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HAZARD PROFILE ......................................................................................................................................................................................................... 225 SECONDARY HAZARDS ................................................................................................................................................................................................. 232 EXPOSURE ...................................................................................................................................................................................................................... 232 VULNERABILITy ............................................................................................................................................................................................................ 233 FUTURE TRENDS IN DEVELOPMENT ......................................................................................................................................................................... 234 SCENARIO ...................................................................................................................................................................................................................... 234 ISSUES ............................................................................................................................................................................................................................ 235 TSUNAMI .................................................................................................................................................................................................... 236 GENERAL BACKGROUND ............................................................................................................................................................................................. 236 HAZARD PROFILE .......................................................................................................................................................................................................... 238 SECONDARY HAZARDS ................................................................................................................................................................................................. 241 EXPOSURE AND VULNERABILITY ............................................................................................................................................................................... 241 FUTURE TRENDS IN DEVELOPMENT ......................................................................................................................................................................... 242 SCENARIO ...................................................................................................................................................................................................................... 242 ISSUES ............................................................................................................................................................................................................................ 242 WILDFIRE .................................................................................................................................................................................................. 243 GENERAL BACKGROUND ............................................................................................................................................................................................. 243 HAZARD PROFILE ......................................................................................................................................................................................................... 243 SECONDARY HAZARDS ................................................................................................................................................................................................. 24 7 EXPOSURE ...................................................................................................................................................................................................................... 248 VULNERABILITy ............................................................................................................................................................................................................ 251 FUTURE TRENDS IN DEVELOPMENT ......................................................................................................................................................................... 253 SCENARIO ...................................................................................................................................................................................................................... 253 ISSUES ............................................................................................................................................................................................................................ 253 CLIMATE CHANGE ...................................................................................................................................................................................... 255 GENERAL BACKGROUND ............................................................................................................................................................................................. 255 VULNERABI LlTY ASSESSMENT- HAZARDS OF CONCERN .................................................................................................................................... 262 VULNERABILITY ASSESSMENT-SEA LEVEL RISE ................................................................................................................................................. 269 ISSUES ............................................................................................................................................................................................................................ 272 OTHER HAZARDS OF INTEREST ................................................................................................................................................................ 273 GENERAL BACKGROUND ............................................................................................................................................................................................. 273 HAZARD PROFILE ......................................................................................................................................................................................................... 294 IDENTIFIED NEEDS ...................................................................................................................................................................................................... 302 PART III: MITIGATION STRATEGY .................................................................................................................................................. 304 GOALS AND OB'ECTIVES ............................................................................................................................................................................ 305 GUIDING PRINCIPLE ..................................................................................................................................................................................................... 305 GOALS ............................................................................................................................................................................................................................. 305 OBJECTIVES ................................................................................................................................................................................................................... 305 MITIGATION ALTERNATIVES .................................................................................................................................................................... 307 AREA-WIDE ACTION PLAN AND IMPLEMENTATION .............................................................................................................. ; ................ 316 PLAN ADOPTION ........................................................................................................................................................................................................... 319 PLAN MAINTENANCE STRATEGY ............................................................................................................................................................................... 319 REFERENCES ............................................................................................................................................................................................... 326 GLOSSARY ............................................................................................................................................................................... " •• " ............. 330 ACRONYMS .................................................................................................................................................................................................................... 330 DEFINITIONS ................................................................................................................................................................................................................. 332 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 5
APPENDICES
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Appendix A. Public Outreach Materials .......................................................................................................... 342 Appendix B. Progress Report Template ........................................................................................................... 371 Appendix C. Plan Adoption Resolutions from Planning Partners ............................................................... 376 TABLES
Table 2-1. Plan Changes Crosswalk .................................................................................................................... 23 Table 3-1. Municipal Planning Partners ............................................................................................................. 30 Table 3-2. Santa Clara County Operational Area LHMP Working Group Members .................................. 31 Table 3-3. Summary of Public Meetings ............................................................................................................. 39 Table 3-4. Plan Development Chronology /Milestones ................................................................................. ..40 Table 4-1. Presidential Disaster Declarations ................................................................................................... .43 Table 4-2. San Jose Normal Precipitation and Temperatures, 1981 - 2010 .................................................... 45 Table 4-3. Unincorporated Santa Clara County Present Land Use .............................................................. ..45 Table 4-4. Critical Facilities and Infrastructures in OA .................................................................................. ..46 Table 4-5. Recent Population Data ................. ..................................................................................................... 50 Table 4-6. Hourly Living Wage Calculation for Santa Clara County, California (2015) ............................ .54 Table 5-1. Probability of Hazards ........................................................................................................................ 75 Table 5-2. Impact on People from Hazards ........................................................................................................ 77 Table 5-3. Impact on Property from Hazards .................................................................................................... 77 Table 5-4. Impact on Economy from Hazards ............... .................................................................................... 77 Table 5-5. Hazard Risk Rating ............................................................................................................................. 78 Table 5-6. Hazard Risk Ranking .......................................................................................................................... 78 Table 5-7. Hazus Model Data Documentation .................................................................................................. 82 Table 6-1. Santa Clara County High Hazard Dam Inspection Dates ............................................................. 87 Table 6-2. High Hazard Dams in the Santa Clara County OA ........................................................................ 90 Table 6-3. Levees in Santa Clara County ............................................................................................................ 91 Table 6-4. Corps of Engineers Hazard Potential Classification ...................................................................... 91 Table 6-5. Population within Anderson and Lexington Dam Failure Inundation Areas ............................ 93 Table 6-6. Population within Searsville and Stevens Dam Failure Inundation Areas ................................. 94 Table 6-7. Population within Levee Failure Inundation Area ......................................................................... 94 Table 6-8. Exposure and Value of Structures in Anderson Dam Failure Inundation Areas ....................... 95 Table 6-9. Structures Exposed to Anderson Dam Failure by Land Use Type ............................................... 96 Table 6-10. Exposure and Value of Structures in Lexington Dam Failure Inundation Areas .................... 96 Table 6-11. Exposure and Value of Structures in Searsville Dam Failure Inundation Areas ..................... 97 Table 6-12. Exposure and Value of Structures in Stevens Creek Dam Failure Inundation Areas ............. 97 Table 6-13. Structures Exposed to Lexington Dam Failure by Land Use Type ............................................ 98 Table 6-14. Structures Exposed to Searsville Dam Failure by Land Use Type ............................................. 98 Table 6-15. Structures Exposed to Stevens Creek Dam Failure by Land Use Type ..................................... 99 Table 6-16. Critical Facilities in Anderson Dam Failure Inundation Areasa ................................................. 99 Table 6-17. Loss Estimates for Dam Failure ..................................................................................................... 100 Table 6-18. Loss Estimates for Levee Failure ................................................................................................... 101 6 I Page Santa Clara County Operational Area Mitigation Plan 10/lS/17
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Table 8-1. Mercalli Scale and Peak Ground Acceleration Comparison ....................................................... 126 Table 8-2. NEHRP Soil Classification System .................................................................................................. 127 Table 8-3. Recent Earthquakes Magnitude 5.0 or Larger Within 100-mile Radius of the OA .................. 129 Table 8-4. Earthquake Probabilities for the San Francisco Bay Area Region, 2014-2043 ........................... 141 Table 8-5. Earthquake Exposure by Municipality .............................. ............................................................. 145 Table 8-6. Estimated Earthquake Impact on Persons ..................................................................................... 146 Table 8-7. Age of Structures in OA .................................................................................................................... 146 Table 8-8. Loss Estimates for 100-Year Probabilistic Earthquake ................................................................. 148 Table 8-9. Loss Estimates for 500-Year Probabilistic Earthquake ................................................................. 148 Table 8-10. Loss Estimates for San Andreas Fault Scenario Earthquake ..................................................... 149 Table 8-11. Loss Estimates for Hayward Fault Scenario Earthquake ........................................................... 149 Table 8-12. Loss Estimates for Calaveras Fault Scenario Earthquake .......................................................... 150 Table 8-13. Estimated Earthquake-Caused Debris .................. ........................................................................ 150 Table 8-14. Estimated Damage to Critical Facilities from 100-Year Earthquake ........................................ 151 Table 8-15. Estimated Damage to Critical Facilities from 500-Year Earthquake ........................................ 151 Table 8-16. Estimated Damage to Critical Facilities from Hayward Fault.. ................................................ 152 Table 8-17. Estimated Damage to Critical Facilities from San Andreas Fault ............................................ 152 Table 8-18. Estimated Damage to Critical Facilities from Calaveras ............................................................ 152 Table 8-19. Functionality of Critical Facilities for 100-Year Event... ............................................................. 153 Table 8-20. Functionality of Critical Facilities for 500-Year Event.. .............................................................. 153 Table 8-21. Functionality of Critical Facilities for Hayward Fault... ............................................................. 153 Table 8-22. Functionality of Critical Facilities for San Andreas Fault.. ........................................................ 154 Table 8-23. Functionality of Critical Facilities for Calaveras Fault.. ............................................................. 154 Table 9-1. NFIP Status in the Operational Area .............................................................................................. 160 Table 9-2. CRS Community Status in the OA .................................................................................................. 163 Table 9-3. History of Flood Events .................................................................................................................... 168 Table 9-4. Crop Insurance Claims Paid from Excessive Moisture and Flood, 2003-2016 .......................... 169 Table 9-5. Summary of Peak Discharges Within the OA ............................................................................... 171 Table 9-6. Population Within the 10-Percent, I-Percent and 0.2-Percent Annual Chance Flood Hazard Areas ...................................................................................................................................................................... 181 Table 9-7. Area and Structures in the 10-Percent Annual Chance Flood Hazard Area ............................. 182 Table 9-8. Area and Structures in the I-Percent Annual Chance Flood Hazard Area ............................... 182 Table 9-9. Area and Structures in the 0.2-Percent Annual Chance Flood Hazard Area ............................ 183 Table 9-10. Value of Structures in the 10-Percent Annual Chance Flood Hazard Area ............................ 183 Table 9-11. Value of Structures in the I-Percent Annual Chance Flood Hazard Area .............................. 184 Table 9-12. Value of Structures in the 0.2-Percent Annual Chance Flood Hazard Area ........................... 184 Table 9-13. Unincorporated Santa Clara County Land Use in the I-Percent Annual Chance Flood Hazard Area ....................................................................................................................................................................... 185 Table 9-14. Unincorporated Santa Clara County Land Use in the 0.2-Percent Annual Chance Flood Hazard Area ......................................................................................................................................................... 185 Table 9-15. Critical Facilities in the 10-Percent Annual Chance Flood Hazard Area ................................. 186 Table 9-16. Critical Facilities in the I-Percent Annual Chance Flood Hazard Area ................................... 186 Table 9-17. Critical Facilities in the O.2-Percent Annual Chance Flood Hazard Area ................................ 187 Table 9-18. Estimated Flood Impact on Persons and Households ............................................................... 189 Table 9-19. Loss Estimates for 10-Percent-Annual-Chance Flood ................................................................ 191 Table 9-20. Loss Estimates for 1-Percent-Annual-Chance Flood .................................................................. 191 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 7
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Table 9-21. Loss Estimates for 0.2-Percent-Annual-Chance Flood ............................................................... 192 Table 9-22. Estimated Flood-Caused Debris .................................................................................................... 193 Table 9-23. Estimated Insurable Annual Crop Loss Resulting From Flood .... ............................................ 193 Table 9-24. Flood Insurance Statistics ............................................................................................................... 194 Table 9-25. Repetitive Loss Properties .................................................... .......................................................... 196 Table 9-26. Estimated Damage to Critical Facilities and Infrastructure from the 10% Annual Chance Flood ................................... ............................................................................................................................................. 198 Table 9-27. Estimated Damage to Critical Facilities and Infrastructure from the 1 % Annual Chance Flood ..................................................................................................................................................... ........................... 198 Table 9-28. Estimated Damage to Critical Facilities and Infrastructure from the 0.2% Annual Chance Flood ...................................................................................................................................................................... 198 Table 10-1. Landslide Events in Santa Clara County ...................................................................................... 207 Table 10-2. Exposure and Value of Structures in Moderate Landslide Risk Areas .................................... 212 Table 10-3. Exposure and Value of Structures in High Landslide Risk Areas ............................................ 212 Table 10-4. Exposure and Value of Structures in Very High Landslide Risk Areas .................................. 213 Table 10-5. Land Use in Landslide Hazard Areas ........................................................................................... 213 Table 10-6. Critical Facilities and Infrastructure in Moderate Landslide Risk Areas ................................ 214 Table 10-7. Critical Facilities and Infrastructure in High Landslide Risk Areas ........................................ 214 Table 10-8. Critical Facilities and Infrastructure in Very High Landslide Risk Areas ............................... 215 Table 10-9. Loss Potential (based on all building Stock in aggregated landslide areas) ........................... 216 Table 11-1. Past Severe Weather Events Impacting OA ................................................................................. 226 Table 11-2. Crop Insurance Claims Paid from Heat, Excess Wind, Frost, and Cold Wet Weather, 2003- 2016 ........................................................................................................................................................................ 229 Table 11-3: Loss Potential for Severe Weather ................................................................................................. 233 Table 11-4. Estimated Insurable Annual Crop Loss Resulting From Severe Weather .............................. 234 Table 13-1. Record of Fire Affecting OA ......................................................................................................... .247 Table 13-2. Population Within Wildfire Hazard Areas .................................................... .............................. 248 Table 13-3. Exposure and Value of Structures in Very High Wildfire Hazard Areas ............................... 249 Table 13-4. Exposure and Value of Structures in High Wildfire Hazard Areas ......................................... 249 Table 13-5. Exposure and Value of Structures in Moderate Wildfire Hazard Areas ................................ .250 Table 13-6. Land Use Within the Wildfire Hazard Areas .............................................................................. 250 Table 13-7. Critical Facilities and Infrastructure in Wildfire Hazard Areas ................................................ 250 Table 13-8. Loss Estimates for Wildfire (Aggregate of all Fire Severity zones assessed) .......................... 252 Table 14-1. Summary of Primary and Secondary Impacts Likely to Affect the OA .................................. 258 Table 14-2. Estimated Population Residing in Sea Level Rise Inundation Areas ....................................... 269 Table 14-3. Structure Type in Sea Level Rise Inundation Areas ................................................................... 270 Table 14-4. Structure and Contents Value in Sea Level Rise Inundation Areas ......................................... 270 Table 14-5. Critical Facilities in Sea Level Rise Inundation Areas ................................................................ 271 Table 15-1. Event Profiles for Terrorism ........................................................................................................... 275 Table 15-2. Common Mechanisms for Cyber Attacks .................................................................................... 278 Table 15-3. Corrosion Types ............................................................................................................................... 285 Table 15-4. Leak Classification ........................................................................................................................... 287 Table 17-1. Alternatives to Mitigate the Dam and Levee Failure Hazard ................................................... 308 Table 17-2. Alternatives to Mitigate the Drought Hazard ............................................................................. 309 8 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17
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Table 17-3. Alternatives to Mitigate the Earthquake Hazard ........................................................................ 310 Table 17-4. Alternatives to Mitigate the Flooding Hazard ............................................................................ 311 Table 17-5. Alternatives to Mitigate the Landslide/Mass Movement Hazard ........................................... 311 Table 17-6. Alternatives to Mitigate the Severe Weather Hazard ................................................................. 313 Table 17-7. Alternatives to Mitigate the Tsunami Hazard ............................................................................. 314 Table 17-8. Alternatives to Mitigate the Wildfire Hazard ............................................................................. 315 Table 18-1. Santa Clara County Operational Area Action Plan ..................................................................... 316 Table 18-2. Prioritization of Operational Area-Wide Mitigation Actions ................................................... 317 Table 18-3. Analysis of Mitigation Actions ...................................................................................................... 318 Table 18-4. Plan Maintenance Matrix ............................................................................................................... 320
FIGURES
Figure 3-1. Introductory Page from Survey Distributed to the PubIic ........................................................... 35 Figure 3-2. Campbell Farmer' s Market ............................................................................................................... 36 Figure 3-3. Campbell Farmer's Market. .............................................................................................................. 36 Figure 3-4. Sunnyvale Farmer's Market ............................................................................................................. 36 Figure 3-5. Public Comment Narrated Presentation ........................................................................................ 37 Figw'e 3-6. Sample Page from Hazard Mitigation Plan Web Site ................................................................... 38 Figure 4-1. Santa Clara County Operational Area (Planning Area) .............................................................. .42 Figure 7-1. Palmer Crop Moishlre Index for Week Ending April 8, 2017 ................................................... 105 Figure 7-2. Palmer Drought Index for April 8. 2017 ....................................................................................... 106 Figure 7-3. Palmer Z Index Short-Term Drought Conditions for March 2017 ............................................ 107 Figure 7-4. Palmer Hydrological Drought Index Long-Term Hydrologic Conditions for March 2017 .. 108 Figure 7-5. 24-Month Standardized Precipitation Index through the end of March 2017 ........................ 109 Figure 7-6. Santa Clara Valley Water District System Water Supply ........................................................... 112 Figure 7-7. Hetch-HetchyWater System .......................................................................................................... 112 Figure 7-8. Santa Clara County Municipal Water SOurce ............................................. ; ................................ 113 Figure 7-9. Santa Clara County Tree Mortality Exposure .............................................................................. 119 Figu re 8-1. Peak Acceleration (% g) with 10% Probability of Exceedance in 50 Years ............................... 126 Figure 8-2. Recent Earthquakes Within 100-mile Radius of the OA ............................................................ 129 Figure 8-6. Hayward M7.0 Fault Scenario Peak Ground Acceleration ........................................................ 137 Figure 8-9. National Earthquake Hazard Reduction Program Soil Classifications ................................... 140 Figure 8-11. Peak Ground Acceleration w ith 10-percent Probability of Exceedance in 50 Years ............ 143 Figure 9-1. CRS Communities by Class Nationwide as of October 2016 ..................................................... 162 FiguTe 9-2. Mapped Flood Hazard Areas in the Operational Area .............................................................. 170 Figure 9-3. Repetitive Loss Areas in the Operational Area ........................................................................... 197 Figure 10-1. Deep Seated Slide ........................................................................................................................... 203 Figure 10-2. Shallow Colluvial Slide ................................................................................................................. 203 Figure 10-3. Bench Slide ...................................................................................................................................... 203 Figure 10-4. Large Slide ...................................................................................................................................... 203 Figure 10-5. Typical Debris Avalanche Scar and Track ................................................................................. 204 Figure 10-6. SCVWD Timeline of Water Importation and Groundwater Management .......................... .209 Figure 11-1. The Thunderstorm Life Cycle ...................................................................................................... 220 Figure 11-2. NWS Heat Index ............................................................................................................................ 222 Figure 11-3. NOAA Space Weather Scales ....................................................................................................... 225 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 9
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Figure 11-4. Annual Number of Thunderstorms in the United States ......................................................... 230 Figure 11-5. Wind Zones in the United States ................................................................................................. 230 Figure 12-1. Potential Tsunami Travel Times in the Pacific Ocean, in Hours ............................................. 237 Figure 12-2. Tsunami Inundation Area ............................................................................................................ 240 Figure 13-1. Wildfire Severity Zones and Historical Perimeters ................................................................. .246 Figure 14-1. Global Carbon Dioxide Concentrations Over Time .................................................................. 256 Figure 14-2. Observed and Projected Average Temperatures in Santa Clara County .............................. 259 Figure 14-3. Projected Number of Extreme Heat Days by Year for OA ...................................................... 260 Figure 14-4. Projected Changes in Fire Risk in Santa Clara County, Relative to 2010 Levels .................. 261 Figure 15-1. Pop-Up Message Indicating Ransomware Infection ................................................................ 279 Figure 15-2. Areas with Confirmed Human Cases of H5N1 2003-2013 ....................................................... 290 Figure 15-3.2014 Distribution of Ebola Virus Outbreaks in Humans and Animals .................................. 292 Figure 15-4. Transmission and Hazardous Liquid Pipelines ........................................................................ 300 10 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17
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ACKNOWLEDGMENTS
COUNTY OF SANTA CLARA
• Darrell G. Ray Jr., CEM, Emergency Management Specialist, Santa Clara County Office of Emergency Services/Santa Clara County Fire Department
• Louay Toma, MPA, Emergency Management Specialist, Santa Clara County Office of - Emergency Services/Santa Clara County Fire Department • Cindy Stewart, Senior Emergency Planning Coordinator, Office of Emergency Services • Dana Reed, Director, Santa Clara County Office of Emergency Services/Santa Clara County Fire Department
• David S. Flamm, CEM, Deputy Director, Santa Clara County Office of Emergency Services
CONSULTANTS
• Rob Flaner, CFM, Tetra Tech, Inc., Project Manager
• Jessica Cerutti, CFM, Tetra Tech, Inc., Lead Project Planner • Carol Bauman, GISP, Tetra Tech, Inc., Risk Assessment Lead • Stephen Veith, MUP, Tetra Tech, Inc., GIS/Hazus Analyst • Kristen Gelino, MOP, CFM, Tetra Tech, Inc., Planner
• Kari Valentine, CFM, Tetra Tech, Inc., Planner
• Emily Slotnick, MUP, ACIP, CFM; Tetra Tech, Inc., Planner • Dan Portman, Tetra Tech, Inc., Technical Editor
STAKEHOLDERS
• Kent Fielden, American Red Cross
• Joseph Cefalu, Campbell Police Department
• Marsha Hovey, Collaborating Agencies Disaster Relief Effort • Kara Gross, Joint Venture
• Jennifer Ponce, Morgan Hill Emergency Services
• Lisa Schoenthal, Santa Clara (City) Emergency Services • Lynn Brown, Mountain View Emergency Services
• Ian Hogg, Mineta San Jose International Airport
• Cay Denise MacKenzie, San Jose Office of Emergency Services • Jared Hart, San Jose Planning, Building and Code Enforcement • Brian Glass, Santa Clara County Fire Department
• Raymond Fields, Santa Clara Valley Water District
• Michael Brill, Valley Transportation Authority
• John Lang, Silicon Valley Economic Development Alliance • Bart Spencer, Central County Fire Department (San Mateo County)
SPECIAL ACKNOWLEDGMENTS
The development of this plan would not have been possible without the dedication and commitment to this process by the Santa Clara County Operational Area Local Hazard. Mitigation Plan Working Group.
The dedication of this volunteer committee to allocate their time to this process is greatly appreciated.
Also, the citizens of Santa Clara County Operational Area are commended for their participation in the outreach strategy implemented for this plan. This outreach success will set the course to the successful implementation of this plan.
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EXECUTIVE SUMMARY
HAZARD MITIGATION PLANNING BACKGROUND
Hazard mitigation is the use of long-term and short-term policies, programs, projects, and other activities to alleviate the death, injury, and property damage that can result from a disaster. Santa Clara County and a partnership of local governments within the county have developed a hazard mitigation plan to reduce risks from natural disasters in the Santa Clara County Operational Area-defined as the unincorporated county and incorporated jurisdictions within the geographical boundaries of the county.
The plan complies with federal and state hazard mitigation planning requirements to establish eligibility for funding under Federal Emergency Management Agency (FEMA) grant programs.
INITIAL REGIONAL PLANNING EFFORTS FOR HAZARD MITIGATION The Association of Bay Area Governments (ABAG) provides communities in the San Francisco Bay area with planning and research resources related to land use, housing, environmental and water resource protection, disaster resilience, energy efficiency, hazardous waste mitigation, risk management and financial services. In 2004, ABAG led a regional effort to address hazard mitigation planning for Bay Area jurisdictions. ABAG's regional template was used by numerous counties and cities to meet federal hazard mitigation planning requirements. The ABAG process enabled individual planning processes to meet local government needs, while pooling resources and eliminating redundant planning efforts.
