Mitigation Planning Approach ...................................................................... 224 6.1.2 FEMA Requirements Addressed in this Section .......................................... 224 6.2 Mitigation Goals and Objectives ........................................................................ 225 6.3 Identification and Analysis of Mitigation Techniques .......................................... 226 6.4 Mitigation Action Plan ........................................................................................ 229 6.4.1 Existing Mitigation Actions........................................................................... 229 6.4.2 Potential Mitigation Actions ......................................................................... 229 7. Plan Maintenance.................................................................................................... 273 7.1 Update Process Summary ................................................................................. 273 7.2 Monitoring, Evaluation and Updating the Plan ................................................... 273 7.3 Incorportation into Other Planning Mechanisms ................................................ 274 7.4 Continued Public Involvement ........................................................................... 274 8. Plan Adoption .......................................................................................................... 275 References .................................................................................................................. 276 Glossary ...................................................................................................................... 282 Acronyms .................................................................................................................... 298 Listing of Appendices .................................................................................................. 303 Appendix A: Questionnaire .....................................................................................