2016 Update to Pre-Disaster Walkerville Mitigation Plan Butte Silver Bow County City and County of Butte-Silver Bow, Montana and Town of Walkerville September 2016 TETRA TECH 2016 UPDATE TO PRE-DISASTER MITIGATION PLAN FOR CITY AND COUNTY OF BUTTE-SILVER BOW, MONTANA AND TOWN OF WALKERVILLE Prepared for: Butte-Silver Bow Office of Emergency Management 3619 Wynne Butte, Montana 59701 Prepared by: Tetra Tech Inc. 303 Irene Street Helena, Montana 59601 (406) 443-5210 September 2016 Table of Contents TABLE OF CONTENTS 1.0 INTRODUCTION ..............................................................................................1-1 1.1 BACKGROUND............................................................................................................................................... 1-1 1.2 AUTHORITY.................................................................................................................................................... 1-1 1.3 ACKNOWLEDGEMENTS............................................................................................................................ 1-2 1.4 SCOPE AND PLAN ORGANIZATION...................................................................................................... 1-2 2.0 PLANNING PROCESS ......................................................................................2-1 2.1 PDM STEERING COMMITTEE................................................................................................................. 2-1 2.2 PROJECT STAKEHOLDERS....................................................................................................................... 2-2 2.3 REVIEW OF EXISTING PLANS AND STUDIES................................................................................... 2-3 2.4 PROJECT WEBSITE...................................................................................................................................... 2-4 2.5 PROJECT MEETINGS................................................................................................................................... 2-4 2.6 PLAN REVIEW............................................................................................................................................... 2-5 3.0 COMMUNITY PROFILE ..................................................................................3-1 3.1 PHYSICAL SETTING .................................................................................................................................... 3-1 3.2 CLIMATE ...................................................................................................................................................... 3-1 3.3 CRITICAL FACILITIES AND INFRASTRUCTURE.............................................................................. 3-4 3.3.1 Water and Wastewater Services......................................................................................................3-5 3.3.2 Utilities.........................................................................................................................................................3-5 3.3.3 Transportation.........................................................................................................................................3-5 3.3.4 Law Enforcement and Emergency Services................................................................................3-6 3.4 POPULATION TRENDS .............................................................................................................................. 3-7 3.5 HOUSING STOCK.......................................................................................................................................... 3-8 3.6 ECONOMY AND SOCIOECONOMICS..................................................................................................... 3-8 3.7 LAND USE AND FUTURE DEVELOPMENT......................................................................................... 3-9 3.7.1 Land Use Implementation Tools.......................................................................................................3-9 3.7.2 Future Development ...........................................................................................................................3-13 4.0 RISK ASSESSMENT AND VULNERABILITY ANALYSIS..........................4-1 4.1 RISK ASSESSMENT METHODOLOGY................................................................................................... 4-1 4.1.1 Critical Facilities and Building Stock.......................................................................................... 4-1 4.1.2 Vulnerable Population....................................................................................................................... 4-2 4.1.3 Hazard Identification......................................................................................................................... 4-2 4.1.4 Hazard Profiles...................................................................................................................................... 4-7 4.1.5 Hazard Ranking and Priorities...................................................................................................... 4-8 4.1.6 Assessing Vulnerability - Estimating Potential Losses..................................................... 4-10 Pre-Disaster Mitigation Plan – Butte-Silver Bow County, Montana September 2016 i Table of Contents TABLE OF CONTENTS 4.1.7 Data Limitations................................................................................................................................ 4-10 4.2 HAZARDOUS MATERIAL INCIDENTS................................................................................................4-13 4.3 WILDFIRE ....................................................................................................................................................4-21 4.4 EARTHQUAKE.............................................................................................................................................4-27 4.5 SEVERE WEATHER AND DROUGHT .................................................................................................4-35 4.6 TRANSPORTATION ACCIDENTS..........................................................................................................4-49 4.7 COMMUNICABLE DISEASE ....................................................................................................................4-54 4.8 TERRORISM, VIOLENCE, CIVIL UNREST..........................................................................................4-58 4.9 FLOODING AN DAM FAILURE .............................................................................................................4-62 4.10 RISK ASSESSMENT SUMMARY.............................................................................................................4-75 5.0 MITIGATION STRATEGY...............................................................................5-1 5.1 BACKGROUND AND PAST MITIGATION ACCOMPLISHMENTS................................................ 5-1 5.2 GENERAL MITIGATION PLANNING APPROACH............................................................................. 5-3 5.3 MITIGATION GOALS AND OBJECTIVES.............................................................................................. 5-4 5.4 CAPABILITY ASSESSMENT ...................................................................................................................... 5-6 5.4.1 Summary of Programs and Resources Available to Support Mitigation.......................5-6 5.4.2 Administrative and Technical Capabilities............................................................................ 5-6 5.4.3 Fiscal Capabilities........................................................................................................................... 5-9 5.5 MITIGATION STRATEGY DEVELOPMENT.......................................................................................5-12 5.5.1 Mitigation Strategy Update and Reconciliation................................................................5-12 5.5.2 Mitigation Strategy Benefit/Cost Review and Prioritization .......................................5-13 5.5.3 Project Implementation..............................................................................................................5-14 6.0 PLAN MAINTENANCE PROCEDURES.........................................................6-1 6.1 MONITORING, EVALUATING AND UPDATING THE PLAN ......................................................... 6-1 6.1.1 2010 PDM Plan.........................................................................................................................................6-1 6.1.2 2016 PDM Plan.........................................................................................................................................6-1 6.2 MONITORING PROGRESS OF MITIGATION ACTIVITIES............................................................. 6-2 6.2.1 2010 PDM Plan.........................................................................................................................................6-2 6.2.2 2016 PDM Plan.........................................................................................................................................6-2 6.3 IMPLEMENTATION THROUGH EXISTING PROGRAMS................................................................ 6-3 6.4 CONTINUED PUBLIC INVOLVEMENT ................................................................................................