In 2010, ABAG conducted its second regional planning effort. Municipalities that used the 2010 updated ABAG tools to meet federal hazard mitigation planning requirements included the County of Santa Clara and the cities of Campbell, Cupertino, Gilroy, Los Altos, Los Altos Hills, Los Gatos, Milpitas, Monte Sereno, Morgan Hill, Mountain View, Palo Alto, San Jose, Santa Clara, Saratoga and Sunnyvale. ABAG discontinued its full support of the regional planning concept in 2015, so jurisdictions that were covered under the regional plan must initiate individual or reformed multijurisdictional planning efforts to continue to comply with federal mitigation planning requirements.
THE 2016 SANTA CLARA COUNTY OPERATIONAL AREA PLANNING EFFORT In 2016, Santa Clara County, the Santa Clara County Fire Department, and all incorporated cities in Santa Clara County teamed together to prepare an updated multi-jurisdiction hazard mitigation plan tailored to the local needs and capabilities of the Santa Clara County Operational Area. The planning partnership developed a new plan from scratch, using lessons learned from the earlier ABAG planning efforts. The 2016 plan differs from previous plans in the following ways:
• The plan is not a subset of a larger regional effort. It focuses on the geographic region of the Santa Clara County Operational Area and on hazards of concern specific to that area. • The plan follows the planning guidance of FEMA's Community Rating System so that it maximizes the planning benefit for the nine communities in the Operational Area participating in that program.
• Newly available data and tools provide for a more detailed and accurate risk assessment. • The risk assessment has been formatted to provide information on risk and vulnerability that will allow a measurement of cost-effectiveness, as required under FEMA mitigation grant programs.
• The update gave the planning partners an opportunity to engage local citizens and gauge their perception of risk and support for risk reduction through mitigation. 10/15/17 Santa Clara County Operational Area Mitigation Plan Page 113
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PLAN DEVELOPMENT APPROACH
PHASE i-ORGANIZATION
A core planning group consisting of a contract consultant and Santa Clara County Office of Emergency Services staff was assembled to facilitate the update of this plan. A planning partnership was formed by engaging the eligible local governments within the Operational Area and making sure they understood their expectations for compliance under the updated plan. A 19-member working group was assembled to oversee the plan update, consisting of both governmental and not-governmental stakeholders within the Operational Area. Coordination with other county, state, and federal agencies involved in hazard mitigation occurred throughout the plan update process. This phase included a review of the existing ABAG hazard mitigation plan, the California statewide hazard mitigation plan, and existing programs that may support hazard mitigation actions.
PHASE 2-RrSK ASSESSMENT
Risk assessment is the process of measuring the potential loss of life resulting from natural hazards, as well as personal injury, economic injury and property damage, in order to determine the vulnerability of people, buildings, and infrastructure to natural hazards. For this update, risk assessment models were enhanced with new data and technologies that have become available since 2010. The Working Group used the risk assessment to rank risk and to gauge the potential impacts of each hazard of concern in the Operational Area. The risk assessment included the following:
• Hazard identification and profiling
• Assessment of the impact of hazards on physical, social, and economic assets • Identification of particular areas of vulnerability
• Estimates of the cost of potential damage.
Based on the risk assessment, hazards were ranked for the risk they pose to the overall Operational Area, as shown in Table ES-1.
1 Earthquake High
2 Flood High
3 Severe Weather High
4 Dam and Levee Failure Medium
5 Landslide Medium
6 Wildfire Medium
7 Drought Medium
Each planning partner also ranked hazards for its own area. Table ES-2 summarizes the categories of high, medium and low (relative to other rankings) based on the numerical ratings that each jurisdiction assigned each hazard.
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T ble ES 2 S a f Ha d R k' • R It
i'Jl.lmbero!~url!;dlctlon~ J\s~gnlng anki~R to Haza~ ____ ._ _ ____ _ I High Medium Low Not Ranked
Dam Failure 0 4 10 3
Drought 0 15
Earthquake 17 0 0 0
Flood 0 17 0 0
Landslide 1 10 3 3
Severe weather 2 15 0 0
Wildfire 5 5 3 4
The results indicate the following general patterns:
• The earthquake hazard was most commonly ranked as high. • The flood, landslide and severe weather hazards were most commonly ranked as medium. • The dam failure and drought hazards were most commonly ranked as low.
PHASE 3-PUBLIC OUTREACH
The Core Planning Group implemented a multi-media public involvement strategy utilizing the outreach capabilities of the planning partnership that was approved by the Working Group. The strategy included public meetings to introduce the planning process and present the risk assessment, a hazard mitigation survey, a project website, the utilization of social media (Facebook, Twitter and Nextdoor) and multiple media releases.
PHASE 4-GOALS, OBJECTIVES AND ACTIONS
The Working Group reviewed and updated the goals from the 2010 ABAG plan and developed a set of objectives. The planning partnership selected a range of appropriate mitigation actions to work toward achieving the goals set forth in this plan update. Additionally, the Working Group selected a set of county-wide mitigation actions.
PHASE S-IMPLEMENTATION AND MAINTENANCE STRATEGY
The Working Group developed a plan implementation and maintenance strategy that includes annual progress reporting, a strategy for continued public involvement, a commitment to plan integration with other relevant plans and programs, and a recommitment from the planning partnership to actively maintain the plan over the five-year performance period.
PHASE 6-PLAN DOCUMENT DEVELOPMENT
The Core Planning Group and Working Group assembled a document to meet federal hazard mitigation planning requirements for all partners. The updated plan contains two volumes. Volume 1 contains components that apply to all partners and the broader Operational Area. Volume 2 contains all components that are jurisdiction-specific. Each planning partner has a dedicated annex in Volume 2.
PHASE 7-ADOPTION
Once pre-adoption approval has been granted by the California Office of Emergency Services and FEMA Region IX, the final adoption phase will begin. Each planning partner will individually adopt the updated plan.
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PHASE 8-PLAN IMPLEMENTATION
Plan implementation will occur over the next five years as the planning partnership begins to implement the countywide and jurisdiction-specific actions identified in this plan.
MITIGATION GOALS AND OBJECTIVES
The following guiding principle guided the Working Group and the planning partnership in selecting the actions contained in this plan update:
Carefully plan for the maintenance and enhancement of a disaster-resistant Operational Area by reducing the current and future potential loss of life, property damage, and environmental degradation from various hazards, while accelerating economic recovery from those hazards.
GOALS
The Working Group and the planning partnership established the following goals for the plan update:
1. Actively develop community awareness, understanding, and interest in hazard mitigation and empower the Operational Area to engage in the shaping of associated mitigation policies and programs.
2. Minimize potential for loss of life, injury, social impacts, and dislocation due to hazards.
3. Minimize potential for damage to property, economic impacts, and unusual public expense due to hazards.
4. Provide essential information to the whole community that promotes personal preparedness and includes advice to reduce personal vulnerability to hazards.
5. Encourage programs and projects that promote community resiliency by maintaining the functionality of critical Operational Area resources, facilities, and infrastructure.
6. Promote an adaptive and resilient Operational Area that proactively anticipates the impacts of climate change.
The effectiveness of a mitigation strategy is assessed by determining how well these goals are achieved.
OBJECTIVES
The following objectives were identified to help establish priorities for recommended mitigation actions.
Each selected objective meets multiple goals, serving as a stand-alone measurement of the effectiveness of a mitigation action, rather than as a subset of a goal. The objectives are as follows:
1. Develop and provide updated information about threats, hazards, vulnerabilities, and mitigation strategies to state, regional, and local agencies, as well as private sector groups.
2. Improve understanding of the locations, potential impacts, and linkages among threats, hazards, vulnerability, and measures needed to protect life.
3. Encourage the incorporation of mitigation best management measures into plans, codes, and other regulatory standards for public, private, and non-governmental entities within the Operational Area.
4. Inform the public on the exposure to natural hazard risk and ways to increase the public's capability to prevent, prepare, respond, recover, and mitigate impacts of natural hazard events.
5. Establish and maintain partnerships in the identification and implementation of mitigation measures in the Operational Area.
6. Advance community and natural environment sustainability and resilience to future impacts through preparation and implementation of state, regional, and local projects.
7. Reduce repetitive property losses from all hazards.
8. Where feasible and cost-effective, encourage property protection measures for vulnerable 16 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17
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structures located in hazard areas.
9. Improve systems that provide warning and emergency communications.
MITIGATION ACTION PLAN
Mitigation actions presented in this update are activities designed to reduce or eliminate losses resulting from natural hazards. The update process resulted in the identification of more than 344 mitigation actions for Implementation by individual planning partners, as presented in Volume 2 of this plan. In addition, the Working Group and planning partnership identified countywide actions benefiting the whole partnership, as listed in Table ES-3.
TABLE ES-3. HAZARD MITIGATION ACTION PLAN MATRIX
Action Number and Deseri tion Priorit
Action SCOA·1-Continue to maintain a website that will house the Operational Area hazard mitigation plan, its progress reports, and all components of the plan's maintenance strategy to provide the planning partners and public ongoing access High to the plan and its implementation.
Action SCOA·2-Continue to leverage, support and enhance ongoing, regional public education and awareness programs H' h as a method to educate the public on risk, risk reduction and community resilience. Ig Action SCOA·3-Continue ongoing communication and coordination in the implementation of the Santa Clara County H' h Operational Area Hazard Mitigation Plan. Ig
Action SCOA·4-Continue to support the use., development and enhancement of a regional crisis communications system. High Action SCOA·5-Strive to capture time-sensitive, perishable data-such as high water marks, extent and location of H' h hazard, and loss information-following hazard events to support future updates to the risk assessment. Ig Action SCOA·6-ldentify new and comprehensive hazard datasets to improve and augment future updates to the risk Hi h assessment g
IMPLEMENTATION
Full implementation of the recommendations of this plan will require time and resources. The measure of the plan's success will be its ability to adapt to changing conditions. The County of Santa Clara and its planning partners will assume responsibility for adopting the recommendations of this plan and committing resources toward implementation. The framework established by this plan commits all planning partners to pursue actions when the benefits of a project exceed its costs. The planning partnership developed this plan with extensive public input, and public support of the actions identified in this plan will help ensure the plan's success.
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PART I: PLANNING PROCESS AND COMMUNITY PROFILE
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INTRODUCTION TO HAZARD MITIGATION PLANNING
WHY PREPARE THIS PLAN?
THE BIG PICTURE
Hazard mitigation is defined as any action taken to reduce or alleviate the loss of life, personal injury, and property damage that can result from a disaster. It involves long- and short-term actions implemented before, during and after disasters. Hazard mitigation activities include planning efforts, policy changes, programs, studies, improvement projects, and other steps to reduce the impacts of hazards.
For many years, federal disaster funding focused on relief and recovery after disasters occurred, with limited funding for hazard mitigation planning in advance. The Disaster Mitigation Act (DMA; Public Law 106-390), passed in 2000, shifted the federal emphasis toward planning for disasters before they occur. The DMA requires state and local governments to develop hazard mitigation plans as a condition for federal disaster grant assistance. Regulations developed to fulfill the DMA's requirements are included in Title 44 of the Code of Federal Regulations (44 CFR).
The responsibility for hazard mitigation lies with many, including private property owners, commercial interests, and local, state and federal governments. The DMA encourages cooperation among state and local authorities in pre-disaster planning. The enhanced planning network called for by the DMA helps local governments to articulate accurate needs for mitigation, resulting in faster allocation of funding and more cost-effective risk-reduction projects.
The DMA also promotes sustainability in hazard mitigation. To be sustainable, hazard mitigation needs to incorporate sound management of natural resources and address hazards and mitigation in the largest possible social and economic context.
PURPOSES FOR PLANNING
Fourteen jurisdictions within the Santa Clara County Operational Area (OA)-defined as the unincorporated county and incorporated jurisdictions within the geographical boundaries of Santa Clara County-participated in the regional hazard mitigation plan prepared in 2010 by Santa Clara County Office of Emergency Services with support from Dewberry Consultants and in collaboration with the Association of Bay Area Governments (ABAG). That regional plan was adopted and approved in compliance with the DMA. It called for updates on a five-year cycle. This update fulfills that requirement.
This hazard mitigation plan update identifies resources, information, and strategies for reducing risk from natural hazards. Participating jurisdictions are referred to in this plan as planning partners.
Elements and strategies in the plan were selected because they meet a program requirement and because they best meet the needs of the planning partners and their citizens. One of the benefits of multijurisdictional planning is the ability to pool resources and eliminate redundant activities within the OA that have uniform risk exposure and vulnerabilities. The Federal Emergency Management Agency (FEMA) encourages multi-jurisdictional planning under its guidance for the DMA. This plan will help guide and coordinate mitigation activities throughout the OA. It was developed to meet the following objectives:
• Meet or exceed requirements of the DMA.
• Enable all planning partners to continue using federal grant funding to reduce risk through mitigation.
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• Meet the needs of each planning partner as well as state and federal requirements. • Create a risk assessment that focuses on local hazards of concern. • Meet the planning requirements of FEMA's Community Rating System (CRS), allowing planning partners that participate in the CRS program to maintain or enhance their CRS classifications.
• Coordinate existing plans and programs so that high-priority projects to mitigate possible disaster impacts are funded and implemented.
WHO WILL BENEFIT FROM THIS PLAN?
The whole community of the Santa Clara County OA - including residents, visitors, and industry - is the ultimate beneficiary of this hazard mitigation plan. The plan reduces risk for those who live in, work in, and visit the OA. It provides a viable planning framework for all foreseeable natural hazards.
Participation in development of the plan by key stakeholders helped ensure that outcomes will be mutually beneficial. The resources and background information in the plan are applicable across the OA, and the plan's goals and recommendations can lay groundwork for the development and implementation of local mitigation activities and partnerships.
CONTENTS OF THIS PLAN
This plan has been set up in two volumes so that elements that are jurisdiction-specific can easily be distinguished from those that apply to the overall Santa Clara County OA:
• Volume 1-Volume 1 includes all federally required elements of a disaster mitigation plan that apply to the OA. This includes the description of the planning process, public involvement strategy, goals and objectives, hazard risk assessment, mitigation actions, and a plan maintenance strategy.
• Volume 2-Volume 2 includes all federally required jurisdiction-specific elements, in annexes for each participating jurisdiction. It includes a description of the participation requirements established for participants in this plan, as well as instructions and templates that the partners used to complete their annexes. Volume 2 also includes "linkage" procedures for eligible jurisdictions that did not participate in development of this plan but wish to adopt it in the future.
Both volumes include elements required under federal guidelines. DMA compliance requirements are cited at the beginning of subsections as appropriate to illustrate compliance.
The following appendices provided at the end of Volume 1 include information or explanations to support the main content of the plan:
• Appendix A-Public outreach information used in preparation of this update. • Appendix B-Template for progress reports to be completed as this plan is implemented. • Appendix C-Plan adoption resolutions from planning partners.
All planning partners will adopt Volume 1 in its entirety and at least the following parts of Volume 2:
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PLAN UPDATE-WHAT HAS CHANGED
THE PREVIOUS PLAN
Fourteen jurisdictions in the Santa Clara County OA were covered under the 2010 Association of Bay Area Governments regional planning effort. The planning process used to develop the updated ABAG plan was as follows:
• Reevaluate the Functional Areas of the 2005 plan based on prioritizing mitigation for longterm recovery issues-this reevaluation was accomplished through a series of issue-oriented forums at meetings of its main policy standing committee, the Regional Planning Committee. • Regional mitigation priority setting by cities, counties, and special districts with public involvement-this objective was met through a series of workshops where strategies were reviewed for relevance and clarity. Three regional workshops were held to review draft priorities, and the draft priorities were posted on line for public comment. • Develop chapters to highlight functional areas - to make a better connection between the functional areas in the 2010 plan, chapters were developed to address mitigation strategies and how they achieved functionality.
• Raise public awareness - Public awareness was achieved through a series of campaigns, including an 1/ op-ed" hazard mitigation piece on the anniversary of the Lorna Prieta earthquake, securing an opportunity for free print ad and community service space, and public meetings focusing on specific aspects of the plan. • Focused outreach in partnership with local jurisdictions-the 2010 planning process allowed for two opportunities for public comment.
WHY UPDATE?
FEDERAL ELIGIBILITY
Title 44 of the Code of Federal Regulations (44 CFR) stipulates that hazard mitigation plans must present a schedule for monitoring, evaluating, and updating the plan. This provides an opportunity to reevaluate recommendations, monitor the impacts of actions that have been accomplished, and determine if there is a need to change the focus of mitigation strategies. A jurisdiction covered by a plan that has expired is not able to pursue elements of federal funding under the Robert T. Stafford Act for which a current hazard mitigation plan is a prerequisite.
CHANGES IN DEVELOPMENT
Hazard mitigation plan updates must be revised to reflect changes in development within the OA since the previous plan (44 CPR Section 201.6(d)(3)). The plan must describe changes in development in hazard-prone areas that increased or decreased vulnerability for each jurisdiction since the last plan was approved. If no changes in development impacted the jurisdiction's overall vulnerability, plan updates may validate the information in the previously approved plan. The intent of this requirement is to ensure that the mitigation strategy continues to address the risk and vulnerability of existing and potential development and takes into consideration possible future conditions that could impact vulnerability.
According to data from the California Department of Finance, the OA experienced a 7.6-percent increase in population between 2010 and 2015, an average annual growth rate of 1.52 percent per year.
Participating planning partners have adopted general plans that govern land-use decisions and policymaking, as well as building codes and specialty ordinances based on state and federal mandates. This 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 21
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plan update assumes that some new development triggered by the increase in population occurred in hazard areas. Because all such new development would have been regulated pursuant to local programs and codes, it is assumed that vulnerability did not increase even if exposure did.
NEW ANALYSIS CAPABILITIES
The risk assessment for the previous Santa Clara County OA hazard mitigation plan used both quantitative and qualitative analyses. Building count data and annualized average loss estimates were provided for some, but not all, hazards of concern. These estimates were predominantly reported at the countywide scale. The updated risk assessment provides more detailed information on exposed population and building counts for each hazard of concern. This update also expands the level of detail in the loss estimate modeling for dam and levee failure, earthquake, and flood. Exposure and vulnerability estimates are presented at the community level. This enhanced risk assessment, and the full participation of every local jurisdiction within the county, allows for a more detailed understanding of the ways risk in the OA is changing over time.
THE UPDATED PLAN-WHAT Is DIFFERENT?
Although the Santa Clara County OA's 2010 hazard mitigation plan update was prepared under the ABAG process, the OA's stakeholders, including County agencies, municipalities, and special districts, determined that a new Operational Area-wide hazard mitigation plan would better suit the needs and capabilities of the planning partners. The plan update process included a greater focus on public involvement that concentrated on targeted public engagement instead of simply opening technical workshops to the public. A renewed effort was made to establish a plan maintenance and implementation protocol that clearly defines ongoing commitment to the plan's success. Some of the major differences between the current and previous plans are as follows:
• The plan has been totally restructured as an Operational Area plan, focusing only on the geographic area of Santa Clara County. The risk assessment is not a subset of a larger regional effort. Instead, it is isolated to the Santa Clara County OA and focuses on the hazards of concern for the OA.
• The risk assessment has been prepared to best support future grant applications by providing information on risk and vulnerability that will directly support the measurement of "costeffectiveness" required under FEMA mitigation grant programs. • Newly available data and tools provide for a more detailed and accurate risk assessment using means such as FEMA's Hazards U.S. (Hazus) Multi-Hazard computer model or new data such as FEMA's countywide Digital Flood Insurance Rate Maps. • The planning process creates the opportunity for all municipal planning partners to prepare to meet the requirements of California Senate Bill 379 during the next plan update. That bill will require integration of quantitative climate change risk assessment in the development of climate change related initiatives as part of the safety element of general plans. • The plan is more user-friendly because it is confined to one package. • The update created an opportunity for the County of Santa Clara, local cities, and other planning partners to engage citizens directly in a coordinated approach to gauge their perception of risk and support of the concept of risk reduction through mitigation. • The plan's goals objectives and actions are more clearly defined. The plan identifies actions rather than strategies as was the case with the prior plans. Strategies provide direction, but actions are fund able under grant programs. This plan replaces strategies with a guiding 22 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17
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principle, goals, and objectives. The actions identified meet multiple objectives that are measurable, so that each planning partner can measure the effectiveness of its mitigation actions, which was difficult prior to this plan update. • This plan update includes local jurisdictions that did not participate during the 2010 ABAG process, including the Town of Los Altos Hills, the City of Milpitas, and the Santa Clara County Fire Department. The inclusion of these jurisdictions has provided area planners with a greater understanding of risk exposure and mitigation needs across the wider OA.
Additionally, their participation in this latest plan update will benefit the wider OA planning community by amplifying the benefits of multi-jurisdictional mitigation projects, ultimately making all local jurisdictions more competitive for mitigation grant funding.
There are fundamental differences in the planning process conducted for this update and past planning efforts under the ABAG initiative. The planning partners have treated this update as an opportunity to perform a "functional reset" in mitigation planning. The focus of this update was to transition from a nine-county regional scale, to an OA-specific scale. Given the extent of changes in this update, reviewers should consider this document to be a new plan. When relevant, the update discusses correlations with the initial plan, especially when data or information is being carried over to this update. Table 2-1 . indicates the major changes between the two plans as they relate to 44 CFR planning requirements.
TABLE 2-1. PLAN CHANGES CROSSWALK
44 CFR Re ulrement PrevIous Plan U dated Plan
§201.6(b): In order to develop a more
comprehensive approach to reducing the
effects of natural disasters, the planning
process shall include:
• (1) An opportunity for the public to
comment on the plan during the drafting
stage and prior to plan approval;
• (2) An opportunity for neighboring
communities, local and regional agencies
involved in hazard mitigation activities,
and agencies that have the authority to
regulate development, as well as
businesses, academia and other private
and non-profit interests to be involved in
the planning process; and
• (3) Review and incorporation, if
appropriate, of existing plans, studies,
reports, and technical information.
Appendix A of the ABAG Plan The pian development process for this update was includes a description of the based upon the CRS 10-step planning process, planning process. It includes detail which emphasizes comprehensive risk of coordination with other assessment and public engagement. Volume 1 agencies and review of the Chapters 2, 3, 4, and 5 describe the planning previous plan. process for the update.
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44 CFR Re ulrement PrevIous Plan U dated Plan
Appendix C of the ABAG plan
§201.6(c)(2): The plan shall include a risk includes a risk assessment for assessment that provides the factual basis for nine hazards (earthquake, activities proposed in the strategy to reduce tsunami, flood, landslide, wildfire, losses from identified hazards. Local risk drought, climate change, dam assessments must provide sufficient failure, and delta levee failure) for information to enable the jurisdiction to the nine-county regional area. identify and prioritize appropriate mitigation These are primarily qualitative risk actions to reduce losses from identified assessments with quantitative hazards. . modeling for the earthquake
hazard using Hazus.
§201.6(c)(2)(i): [The risk assessment shall Appendix C of the ABAG plan include a] description of the ... location and includes a risk assessment for six extent of all natural hazards that can affect the hazards (earthquake, severe jurisdiction. The plan shall include information weather, flood, wildfire, landslide on previous occurrences of hazard events and and tsunami) for the multi-county on the probability of future hazard events. regional area.
