Assignment: Local Mitigation Plan

2015 – 2016 Update

CHARLESTON

REGIONAL HAZARD

MITIGATION PLAN

Jurisdictions Represented and Participating in

the Charleston Regional Hazard Mitigation Plan

Unincorporated Charleston County

Town of Awendaw

City of Charleston

City of Folly Beach

Town of Hollywood

City of Isle of Palms

Town of James Island

Town of Kiawah Island

Town of Lincolnville

Town of McClellanville

Town of Meggett

Town of Mt. Pleasant

City of North Charleston

Town of Ravenel

Town of Rockville

Town of Seabrook Island

Town of Sullivan’s Island

Government Entities Represented and Participating in this Plan

Charleston County Parks & Recreation Commission

Charleston County School District

Charleston Water System

College of Charleston

Cooper River Parks & Playground Commission

James Island Public Service District Commission

Mt. Pleasant Water Works Commission

North Charleston District

North Charleston Sewer District

Roper St. Francis

St. Andrews Parish Park & Recreation Commission

St. Andrews Public Service District

St. John’s Fire District Commission

St. Paul’s Fire District Commission

CONTACT US ABOUT THE PLAN:

The Charleston Regional Hazard Mitigation Plan involves all participating jurisdictions but is

maintained by Charleston County’s Building Inspection Services Department. This plan is

published on the Charleston County Building Inspection Services website and is available in the

department office.

Public comment on the plan is always welcome and incorporated into the yearly updates. For any

questions on the plan or for information on how to be involved with the Plan, please contact

Charleston County Building Inspection Services. Thank you for your interest.

Email: [email protected] Phone: 843-202-6940

Fax: 843-202-6954

Charleston Regional Hazard Mitigation Plan

Table of Contents Executive Summary ……………………………………………………………………………………………………………. 8

1.1 – Planning Process ……………………………………………………………………………………………………… 8

1.2 – Hazard Assessment …………………………………………………………………………………………………. 9

1.3 – Hazard Identification and Risk Assessment (HIRA) ………………………………………………… 9

1.4 – Problem Assessment ………………………………………………………………………………………………. 10

1.5 – Goals ……………………………………………………………………………………………………………………… 11

1.6 – Review of Possible Activities ………………………………………………………………………………….. 11

1.7 – Adopting Resolution ……………………………………………………………………………………………… 12

1.8 – Action Plan …………………………………………………………………………………………………………….. 12

1.9 – Conclusion …………………………………………………………………………………………………………….. 12

Planning Process ………………………………………………………………………………………………………………. 14

2.1 – Direction of Professional Planner …………………………………………………………………………… 14

2.2 – Pre Planning Request for Input from Interested Parties …………………………………………. 14

2.3 – Planning Committee ………………………………………………………………………………………………. 16

2.4 – Public Input ……………………………………………………………………………………………………………. 18

2.5 – Local Jurisdiction Adoption …………………………………………………………………………………… 20

2.6 – Implementation Plan ……………………………………………………………………………………………… 20

2.7 – Planning Process Summary ……………………………………………………………………………………. 22

Attachment 2-A: Charleston Regional Hazard Mitigation Plan Questionnaire ………………. 26

Attachment 2-B: CRS/Hazard Mitigation Plan Questionnaire Distribution …………………… 33