Utilizing existing studies and
Volume 1 Part 2 presents a risk assessment of
nine hazards of concern: Climate change, dam
failure, drought, earthquake, flood, landslide,
severe weather, tsunami, and wildfire. These
hazards are profiled as they impact the Santa
Clara County OA.
The risk assessment includes multiple-scenario
modeling for dam failure, earthquake, flood and
sea-level rise. Hazard profiles are standardized for
each hazard of concem, so that there is uniformity
in the discussion of each hazard and the
information provided can support ranking of risk for
each jurisdiction.
Other hazards of interest were qualitatively
assessed to develop a more complete picture of
the hazards facing the OA.
Volume 1 Part 2 presents a risk assessment of
each hazard of concern. Each chapter includes the
following components:
Hazard profile,-including maps of extent and
location, historical occurrences, frequency,
severity, and warning time.
Secondary hazards
Climate change impacts
Exposure of people, property, critical facilities and
environment.
Vulnerability of people, property, critical facilities
and environment.
Future trends in development
Scenarios
Issues
documents, the ABAG plan Vulnerability was assessed for all hazards of discussed vulnerability with an concern. The Hazus computer model was used for §201,6(c)(2)(ii): [The risk assessment shall emphasis on exposure and land the dam failure, earthquake, and flood hazards. include a] description of the jurisdiction's use. There was extensive These were Level 2-user defined analyses using vulnerability to the hazards described in discussion on the vulnerability to city and county data. paragraph (c)(2)(i). This description shall the earthquake hazard. The ABAG Site-specific data on County-identified critical include an overall summary of each hazard risk assessment attempts to facilities were entered into the Hazus model. and its impact on the community estimate potential damage from , Hazus outputs were generated for other hazards . future events. ABAG concluded by applying an estimated damage function to an that Hazus was not an adequate asset inventory was extracted from Hazus. tool for planning purposes.
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44 CFR Re Ulrement I PrevIous Plan I U dated Plan
The ABAG plan includes summary
information by county on identified
repetitive losses. The plan
includes a link to a website that
§201.6(c)(2)(ii): [The risk assessment] must includes more detailed information also address National Flood Insurance on repetitive losses which is no Program insured structures that have been longer maintained. Within the plan repetitively damaged floods itself, while there are inventories on the numbers and types of
structures in repetitive loss areas,
there is no description of the
causes of repetitive flooding.
The focus of the ABAG plan is on
The plan includes a comprehensive analysis of
repetitive loss areas that includes an inventory of
the number and types of structures in the repetitive
loss area.
Repetitive loss areas are delineated, causes of
repetitive flooding are cited, and these areas are
reflected on maps.
.. . e~isting land use without detailed A complete inventory of the numbers and types of §201.6(c)(2)(1I)~A): The plan should descnbe iS cus~lo n on fu ~re ~d use. buildings exposed was generated for each hazard vulnerability In. t~rms of the types. and There IS no consistent Inventory of of concern. Critical facilities were defined for the numbers of eXisting and future buildings, the number and types of OA d th f Tf . t' d b infrastructure, and critical facilities located in structures exposed to each hazard ' an Eesehahcl !leds wheretlnven o:dle y . . . d . exposure. ac azar c ap er provi es a the Identified hazard area. of concern. The plan oes prOVide d' . f t d Itt d an inventory of identified critical Iscusslon on u ure eve opmen ren s. facilities.
'The ABAG plan relied on creating Loss estimations in terms of dollar loss were regional correlations from past generated for all hazards of concern. These §201.6(c)(2)(ii)(B): [The plan should describe observed damage to create estimates were generated by Hazus for the dam vulnerability in terms of an] estimate of the estimates of future losses from the failure, earthquake, and flood hazards. For the potential dollar losses to vulnerable hazards of concern. other hazards, loss estimates were generated by structures identified in paragraph (c)(2)(i)(A) Appendix F assesses vulnerability applying a regionally relevant damage function to and a description of the methodology used to by providing private building the exposed inventory. In all cases, a damage prepare the estimate. exposure estimates for function was applied to an asset inventory. earthquake, landslide, wildfire, The asset inventory was the same for all hazards dam failure, and 1 ~O-year flood. and was generated in Hazus.
A strong component of the ABAG
§201.6(c)(2)(ii)(C): [The plan should describe plan is its look at existing land use vulnerability In terms ot] providing a general ' in hazard areas, especially for description of land uses and development , earthquake. Appendix E provides trends within the community so that mitigation additional detail on existing land options can be considered in future land use use, with a brief discussion of decisions. future land use (through 2030) by
county.
§201.6(c)(3): The plan shall include a The ABAG plan has identified a mitigation strategy that provides the comprehensive list of mitigation jurisdiction's blueprint for reducing the strategies for each planning potential losses identified in the risk partner to consider when creating assessment, based on existing authorities, annexes to the plan. These policies, programs and resources, and its strategies were created via a ability to expand on and improve these facilitated process chronicled in existing tools. the plan.
There is a discussion on future development
trends as they pertain to each hazard of concern.
This discussion looks predominantly at the existing
land use and the current regulatory environment
that dictates this land use.
The plan contains a guiding principal, goals,
I objectives and actions. The guiding principal,
planning partners. The actions are jurisdiction
specific and strive to meet multiple objectives. The
objectives of this plan are broad, similar to the
strategies identified in the ABAG plan. All
objectives meet multiple goals and stand alone as
components of the plan. Each planning partner
was asked to complete a capability assessment
that looks at its regulatory, technical and financial
capabilities.
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44 CFR Re ulrement PrevIous Plan U dated Plan
§201 .6(c)(3)(i): [The haz~rd miti~a.tlo~ strategy The ABAG plan has identified one shall include a] description of mltlgatl~~ ~oals overall goal and basic to reduce or avoid long-term vulnerabilities to I "commitments· for the plan. the identified hazards. §201.6(c)(3)(ii): [The mitigation strategy shall ,
include a] section that identifies and analyzes The ABAG plan contains a a comprehensive range of specific mitigation discussion on t~~ pr?cess us~ to actions and projects being considered to generate the millgation strate~les , reduce the effects of each hazard, with but it does include an alternatIVes particular emphasis on new and existing review.
buildings and infrastructure.
A guiding principal, seven goals, and 11 objectives
are described in Chapter O. These goals and
objectives targeted specifically for this hazard
mitigation plan are completely new. They were
identified based upon the capabilities of the
planning partnership.
Volume 1, Part 3 includes a hazard mitigation
catalog that was developed through a facilitated
process. This catalog identifies actions that
manipulate the hazard, reduce exposure to the
hazard, reduce vulnerability, and increase
mitigation capability. The catalog further
segregates actions by scale of implementation. A
table in the action plan section analyzes each
action by mitigation type to illustrate the range of
, actions selected,
All municipal planning partners that participate in
Strategy GOVT-c-5 deals with the National Flood Insurance Program have §201 .6(c)(3)(ii): [The mitigation strategy] must I maint~ini~g compli~nce and good identified an action stating their commitment to also address the jurisdiction's participation in standing In the Nallonal Flo~d maintain compliance and good standing under the the National Flood Insurance Program, and Insurance Program. Strategies National Flood Insurance Program. Communities continued compliance with the program's HSNG-h-1, LAND-~-.4 , ~nd ~CON- that participate in the Community Rating System requirements, as appropriate. ,f-1 encourage participation In the have identified actions to maintain or enhance their CRS program, standing under the CRS program.
Under the ABAG plan, priorities
are organized based on the
§201.6(c)(3)(iii): [The mitigation strategy shall follOwing categorles - describe] how the actions identified in Section. Existing (c)(3)(ii) will be prioritized, imple~e~te~, and • Existing/underfunded administered by the local .Jurlsdlction . • Very High
Prioritization shall include a special emphasis ,. High on the extent to which benefits are. maximized • Moderate according to. a cost be~efit rev.lew of the • Under study proposed projects and their associated costs. N t I' bl • 0 app Ica e • Not yet considered
§201 .6(c)(4)(i): [The plan maintenance process .
shall include a] section describing the method Appe~dlx B of the ~BAG plan and schedule of monitoring, evaluating, and contains a plan maintenance and updating the mitigation plan within a five-year update process. cycle.
Each of the recommended initiatives is prioritized
using a qualitative methodology that looked at the
objectives the project will meet, the timeline for
completion, how the project will be funded, the
impact of the project, the benefits of the project
and the costs of the project. This prioritization
scheme is detailed in Chapter O.
Volume 1, Part 3 details a plan maintenance
strategy that contains additional detail addressing
deficiencies observed during the 2010 update
process. This update includes a more defined role
and vehicle for facilitating the annual review of the
plan
Volume 1, Part 3 details recommendations for
incorporating the plan into other planning
mechanisms, such as: §201 .6(c)(4)(ii): [The plan shall include a] , General Plan process by which local governments Appe~dlx B ~f th~ ABA~ plan Emergency response plan incorporate the requirements of the mitigation ~ontalns a. brief dlSCusslo,n on Capital Improvement Programs plan into other planning mechanisms such as Incor~orall on of t~e plan Into other Municipal code comprehensive or capital improvement plans, planning mechanisms. Specific current and future plan and program when appropriate. integration activities are detailed in each participating jurisdiction's annex located in
Volume 2.
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44 CFR Re ulrement PrevIous Plan U dated Plan
The ABAG plan does not contain
§201 6( )(4)(''') [Th I ' t a process for how each jurisdiction ,c III : e p an main enance 'II t' bl' rt" r '
process shall include a] discussion on how ~ c~n Inu~ u IC pa IClpa Ion m Volume 1, Part 3 details a comprehensive strategy the community will continue public S e p ant ~al~ en~nce proces~ , for continuing public involvement. participation in the plan maintenance process, orne 0 e to?athg,ovd~rnme~ annexes con am IS IScusslon, however,
§201.S(c){5): [The local hazard mitigation plan
shall include] documentation that the plan has All ' t'l" th ABAG b f II d h 'b agencies u Ilzlng e V 1 C' I' f een orma yadopte by t e governmg ody t I b 'tt d t th t t d olume, Appendix contains the reso utlons 0 f th ' ' d' t' t' I f th 00 S su ml e 0 e s a e an II I ' rt th t d t d th' I o e JUriS IC Ion reques Ing approva 0 e FEMA ' d' 'd II a panning pa ners a a op e IS pan, plan (e,g" City Council, County Commission, In IVI ua y, Tribal Council),
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The process followed to develop the Error! No text of specified style in document. had the following primary objectives:
• Secure grant funding.
• Form a planning group.
• Identify Stakeholders
• Establish a planning partnership.
• Define the Santa Clara County OA.
• Establish a volunteer working group.
• Coordinate with other agencies.
• Review existing programs.
• Engage the public.
These objectives are discussed in the following sections.
GRANT FUNDING
This planning effort was supplemented by a FEMA Hazard Mitigation Assistance grant in fiscal year 2014. Santa Clara County Office of Emergency Services (OES) was the applicant agent for the grant. It covered 75-percent of the cost for development of this plan; the planning partners covered the balance through in-kind contributions.
FORMATION OF THE PLANNING GROUP
Santa Clara County OES hired Tetra Tech, Inc. to assist with development and implementation of the plan. The Tetra Tech project manager assumed the role of the lead planner, reporting directly to the Santa Clara County OES project manager. A planning group was formed to lead the planning effort, made up of the following members:
• Darrell Ray, Santa Clara County Office of Emergency Services/Santa Clara County Fire Department
• Louay Toma, Santa Clara County Office of Emergency Services/Santa Clara County Fire Department
• Rob Flaner, Tetra Tech
• Carol Baumann, Tetra Tech
This planning group-designated the Santa Clara County Operational Area Local Hazard Mitigation Plan (LHMP) Core Planning Group (or the Core Planning Group)-coordinated regularly during the course of this project to track plan development milestones and to identify meeting content for a working group established to help with development of the update.
DEFINING STAKEHOLDERS
For this planning process, "stakeholder" was defined as: any person or public or private entity that owns or operates facilities that would benefit from the mitigation actions of this plan, and/or has an authority or capability to support mitigation actions identified by this plan. Stakeholders were separated into two categories:
• Participatory Stakeholders-Stakeholders that actively participated in the planning process as planning partners or members of the Steering Committee. 28 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17
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• Coordinating Stakeholders-Stakeholders that were not able to commit to actively participating in the process as a participatory stakeholder, but were kept apprised of plan development milestones or were able to provide data that was used in the plan development.
At the beginning of the planning process, the planning team identified a list of stakeholders to engage during the development of the Santa Clara County Operational Area Hazard Mitigation Plan. The following stakeholders played a role in the planning process:
• Federal Agencies:
.:. FEMA Region IX provided updated planning guidance, provided summary and detailed data for the planning area from the National Flood Insurance Program (NFIP) (including repetitive loss information), and conducted plan review .
• :. The U.S. Geological Survey (USGS) provided ShakeMaps to support the earthquake risk assessment.
• State Agencies:
.:. The California Governor's Office of Emergency Services (CalOES) facilitated FEMA review, provided updated planning guidance, and reviewed the draft and final versions of the plan prior to FEMA review .
• :. The California Department of Forestry and Fire Protection (CAL FIRE) provided fire severity mapping to support the wildfire risk assessment.
.:. The California Department of Water Resources provided information on NFIP compliance for the cities.
• Regional and Local Stakeholders - The planning team offered regional and local stakeholders the opportunity to be informed about the planning process. The following organizations received information about the planning process, were invited to provide input, and elected to participate in the planning process as full members of the Working Group:
.:. Santa Clara County agencies:
o Santa Clara County Fire Department
o Santa Clara Valley Water District
o Santa Clara Valley Transportation Authority
o Mineta San Jose International Airport
o American Red Cross, Santa Clara Valley Chapter
o Santa Clara County, Community Emergency Response Team (CERT) o Santa Clara County Office of Education
.:. San Mateo County
.:. Alameda County
.:. Pacific Gas and Electric (PG&E)
ESTABLISHMENT OF THE PLANNING PARTNERSHIP
Santa Clara County OES opened this planning effort to all eligible local governments within the OA. The Core Planning Group made a presentation at a stakeholder meeting on July 19, 2016 to introduce the mitigation planning process and solicit planning partners. Key meeting objectives were as follows:
• Provide an overview of the Disaster Mitigation Act.
• Describe the reasons for a plan.
• Outline the hazard mitigation work plan.
10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 29 • Outline planning partner expectations.
• Seek commitment to the planning partnership.
• Seek volunteers for the working group.
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Each jurisdiction wishing to join the planning partnership was asked to provide a "letter of intent to participate" that designated a point of contact for the jurisdiction and confirmed the jurisdiction's commitment to the process and understanding of expectations. Linkage procedures have been established (see Volume 2 of this plan) for any jurisdiction wishing to link to the Error! No text of specified style in document. in the future. The planning partners covered under this plan are listed below.
TABLE 3.1. MUNICIPAL PLANNING PARTNERS
JUrisdiction POint of Contact Title
County of Santa Clara
City of Campbell
City of Cupertino
City of Gilroy
City of Los Altos
Town of Los Altos Hills
Town of Los Gatos
City of Milpitas
City of Monte Sereno
City of Morgan Hill
City of Mountain View
City of Palo Alto
City of San Jose
City of Santa Clara
City of Saratoga
City of Sunnyvale
David Flamm
Joe Cefalu
Timm Borden
Roy Shackel
Scott McCrossin
Marsha Hovey
Laurel Prevetti
Toni Charlop
Debra Figone
Jennifer Ponce
. Lynn Brown
Nathan Rainey
Cay Denise MacKenzie
Lisa Schoenthal
Michael Taylor
Vinnie Mata
Santa Clara County Fire Department Brian Glass
DEFINING THE PLANNING AREA
Deputy Director, Emergency Services
Captain, Police Department
Director, Public Works
Fire Captain OES Coordinator
Captain, Police Department
Emergency Preparedness Consultant
Town Manager
Manager, Emergency Services
Interim City Manager
Coordinator, Emergency Services
Coordinator, Emergency Services
Coordinator, Emergency Services
Senior Emergency Services Planner
Coordinator, Emergency Services
Director, Recreation and Facilities
Captain, Public Safety
Battalion Chief
The defined planning area for this update has been defined as the Santa Clara County Operational Area (OA). The OA is defined as the unincorporated county and incorporated cities within the geographical boundary of Santa Clara County. Relevant OA characteristics are described in Chapter O. All partners to this plan have jurisdictional authority within this OA. Figure 4-1 in Chapter 4 shows the geographic boundary of the defined planning area for this plan update.
ESTABLISHMENT OF A WORKING GROUP
Hazard mitigation planning enhances collaboration and support among diverse parties whose interests can be affected by hazard losses. A working group, made up of participatory stakeholders, was formed to oversee all phases of this plan. The official title for this group was the Santa Clara County Operational Area LHMP Working Group (or the Working Group). Its members included key planning partner staff, citizens, and other stakeholders from within the OA. The Core Planning Group assembled a list of candidates willing to fully participate in the planning process, with interests within the OA that could 30 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17
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have recommendations for the plan or be impacted by its recommendations. The planning partners confirmed a committee of19 members at the kickoff meeting. Table 3-1 lists the Working Group members.
TABLE 3-2. SANTA CLARA COUNTY OPERATIONAL AREA LHMP WORKING GROUP MEMBERS Name ) itle JUrisdictlon/A enc
David Flamm
Darrell Ray
Louay Toma
Kent Fielden
Joseph Cefalu
Marsha Hovey
Kara Gross
Jennifer Ponce
Lisa Schoenthal
Lynn Brown
AnneWein
Ian Hogg
Cay Denise MacKenzie
Jared Hart
Brian Glass
Raymond Fields
Michael Brill
John Lang
Bart Spencer
Deputy Director
Emergency Management Planner
Emergency Management Planner
Volunteer
Captain
Volunteer
Executive Director
Coordinator
Coordinator
Coordinator
Operations Research Analyst
Superintendent
Director
Planner
Battalion Chief
Project Manager
, System Safety
Economic Development Coordinator
Emergency Services Coordinator
Santa Clara County OES
Santa Clara County OES/Fire Department
Santa Clara County OES/Fire Department
American Red Cross, Santa Clara Valley Chapter
Campbell Police Department
Collaborating Agencies Disaster Relief Effort
Joint Venture, Silicon Valley
Morgan Hill Emergency Services
Santa Clara (City) Emergency Services
Mountain View Emergency Services
US Geological Survey (USGS)
Mineta San Jose International Airport
Senior Emergency Services Planner
San Jose Planning
Santa Clara County Fire Department
Santa Clara Valley Water District
Santa Clara Valley Transportation Authority
Silicon Valley Economic Development Alliance
Central County Fire
Leadership roles and ground rules were established during the Working Group's initial meeting on August 24, 2016. The Working Group agreed to meet once per month, as needed throughout the course of the plan's development. The Core Planning Group facilitated each Working Group meeting, which addressed a set of objectives based on an established work plan. The Working Group met eight times from August 2016 through April 2017. Meeting agendas, notes and attendance logs are available for review upon request. All Working Group meetings were open to the public and advertised as such via the hazard mitigation planning website. Agendas and meeting notes were posted to the hazard mitigation plan website.
COORDINATION WITH OTHER AGENCIES
Opportunities for involvement in the planning process must be provided to neighboring communities, local and regional agencies involved in hazard mitigation, agencies with authority to regulate development, businesses, academia, and other private and nonprofit interests (44 CFR, Section 201.6(b)(2». This task was accomplished by the Core Planning Group as follows:
• Working Group Involvement - Identified participatory stakeholders were invited to participate on the Working Group by formal invitation from the Core Planning Group via email.
• Agency Notification- The following agencies and contacts were invited to participate in the plan development process from the beginning and were kept apprised of plan development milestones through regular participation as full Steering Committee members. These were considered coordinating stakeholders as defined in Section 3.3:
.:. California Office of Emergency Services (CaIOES), Emergency Services Coordinator .:. FEMA Region IX, Lead Community Planner
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.:. California Department of Water Resources, California State NFIP Coordinator .:. Association of Bay Area Governments, Resilience Program Coordinator .:. Santa Clara Valley Water District, Security and Emergency Services Unit Manager .:. American Red Cross .
• :. NASA Ames Research Center, Risk Manager
.:. Collaborating Agencies Disaster Relief Effort.
.:. Silicon Valley Community Foundation.
These agencies received meeting announcements, meeting agendas, and meeting minutes by e-mail throughout the plan development process. Some of these agencies supported the effort by attending meetings or providing feedback on issues.
• Pre-Adoption Review-all the agencies listed above were provided an opportunity to review and comment on this plan, primarily through the hazard mitigation plan website (see Section 0). Each agency was sent an e-mail message informing them that draft portions of the plan were available for review. In addition, the complete draft plan was sent to CalOES and FEMA for a pre-adoption review to ensure program compliance.
REVIEW OF EXISTING PROGRAMS
Hazard mitigation planning must include review and incorporation, if appropriate, of existing plans, studies, reports and technical information (44 CFR, Section 201.6(b)(3». Chapter 0 of this plan provides a review of laws and ordinances in effect within the OA that can affect hazard mitigation actions. In addition, the following programs can affect mitigation within the OA:
• California Fire Code.
• 2016 California Building Code.
• California State Hazard Mitigation Forum.
• Local Capital Improvement Programs.
• Local Emergency Operations Plan.
• Local General Plans.
• Housing Element.
• Safety Element.
• Local Zoning Ordinances.
• Local Coastal Program Policies.
An assessment of all planning partners' regulatory, technical and financial capabilities to implement hazard mitigation actions is presented in Chapter 0 and in the individual jurisdiction-specific annexes in Volume 2. Many of these relevant plans, studies and regulations are cited in the capability assessment.
PUBLIC INVOLVEMENT
Broad public participation in the planning process helps ensure that diverse points of view about the OA's needs are considered and addressed. The public must have opportunities to comment on disaster mitigation plans during the drafting stages and prior to plan approval (44 CFR, Section 201.6(b)(1». The Community Rating System expands on these requirements by making CRS credits available for optional public involvement activities.
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STRATEGY
The strategy for involving the public in this plan emphasized the following elements:
• Include members of the public on the Working Group.
• Use a survey to determine if the public's perception of risk and support of hazard mitigation has changed since the initial planning process.
• Attempt to reach as many OA citizens as possible using multiple media. • Identify and involve OA stakeholders.
Stakeholders and the Santa Clara County Operational Area lHMP Working Group Stakeholders are the individuals, agencies and jurisdictions that have a vested interest in the recommendations of the hazard mitigation plan, including all planning.partners. The effort to include stakeholders in this process included stakeholder participation on the Working Group.
The planning process involved a broad range of federal, state, regional, and local stakeholders. The following stakeholders played a role in the planning process:
• Federal Agencies - FEMA Region IX provided updated planning guidance, provided summary and detailed data for the OA from the Nationall Flood Insurance Program (including repetitive loss information), and conducted plan review. Representatives from the National Weather Service and U.S. Geological Survey served as subject matter advisors for the Working Group. • State Agencies-CaIOFS facilitated FEMA review, provided updated planning guidance, and reviewed the draft and final versions of the plan prior to FEMA review. • Regional and Local Stakeholders - The Core Planning Group offered regional and local stakeholders the opportunity to remain informed about the planning process. The following organizations received information about the planning process and invitations to provide input, and elected to participate in the planning process as members or subject matter advisors to the Working Group:
o City of Campbell
o City of Cupertino
o City of Gilroy
o City of Milpitas
o City of Monte Sereno
o City of Mountain View
o City of Morgan Hill
o City of Palo Alto
o City of San Jose
o City of Santa Clara
o City of Saratoga
o City of Sunnyvale
o Town of Los Altos Hills
o Town of Los Gatos
o County of Santa Clara
o America Red Cross (ARC)
o Central County (San Mateo) Fire District
o Joint Venture Silicon Valley
o Mineta International Airport
o Santa Clara County Fire Department
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o Santa Clara Valley Water District (SCVWD)
o Silicon Valley Economic Development Alliance
o Valley Transportation Authority (VTA).
Survey
A hazard mitigation plan survey (see Figure 3-1) was developed by the Core Planning Group with guidance from the Working Group. The survey was used to gauge household preparedness for natural hazards and the level of knowledge of tools and techniques that assist in reducing risk and loss from natural hazards. This survey was designed to help identify areas vulnerable to one or more natural hazards. The answers to its 30 questions helped guide the Working Group in selecting goals, objectives and mitigation sb·ategies. The survey was made available on the hazard mitigation plan website and advertised throughout the course of the planning process.
The results of this survey were provided to each of the planning partners in a toolkit used to support the jurisdictional annex process (as described in the introduction to Volume 2 of this plan). Each planning partner was able to use the survey results to help identify actions as follows:
• Gauge the public's perception of risk and identify what citizens are concerned about. • Identify the best ways to communicate with the public. • Determine the level of publiC support for the different mitigation strategies. • Understand the public's willingness to invest in hazard mitigation.
Approximately 2,100 surveys were completed during the course of this planning process. The complete survey and a summary of its findings can be found in Appendix A of this volume.
Information Booths
Hazard mitigation information booths were hosted at two farmer's markets, on January 15, 2017 in Campbell and on January 21, 2017 in Sunnyvale (see Figure 3-2 through Figure 3-4). Each was open from 9 a.m. to 1 p.m. During these events, Core Planning Group members spoke with members of the public about the project and invited them to take the sw·vey and visit the project website. Members of the public were invited to receive a personalized risk assessment based on the project risk assessment results. A computer workstation allowed citizens to see information on their property, including exposure and damage estimates for earthquake and flood hazard events. Participating property owners were provided printouts of this information for their properties.
Final Public Comment period
A final public comment period was conducted to allow the public to provide comment on the proposed draft of the plan prior to submittal to CalOES for pre-adoption review and approval. This public comment period ran for 14 days from April 5 to April 21, 2017. The public comment period was advertised via a formal press release disseminated on April 5, 2017 and well as being posted on the hazard mitigation plan website:
(https:!!www .sccgov.org! sites! oes!SCCOAHMP20162017!Pages!home.aspx). The posted draft plan was accompanied by a narrated PowerPoint presentation (see Figure 3-5) accessible on the website that explained to the public the content of the plan and the basis for its preparation. The website provided the public with a point of contact to provide formal comment if they so desired. 341 Page Santa Clara County Operational Area Mitigation Plan 10/15/17
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1. Survey Introduction
Santa Clara Operational Area
2016/2017 Hazard Mitigation Plan Survey
Santa Clara Operational Area Hazard Mitigation Questionnaire A range of natural and human-caused disasters can affect any communify_ Santa Clara County and its incorporated cities, collectively known as the Santa Clara Operational Area, work diligently to mitigate threats and prepare for disasters_ To maintain a high level of preparedness, we need your help to identify and plan for future disasters. Data collected through this survey will help the Santa Clara Operational Area Local Hazard Mitigation Plan Workgroup to:
- Assess our residents' level of awareness regarding disasters; - Determine areas vulnerable to various types of disasters; - Coordinate activities to reduce the risk of injury or property damage in the future; and, - Update the multi-jurisdiction Local Hazard Mitigation Plan _ Local Hazard Mitigation Plans are required to be updated every five years by the federal Disaster Mitigation Act of 2000 in order for the Operational Area to remain eligible for certain federal pre-disaster and post-disaster assistance. The Plan details the risks of both natural and human-caused hazards in the Santa Clara Operational Area and includes programs and projects that can help reduce the exposure of residents and businesses should an event occur.
This survey consists of three sets of questions. The first section is about your experience and knowledge of natural and humancaused hazards in general, and steps your household has taken to prepare for disasters. The second section IS about the potential hazards near you and whether your knowledge of potential hazards influenced where you chose to live. The lasl section consists of demograplllc infomlation Ihat Will be used in evaluatmg the responses to the questionnaire.
Please note that the information collected through this survey will be used solely for mitigation planning activities_ Thank you for taking the time to participate in the 2016/2017 Hazard Mitigation Questionnaire! FIGURE 3-1. INTRODUCTORY P AGE FROM SURVEY D ISTRillUTED TO THE PUBLIC 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 35 36 I Page
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FIGURE 3-2. CAMPBELL FARMER'S MARKET
FIGURE 3-3. CAMPBELL FARMER'S MARKET
FIGURE 3-4. SUNNYVALE FARMER'S
MARKET
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Santa Clara County Operational Area
Hazard Mitigation Plan
Public Comment Period
FIGURE 3-5. PUBLIC COMMENT NARRATED PRESENTATION
The Core Planning Group received five comments from the public during this comment period. These comments were reviewed by the Core Planning Group and incorporated in to the final plan as appropriate.
Press Releases
Press releases distributed in tandem with social media blasts were distributed over the course of the plan's development as key milestones were achieved and prior to each public meeting. The planning effort received the following press coverage:
• Wednesday, September 14, 2016-Announcement regarding the launch of the planning process distributed to news media for publishing and inquiry. • Tuesday, December 27, 2016 - Announcement regarding the first round of public information booth meetings distributed for publishing and inquiry.
• Wednesday, AprilS, 2017 -Announcement of the initiation of the AprilS - 21, 2017 public comment period for the draft plan.
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Internet
At the beginning of the plan development process, a website hosted on the Santa Clara County OES main website was created to keep the public posted on plan development milestones and to solicit relevant input (see Figure 3-6). The site's address
(h:ttps:/Iwww.sccgov.org/sites/oes/SCCOAHMP20162017/Pages/home.aspx) was publicized in all press releases, mailings, surveys and public meetings. Information on the plan development process, the Working Group, the survey and phased drafts of the plan was made available to the public on the site throughout the process. Santa Clara County OES intends to keep a website active after the plan's completion to keep the public informed about successful mitigation projects and future plan updates.
Welcome to th e Santa Clara County Operational Area Hazard ~lltloatlon Plan (H~IP) Update Website. TIlls website provides project updates, resources, and links to hazard mitigation In ~upport of the H~ P project.
The goal of the project Is to save lives and property through the reduction of the Operational Area's vulnerabilily to local nalura' hazards. Throuohout this' plan update process. local leaders and members of th e community will work In together to Identify risks, assess capabilities, and develop strategies for reducing our disaster vulnerability.
Public participation and feedback are vital parts of the hazard mitigation plan ning process. 'The Sant a Clara County Operational Area Hazard 1Itlgatlon Steering Committee will be developing a survey for citizens to provide their Input (or Incorporation In the Santa dara County Operational Area Hazard MItigation Plan update.
If you would like more Information regarding holY to get involved in this project, please contact the County of Santa Clara County Office of Emergency Services at (408) 808-7000.
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A<I::e:s!tIIJlhty Tpml§ of Use Pnvacy Policy links Policy I County Holldavs Contad SCCGOV AI Content Cop IrIQht l"&l 2016. Countv of Santd Oara. eA -- - --- -- - - - - - ---- ---- --- - -- --- -- FIGURE 3-6. SAMPLE PAGE FROM HAZARD MITIGATION PLAN WEB SITE 38 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17
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PUBLIC INVOLVEMENT RESULTS
Survey Outreach
Completed surveys were received from 2,092 respondents. Of these respondents, 99 percent indicated that they live in the Santa Clara County OA, 72 percent work in San Clara County, and 87 percent own property in the OA. Survey results were shared with the planning partners. Detailed survey results are provided in Appendix A of this volume. Key results are summarized as follows:
• Survey respondents ranked earthquake as the hazard of highest concern, followed by drought, and wildfire.
• The majority of respondents expect to receive information on immediate threats caused by hazards from the radio, followed by television, and the Santa Clara County Operational Area's alert system, AlertSCC.
• Respondents were overwhelmingly concerned about response resources for individuals with disabilities and others with access and functional needs. • Respondents indicated concern about isolation and transportation gridlock during a major disaster.
• Approximately 45 percent and 38 percent of respondents were unaware if their residence was located in a high liquefaction zone or floodplain, respectively.
Public Meetings
By engaging the public through the public involvement strategy, the concept of mitigation was introduced to the public, and the Working Group received written feedback that was used in developing the plan. The Working Group answered multiple technical questions regarding the plan during all meetings, but no verbal comments were received on the plan. Table 3-2 summarizes details of contacts made during these events.
TABLE 3-1. SUMMARY OF PUBLIC MEETINGS
Date LocatIon Number of PublIC Contacts
1/15/2017
1/21/2017
Campbell Farmer's Market, East Campbell Avenue
and North 1st Street, Campb.ell, CA
Sunnyvale Farmer's Market, W. Washington Avenue
and S. Murphy Avenue, Sunnyvale, CA
59 fliers distributed, 24 individual risk assessments conducted, 75+ contacts made regarding the plan
64 flyers distributed, 27 individual risk assessment conducted, 80+ contacts made regarding the plan
PLAN DEVELOPMENT CHRONOLOGy/MILESTONES
Table 3-3 summarizes important milestones in the plan update process. 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 39
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TABLE 3-2. PLAN DEVELOPMENT CHRONOLOGY/ MILESTONES
Date Event Oeser! tion
2016
7/19 Stakeholder Kickoff
8/24 Working Group Meeting #1
9/7 Initial Press Release
9/14 Working Group Meeting #2
10/12 Working Group Meeting #3
11/9 Working Group Meeting #4
11/28 Survey Release
12/14 Working Group Meeting #5
12/15 Annex Workshop #1
12/19 Annex Workshop #2
12/27 Press Release - Information
Booths
2017
1/11 Working Group Meeting tIS
1/15 Campbell Farmers MarketInformation Booth
1/21 Sunnyvale Farmers MarketInformation Booth
2/8 1 Working Group Meeting #7
2/9 ,Jurisdictional Annex Process
3/8 Working Group Meeting #8
4/5 Public Outreach
4/21 Public Outreach
4/28 Plan submittal
40 I Page
Planning partners convened to kick off the project.
Review project timeline, establish Working Group ground rules, discuss state and previous plan.
Press release announcing the beginning of the plan update process and the Working Group meeting schedule.
Discuss state and previous plan, discuss mission statement and goals.
Confirm mission statement and goals, discuss objectives and critical facilities.
Confirm objectives and critical facilities, discuss public outreach Phase 1 opportunities, confirm survey.
Coordinated jurisdictional release of the public survey via multiple social media platforms.
Planning partners encouraged to link to the survey from their jurisdictional web pages.
Review risk assessment results, discuss strengths, weaknesses, obstacles and opportunities for the Operational Area, review initial public survey results.
Guidance to planning partners on completing the jurisdictional annex, ranking risk, identifying local vulnerabilities, and selecting mitigation strategies.
Guidance to planning partners on completing the jurisdictional annex, ranking risk, identifying local vulnerabilities, and selecting mitigation strategies.
Press release regarding location and time of the two farmer's market information booths in Campbell and Sunnyvale.
Discuss plan maintenance, continued discussion of strengths, weaknesses, obstacles and opportunities, planning partner update.
Hazard mitigation information booth as part of farmer's market. Residents provided with a mitigation flier that provided information on the project and advertised the project website and ,survey, property risk assessment, and general preparedness materials.
Hazard mitigation information booth as part of farmer's market. Residents provided with a mitigation flier that provided information on the project and advertised the project website and survey, property risk assessment, and general preparedness materials. . Confirmed plan maintenance, discussed Operational Area initiatives, critical facilities, and . California Environmental Quality Act compliance.
Phase 3 annexes due to the Core Planning Group.
Presented draft plan to the Working Group to finalize internal review. Finalized public comment period approach. Presentation on CDBG-DR.
Initiation of the public comment period for the draft plan. Press release disseminated to all media ouUets. Draft plan posted to the website with a narrated PowerPoint presentation.
Conclusion of final public comment period.
Final draft plan submitted to CalOES for review and approval.
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SANTA CLARA COUNTY OPERATIONAL AREA PROFILE
GEOGRAPHIC OVERVIEW
The Santa Clara County Operational Area is located in north-central California in the southern portion of the San Francisco Bay area (see Figure 4-1). With its numerous natural amenities and one of the highest standards of living in the country, the OA has long been considered one of the best areas in the U.S. in which to live and work. The county is also referred to as "Silicon Valley./I The Santa Clara County OA has a total area of 1,312 square miles. With a diverse population of more than 1.9 million residents (based on the 2016 census estimate), it is one of the largest counties in the state and encompasses 15 incorporated cities.
San Jose is the largest city, with over 1 million people, followed by Sunnyvale and Santa Clara; the west valley bedroom communities of Los Altos, Los Altos Hills, Los Gatos, Monte Sereno, and Saratoga; the high-tech communities of Campbell, Cupertino, Mountain View, and Palo Alto; industrial Milpitas, and the south county suburban expansion/ rural interface areas of Gilroy, Morgan Hill, and their surrounding unincorporated areas. A significant portion of the county's land area is unincorporated ranch and farmland.
The Santa Clara County OA has a rich culture of ethnic diversity, artistic endeavors, sports venues, and academic institutions. Numerous public and private golf courses are located throughout the OA and Santa Clara County operates 28 parks covering more than 50,000 acres, including lakes, streams, and miles of hiking and biking trails. The OA is home to three major universities - Stanford University, Santa Clara University, and San Jose State University-as well as several community colleges.
HISTORICAL OVERVIEW
The early inhabitants of Santa Clara County were the indigenous Ohlone People, thought to occupy the area at least 1,000 years before Spain began to colonize California in the 18th century.
Spanish settlers established the valley'S first mission and pueblo in Santa Clara and San Jose, respectively, and governed "EI Llano de los Robles" (Plain of the Oaks), until the Mexican Revolution led to Mexican control from the 1820s through 1840s. In 1850, California was admitted to the United States, and Santa Clara County was incorporated as one of the state's original 27 counties. Deriving its name from Mission Santa Clara, the county originally included much of what was Washington Township (part of Union City and Fremont) in what is now Alameda County. The current county boundaries were set in 1853 when Alameda County was established. .
From 1850 to 1870, ranchers made a transition from raising cattle and sheep to cultivating hay and grain.
French immigrants planted the first vineyards. Mercury mining flourished. California's first colleges were founded in Santa Clara County. The coming of the railroad produced a small boom in real estate.
After 1870, orchards began displacing grain fields and vineyards. The Santa Clara Valley became the world's leading producer of canned fruit and processed dried fruit. By the end of the 19th century, wealthy San Franciscans, such as Leland Stanford and James Lick, established farms and summer homes in the county.
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Figure 4·1.
Santa Clara County
Operational Area
(Planning Area)
D Sanla Clara County Boundary
o County Boundaries
Water Bodies & Channels
City Boundaries
Q Campbell
". Cupertino
Q Gilroy
". Los Altos
Q Los Altos Hills
Los Gatos'
Milp~as
Monte Sereno
Morgan Hill
Mountain VieW
Palo Alto
San Jose
Santa Clara
Saratoga
Sunnyvale
~TETRATECH
Mlp Data Sources: santa Clara County,
Corn.ns. USDA .
FIGURE 4-1. SANTA CLARA COUNTY OPERATIONAL AREA (PLANNING AREA) 42 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17
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Santa Clara County remained pastoral until World War II, when many people gravitated to California to work in war-related industries. To accommodate the growing population, mass-produced housing spread across the Santa Clara Valley, and agricultural land was subdivided and developed for housing.
Like much of the rest of the United States in the decades immediately following the war, development in the county shifted from largely agricultural to largely suburban.
At the same time, technology companies began to flourish in Santa Clara County, with significant support and encouragement from Stanford University. The Stanford Industrial Park, established in 1951, later became the Stanford Research Park and provided space for companies such as Hewlett-Packard, Eastman Kodak, General Electric and Lockheed. Related companies began to form around the region, and by the 1970s Santa Clara County and surrounding areas had become known as a center of hightechnology development. The term silicon valley was coined in 1971, referring to the high concentration of companies in the area that are involved in making silicon semiconductors and the computers that rely on them. Technology industries remain central to the area economy to this day.
MAJOR PAST HAZARD EVENTS
Presidential disaster declarations are typically issued for hazard events that cause more damage than state and local governments can handle without assistance from the federal government, although no specific dollar loss threshold has been established for these declarations. A presidential disaster declaration puts federal recovery programs into motion to help disaster victims, businesses and public entities. Some of the programs are matched by state programs. Santa Clara County has experienced 14 events (11 major disaster declarations, one emergency declaration, one fire management assistance declaration, and one fire suppression declaration) since 1950 for which presidential disaster declarations were issued. These events are listed in Table 4-1.
TABLE 4-1. PRESIDENTIAL DISASTER DECLARATIONS
Type of Event FEMA Disaster Numbera Date
Severe Winter Storms, Flooding, Mudslides DR-4308 April 1 , 2017 Severe Winter Storms, Flooding, and Mudslides DR-4301 February 14, 2017 Summit Fire FM-2766 May 22, 2008
Croy Fire FS-2465 September 25, 2002
Severe Winter Storms and Flooding DR-1203 February 9, 1998 Severe Storms, Flooding, Mud and Landslides DR-1155 January 4, 1997 Severe Winter Storms, Flooding Landslides, Mud Flow DR-1046 March 12, 1995 Severe Winter Storms, Flooding, Landslides, Mud Flows DR-1044 January 10,1995 Severe Freeze DR-894 February 11, 1991
Loma Prieta Earthquake DR-845 October 18,1989
Severe Storms and Flooding DR-758 February 21, 1986
Grass, Wildlands, and Forest Fires DR-739 July 18, 1985 Coastal Storms, Floods, Slides, and Tornadoes DR-677 February 9, 1983 Severe Storms, Flood, Mudslides, and High Tide DR-651 January 7, 1982 Drought EM-3023 January 20, 1977
a. DR = Disaster Declaration; EM = Emergency Declaration; FM = Fire Management; FS = Fire Suppression Source: FEMA, 2016
Review of these events helps identify targets for risk reduction and ways to increase a community's capability to avoid large-scale events in the future. Still, many natural hazard events do not trigger 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 43
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federal disaster declaration protocol but have significant impacts on their communities. These events are also important to consider in establishing recurrence intervals for hazards of concern.
PHYSICAL SETTING
GEOLOGY AND TOPOGRAPHY
The OA's topography is characterized by its location in the southern San Francisco Bay area. The Santa Clara Valley runs the entire length of the county from north to south, ringed by the rolling hills of the Diablo Range on the east, and the Santa Cruz Mountains on the west. Salt marshes and wetlands lie in the northwestern part of the county, adjacent to the waters of San Francisco Bay.
SOILS
Prior to 1950 and as far back as the late 1800s, Santa Clara Valley was the scene of vibrant and productive agriculture. Many of the soils of the Santa Clara Valley are alluvial, deposited on fans or floodplains within the valley. The young, deep soils (Elder, Elpaloalto, Still, Stevens Creek, Landelspark, Botella, and Campbell) are naturally very fertile. Field crops were grown on the lower parts of the valley, and orchards spanned from the hills east of Milpitas and San Jose across the valley to Los Altos and Palo Alto.
With the introduction of the electric water pump in the early 20th century, irrigation water from the plentiful ground-water supply became readily available on every farm, thus increasing productivity. The Santa Clara Valley became widely known for the production of high-quality orchard fruits, which were shipped across the United States.
Darns were constructed on major streams to store irrigation water and control flooding. As groundwater was rapidly pumped from a depth of several hundred feet, subsurface materials compacted and led to land subsidence. Subsidence damaged pipes and other in-ground structures, and levees were required to block tidewater from entering subsided land. The benefit of the control of streams and pumping of groundwater was a valley relatively free from flooding and high groundwater, an ideal condition for the rapid urban expansion that followed.
After World War II, urban growth in the San Francisco Bay area began to expand down to the south end of the bay and into the Santa Clara Valley. Subdivisions began to spring up as the development pace quickened after 1950. The first wave of development occurred on the soils along the El Camino Real corridor, where the alluvial fans were relatively level, with slopes of 2 percent or less. Development exploded in the 1960s and topsoil was moved to house lots was from the street areas. This type of subdivision construction continued until about 1980, when more shaping of house lots to control drainage began. By 1980, horne construction was slowing because relatively level areas that were easy for construction were already developed.
After 1980, subdivision development moved into areas of alluvial fans and greater slopes, and lotshaping became more common. After 1990, development moved into steep areas at the edge of the valley and the foothills. Soil disturbance can be severe in these areas, with more than 5 feet of cuts or fills. Fills may be materials from several feet below the soil surface, have a high content of clay or fragments, and be low in organic matter and fertility. Cut areas may have subsoil materials at the surface, which also may have a high content of clay or fragments and be low in organic matter and fertility. Many residents have modified the soil surface texture in garden areas with sandy materials and mulches. In areas of the basin soils (Hangerone, Clear Lake, and Embarcadero), clay surface and subsurface textures and slow internal drainage due to a high clay content are problems for gardens, ornamental plants, and lawns (USDA,2015).
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CLIMATE
Table 4-2 summarizes normal climate date from 1981 through 2010 at the National Climatic Data Center weather station at San Jose. The Mediterranean climate of the OA remains temperate year round due to the area's geography and its proximity to the Pacific Ocean. The area is warm and dry much of the year.
Rarely is the humidity uncomfortable, and the thermometer seldom drops below freezing. Rain is generally limited to winter and snow to the tops of local mountains.
TABLE 4-2. SAN JOSE NORMAL PRECIPITATION AND TEMPERATURES, 1981 - 2010 Months Mean Preci itation inches Minimum Tem erature (F Maximum Tem erature F January 3.07 42.0 58.1
February , 3.1 1 44.7 61.9
March 2.54 46.6 65.7
April 1.18 48.6 69.3
May 0.51 52.4 74.3
June 0.10 56.0 79.1
July 0.02 58.1 81.9
August 0.02 58.3 81.9
Septe."!ber. _ 0.18 56.8 80.1
October 0.80 52.5 74.0
November 1.68 46.0 64.3
December 2.61 41.9 58.0
Annu,d 15.82 50.4 70.8
DEVELOPMENT PROFILE
LAND USE
Table 4-3 shows current land use for unincorporated Santa Clara County; complete land use data was not available for municipalities in the OA. Land use information is analyzed in this plan for each identified hazard that has a defined spatial extent and location. For hazards that lack this spatial reference, the information in the table serves as a baseline estimate of land use and exposure. The distribution of land uses for the unincorporated county will change over time.
TABLE 4-3. UNINCORPORATED SANTA CLARA COUNTY PRESENT LAND USE T e of Land Use Area acres Percenta e of Total Area
Agricultural 33,355.5 5.53
General/Institutional 5,381.3 0.89
Open Space _ ?48,603.4 90.88
Low Density Residential 15,988.7 2.65
High Density Residential 68.6 0.01
Commercial 161.8 0.03
Industrial 85.0 0.01
Total S • .s 1 ...
CRITICAL FACILITIES, INFRASTRUCTURE AND ASSETS
Critical facilities and infrastructure are those that are essential to the health and welfare of the population.