Attachment 2-C: Members of the Charleston Regional Hazard Mitigation Project

Committee ……………………………………………………………………………………………………………………… 35

Attachment 2-D: Recognizing & Adopting the Committee/Plan …………………………………… 37

Hazard Assessment …………………………………………………………………………………………………………… 39

3.1 – Hurricane ………………………………………………………………………………………………………………. 41

3.2 – Flood ……………………………………………………………………………………………………………………… 46

3.3 – Wildfire ………………………………………………………………………………………………………………….. 50

3.4 – Tornado …………………………………………………………………………………………………………………. 54

3.5 – Earthquake …………………………………………………………………………………………………………….. 57

3.6 – Hazardous Materials ……………………………………………………………………………………………… 61

3.7 – Rip Currents …………………………………………………………………………………………………………… 65

Charleston Regional Hazard Mitigation Plan

3.8 – Severe Storm ………………………………………………………………………………………………………….. 68

3.9 – Drought …………………………………………………………………………………………………………………. 73

3.10 – Winter eather ……………………………………………………………………………………………………….. 78

3.11 – Avian Flu/Pandemic ……………………………………………………………………………………………. 80

3.12 – Dam Failure …………………………………………………………………………………………………………. 83

3.13 – Terrorism ……………………………………………………………………………………………………………… 85

3.14 – Tsunamis ……………………………………………………………………………………………………………… 89

3.15 – Summary of Jurisdictions Affected ………………………………………………………………………. 91

3.16 – Summary of Hazard Extent ………………………………………………………………………………….. 92

3.17 – Summary of Hazard Probability …………………………………………………………………………… 94

Problem Assessment ………………………………………………………………………………………………………… 96

4.1 – Hazard Vulnerability ……………………………………………………………………………………………… 96

4.2 – Vulnerable Buildings ……………………………………………………………………………………………. 112

4.3 – Infrastructure Vulnerability………………………………………………………………………………….. 126

4.4 – Known Flood Damages ………………………………………………………………………………………… 135

4.5 – Past Flood Impacts ……………………………………………………………………………………………….. 137

4.6 – Emergency Warning Needs ………………………………………………………………………………….. 137

4.7 – Critical Facilities …………………………………………………………………………………………………… 140

4.8 – Natural and Beneficial Functions of Floodplains ………………………………………………….. 148

4.9 – Development and Population Trends …………………………………………………………………… 156

4.10 – Economic Impact ………………………………………………………………………………………………… 171

Attachment 4-A: Repetitive Loss Areas within the Charleston Region ………………………… 199

Attachment 4-B: Critical Facilities Located within Charleston County ………………………… 204

Attachment 4-C: Charleston Region Buildings Vulnerable to Flooding Due to Location in

the Special Flood Hazard Area (SFHA) Only ……………………………………………………………….. 213

Attachment 4-D: Charleston Region Buildings Vulnerable to Flooding Due to Year of

Construction and Location in the Special Flood Hazard Area (SFHA) …………………………. 214

Attachment 4-E: Charleston Region Average Valuation of Buildings and Mobile Homes

…………………………………………………………………………………………………………………………………….. 215

Attachment 4-F: Charleston Region Average Valuation of Site-Built Buildings by Flood

Zone …………………………………………………………………………………………………………………………….. 216

Goals ……………………………………………………………………………………………………………………………….. 217

Possible Activities …………………………………………………………………………………………………………… 221

6.1 – Program for Public Information ……………………………………………………………………………. 223

6.2 – Preventive Activities …………………………………………………………………………………………….. 225

Charleston Regional Hazard Mitigation Plan

6.3 – Property Protection ………………………………………………………………………………………………. 227

6.4 – Natural and Beneficial Functions of Floodplains/Resource Preservation …………….. 231

6.5 – Emergency Services ……………………………………………………………………………………………… 233

6.6 – Structural Projects ………………………………………………………………………………………………… 236

6.7 – Public Information Activities ……………………………………………………………………………….. 238

Attachment 6-A: A Chart of Project Prioritization Factors Based Upon Questionnaire

Responses …………………………………………………………………………………………………………………….. 241

Attachment 6-B: A Chart of Property Protection Project Prioritization Based Upon

Questionnaire Responses ……………………………………………………………………………………………… 242

Attachment 6-C: Drainage Improvement Projects ……………………………………………………….. 243

Attachment 6-D: Program for Public Information ……………………………………………………….. 254

Adopting Resolution and Jurisdiction-Specific Action Plans ………………………………………… 259

7.1 – Unincorporated Charleston County ……………………………………………………………………… 261

7.2 – Town of Awendaw ………………………………………………………………………………………………. 287

7.3 – City of Charleston ………………………………………………………………………………………………… 312

7.4 – City of Folly Beach ……………………………………………………………………………………………….. 322

7.5 – Town of Hollywood ……………………………………………………………………………………………… 332

7.6 – City of Isle of Palms ……………………………………………………………………………………………… 357

7.7 – Town of James Island …………………………………………………………………………………………… 364

7.8 – Town of Kiawah Island ………………………………………………………………………………………… 387

7.9 – Town of Lincolnville …………………………………………………………………………………………….. 397

7.10 – Town of McClellanville ………………………………………………………………………………………. 413

7.11 – Town of Meggett ………………………………………………………………………………………………… 427

7.12 – Town of Mt. Pleasant ………………………………………………………………………………………….. 450

7.13 – City of North Charleston…………………………………………………………………………………….. 471

7.14 – Town of Ravenel…………………………………………………………………………………………………. 494

7.15 – Town of Rockville ………………………………………………………………………………………………. 517

7.16 – Town of Seabrook Island ……………………………………………………………………………………. 540

7.17 – Town of Sullivan’s Island …………………………………………………………………………………… 564

7.18 – Charleston County Parks & Recreation Commission ………………………………………….. 577

7.19 – Charleston County School District ……………………………………………………………………… 582

7.20 – Charleston Water System ……………………………………………………………………………………. 588

7.21 – College of Charleston …………………………………………………………………………………………. 604

7.22 – Cooper River Parks & Playground Commission …………………………………………………. 610

Charleston Regional Hazard Mitigation Plan

7.23 – James Island Public Service District Commission ……………………………………………….. 615

7.24 – Mt. Pleasant Water Works Commission ……………………………………………………………… 628

7.25 – North Charleston District …………………………………………………………&#x2