These features become especially important after a hazard event. Critical facilities typically include police 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 45
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and fire stations, schools, department operation centers, and emergency operations centers. Critical infrastructure can include the roads and bridges that provide ingress and egress and allow emergency vehicles access to those in need, and the utilities that provide water, electricity, and communication services to the community. Critical facilities identified in this plan were selected, mapped, and included in geographic information system (GIS) databases based 'on information provided through the Working Group meetings, stakeholder information requests, and the 2013 State of California Multi-Hazard Mitigation Plan. The Working Group created the categories for critical facilities and infrastructure listed in the table below.
TABLE 4-4. CRITICAL FACILITIES AND INFRASTRUCTURES IN OA Emergency
J d t R / P bl Infrastructure MIlitary Recovery Socioeconomic Hazardous Ttl UriS IC Ion esponse U IC 0 a
Health & Safet Lifeline FaCilities FaCIlities FaCIlities Materials Cupertino 8 36 0 0 47 4 95
Gilroy 15 45 0 1 50 '7 118
Los Altos 6 '31 0 0 36 0 7.3
Los Altos Hills 1 !48 0 0 6 0 55
Los Gatos 14 40 0 0 24 1 79
Milpitas 12 68 0 0 56 42 178
Monte Sereno 1 2 0 0 2 0 6
Morgan Hill 9 14 0 0 39 7 69
Mountain View 17 :84 0 0 50 23 1r4
Palo Alto 19 ;71 0 0 95 22 207
San Jose 116 .593 0 1 654 115 1479
Santa Clara (city) 19 :79 0 0 103 ;94 295
Saratoga 7 33 0 0 30 0 70
Sunnyvale 16 81 0 0 86 49 232
Unincorporated County 20 ,248 1 2 51 5 327
lotal 28e 1500 1 4 1382 374 3549
Although many facilities and assets of the Santa Clara County OA are important to the quality of life, this plan focuses on those whose loss would result in the greatest impacts on life and safety in the event of a natural hazard. As defined for this hazard mitigation plan update, critical facilities are:
Structures or other improvements, public or private, that, because of function, size, service area, or uniqueness, have the potential to cause serious bodily harm, extensive property damage, or disruption of vital socioeconomic activities if it is destroyed or damaged or if its functionality is impaired. Critical facilities may include but are not limited to health and safety facilities, utilities, government facilities, hazardous materials facilities, or vital community economic facilities.
All critical facilities/infrastructure were analyzed in Hazus to help rank risk and identify mitigation actions. The risk assessment for each hazard qualitatively discusses critical facilities with regard to that hazard. Table 4-4 summaries of the general types of critical facilities and infrastructure by local jurisdiction. Figure 4-2 and 4-3 show the location of critical facilities and infrastructure in the OA. Due to the sensitivity of this information, a detailed list of facilities is not provided. The list is on file with Santa Clara County OES.
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FIGURE 4-2. CRITICAL FACILITIES IN OPERATIONAL AREA
16 Miles
10/15/17 Santa Clara County Operational Area Mitigation Plan ~
•
~
"*
<f>
l1li
~
-
•
.&
Figure 4-2.
Critical Facilities in the
Operational Area
Emergency Response
(Operation Centers)
Emergency Response (Fire)
Emergency Response (Police)
Milrtary Facilities
Public Heallh & Safety (Medical
Care)
Public Heallh & Safety
(Government)
Hazardous Materials
Recovery Facilrties
Socioeconomic Facilities
(Chlldalre)
Socioeconomic Facilities
(Schools)
o Sanla Clara County Boundary
o County BOl\l1daries
Water BOdies & Channels
~nTRATECH
Map Data Sources: Santa C~nI county,
Camans. H •• us 3.1, EPA. SCVWD. USDA
Page I 47
/
Monte r e y
Bay
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Figure 4-3.
Critical Infrastructure in
the Operational Area
Airport Facil~ies
Bus Facilities
Communication Facimias
Dams
, Electric Power Faciities
ClI Highway Bridges
fiI Rail I Ught Rail Facilities
• Rail I Ught Rail Bridges
• Petroleum Faciltties
• Potable Water Facilities
~ Wastewater Facilities
D Santa Clara County Boundary
o County Boundaries
Waler Bodies & Channels
~TETRAT"CH
Map Dill Sourcos: Slnla Clara Countv.
Cal'll'ons, Hazus 3.1, EPA. SCVWD, USDA
FIGURE 4-3. CRITICAL INFRASTRUCTURE IN THE OPERATIONAL AREA 48 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17
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FUTURE TRENDS IN DEVELOPMENT
An understanding of population and development trends can assist in planning for future development and ensuring that appropriate mitigation, planning, and preparedness measures are in place to protect human health and community infrastructure. The DMA requires that communities consider land use trends, which can alter the need for, and priority of, mitigation options over time. Land use and development trends significantly affect exposure and vulnerability to various hazards. For example, significant development in a hazard area increases the building stock and population exposed to that hazard. New development that has occurred in the last five years within the OA and potential future development in the next five years, as identified by each jurisdiction, is addressed in the jurisdictional annexes located in Volume 2 of this plan.
The municipal planning partners have adopted general plans that govern land use decision and policy making for their jurisdictions. Decisions on land use will be governed by these programs. This plan will work together with these programs to support wise land use in the future by providing vital information on the risk associated with natural hazards in the OA. All municipal planning partners will incorporate this hazard mitigation plan in their general plans by reference. This will ensure that future development trends can be established with the benefits of the information on risk and vulnerability to natural hazards identified in this plan.
DEMOGRAPHICS
Some populations are at greater risk from hazard events because of decreased resources or physical abilities. Elderly people, for example, may be more likely to require additional assistance. Research has shown that people living near or below the poverty line, the elderly, women, children, ethnic minorities, renters, individuals with disabilities, and others with access and functional needs, all experience more severe effects from disasters than the general population. These vulnerable populations may vary from the general population in risk perception, living conditions, access to information before, during and after a hazard event, capabilities during an event, and access to resources for post-disaster recovery.
Indicators of vulnerability - such as disability, age, poverty, and minority race and ethnicity - often overlap spatially and often in the geographically most vulnerable locations. Detailed spatial analysis to locate areas where there are higher concentrations of vulnerable community members would help to extend focused public outreach and education to these most vulnerable citizens.
POPULATION
Resident Population
Information about population is a critical part of planning because it directly relates to land needs such as housing, industry, stores, public facilities and services, and transportation. The California Department of Finance estimated the OA's population at 1,927,888 as of January 1, 2016.
Population changes are useful socio-economic indicators. A growing population generally indicates a growing economy, while a decreasing population signifies economic decline. Table 4-5 shows the population in the OA from 2000 to 2016. Figure shows the OA population change compared to that of the State of California. Between 2000 and 2015, California's population grew by 14.8 percent (about 0.93 percent per year) while the OA's population increased by 12.6 percent (0.79 percent per year). 10/15/17 Santa Clara County Operational Area Mitigation Plan Page 149
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TABLE 4-5. RECENT POPULATION DATA
JUrisdiction P~pulat~o~ - . --. --- --, - - ~- 2000 2005 2010 2015 2016 Citl of c:ampb4!" ' ,j ~8 37,406 39,349 41 ,986 42,584
City, of Cupertino :50,546 53,632 58,302 58,038 5~ 185
City of Gilroy 141 ,464 45,782 48,821 54,324 55,170
City of Los Altos i27,693 27,381 28,976 30,513 31 ,353
T own of Los Altos Hills 7,902 7,852 7,922 8,595 8,658
Town of Los Gatos 28,592 28,070 29,413 31,157 31 .376
City of Milpitas 62,698 ,62,177 66,799 74,140 75,521
City of Monte Sereno ' 3,483 3,324 3,341 3,445 3,475
City of ~organ Hill .33,556 35,911 37,822 42,382 43,645 Citl of Mountain View 70,708 70,629 74,066 76,712 77,925 City of Palo Alto 58,598 60,723 64,403 67,331 68,207
City of San Jose 894,943 901,159 945,942 1,030,053 1,042.094 City of Santa Clara 102,361 ! 107,058 116,468 ' 121 ,580 123,752 City of Saratoga 29,843 :29,630 29,926 30,060 30,219
City of Sunnyvale 131 ,760 ;131,853 140,081 146,629 148,372 Unincorporated County 100,300 96,547 90020 87,029 87.352 Total 11682,585 1.698,234 1,781/642 1,903,974 1,927.888
6.87%
4.44%
- State
Santa Clara OA
2000 2005 2010 2015
YEAR
FIGURE 4-4-. CALIFORNIA AND SANTA CLARA COUNTY OA POPULATION PERCENTAGE GROWTH COMPARISON [2000-2015]
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Daily Commuting Population
According to the California Employment Development Department, 208,965 daily commuters who worked in the Santa Clara County OA in 2013 lived in other locations. Most came from Alameda County, followed by San Mateo County and San Francisco County. Some commuters travel to the Santa Clara County OA from as far as Sacramento and Amador Counties. Conversely, 109,000 residents of the Santa Clara County OA commute outside of the OA daily. Figure provides the county-to-county commuting estimates to the Santa Clara County OA from other counties.
Source: California Employment Development Department, 2015 Workers Commutlng To
Santa Clara From Other Counties
n 11 -100
D 101 ·500
_ 501·1,000
1.001 ·5,000
5,001 ·64,696
D Santa Clara
D No Commulers From This County
Total Workers Commuting In: 208,965
FIGURE 4-5. 2010 COUNTY-TO-COUNTY COMMUTING ESTIMATES
Tuolumne
99 This large commuter contingent has impacts on planning for the OA's infrastructure and service needs, as well as on planning for hazard mitigation and emergency management. Commuters may be familiar with the area immediately surrounding their place of business or regular route to work, but may be less familiar with the services and resources provided to the population during a disaster event.
The U.s. Census estimates that over 76 percent of workers in the OA commute alone (by car, truck or van) to work, and mean travel time to work is 27 minutes (the state average is 28 minutes).
AGE DISTRIBUTION
As a group, the elderly are more apt to lack the physical and economic resources necessary for response and resiliency for hazard events and are more likely to suffer health-related consequences making recovery slower. They are more likely to be vision, hearing, and/ or mobility impaired, and more likely to experience mental impairment or dementia. Additionally, the elderly are more likely to live in assistedliving facilities where emergency preparedness occurs at the discretion of facility operators. These facilities are typically identified as II critical facilities" by emergency managers because they require extra notice to implement evacuation. Elderly residents living in their own homes may have more difficulty evacuating their homes and could be stranded in dangerous situations. This population group is more 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 51
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likely to need special medical attention, which may not be readily available during natural disasters due to isolation caused by the event. Specific planning attention for the elderly is an important consideration given the current aging of the American population.
Children under 14 are particularly vulnerable to disaster events because of their young age and dependence on others for basic necessities. Additionally, very young children may be vulnerable to injury or sickness; this added vulnerability can be worsened during a natural disaster because they may not understand the measures that need to be taken to protect themselves from hazards.
The overall age distribution for the OA is illustrated in Figure. Based on U.S. Census 2010-2014 American Community Survey 5-Year Estimates, 11.7 percent of the OA's population is 65 or older, compared to the state average of 12.1 percent. The Census data also indicate that 33.4 percent of the over-65 population has disabilities of some kind and 8.6 percent have incomes below the poverty line. Children under 18 account for nearly 12 percent of individuals who are below the poverty line. An estimated 20 percent of the OA population is 14 or younger, compared to the state average of 20 percent. 85 years and over
75 to 84 years
65 to 74 years
60 to 64 years
55 to 59 years
45 to 54 years . - .. - --- -- =-~-~- ~- ~- ~ -----~~-- GI
en
c( 35 to 44 years - -~ - --.--. - - - -~------
25 to 34 years _ • _~ ____ ._ •• ..L. _______ _
--
20 to 24 years
15 to 19 years ,._- ~- --- ---,--- - -
10 to 14 years
5 to 9 years
Under 5 years - ---- ----~ -.. -.-
o 50,000 100,000 150,000 200,000 250,000 300,000
Number of People
FIGURE 4-6. OA AGE DISTRIBUTION
RACE, ETHNICITY AND LANGUAGE
Research shows that minorities are less likely to be involved in pre-disaster planning and experience higher mortality rates during a disaster event. Post-disaster recovery can be ineffective and is often characterized by cultural insenSitivity. Since higher proportions of ethnic minorities live below the poverty line than the majority white population, poverty can compound vulnerability. According to the U.s. Census, the racial composition of the OA is predominantly white, at about 49 percent. The largest minority population is Asian, at 33 percent. Figure shows the racial distribution in the OA. 52 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17
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The OA has a 37 percent foreign-born population. Other than English, the most commonly spoken languages in the OA are Asian languages. The census estimates 21 percent of the residents speak English "less than very well."
AmHrican Indian
and A!aska Native
1%
African American
3%
49%
"
FIGURE 4-7. OA RACE DISTRIBUTION
INDIVIDUALS WITH DISABILITIES OR WITH ACCESS OR FUNCTIONAL NEEDS . Native Hawaiian
and Oth~t Pac~f'G
Islander
0%
'- Other
9%
Two or More Races
5%
The 2010 U.s. Census estimates that 54 million non-institutionalized Americans with disabilities live in the U.s. This equates to about one-in-five persons. Individuals with disabilities are more likely to have difficulty with resilience and responding to a hazard event than the general population. Local government may be the first level of response to assist these individuals, and coordination of efforts to meet their access and functional needs is paramount to life safety efforts. It is important for emergency and incident managers to distinguish between functional and medical needs in order to plan for incidents that require evacuation and sheltering. Knowing the percentage of population with a disability will allow emergency management personnel and first responders to have personnel available who can provide services needed by those with access and functional needs.
According to the u.s. Census 2010-2014 American Community Survey 5-Year Estimates, there are 141,397 individuals with some form of disability in the OA.
ECONOMY
INCOME
In the United States, individual households are expected to use private resources to prepare for, respond to and recover from disasters to some extent. This means that households living in poverty are automatically disadvantaged when confronting hazards. Additionally, the poor typically occupy more poorly built and inadequately maintained housing. Mobile or ~odular homes, for example, are more susceptible to damage in earthquakes and floods than other types of housing. In urban areas, the poor often live in older houses and apartment complexes, which are more likely to be made of un-reinforced masonry, a building type that is particularly susceptible to damage during earthquakes. Furthermore, 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 53
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residents below the poverty level are less likely to have insurance to compensate for losses incurred from natural disasters. This means that residents below the poverty level have a great deal to lose during an event and are the least prepared to deal with potential losses. The events following Hurricane Katrina in 2005 illustrated that personal household economics significantly impact people's decisions on evacuation.
Indivi~uals who cannot afford gas for their cars will likely decide not to evacuate.
Based on U.s. Census Bureau estimates, per capita income in the OA in 2015 was $46,631, and the median household income was $93,840. It is estimated that about 18 percent of households receive an income between $100,000 and $149,999 per year and over 15 percent of household incomes are above $150,000 annually. About 8 percent of the households in the OA make less than $25,000 per year and are therefore below the poverty level. The weighted average poverty threshold for a family of four in 2015 was $24,120; for a family of three, $19,096; for a family of two, $15,391 and for unrelated individuals, $12,082.
A living wage calculator developed at the Massachusetts Institute of Technology estimates the hourly living wage needed t() support different types of families. The calculator takes into consideration basic needs such as health, housing, transportation, and other necessities and interprets the living wage as a geographically specific hourly rate required to acquire basic minimum necessities cost. Table 4-6 presents summary information from the living wage calculator for 2015. Each hourly rate is adjusted per each working adult.
TABLE 4-6. HOURLY LIVING WAGE CALCULA nON FOR SANTA CLARA COUNTY '-r>.Lll'-'''' Living Wage
Poverty Wage
Minimum Wage
$14.52
$5.00
$9.00
$33.63
$10.00
;$9.00
INDUSTRY, BUSINESSES AND INSTITUTIONS
$11.30
$11.00
.$9.00
$15.83
$4.00
$9.00
The OA's economy is strongly based in the professional, scientific, and management, and administrative and waste management services industry (18.3 percent), followed by educational services and health care and social assistance, manufacturing, and retail trade. Public administration, wholesale trade and agriculture make up the smallest source of the local economy. Figure shows the breakdown of industry types in the OA.
The OA benefits from a variety of business activity. Major businesses include Apple, Inc, Alphabet Inc. (Google), Netflix, Roku, Inc. Shockley Semiconductor Laboratory, eBay Inc., Cisco Systems Inc., Applied Materials Inc., Flextronics International, Intel Corp, Kaiser Permanente Medical Center, Liberty Tax Service, Lockheed Martin Space Systems, NASA, Phillips Lumileds Lighting Company, Santa Clara Valley Medical Center, and many others.
Major educational and research institutions in the OA include Stanford University, San Jose State University, Santa Clara University, Mission College, De Anza College, Foothill College, West Valley College, Mission College, Evergreen Valley College, San Jose City College and Gavilan College.
EMPLOYMENT TRENDS AND OCCUPATIONS
According to the American Community Survey, 67 percent of the OA's population is in the labor force.
Of the working-age population group (ages 20-64), 40 percent of men and 60 percent of women are in the labor force.
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The figure below compares California's and the Santa Clara County OA's unemployment trends from 2007 through 2014. The Santa Clara County OA's unemployment rate was lowest in 2007, at 4.7 percent.
Unemployment rates peaked in 2010, at 11.1 percent, but have been on a downward trend ever since.
Finance and
insurance, and real
estate and rental
and leasing
5.1%
5.3%
Transportation and
warehousing, and
utilities
2.9%
Retail trade
9.2%
Professional,
scientific, and
management, and
administrative and
waste management
Wholesale trade
2.5%
FIGURE 4-8. INDUSTRY IN THE OA
Educational
services, and
health care and
social assistance
18.1% Arts, entertainment,
and recreation, and
accommodation
and food services
8.1%
Other services
4.5%
Public
- __ administration
2.3%
Manufacturing
18.0%
Construction
5.3%
Agriculture,
forestry, fishing
and hunting, and
mining
0.6%
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~
~ 0
;u- 10
~ I- 8
z
w
:!i
b 6
..J
0-
:!i
w 4
Z
::J
2 0
2007 2008 2009 2010 2011
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- California
- Santa Clara County
2012 2013 2014
FIGURE 4-9. CALIFORNIA AND SANTA CLARA COUNTY OA UNEMPLOYMENT RATE Management, business, science and arts, and sales and office occupations make up 70 percent of jobs in the OA. Management, business, science, and arts occupations make up 51 percent of the local working population. Other major occupations are sales and office (19 percent) and service (15 percent). Only about 15 percent of the employment in the OA is in production, transportation, and material moving and natural resources. The largest employers are eBay Inc. and Cisco Systems Inc., both with over 10,000 employees. Nine other employers employ between 5,000 and 9,999 employees. 56 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17
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Natural Resources,
Construction and
Maintenance
7%
Sales & Office
19%
Service
15%
Production, Transportation,
and Material Moving
8%
FIGURE 4-10. OCCUPATIONS IN THE OA
LAWS AND ORDINANCES
Management,
Science
and Arts
51%
Existing laws, ordinances and plans at the federal, state and local level can support or impact hazard mitigation actions identified in this plan. Hazard mitigation plans are required to include a review and incorporation, if appropriate, of existing plans, studies, reports, and technical information as part of the planning process (44 CFR, Section 201.6(b)(3». The following federal and state programs have been identified as programs that may interface with the actions identified in this plan. Each program enhances capabilities to implement mitigation actions or has a nexus with a mitigation action in this plan.
Information presented in this section can be used in review local capabilities to implement the actions found in the jurisdictional annexes of Volume 2. Each planning partner has individually reviewed existing local plans, studies, reports, and technical information in its jurisdictional annex, presented in Volume 2.
FEDERAL
Disaster Mitigation Act
The DMA is the current federal legislation addressing hazard mitigation planning. It emphasizes planning for disasters before they occur. It specifically addresses planning at the local level, requiring plans to be in place before Hazard Mitigation Grant Program funds are available to communities. This plan is designed to meet the requirements of DMA, improving eligibility for future hazard mitigation funds.
National Environmental Policv Act
The National Environmental Policy Act (NEPA) requires federal agencies to consider the environmental impacts of proposed actions and reasonable alternatives to those actions, alongside technical and 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 57
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economic considerations. NEP A established the Council on Environmental Quality (CEQ), whose regulations (40 CFR Parts 1500-1508) set standards for NEPA compliance. Consideration and decisionmaking regarding environmental impacts must be documented in an environmental impact statement or environmental assessment. Environmental impact assessment requires the evaluation of reasonable alternatives to a proposed action, solicitation of input from organizations and individuals that could be affected, and an unbiased presentation of direct, indirect, and cumulative environmental impacts. FEMA hazard mitigation project grant applications require full compliance with applicable federal acts. Any action identified in this plan that falls within the scope of this act will need to meet its requirements.
Endangered Species Act
The federal Endangered Species Act (ESA) was enacted in 1973 to conserve species facing depletion or extinction and the ecosystems that support them. The act sets forth a process for determining which species are threatened and endangered and requires the conservation of the critical habitat in which those species live. The ESA provides broad protection for species of fish, wildlife and plants that are listed as threatened or endangered. Provisions are made for listing species, as well as for recovery plans and the designation of critical habitat for listed species. The ESA outlines procedures for federal agencies to follow when taking actions that may jeopardize listed species and contains exceptions and exemptions.
It is the enabling legislation for the Convention on International Trade in Endangered Species of Wild Fauna and Flora. Criminal and civil penalties are provided for violations of the ESA and the Convention.
Federal agencies must seek to conserve endangered and threatened species and use their authorities in furtherance of the ESA's purposes. The ESA defines three fundamental terms:
• Endangered means that a species of fish, animal or plant is "in danger of extinction throughout all or a significant portion of its range." (For salmon and other vertebrate species, this may include subspecies and distinct population segments.) • Threatened means that a species "is likely to become endangered within the foreseeable future." Regulations may be less restrictive for threatened species than for endangered species. • Critical habitat means "specific geographical areas that are ... essential for the conservation and management of a listed species, whether occupied by the species or not." Five sections of the ESA are of critical importance to understanding it:
• Section 4: Listing of a Species-The National Oceanic and Atmospheric Administration (NOAA) Fisheries Service is responsible for listing marine species; the U.s. Fish and Wildlife Service is responsible for listing terrestrial and freshwater aquatic species. The agencies may initiate reviews for listings, or citizens may petition for them. A listing must be made "solely on the basis of the best scientific and commercial data available." After a listing has been proposed, agencies receive comment and conduct further scientific reviews for 12 to 18 months, after which they must decide if the listing is warranted. Economic impacts cannot be considered in this decision, but it may include an evaluation of the adequacy of local and state protections. Critical habitat for the species may be designated at the time of listing. • Section 7: Consultation - Federal agencies must ensure that any action they authorize, fund, or carry out is not likely to jeopardize the continued existence of a listed or proposed species or adversely modify its critical habitat. This includes private and public actions that require a federal permit. Once a final listing is made, non-federal actions are subject to the same review, termed a "consultation." If the listing agency finds that an action will "take" a species, it must 58 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17
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propose mitigations or "reasonable and prudent" alternatives to the action; if the proponent rejects these, the action cannot proceed.
• Section 9: Prohibition of Take-It is unlawful to "take" an endangered species, including killing or injuring it or modifying its habitat in a way that interferes with essential behavioral patterns, including breeding, feeding or sheltering.
• Section 10: Permitted Take - Through voluntary agreements with the federal government that provide protections to an endangered species, a non-federal applicant may commit a take that would otherwise be prohibited as long as it is incidental to an otherwise lawful activity (such as developing land or building a road). These agreements often take the form of a "Habitat Conservation Plan."
• Section 11: Citizen Lawsuits-Civil actions initiated by any citizen can require the listing agency to enforce the ESA's prohibition of taking or to meet the requirements of the consultation process.
FEMA hazard mitigation project grant applications require full compliance with applicable federal acts.
Any action identified in this plan that falls within the scope of this act will need to meet its requirements.
The Clean Water Act
The federal Clean Water Act (CWA) employs regulatory and non-regulatory tools to reduce direct pollutant discharges into waterways, finance municipal wastewater treatment facilities, and manage polluted runoff. These tools are employed to achieve the broader goal of restoring and maintaining the chemical, physical, and biological integrity of the nation's surface waters so that they can support "the protection and propagation of fish, shellfish, and wildlife and recreation in and on the water." Evolution of CW A programs over the last decade has included a shift from a program-by-program, source-by-source, and pollutant-by-pollutant approach to more holistic watershed-based strategies.
Under the watershed approach, equal emphasis is placed on protecting healthy waters and restoring impaired ones. A full array of issues are addressed, not just those subject to CWA regulatory authority.
Involvement of stakeholder groups in the development and implementation of strategies for achieving and maintaining water quality and other environmental goals is a hallmark of this approach.
FEMA hazard mitigation project grant applications require full compliance with applicable federal acts.
Any action identified in this plan that falls within the scope of this act will need to meet its requirements.
National Flood Insurance Program
The National Flood Insurance Program (NFIP) provides federally backed flood insurance in exchange for communities enacting floodplain regulations. Participation and good standing under NFIP are prerequisites to grant funding eligibility under the Robert T. Stafford Act. Santa Clara County and most of the partner cities for this plan participate in the NFIP and have adopted regulations that meet the NFIP requirements. At the time of the preparation of this plan, all participating jurisdictions in the partnership were in good standing and in full compliance with the minimum requirements of the NFIP.
Coastal Zone Management Act
The national Coastal Zone Management Act requires federal agencies to conduct their planning, management, development, and regulatory activities in a manner consistent to the maximum extent practicable with the policies of state Coastal Zone Management (CZM) programs. State CZM lead agencies have the authority to review federal actions for consistency with their federally approved CZM programs. In California, the California Coastal Commission, the Bay Conservation and Development Commission, and the California Coastal Conservancy are the three CZM agencies empowered to conduct 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 59
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federal consistency reviews. The informational and procedural requirements for CZM federal consistency reviews are prescribed by federal regulations (15 CFR 930). Any action identified in this plan that falls within the scope of this act will need to meet its requirements.
National Incident Management System
The National Incident Management System is a systematic approach for government, nongovernmental organizations, and the private sector to work together to manage incidents involving hazards. The system provides a flexible but standardized set of incident management practices. Incidents typically begin and end locally, and they are managed at the lowest possible geographical, organizational, and jurisdictional level. In other instances, success depends on the involvement of multiple jurisdictions, levels of government, functional agencies, and emergency-responder disciplines. These instances necessitate coordination across this spectrum of organizations. Communities using the National Incident Management System follow a comprehensive national approach that improves the effectiveness of emergency management and response personnel across the full spectrum of potential hazards (including natural hazards, terrorist activities, and other human-caused disasters) regardless of size or complexity.
Although participation is voluntary, federal departments and agencies are required to make adoption of NIMS by local and state jurisdictions a condition to receive federal preparedness grants and awards. The content of this plan is considered to be a viable support tool for any phase of emergency management.
The NIMS program is considered as a response function, and information in this hazard mitigation plan can support the implementation and update of all NIMS-compliant plans within the planning area.
Americans with Disabilities Act and Amendments
The Americans with Disabilities Act (ADA) seeks to prevent discrimination against people with disabilities in employment, transportation, public accommodation, communications, and government activities. The most recent amendments became effective in January 2009 (P.L. 110-325). Title II of the ADA deals with compliance with the act in emergency management and disaster-related programs, services, and activities. It applies to state and local governments as well as third parties, including religious entities and private nonprofit organizations.
The ADA has implications for sheltering requirements and public notifications. During an emergency alert, officials must use a combination of warning methods to ensure that all residents have any necessary information. Those with hearing impairments may not hear radio, television, sirens, or other audible alerts, while those with visual impairments may not see flashing lights or visual alerts. Two stand-alone technical documents have been issued for shelter operators to meet the needs of people with disabilities.
These documents address physical accessibility as well as medical needs and service animals.
The ADA also intersects with disaster preparedness programs in regards to transportation, social services, temporary housing, and rebuilding. Persons with disabilities may require additional assistance in evacuation and transit (such as vehicles with wheelchair lifts or paratransit buses). Evacuation and other response plans should address the unique needs of residents. Local governments may be interested in implementing a special-needs registry to identify the home addresses, contact information, and needs for residents who may require more assistance.
FEMA hazard mitigation project grant applications require full compliance with applicable federal acts.
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Civil Rights Act of 1964
The Civil Rights Act of 1964 prohibits discrimination based on race, color, religion, sex or national origin and requires equal access to public places and employment. The act is relevant to emergency management and hazard mitigation in that it prohibits local governments from favoring the needs of one population group over another. Local government and emergency response must ensure the continued safety and well-being of all residents equally, to the extent possible. FEMA hazard mitigation project grant applications require full compliance with applicable federal acts. Any action identified in this plan that falls within the scope of this act will need to meet its requirements.
Rural Development Program
The mission of the U.s. Department of Agriculture (USDA) Rural Development Program is to help improve the economy and quality of life in rural America. The program provides project financing and technical assistance to help rural communities provide the infrastructure needed by rural businesses, community facilities, and households. The program addresses rural America's need for basic services, such as clean running water, sewage and waste disposal, electricity, and modern telecommunications and broadband. Loans and competitive grants are offered for various community and economic development projects and programs, such as the development of essential community facilities including fire stations. Some of the actions identified in this plan may be eligible for funding available under this program.
Community Development Block Grant Disaster Resilience Program In response to disasters, Congress may appropriate additional funding for the u.s. Department of Housing and Urban Development Community Development Block Grant programs to be distributed as Disaster Recovery grants (CDBG-DR). These grants can be used to rebuild affected areas and provide seed money to start the recovery process. CDBG-DR assistance may fund a broad range of recovery activities, helping communities and neighborhoods that otherwise might not recover due to limited resources. CDBG-DR grants often supplement disaster programs of FEMA, the Small Business Administration, and the U.S. Army Corps of Engineers. Housing and Urban Development generally awards noncompetitive, nonrecurring CDBG-DR grants by a formula that considers disaster recovery needs unmet by other federal disaster assistance programs. To be eligible for CDBG-DR funds, projects must meet the following criteria:
• Address a disaster-related impact (direct or indirect) in a presidentially declared county for the covered disaster.
• Be a CDBG-eligible activity (according to regulations and waivers). • Meet a national objective.
Incorporating preparedness and mitigation into these actions is encouraged, as the goal is to rebuild in ways that are safer and stronger. CDGB-DR funding is a potential alternative source of funding for actions identified in this plan.
Emergency Watershed Program
The USDA Natural Resources Conservation Service administers the Emergency Watershed Protection Program, which responds to emergencies created by natural disasters. Eligibility for assistance is not dependent on a national emergency declaration. The program is deSigned to help people and conserve natural resources by relieving imminent hazards to life and property caused by floods, fires, wind-storms, and other natural occurrences. The Emergency Watershed Protection is an emergency recovery program. 10/15/17 Santa Clara County Operational Area Mitigation Plan Page 161
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Financial and technical assistance are available for the following activities (National Resources Conservation Service, 2016):
• Remove debris from stream channels, road culverts, and bridges. • Reshape and protect eroded banks.
• Correct damaged drainage facilities.
• Establish cover on critically eroding lands.
• Repair levees and structures.
• Repair conservation practices.
This federal program could be a possible funding source for actions identified in this plan.
Presidential Executive Orders 11988 and 13690
Executive Order 11988 requires federal agencies to avoid to the extent possible the long and short-term adverse impacts associated with the occupancy and modification of floodplains and to avoid direct and indirect support of floodplain development wherever there is a practicable alternative. It requires federal agencies to provide leadership and take action to reduce the risk of flood loss, minimize the impact of floods on human safety, health, and welfare, and restore and preserve the natural and beneficial values of floodplains. The requirements apply to the following activities (FEMA, 2015d):
• Acquiring, managing, and disposing of federal lands and facilities. • Providing federally undertaken, financed, or assisted construction and improvements. • Conducting federal activities and programs affecting land use, including but not limited to water and related land resources planning, regulation, and licensing.
Executive Order 13690 expands Executive Order 11988 and acknowledges that the impacts of flooding are anticipated to increase over time due to the effects of climate change and other threats. It mandates a federal flood risk management standard to increase resilience against flooding and help preserve the natural values of floodplains. This standard expands management of flood issues from the current base flood level to a higher vertical elevation and corresponding horizontal floodplain when federal dollars are involved in a project. The goal is to address current and future flood risk and ensure that projects funded with taxpayer dollars last as long as intended (Office of the Press Secretary, 2015). All actions identified in this plan will seek full compliance with all applicable presidential executive orders.
Presidential Executive Order 11990
Executive Order 11990 requires federal agencies to provide leadership and take action to minimize the destruction, loss or degradation of wetlands, and to preserve and enhance the natural and beneficial values of wetlands. The requirements apply to the following activities (National Archives, 2016):
• Acquiring, managing, and disposing of federal lands and facilities. • Providing federally undertaken, financed, or assisted construction and improvements. • Conducting federal activities and programs affecting land use, including but not limited to water and related land resources planning, regulation, and licensing.
All actions identified in this plan will seek full compliance with all applicable presidential executive orders.
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Emergency Relief for Federally Owned Roads Program
The U.s. Forest Service's Emergency Relief for Federally Owned Roads Program was established to assist federal agencies with repair or reconsb·uction of tribal transportation facilities, federal lands transportation facilities, and other federally owned roads that are open to public travel and have suffered serious damage by a natural disaster over a wide area or by a catastrophic failure. The program funds both emergency and permanent repairs (Office of Federal Lands Highway, 2016). Eligible activities under this program meet some of the goals and objectives for this plan and the program is a possible funding source for actions identified in this plan.
u.s. Army Corps of Engineers Programs
The U.S. Army Corps of Engineers has several civil works authorities and programs related to flood risk and flood hazard management:
• Floodplain Management Services are 100-percent federally funded technical services such as development and interpretation of site-specific data related to the extent, duration and frequency of flooding. Special studies may be conducted to help a community understand and respond to flood risk. These may include flood hazard evaluation, flood warning and preparedness, or flood modeling.
• For more extensive studies, the Corps of Engineers offers a cost-shared program called Planning Assistance to States and Tribes. Studies under this program generally range from $25,000 to $100,000, with the local jurisdiction providing 50 percent of the cost. • The Corps of Engineers has severa] cost-shared programs (typically 65 percent federal and 35 percent non-federal) aimed at developing, evaluating and implementing structural and nonstructural capital projects to address flood risks at specific locations or within a specific watershed:
.:. The Continuing Authorities Program for smaller-scale projects includes Section 205 for Flood Control, with a $7 million federal limit and Section 14 for Emergency Streambank Protection with a $1.5 million federal limit. These can be implemented without specific authorization from Congress .
• :. Larger scale studies, referred to as General Investigations, and projects for flood risk management, for ecosystem restoration or to address other water resource issues, can be pursued through a specific authorization from Congress and are cost-shared, typically at 65 percent federal and 35 percent non-federal.
.:. Watershed Management planning studies can be specifically authorized and are cost-shared at 50 percent federal and 50 percent non-federal.
• The Corps of Engineers provides emergency response assistance during and following natural disasters. Public Law 84-99 enables the Corps to assist state and local authorities in flood fight activities and cost share in the repair of flood protective structures. Assistance afforded under PL 84-99 is broken down in to the following categories:
.:. Preparedness - The Flood Control and Coastal Emergency Act establishes an emergency fund for preparedness for emergency response to natural disasters; for flood fighting and rescue operations; for rehabilitation of flood control and hurricane protection structures. Funding for Corps of Engineers emergency response under this authority is provided by Congress through the annual Energy and Water Development Appropriation Act. Disaster preparedness activities include coordination, planning, training and conduct of response exercises with local, state and federal agencies.
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.:. Response Activities-PL 84-99 allows the Corps of Engineers to supplement state and local entities in flood-fighting for urban and other non-agricultural areas under certain conditions (Engineering Regulation 500-1-1 provides specific details). All flood-fight efforts require a Project Cooperation Agreement (PCA) signed by the public sponsor and a requirement for the sponsor to remove all flood-fight material after the flood has receded. PL 84-99 also authorizes emergency water support and drought assistance in certain situations and allows for II advance measures" assistance to prevent or reduce flood damage conditions of imminent threat of unusual flooding .
• :. Rehabilitation - Under PL 84-99, an eligible flood protection system can be rehabilitated if damaged by a flood event. The flood system would be restored to its pre-disaster status at no cost to the federal system owner, and at 20-percent cost to the eligible non-federal system owner. All systems eligible for PL 84-99 rehabilitation assistance have to be in the Rehabilitation and Inspection Program prior to the flood event. Acceptable operation and maintenance by the public levee sponsor are verified by levee inspections conducted by the Corps on a regular basis. The Corps has the responsibility to coordinate levee repair issues with interested federal, state, and local agencies following natural disaster events where flood control works are damaged.
All of these authorities and programs are available to the planning partners to support any intersecting mitigation actions.
STATE
Alquist-Priolo Earthquake Fault Zoning Act
The Alquist-Priolo Earthquake Fault Zoning Act was enacted in 1972 to mitigate the hazard of surface faulting to structures for human occupancy. The Alquist-Priolo Earthquake Fault Zoning Act's main purpose is to prevent construction of buildings used for human occupancy on the surface trace of active faults. Before a new project is permitted, cities and counties require a geologic investigation to demonstrate that proposed buildings will not be constructed on active faults. The act addresses only the hazard of surface fault rupture and is not directed toward other earthquake hazards, such as liquefaction or seismically induced landslides. The law requires geologists from the State of California to establish regulatory zones around the surface traces of active faults and to issue appropriate maps. The maps are distributed to all affected cities, counties, and state agencies for their use in planning and controlling new or renewed construction. Local agencies must regulate most development projects within the zones.
Projects include all land divisions and most structures for human occupancy. All seismic hazard mitigation actions identified in this plan will seek full compliance with the Alquist-Priolo Earthquake Fault Zoning Act.
California General Planning Law
California state law requires that every county and city prepare and adopt a comprehensive long-range plan to serve as a guide for community development. The general plan expresses the community's goals, visions, and policies relative to future land uses, both public and private. The general plan is mandated and prescribed by state law (Cal. Gov. Code §65300 et seq.), and forms the basis for most local government land use decision-making.
The plan must consist of an integrated and internally consistent set of goals, policies, and implementation measures. In addition, the plan must focus on issues of the greatest concern to the community and be written in a clear and concise manner. City and county actions, such as those relating to land use 64 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17
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allocations, annexations, zoning, subdivision and design review, redevelopment, and capital improvements, must be consistent with the plan.
All municipal planning partners to this plan have general plans that are currently compliant with this law and have committed to integrating this mitigation plan with their general plans through provisions referenced below (AB-2140 and SB-379)
California Environmental Quality Act
The California Environmental Quality Act (CEQA) was passed in 970, shortly after the federal government enacted the National Environmental Policy Act, to institute a statewide poHcy of environmental protection. CEQA requires state and local. agencies in California to follow a protocol of analysis and public disclosure of the potential environmental impacts of development projects. CEQA makes environmental protection a mandatory part of every California state and local agency's decision making process.
CEQA establishes a statewide environmental policy and mandates actions all state and local agencies must take to advance the policy. Jurisdictions conduct analysis of the project to determine if there are potentially significant environmental impacts, identify mitigation measures, and possible project alternatives by preparing environmental reports for projects that requires CEQA review. This environmental review is required before an agency takes action on any policy, program, or project.
Santa Clara County has sought exemption from CEQA for the Hazard Mitigation Plan based on four different sections of the CEQA Guidelines:
• Section 15183( d): "The project is consistent with ... a general plan of a local agency, and an EIR was certified by the lead agency for the ... general plan." • Section 15262: "A project involving only feasibility or planning studies for possible future actions which the agency, board or commission has not approved, adopted, or funded does not require the preparation of an EIR or negative declaration but does require consideration of environmental factors. This section does not apply to the adoption of a plan that will have a legally binding effect on later activities."
• Section 15306: "(Categorical Exemption) Class 6 consists of basic data collection, research, experimental management, and resource evaluation activities which do not result in a serious or major dislurbance to an environmental resource. These may be strictly for information gathering purposes, or as part of a study leading to an action which a public agency has not yet approved, adopted or funded."
• Section 15601(b)(3): " ... CEQA applies only to projects which have the potential for causing a significant effect on the environment. Where it can be seen with certainty that there is no possibility that the activity in question may have a significant effect on the environment, the activity is not subject to CEQA." .
Planning partners may seek exemption at their discretion.
California Coastal Management Program
The California Coastal Management Program under the California Coastal Act requires each city or county lying whoUy or partly within the coastal zone to prepare a local coastal plan. The specific contents of such plans are not specified by state law, but they must be certified by the Coastal Commission as consistent Witll policies of the Coastal Act (public Resources Code, Division 20). The Coastal Act has provisions relating to geologie hazards, but does not mention tsunamis specificaUy. Section 30253(1) of the Coastal Act states that new development shall minimize risks to life and property in areas of high 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 65
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geologic, flood, and fire hazard. Development should be prevented or limited in high hazard areas whenever possible. However, where development cannot be prevented or limited, land use density, building value, and occupancy should be kept at a minimum.
There are identified coastal zones in the Santa Clara County Operational Area, and affected planning partners have developed local coastal plans to address them. Any mitigation project identified in this plan that intersects the mapped coastal zone wiU be consistent with the recommendations of the local coastal pl?n.
AB 162: Flood Planning, Chapter 369, Statutes of 2007
This California State Assembly Bill passed in 2007 requires cities and counties to address flood-related matters in the land use, conservation, and safety and housing elements of their general plans. The land use element must identify and annually review the areas covered by the general plan that are subject to flooding as identified in floodplain mapping by either FEMA or the Department of Water Resources (DWR). During the next revision of the housing element on or after January 1, 2009, the conservation element of the general plan must identify rivers, creeks, streams, flood corridors, riparian habitat, and land that may accommodate floodwater for groundwater recharge and stormwater management. The safety element must identify information regarding flood hazards, including:
• Flood hazard zones.
• Maps published by FEMA, DWR, the U.S. Army Corps of Engineers, the Central Valley Flood.
Protection Board, and CaIOES.
• Historical data on flooding.
• Existing and planned development in flood hazard zones.
The general plan must establish goals, policies and objectives to protect from unreasonable flooding risks, including:
• A voiding or minimizing the risks of flooding new development. • Evaluating whether new development should be located in flood hazard zones. • Identifying construction methods to minimize damage.
AB 162 establishes goals, policies and objectives to protect from unreasonable flooding risks. It establishes procedures for the determination of available land suitable for urban development, which may exclude lands where FEMA or DWR has concluded that the flood management infrastructure is not adequate to avoid the risk of flooding.
AB 2140: General Plans: Safety Element, Chapter 739, Statutes of 2006 This bill provides that the state may allow for more than 75 percent of public assistance funding under the California Disaster Assistance Act only if the local agency is in a jurisdiction that has adopted a local hazard mitigation plan as part of the safety element of its General Plan. The local hazard mitigation plan needs to include elements specified in this legislation. In addition, this bill requires CalOES to give preference for federal mitigation funding to cities and counties that have adopted local hazard mitigation plans. The intent of the bill is to encourage cities and counties to create and adopt hazard mitigation plans.
AB 70: Flood Liability, Chapter Number 367, Statutes of 2007 This bill provides that a city or county may be required to contribute a fair and reasonable share to compensate for property damage caused by a flood to the extent that it has increased the state's exposure 66 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17
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to liability for property damage by unreasonably approving new development in a previously undeveloped area that is protected by a state flood control project, unless the city or county meets specified requirements.
AB 32: The California Global Warming Solutions Act
This bill addresses greenhouse gas emissions. It identifies the following potential adverse impacts of global warming:
... the exacerbation of air quality problems, a reduction in the quality and supply of water to the state from the Sierra snowpack, a rise in sea levels resulting in the displacement of thousands of coastal businesses and residences, damage to marine ecosystems and the natural environment, and an increase in the incidences of infectious diseases, asthma, and other human health-related problems.
AB 32 establishes a state goal of reducing greenhouse gas emissions to 1990 levels by 2020 (a reduction of approximately 25 percent from forecast emission levels), with further reductions to follow. The law requires the state Air Resources Board to do the following:
• Establish a program to track and report greenhouse gas emissions. • Approve a scoping plan for achieving the maximum technologically feasible and costeffective reductions from sources of greenhouse gas emissions. • Adopt early reduction measures to begin moving forward. • Adopt, implement and enforce regulations - including market mechanisms such as II cap andtrade" programs-to ensure that the required reductions occur.
The Air Resources Board recently adopted a statewide greenhouse gas emissions limit and an emissions inventory, along with requirements to measure, track, and report greenhouse gas emissions by the industries it determined to be significant sources of greenhouse gas emissions.
AB 2800: Climate Change: Infrastructure Planning
This California State Assembly bill, in effect through July 1, 2020, requires state agencies to take into account the current and future impacts of climate change when planning, designing, building, operating, maintaining, and investing in state infrastructure. The bill requires the agency to establish a climate-safe infrastructure working group by July 1, 2017, to examine how to integrate scientific data concerning projected climate change impacts into state infrastructure engineering.
Senate Bill 97
Senate Bill 97, enacted in 2007, amends CEQA to clearly establish that greenhouse gas emissions and the effects of greenhouse gas emissions are appropriate subjects for CEQA analysis. It directs the Governor's Office of Planning and Research to develop draft CEQA guidelines for the mitigation of greenhouse gas emissions or their effects by July 1, 2009, and directs the California Natural Resources Agency to certify and adopt the CEQA Guidelines by January 1, 2010.
Senate Bill 1000 General Plan Amendments: Safety and Environmental Justice Elements Senate Bill 1000 amends California's Planning and Zoning Law in two ways:
• The original law established requirements for initial revisions of general plan safety elements to address flooding, fire, and climate adaptation and resilience. It also required subsequent review and revision as necessary based on new information. Senate Bill 1000 specifies that the subsequent reviews and revision based on new information are required to address only flooding and fires (not climate adaptation and resilience). 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 67 "
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• Senate Bill 1000 adds a requirement that, upon adoption or revision of any two other general plan elements on or after January I, 2018, an environmental justice element be adopted for the general plan or environmental justice goals, policies and objectives be incorporated into other elements of the plan.
Senate Bill 1241: General Plans: Safety Element-Fire Hazard Impacts In 2012, Senate Bill 1241 was enacted, requiring that all future General Plans address fire risk in state responsibility areas and very high fire hazard severity zones in their safety element. In addition, the bill requires cities and counties to make certain findings regarding available fire protection and suppression services before approving a tentative map or parcel map.
Senate Bill 379: General Plans: Safety Element-Climate Adaptation Senate Bill 379 builds on the flood planning inclusions into the safety and housing elements and the hazard mitigation planning safety element inclusions in General Plans outlined in AB 162 and AB 2140.
Senate Bill 379 specifically focuses on a new requirement that cities and counties include climate adaptation and resiliency strategies in the safety element of their General Plans beginning January I, 2017. In addition, this bill requires general plans to include a set of goals, policies, and objectives, and specified implementation measures based on the conclusions drawn from climate adaptation research and recommendations.
This update process for this hazard mitigation plan was conducted with the intention of full compliance with this bill. However, at the time of the update, there was no clear guidance from the state on what constitutes full compliance or what protocol is to be used to determine compliance. When such guidance has been established, the planning partners will submit this plan or its subsequent updates to the state for review and approval.
California State Building Code
California Code of Regulations Title 24 (CCR Title 24), also known as the California Building Standards Code, is a compilation of building standards from three sources:
• Building standards that have been adopted by state agencies without change from building standards contained in national model codes.
• Building standards that have been adopted and adapted from the national model code standards to meet California conditions.
• Building standards authorized by the California legislature that constitute extensive additions not covered by the model codes adopted to address particular California concerns.
The state Building Standards Commission is authorized by California Building Standards Law (Health and Safety Code Sections 18901 through 18949.6) to administer the processes related to the adoption, approval, publication, and implementation of California's building codes. These building codes serve as the basis for the design and construction of buildings in California. The national model code standards adopted into Title 24 apply to all occupancies in California, except for modifications adopted by state agencies and local governing bodies. Since 1989, the Building Standards Commission has published new editions of Title 24 every 3 years. All municipal planning partners to this plan have adopted building codes that are in full compliance with the California State Building Code. 68 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17
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Standardized Emergency Management System
CCR Title 19 establishes the Standardized Emergency Management System to standardize the response to emergencies involving multiple jurisdictions. The system is intended to be flexible and adaptable to the needs of all emergency responders in California. It requires emergency response agencies to use basic principles and components of emergency management. Local governments must use the Standardized Emergency Management System by December 1, 1996, to be eligible for state funding of response-related personnel costs under CCR Title 19 (Sections 2920, 2925 and 2930). The roles and responsibilities of individual agencies contained in existing laws or the state emergency plan are not superseded by these regulations. This hazard mitigation plan is considered to be a support document for all phases of emergency management, including those associated with SEMS.
State of California Multi-Hazard Mitigation Plan
Under the DMA, California must adopt a federally approved state multi-hazard mitigation plan to be eligible for certain disaster assistance and mitigation funding. The intent of the State of California MultiHazard Mitigation Plan is to reduce or prevent injury and damage from hazards in the state through the following:
• Documenting statewide hazard mitigation planning in California. • Describing strategies and priorities for future mitigation activities. • Facilitating the integration of local and tribal hazard mitigation planning activities into statewide efforts.
• Meeting state and federal statutory and regulatory requirements.
The plan is an annex to the State Emergency Plan, and it identifies past and present mitigation activities, current policies and programs, and mitigation strategies for the future. It also establishes hazard mitigation goals and objectives. The plan will be reviewed and updated annually to reflect changing conditions and new information, especially information on local planning activities.
Under 44 CFR Section 201.6, local hazard mitigation plans must be consistent with their state's hazard mitigation plan. In updating this plan, the Steering Committee reviewed the California State Hazard Mitigation Plan to identify key relevant state plan elements (see Section 0).
Governor's Executive Order 5-13-08
Governor's Executive Order 5-13-08 enhances the state's management of climate impacts from sea level rise, increased temperatures, shifting precipitation and extreme weather events. There are four key actions in the executive order:
• Initiate California's first statewide climate change adaptation strategy to assess expected climate change impacts, identify where California is most vulnerable, and recommend adaptation policies by early 2009. This effort will improve coordination within state government so that better planning can more effectively address climate impacts on human health, the environment, the state's water supply and the economy. • Request that the National Academy of Science establish an expert panel to report on sea level rise impacts in California, to inform state planning and development efforts. • Issue interim guidance to state agencies for how to plan for sea level rise in designated coastal and floodplain areas for new projects.
• Initiate a report on critical infrastructure projects vulnerable to sea level rise. 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 69 LOCAL
Plans, Reports and Codes
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Plans, reports and other technical information were identified and provided directly by participating jurisdictions and stakeholders or were identified through independent research by the planning consultant. These documents were reviewed to identify the following:
• Existing jurisdictional capabilities.
• Needs and opportunities to develop or enhance capabilities, which may be identified within the local mitigation strategies.
• Mitigation-related goals or objectives, considered during the development of the overall goals and objectives.
• Proposed, in-progress, or potential mitigation projects, actions and initiatives to be incorporated into the updated jurisdictional mitigation strategies.
The following local regulations, codes, ordinances and plans were reviewed in order to develop complementary and mutually supportive goals, objectives, and mitigation strategies that are consistent across local and regional planning and regulatory mechanisms:
• General Plans (Housing Elements, Safety Elements).
• Building Codes.
• Zoning and Subdivision Ordinances.
• NFlP Flood Damage Prevention Ordinances.
• Stormwater Management Plans.
• Emergency Management and Response Plans.
• Land Use and Open Space Plans.
• Climate Action Plans.
Capability Assessment
All participating jurisdictions compiled an inventory and analysis of existing authorities and capabilities called a" capability assessment." A capability assessment creates an inventory of a jurisdiction's mission, programs and policies, and evaluates its capacity to carry them out. This assessment identifies potential gaps in the jurisdiction's capabilities.
The Planning Partnership views all core jurisdictional capabilities as fully adaptable to meet a jurisdiction's needs. Every code can be amended, and every plan can be updated. Such adaptability is itself considered to be an overarching capability. If the capability assessment identified an opportunity to add a missing core capability or expand an existing one, then doing so has been selected as an action in the jurisdiction's action plan, which is included in the individual annexes presented in Volume 2 of this plan.
Capability assessments for each planning partner are presented in the jurisdictional annexes in Volume
2. The sections below describe the specific capabilities evaluated under the assessment.
LEGAL AND REGULATORY CAPABILITIES
Jurisdictions have the ability to develop policies and programs and to implement rules and regulations to protect and serve residents. Local policies are typically identified in a variety of community plans, implemented via a local ordinance, and enforced through a governmental body. 70 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17
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Jurisdictions regulate land use through the adoption and enforcement of zoning, subdivision and land development ordinances, building codes, building permit ordinances, floodplain, and stormwater management ordinances. When effectively prepared and administered, these regulations can lead to hazard mitigation.
FISCAL CAPABILITIES
Assessing a jurisdiction's fiscal capability provides an understanding of the ability to fulfill the financial needs associated with hazard mitigation projects. This assessment identifies both outside resources, such as grant-funding eligibility, and local jurisdictional authority to generate internal financial capability, such as through impact fees.
ADMINISTRATIVE AND TECHNICAL CAPABILITIES
Legal, regulatory, and fjscal capabilities provide the backbone for successfully developing a mitigation strategy; however, without appropriate personnel, the strategy may not be implemented. Administrative and technical capabilities focus on the availability of personnel resources responsible for implementing all the facets of hazard mitigation. These resources include teclmical experts, such as engineers and scientists, as well as personnel with capabilities that may be found in multiple departments, such as grant writers.
NFIP COMPLIANCE
Flooding is the costliest natural hazard in the United States and, with the promulgation of recent federal regulation, homeowners throughout the country are experiencing increasingly high flood insurance premiums. Community participation in the NFIP opens up opportunity for additional grant funding associated specifically with flooding issues. Assessment of the jurisdiction's current NFIP status and compliance provides planners with a greater understanding of the local flood management program, opportunities for improvement, and available grant funding opportunities.
PUBLIC OUTREACH CAPABILITY
Regular engagement with the public on issues regarding hazard mitigation provides an opportunity to directly interface with community members. Assessing this outreach and education capability illustrates the connection between the government and community members, which opens a two-way dialogue that can result in a more resilient community based on education and public engagement.
PARTICIPATION IN OTHER PROGRAMS
Other programs, such as the Community Rating System, Storm Ready, and Firewise, enhance a jurisdiction's ability to mitigate, prepare for, and respond to natural hazards. These programs indicate a jurisdiction's desire to go beyond minimum requirements set forth by local, state and federal regulations in order to create a more resilient community. These programs complement each other by focusing on communication, mitigation, and community preparedness to save lives and minimize the impact of natural hazards on a community.
DEVELOPMENT AND PERMITTING CAPABILITY
Identifying previous and future development trends is achieved through a comprehensive review of permitting since completion of the previous plan and in anticipation of future development. Tracking previous and future growth in potential hazard areas provides an overview of increased exposure to a hazard within a community.
ADAPTIVE CAPACITY
An adaptive capacity assessment evaluates a jurisdiction's ability to anticipate impacts from future conditions. By looking at public support, technical adaptive capacity, and other factors, jurisdictions identify their core capability for resilience against issues such as sea level rise. The adaptive capacity 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 71
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assessment provides jurisdictions with an opportunity to identify areas for improvement by ranking their capacity high, medium or low.
INTEGRATION OPPORTUNITY
The assessment looked for opportunities to integrate this mitigation plan with the legaJj regulatory capabilities identified. Capabilities were identified as integration opportunities if they can support or enhance the actions identified in this plan or be supported or enhanced by components of this plan.
Planning partners considered actions to implement this integration as described in their jurisdictional annexes.
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PART II: RISKASSESSMENT
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IDENTIFIED HAZARDS OF CONCERN AND RISK ASSESSMENT
METHODOLOGY
Risk assessment is the process of measuring the potential loss of life, personal injury, economic injury, and property damage resulting from identified hazards. It allows emergency management personnel to establish early response priorities by identifying potential hazards and vulnerable assets. The process focuses on the following elements:
• Hazard identification - Use all available information to determine what types of hazards may affect a jurisdiction, how often they can occur, and their potential severity. • Exposure identification-Estimate the total number of people and properties in the jurisdiction that are likely to experience a hazard event if it occurs. • Vulnerability identification and loss estimation - Assess the impact of hazard events on the people, property, environment, economy and lands of the region, including estimates of the cost of potential damage or cost that can be avoided by mitigation.
The risk assessment for this hazard mitigation plan update evaluates the risk of natural hazards prevalent in the OA and meets requirements of the Disaster Mitigation Act (44 CFR, Section 201.6(c)(2)).
To protect individual privacy and the security of critical facilities, information on properties assessed is presented in aggregate, without details about specific individual personal or public properties.
IDENTIFIED HAZARDS OF CONCERN
The Core Planning Group considered the full range of natural hazards that could affect the OA and then listed hazards that present the greatest concern. The process incorporated a review of state and local hazard planning documents as well as information on the frequency of, magnitude of, and costs associated with hazards that have struck the OA or could do so. Anecdotal information regarding natural hazards and the perceived vulnerability of the OA's assets to them was also used. Based on the review, this plan addresses the following hazards of concern (presented in alphabetical order; the order of listing does not indicate the hazards' relative severity):
• Climate change/sea-level rise.
• Dam and levee failure.
• Drought.
• Earthquake.
• Flood.
• Landslide.
• Severe weather.
• Tsunami.
• Wildfire.
In addition to the hazards of concern for which full risk assessments were performed, other hazards of interest were identified for inclusion in this plan: intentional hazards, technological hazards, and epidemic and pandemic. These hazards are of interest because they present risk to the OA. However, no methodologies are currently available to perform risk assessments on them that are equivalent to those used for the natural hazards of concern addressed in detail in this plan. 741 Page Santa Clara County Operational Area Mitigation Plan 10/15/17
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HAZARD RISK RANKING
FEMA requires all hazard mitigation planning partners to have jurisdiction-specific mitigation actions based on local risk, vulnerability and community priorities (FEMA, 2011). This plan included a risk ranking protocol for each planning partner, in which "risk" was calculated by multiplying probability by impact on people, property and the economy. All planning partners ranked risk for their own jurisdictions following the same methodology. Numerical ratings of probability and impact were based on the hazard profiles and exposure and vulnerability evaluations presented in Chapters 0 through O.
Using that data, each planning partner ranked the risk of aU the natural hazards of concern described in this plan except tsunami; the risk assessment demonstrated the low risk to the OA from the tsunami hazard, given the small portion of the area along the uppermost part of San Francisco Bay that would be affected. Other hazards of interest were not ranked for the following reasons:
• A key component of risk as defined for the planning effort is probability of occurrence. While it is possible to assign a recurrence interval for natural hazards because of historical occurrence, it is not feasible to assign recurrence intervals for the other hazards of interest, which lack such historical precedent.
• Federal hazard mitigation planning regulations do not require the assessment of non-natural hazards (44 CFR, 201.6). It is FEMA's position that this is a local decision.
The risk ranking at the planning partner scale was used to inform the action plan development process for each partner. Planning partners were directed to identify mitigation actions addressing hazards that, at a minimum, had a "high" or "medium" risk ranking (see Section 0). Actions that address hazards with a low or no hazard ranking are considered optional by this planning process.
Volume 2 presents the risk rankings for each planning partner. The following Operational Area-wide risk ranking was conducted via facilitated brainstorming sessions with the Core Planning Group.
Estimates of risk were generated with data from Hazus using methodologies promoted by FEMA. The results are used in establishing mitigation priorities.
PROBABILITY OF OCCURRENCE
The probability of occurrence of a hazard is indicated by a probability factor based on likelihood of annual occurrence:
• High - Hazard event is likely to occur within 25 years (Probability Factor = 3). • Medium - Hazard event is likely to occur within 100 years (Probability Factor =2). • Low-Hazard event is not likely to occur within 100 years (Probability Factor =1). • No exposure-There is no probability of occurrence (Probability Factor = 0).
The assessment of hazard frequency is generally based on past hazard events in the area. Table 55-1 summarizes the probability assessment for each hazard of concern for this plan.
TABLE 55-1. PROBABILITY OF HAZARDS
Hazard Event Probabllit high, medium , low) I Probability Factor Dam and levee Failure
Drought
Flood
Earthgu~ ke
landslide
Severe Weather
10/15/17
Low
H~h 3
High 3
High 3
~h 3
High 3
Santa Clara County Operational Area Mitigation Plan Page I 75 Wildfire High
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3 IMPACT
Hazard impacts were assessed in three categories: impacts on people, impacts on property and impacts on the local economy. Numerical impact factors were assigned as follows:
• People-Values were assigned based on the percentage of the total population exposed to the hazard event. The degree of impact on individuals will vary and is not measurable, so the calculation assumes for simplicity and consistency that all people exposed to a hazard because they live in a hazard zone will be equally impacted when a hazard event occurs. It should be noted that planners can use an element of subjectivity when assigning values for impacts on people. Impact factors were assigned as follows:
.:. High-50 percent or more of the population is exposed to a hazard (Impact Factor == 3) . • :. Medium - 25 percent to 49 percent of the population is exposed to a hazard (Impact Factor == 2) .
• :. Low-25 percent or less of the population is exposed to the hazard (Impact Factor == 1) . • :. No impact-None of the population is exposed to a hazard (Impact Factor == 0). • Property-Values were assigned based on the percentage of the total property value exposed to the hazard event:
.:. High -30 percent or more of the total assessed property value is exposed to a hazard (Impact Factor == 3) .
• :. Medium -15 percent to 29 percent of the total assessed property value is exposed to a hazard (Impact Factor == 2) .
• :. Low-14 percent or less of the total assessed property value is exposed to the hazard (Impact Factor == 1) .
• :. No impact-None of the total assessed property value is exposed to a hazard (Impact Factor == 0).
• Economy - Values were assigned based on the percentage of the total property value vulnerable to the hazard event. Values represent estimates of the loss from a major event of each hazard in comparison to the total replacement value of the property exposed to the hazard. For some hazards, such as wildfire, landslide and severe weather, vulnerability was considered to be the same as exposure due to the lack of loss estimation tools specific to those hazards. Loss estimates separate from the exposure estimates were generated for the earthquake and flood hazards using Hazus .
• :. High - Estimated loss from the hazard is 20 percent or more of the total exposed property value (Impact Factor == 3) .
• :. Medium-Estimated loss from the hazard is 10 percent to 19 percent of the total exposed property value (Impact Factor == 2) .
• :. Low - Estimated loss from the hazard is 9 percent or less of the total exposed property value (Impact Factor == 1) .
• :. No impact- No loss is estimated from the hazard (Impact Factor == 0).
The impacts of each hazard category were assigned a weighting factor to reflect the significance of the impact. These weighting factors are consistent with those typically used for measuring the benefits of 76 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17
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hazard mitigation actions: impact on people was given a weighting factor of 3; impact on property was given a weighting factor of 2; and impact on the economy was given a weighting factor of 1.
Table 5-2, Table 5-3 and Table 5-4 summarize the impacts for each hazard.
TABLE 5-2. IMPACT ON PEOPLE FROM HAZARDS
Hazard Event 1m act hi h, medium , low, no 1m act 1m act Factor Multi lied b Wei htin Factor 3 Dam and Levee Failure High 3 9
Drought No Impact 0 0
Flood Medium ,2 6
Earthquake High 3 9
Landslide Low 1 3
Severe Weather Medium 2 6
Wildfire ILow 3
TABLE 5-3. IMPACT ON PROPERTY FROM HAZARDS
Hazard Event ; 1m act high, medium , low, no 1m act) 1m act Factor Multiplied b Welghtin Factor 2) Dam and Levee Failure High 3 6
Drought Low 1 2
Flood Medium 2 4
Earthquake High 3 6
Landslide Low 2
Severe Weather Medium 2 4
Wildfire Low 2
TABLE 5-4. IMPACT ON ECONOMY FROM HAZARDS
Hazard Event 11m act high, medium , low, no 1m act) 1m act Factor Multi lied b Weightin Factor (1) Dam and Levee Failure High 3 13
Drought High 3 3
Flood Low 1
Earthquake High 3 3
Landslide Low
Severe Weather Low
Wildfire Low
RISK RATING AND RANKING
The risk rating for each hazard was determined by muJtiplying the probability factor by the sum of the weighted impact factors for people, property and economy, as summarized in TabJe 5-5. Based on these ratings, a priority of high, medium or low was assigned to each hazard. The hazard ranked as being of highest concern is earthquake, followed by flood and severe weather. Hazards ranked as being of medium concern are dam and levee fail ure, landslide, and wildfire. The hazard ranked as being of lowest concern is drought. Table 5-6 shows the hazard risk ranking. 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 77
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TABLE 5-5. HAZARD RISK RATING
Hazard Event jProbabilit Factor Sum of Wei hted 1m act Factors Total Probabllit x 1m act Dam and Levee Failure 1 18 18
Drought 3 5 15
Flood 3 16 39
Earthquake 3 18 54
Landslide 3 i6 118
Severe Weather 3 11 33
Wildfire 3 6 18
TABLE 5-6. HAZARD RISK RANKING
Hazard Rankin Hazard Event Cate 0
2 3
4 5
6 7
RISK ASSESSMENT TOOLS
MAPPING
Earthquake
Flood
Severe Weather
Dam and Levee Failure
Landslide
Wildfire
Drought
High
High
High
Medium
Medium
. Medium
Medium
National, state, and county databases were reviewed to locate available spatially based data relevant to this planning effort. Maps were produced using geographic information system (GIS) software to show the spatial extent and location of hazards when such datasets were available. These maps are included in the hazard profile chapters of this document.
HAZUS
Overview
In 1997, FEMA developed the standardized Hazards U.S. (Hazus) model to estimate losses caused by earthquakes and identify areas that face the highest risk and potential for loss. Hazus was later expanded into a multi-hazard methodology with new models for estimating potential losses from hurricanes and floods.
Hazus is a GIS-based software program used to support risk assessments, mitigation planning, and emergency planning and response. It provides a wide range of inventory data, such as demographics, building stock, critical facility, transportation and utility lifeline, and multiple models to estimate potential losses from natural disasters. The program maps and displays hazard data and the results of damage and economic loss estimates for buildings and infrastructure. Its advantages include the follOWing:
• Provides a consistent methodology for assessing risk across geographic and political entities. • Provides a way to save datasets so that they can readily be updated as population, inventory, and other factors change and as mitigation planning efforts evolve. 78 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17
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• Facilitates review of mitigation plans because it helps to ensure that FEMA methodologies are incorporated.
• Supports grant applications by calculating benefits using FEMA definitions and terminology. • Produces hazard data and loss estimates that can be used in communication with local stakeholders.
• Is administered by the local government and can be used to manage and update a hazard mitigation plan throughout its implementation.
Levels of Detail for Evaluation
Hazus provides default data for inventory, vulnerability, and hazards; the default data can be supplemented with local data to provide a more refined analysis. The model can carry out three levels of analysis, depending on the format and level of detail of information about the OA:
• Level 1-All of the information needed to produce an estimate of losses is included in the software's default data. These data are derived from national databases and describe in general terms the characteristic parameters of the OA.
• Level 2 - More accurate estimates of losses require more detailed information about the OA.
To produce Level 2 estimates of losses, detailed information is required about local geology, hydrology, hydraulics, and building inventory, as well as data about utilities and critical facilities. This information is needed in a GIS format. • Level 3 - This level of analysis generates the most accurate estimate of losses. It requires detailed engineering and geotechnical information to customize it for the OA.
RISK ASSESSMENT ApPROACH
The risk assessments in this plan describe the risks associated with each identified hazard of concern.
The following steps were used to define the risk of each hazard:
• Identify and profile each hazard - The following information is given for each hazard:
.:. Geographic areas most affected by the hazard .
• :. Event frequency estimates .
• :. Severity estimates .
• :. Warning time likely to be available for response.
• Determine exposure to each hazard - Exposure was assessed by overlaying hazard maps with an inventory of structures, facilities, and systems to decide which of them would be exposed to each hazard.
• Assess the vulnerability of exposed facilities-Vulnerability of exposed structures and infrastructure was evaluated by interpreting the probability of occurrence of each event and assessing structures, facilities, and systems that are exposed to each hazard. Tools such as GIS and Hazus were used for this assessment for the flood, earthquake, and Anderson Dam failure hazards. Outputs similar to those from Hazus were generated for other hazards, using data generated through GIS.
DAM FAILURE, EARTHQUAKE, AND FLOOD
The following hazards were evaluated using Hazus:
• Flood-A Level 2 user-defined analysis was performed for general building stock in flood zones and for critical facilities and infrastructure. Current flood mapping for the OA was used 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 79
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to delineate flood hazard areas and estimate potential losses from the 10-percent-annualchance, 1-percent-annual-chance and 0.2-percent-annual-chance flood events. To estimate damage that would result from a flood, Hazus uses pre-defined relationships between flood depth at a structure and resulting damage, with damage given as a percent of total replacement value. Curves defining these relationships have been developed for damage to structures and for damage to typical contents within a structure. By inputting flood depth data and known property replacement cost values, dollar-value estimates of damage were generated.
• Dam Failure - A Level 2 analysis was run on the Anderson Dam inflow design flood using the flood methodology described above.
• Earthquake - A Level 2 analysis was performed to assess earthquake exposure and vulnerability for three scenario events and two probabilistic events:
.:. A Magnitude-7.0 event on the Hayward Fault with an epicenter approximately 25 miles north of the City of Palo Alto .
• :. A Magnitude-7.0 event on the Calaveras Fault with an epicenter approximately 25 miles north of the City of Milpitas .
• :. A Magnitude-7.8 event on the San Andreas Fault with an epicenter approximately 148 miles northwest of the City of Palo Alto .
• :. The standard Hazus 100- and 500-year probabilistic events.
DROUGHT
The risk assessment methodologies used for this plan focus on damage to structures. The risk assessment for drought was more limited and qualitative than the assessment for the other hazards of concern because drought does not affect structures.
ALL OTHER ASSESSED HAZARDS
Historical datasets were not adequate to model future losses for most of the hazards of concern. However, areas and inventory susceptible to some of the hazards of concern were mapped by other means and exposure was evaluated. A qualitative analysis was conducted for other hazards using the best available data and professional judgment.
SOURCES OF DATA USED IN HAZUS MODELING
BUILDING AND COST DATA
Replacement cost values and detailed structure information derived from parcel and tax assessor data provided by Santa Clara County were loaded into Hazus. When available, an updated inventory was used in place of the Hazus defaults for critical facilities and infrastructure.
Replacement cost is the cost to replace the entire structure with one of equal quality and utility.
Replacement cost is based on industry-standard cost-estimation models published in RS Means Square Foot Costs (RS Means, 2017). It is calculated using the RS Means square foot cost for a structure, which is based on the Hazus occupancy class (i.e., multi-family residential or commercial retail trade), multiplied by the square footage of the structure from the tax assessor data. The construction class and number of stories for single-family residential structures also factor into determining the square foot costs. 80 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17
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HAZUS DATA INPUTS
The following hazard datasets were used for the Hazus Level 2 analysis conducted for the risk assessment:
• Flood - The effective Digital Flood Insurance Rate Map for the OA was used to delineate flood hazard areas and estimate potential losses from the 10-percent-annual-chance, l-percentannual-chance and O.2-percent-annual-chance flood events. Using the Digital Flood Insurance Rate Map floodplain boundaries and base flood elevation information, and the u.s.
Geological Survey (USGS) 3-meter digital elevation model data, flood depth grids were generated and integrated into the Hazus model.
• Darn Failure - Darn inundation area data for the Anderson Darn provided by the Santa Clara Valley Water District, and the USGS 3-meter digital elevation model were used to develop depth grids that were integrated into the Hazus model.
• Earthquake - Earthquake shake maps and probabilistic data prepared by the USGS were used for the analysis of this hazard. A National Earthquake Hazard Reduction Program soils map from the California Department of Conservation, ABAG's liquefaction susceptibility data and susceptibility to deep-seated landslides from the California Geological Survey were also integrated into the Hazus model.
OTHER LOCAL HAZARD DATA
Locally relevant information on hazards was gathered from a variety of sources. Frequency and severity indicators include past events and the expert opinions of geologists, emergency management specialists, and others. Data sources for specific hazards were as follows:
• Landslide-Susceptibility to deep-seated landslide data were provided by the California Geological Survey.
• Sea Level Rise-Sea level rise data were provided by the San Francisco Bay Conservation and Development Commission. A sea level rise of 6 feet above current mean higher high water was used for the exposure analysis.
• Darn Inundation - Darn inundation exposure areas for the Lexington, Searsville and Stevens Creek darns were provided by ABAG.
• Levee Inundation - Levee inundation exposure areas were defined with boundaries provided by Santa Clara County.
• Severe Storm-No GIS format severe storm area datasets were identified for the OA. • Tsunami - Tsunami inundation map was prepared by California Department of Conservation in cooperation with the University of Southern California, California Geological Survey, and California Emergency Management Agency.
• Wildfire-Fire severity data was acquired from California Department of Forestry and Fire Protection (CAL FIRE).
DATA SOURCE SUMMARY
Table 5-7 summarizes the data sources used for the risk assessment for this plan. 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 81
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TABLE 5-7. HAZUS MODEL DATA DOCUMENT AnON
Data Source Date I Format
Property parcel data Santa Clara County
Building information such as area, occupancy,s t CI C t date of construction, and stories an a ara oun y
2016
2016
Building replacement cost RS Means 2017
Population data
Flood hazard data
F~MA Hazus version 3,1, California Dept. of 2010 2016
Finance '
FEMA 2016
Tsunami ABAG (State of California) 2009
Earthquake shake maps USGS Earthquake Hazards Program website 2012,2014 Liquefaction susceptibility ABAG, USGS 2006
National Earthquake Hazard Reduction Program . California Department of Conservation 2008 Dam Inundation Areas
Anderson Dam
Lexington, Stevens Creek, Searsville Dams
Landslide
Sea Level Rise
Wildfire
Santa Clara Valley Water District
ABAG
California Geological Survey
2016
Unknown
2011
Adapting to Rising Tides - San Francisco '2017
Conservation and Development Commission
CAL FIRE 2008
Digital (GIS) format
Digital (tabular)
format
Paper format.
Digital (GIS and
tabular) format
Digital (GIS) format
Digital (GIS) format
Digital (GIS) format
Digital (GIS) format
Digital (GIS) format
Digital (GIS) format
Digital (GIS) format
Digital (GIS) format
Digital (GIS) format
Digital (GIS) format
Digital Elevation Model
Critical Facilities and Assets
USGS Downloaded 2016 Digital (GIS) format
Emergency operation centers, airport facilities, bus
facilities, light rail facilities, rail facilities, FEMA Hazus version 3.1 Default Critical 2016 communication facilities, electric power facilities, Facilities Data potable water facilities, wastewater facilities
Points of interest (city halls, community centers, other S t CI C t 2016 county facilities, child day care facilities) an a ara oun y Santa Clara County critical facilities (fire stations,
hospitals, skilled nursing facilities and clinics, police S t CI C t 2016 t t
' bl' I 't hi' 't' d an a ara oun y s a Ions, pu IC prlva e sc 00 s, UniverSI les an colleges)
Superfund sites (hazardous material sites) Santa Clara County Toxic release inventory facilities (hazardous material
facilities, designated communications centers, electric Environmental Protection Agency (EPA) power and petroleum facilities)
State and local bridges (highway bridges, light rail S t CI C t bridges, rail bridges, includes pedestrian bridges) an a ara oun y
LIMITATIONS
2016
2016
2016
Digital (GIS) format
Digital (GIS) format
Digital (spreadsheet)
format
Digital (GIS) format
Digital (GIS) format
Digital (GIS) format
Loss estimates, exposure assessments, and hazard-specific vulnerability evaluations rely on the best available data and methodologies. Uncertainties are inherent in any loss estimation methodology and arise in part from incomplete scientific knowledge concerning natural hazards and their effects on the built environment. Uncertainties also result from the following:
• Approximations and simplifications necessary to conduct a study. 82 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17
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• Incomplete or outdated inventory, demographic or economic parameter data. • The unique nature, geographic extent, and severity of each hazard. • Mitigation measures already employed.
• The amount of advance notice residents have to prepare for a specific hazard event. • Lack of a standardized model for assessing sea level rise impacts. Multiple models provide multiple results. Not all models were run in the development of the sea level rise analysis.
These factors can affect loss estimates by a factor of two or more. Therefore, potential exposure and loss estimates are approximate and should be used only to understand relative risk. Over the long term, Santa Clara County will collect additional data to assist in estimating potential losses associated with other hazards.
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DAM AND LEVEE FAILURE
GENERAL BACKGROUND
DAMS
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A darn is an artificial barrier that has the ability to store water, wastewater, or liquid-borne materials for many reasons-flood control, human water supply, irrigation, livestock water supply, energy generation, containment of mine tailings, recreation, or pollution control. Many darns fulfill a combination of these functions. They are an important resource in the DEFINITIONS United States (Association of State Darn Safety
Officials, 2013).
Man-made darns can be classified according to the
type of construction material used, the methods used
in construction, the slope or cross-section of the darn, the way the darn resists the forces of the water
pressure behind it, the means used for controlling
seepage, and, occasionally, according to the purpose
of the darn. The materials used for construction of
darns include earth, rock, tailings from mining or
milling, concrete, masonry, steel, timber,
miscellaneous materials (plastic or rubber), and any
combination of these materials (Association of State
Darn Safety Officials, 2013).
More than a third of the country's darns are 50 or
more years old. Approximately 14,000 of those darns
pose a significant hazard to life and property if
failure occurs. There are about 2,000 unsafe darns in
the United States, located in almost every state.
Darn failures typically occur when spillway capacity
is inadequate and excess flow overtops the darn, or
when internal erosion (piping) through the darn or
foundation occurs. Complete failure occurs if internal
erosion or overtopping results in a complete
structural breach, releasing a high-velocity wall of
debris-filled water that rushes downstream
damaging anything in its path (FEMA, 1996).
LEVEES
Levees are man-made structures, usually an earthen
embankment, designed and constructed to contain,
control, or divert a flow of water in order to protect
land from peak flood levels or to protect land that is
below sea level. Santa Clara Valley Water District
(SCVWD) maintains two types of levees in the OA:
Dam-Any artificial barrier, together with appurtenant
works, that does or may impound or divert water, and
that either (a) is 25 feet or more in height from the
natural bed of the stream or watercourse at the
downstream toe of the barrier (or from the lowest
elevation of the outside limit of the barrier if it is not across a stream channel or watercourse) to the
maximum possible water storage elevation; or (b) has
an impounding capacity of 50 acre-feet or more (CA
Water Code, Division 3).
Levee-A man-made structure, usually an earthen
embankment or concrete floodwall, designed and
constructed in accordance with sound engineering
practices to contain, control, or divert the flow of water.
Dam Failure-An uncontrolled release of impounded
water due to structural deficiencies in a dam.
Levee Failure (Breach)-When part of a levee breaks
away, leaving a large opening for water to flood the land protected by the levee.
Emergency Action Plan-A formal document that
identifies potential emergency conditions at a dam and
specifies actions to be followed to minimize property
damage and loss of life. The plan speCifies actions the dam owner should take to alleviate problems at a dam.
It contains procedures and information to assist the dam owner in issuing early warning and notification
messages to responsible downstream emergency
management authorities of the emergency situation. It
also contains inundation maps to show emergency
management authorities the critical areas for action in case of an emergency. (FEMA, 2013a)
High Hazard Dam-Dams where failure or improper
operatiGlJ:l will probably cause loss of human life. (FEMA, 200~~
Significant Hazard Dam-Dams where failure or
hi'\proper operation will result in no probable loss of human life but oan cause economic loss, environmental
damage or disruption of lifeline facilities, or can impact other concerns. Significant hazard dams are often
located in rural or agricultural areas but could be located n areas with pOli/tllatiGln and significant infrastructure. (FEMA, 200'4)
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• Levees designed to withstand peak flood levels that are caused by rapid snowmelt or intense rainfall and protect the lives and property behind them. • Levees designed to withstand nominal water levels on a continuous basis as well as peak flood levels, such as the levees lining the Sacramento-San Joaquin River Delta on San Francisco Bay, which delivers irrigation and drinking water.
The U.s. Army Corps of Engineers operates, maintains, and evaluates flood protection levees to determine if they meet accreditation requirements. Most levees are owned by local communities and flood control districts that must ensure proper operation and maintenance of the levee system as well (FEMA,2013c).
Levees, when functioning properly, reduce the risk of flooding for communities. However, an unexpected levee breach or failure can be catastrophic, with the flooding causing loss of life, emergency evacuations, and insufficient time to reduce damage to property.
CAUSES OF DAM FAILURE
Darn failures can be catastrophic to human life and property downstream. Darn failures in the United States typically occur in one of four ways:
• Overtopping of the primary darn structure, which accounts for 34 percent of all darn failures, can occur due to inadequate spillway design, settlement of the darn crest, blockage of spillways, and other factors.
• Foundation defects due to differential settlement, slides, slope instability, uplift pressures, and foundation seepage can also cause darn failure. These account for 30 percent of all darn failures.
• Failure due to piping and seepage accounts for 20 percent of all failures. These are caused by internal erosion due to piping and seepage, erosion along hydraulic structures such as spillways, erosion due to animal burrows, and cracks in the darn structure. • Failure due to problems with conduits and valves, typically caused by the piping of embankment material into conduits through joints or cracks, constitutes 10 percent of all failures.
The remaining 6 percent of U.S. darn failures are due to miscellaneous causes. Many darn failures in the United States have been secondary results of other disasters. The prominent causes are earthquakes, landslides, extreme storms, massive snowmelt, equipment malfunction, sb'uctural damage, foundation failures, and sabotage.
The most likely disaster-related causes of dam failure in the OA are earthquake, excessive rainfall, and landslides. Poor construction, lack of maintenance and repair, and deficient operational procedures are preventable or correctable by a program of regular inspections. Terrorism and vandalism are serjous concerns that all operators of public facilities must plan fOf; these threats are under continuous review by public safety agencies.
CAUSES OF LEVEE FAILURE
A levee breach occurs when part of a levee gives way, creating an opening through which floodwaters may pass. A breach may occur gradually or suddenly. The most dangerous breaches happen quickly during periods of high water. The resulting torrent can quickly swamp a large area behind the failed levee with little or no warning. When a levee system fails or is overtopped, severe flood damage can 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 85
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occur due to increased water surface elevation associated with levees and the resulting increase in water velocity.
Earthen levees can be damaged in several ways. For instance, strong river currents and waves can erode the surface. Trees growing on a levee can blow over, leaving a hole where the root wad and soil used to be. Burrowing animals, such as the California ground squirrel, the salt marsh harvest mouse, or the western burrowing owl can create holes that enable water to pass tlU'ough a levee. If severe enough, any of these situations can lead to a zone of weakness that couLd cause a levee breach. In seismically active areas, earthquakes and ground shaking can cause a loss of soil strength, weakening a levee and possibly resulting in failure. Seismic activity can also cause levees to slide or slump, botl'l of which can lead to failure.
No levee provides protection from events for which it was not designed, and levees require maintenance to continue to provide the level of protection they were designed and built to offer. Maintenance responsibilJty belongs to a variety of entities including local, statel and federa l government and private landowners. Well-maintained levees may obtain certification through independent inspections. Levees may not be certified for maintaining flood protection when the levee owner does not maintain the levee or pay for an independent inspection. The impacts of an un-certified levee include higher risk of levee failure. In addition, insurance rates may increase because FEMA iden.tifies on Flood Insurance Rate Maps that the structures are not certified to protect from a I-percent annual chance flood event (FEMA, 2004).
REGULATORY OVERSIGHT
National Dam Safety Act
Potential for catastrophic flooding due to dam failures led to passage of the National Dam Safety Act (public Law 92-367). The National Dam Safety Program requires a periodic engineering analysis of the majority of dams in the country; exceptions include the following:
• Dams under jurisdiction of the Bureau of Reclamation, Tennessee Valley Authority, or International Boundary and Water Commission.
• Dams constructed pursuant to licenses issued under the Federal Power Act. • Dams that the Secretary of the Army determines do not pose any threat to human life or property.
The goal of this FEMA-morutored effort is to identify and mitigate the risk of dam failure so as to protect lives and property of the public. The National Dam Safety Program is a partnership among the states, federal agencies, and other stakeholders that encourages individual and cOJ,Umunity responsibility for dam safety. Under FEMA's leadership, state assistance funds have allowed all participating states to improve their programs through increased inspections, emergency action planning, and purchases of needed equipment. FEMA has also expanded existing and initiated new training programs. Grant assistance from FEMA provides support for improvement of dam safety programs that regulate most of the dams in the United States (FEMA, 2013).
California's Division of Safety of Dams monitors dam maintenance and safety at the state level. When a new dam is proposed, Division engineers and geologists inspect the site and the subsurface. Upon submittal of an application, the Division reviews the plans and specifications prepared by the owner to ensure that the dam is designed to meet minimum requirements and that the design is appropriate for the known geologic conditions. After approval of the application, the Division inspects all aspects of the construction to ensure that the work accords with the approved plans and specifications. After 86 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17
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construction, the Division inspects each dam annually to ensure performance as intended and to identify developing problems. Roughly a third of these inspections include in-depth reviews of instrumentation.
Finally, the Division periodically reviews stability of dams and their major appurtenances in light of improved design approaches, requirements, and new findings regarding earthquake hazards and hydrologic estimates in California (DWR, 2016).
U.S. Army Corps of Engineers Dam Safety Program
The U.s. Army Corps of Engineers is responsible for safety inspections of some federal and non-federal dams in the United States that meet size and storage limitations specified in the National Dam Safety Act.
The Corps has inventoried dams; surveyed each state and federal agency's capabilities, practices, and regulations regarding design, construction, operation, and maintenance of dams; and developed guidelines for inspection and evaluation of dam safety (U.S. Army Corps of Engineers, Date Unknown).
The Corps' National Inventory of Dams provides the most recent inspection dates for 22 high-hazard dams in Santa Clara County (see Table 6-1).
TABLE 6-1. SANTA CLARA COUNfY HIGH HAZARD DAM INSPECTION DATES Santa Clara Count Dam Inspection Date Santa Count Dam Ins ection Date Almaden April 4, 2012 Guadalupe April 4. 2012
Leroy Anderson April 25, 2012 Higuera August 9, 2011
Austrian August 8, 2011 James J. Lenihan April 3. 2012
Calero April 4, 2012 Kuhn April 23, 2012
Cherry Flat April 23, 2012 Lake Ranch August 9, 2011
Columbine August 9, 2011 North Fork January 26. 2012
Coyote November 15, 2011 Peabody January 26, 2012
Debell January 20, 2012 Stevens Creek November 14,2011
Elmer J Chesbro November 15. 2011 Upper Howell August 8, 2011 Felt Lake IJuly 13. 2012 Uvas November 15, 2011
Foothill Park Janua 25. 2012 Vasona Percolatln A ril 3. 2012 Source: U.S. Army Corps of Engineers, 2016b
Federal Energy Regulatory Commission Dam Safety Program The Federal Energy Regulatory Commission (FERC) cooperates with a large number of federal and state agencies to ensure and promote dam safety. More than 3,000 dams are part of regulated hydroelectric projects in the FERC program. Two-thirds of these are more than 50 years old. As dams age, concern about their safety and integrity grows, so overSight and regular inspection are important.
FERC inspects hydroelectric projects on an unscheduled basis to investigate the following:
• Potential dam safety problems.
• Complaints about constructing and operating a project. • Safety concerns related to natural disasters.
• Issues concerning compliance with the terms and conditions of a license.
Every five years, an independent consul ting engineer, approved by the FERC, must inspect and eval uate projects with dams higher than 32.8 feet (10 meters), or with a total storage capacity of more than 2,000 acre-feet.
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FERC monitors and evaluates seismic research in geographic areas such as California where there are concerns about possibly seismic activity. This information is applied in investigating and performing structural analyses of hydroelectric projects. FERC also evaluates the effects of potential and actual large floods on the safety of dams. During and following floods, FERC visits dams and licensed projects, determines the extent of damage, if any, and directs any necessary studies or remedial measures the licensee must undertake. The FERC publication Engineering Guidelines for the Evaluation of Hydropawer Projects guides the FERC engineering staff and licensees in evaluating dam safety. The publication is frequently revised to reflect current information and methodologies.
FERC requires licensees to prepare emergency action plans and conducts training sessions on how to develop and test these plans. The plans outline an early warning system if there is an actual or potential sudden release of water from a dam due to failure. The plans include operational procedures that may be used, such as reducing reservoir levels and reducing downstream flows, as well as procedures for notifying affected residents and agencies responsible for emergency management. These plans are frequently updated and tested to ensure that everyone knows what to do in emergency situations (FERC, 2016).
Corps of Engineers and FEMA Levee Oversight
The Corps and FEMA have differing roles and responsibilities related to levees. The Corps addresses a range of operation and maintenance, risk communication, risk management, and risk reduction issues as part of its responsibilities under the Levee Safety Program. FEMA addresses mapping and floodplain management issues related to levees, and it accredits levees as meeting requirements set forth by the National Flood Insurance Program.
Depending on the levee system, the Corps and FEMA may be involved with a levee sponsor and community independently or jointly. The two agencies' long-term goals are similar: to reduce risk and lessen the devastating consequences of flooding. Corps and FEMA partnering activities related to levees include the following:
• Joint meetings with levee sponsors and other stakeholders. • Integration of levee information into the National Levee Database. • State Silver Jackets teams.
• Sharing of levee information.
• Targeted task forces to improve program alignment.
Coordination between the Corps and FEMA on levees is now standard within many of each agency's policies and practices. Over the past several years, both agencies coordinated policies where appropriate; jointly participated in meetings with stakeholders; and participated in many multiagency efforts, such as the National Committee on Levee Safety, the Federal Interagency Floodplain Management Task Force, and the Silver Jackets Program.
The Silver Jackets is a program that provides an opportunity to consistently bring together multiple state, federal, tribal, and local agencies to learn from each other and apply their knowledge to reduce risk. The Program's primary goals include the following:
• Create or supplement a mechanism to collaboratively identify, prioritize, and address risk management issues and implement solutions.
• Increase and improve risk communication through a unified interagency effort. 88 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17
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• Leverage information and resources and provide access to national programs (FEMA's Risk MAP and the Corps' Levee Inventory and Assessment Initiative). • Provide focused, coordinated hazard mitigation assistance in implementing high-priority actions such as those identified by state hazard mitigation plans. • Identify gaps among agency programs and barriers to implementation, such as conflicting agency policies or authorities, and provide recommendations for addressing these issues.
National Committee on Levee Safety
Congress created the National Committee on Levee Safety to "develop recommendations for a national levee safety program, including a strategic plan for implementation of the program." The Committee adopted a vision of "an involved public and reliable levee systems working as part of an integrated approach to protect people and property from floods," and has been working toward this goal since October 2008 (National Committee on Levee Safety, 2010). The Committee is made up of representatives from state, regional, and local agencies; the private sector; the Corps; and FEMA.
California DWR Levee Repair Program
California initiated this program in 2006 after a state of emergency for heavy rainfall and runoff was declared and California's levee system was compromised. This allowed for $500 million of state funds to repair and evaluate state and federal levees. The project evaluated the stability of the levee system and implemented critically needed repairs to protect communities, farmlands, and infrastructure (California DWR,2016).
HAZARD PROFILE
PAST EVENTS
According to the 2013 State of California Multi-Hazard Mitigation Plan, there have been nine dam failures in the state since 1950, none in the Bay Area. The most recent dam emergency occurred in February 2017 at Oroville Dam in northern California's Butte County when it was on the verge of overflow. The concrete spillway was damaged by erosion and a massive hole developed. The auxiliary spillway was used to preven t overtopping of the dam and it experiences erosion problems also. Evacuation orders were issued out of concern about a potential large uncontrolled release of water from Lake Oroville. Such a release was ultimately prevented, and evacuees returned to their homes.
Historically, overtopping caused two of the state's nine failures; the others were caused by seepage or leaks. One failure, the 1963 Baldwin Hills Dam Failure, resulted in three deaths because the leak turned into a washout. The historical record indicates that California has had about 45 failures of non-federal dams. The failures occurred for a variety of reasons, the most common being overtopping. Other reasons include shortcomings in the dams or an inadequate assessment of surrounding geomorphologic characteristics.
California's first notable dam failure was in 1883 in Sierra County; the most recent failure was in 1965.
The most catastrophic event was the failure of the St. Francis Dam in Los Angeles County, which failed in 1928 and killed an estimated 450 people.
LOCATION
According to DWR, there are 42 dams in the OA and 22 are classified as high-hazard dams, as listed in Table 6-2. All 22 are under the jurisdiction of the state. The Leroy Anderson Reservoir, referred to as the 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 89
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" Anderson Reservoir" is the largest of the 10 water district reservoirs and provides water supply to the OA.
The SCVWD manages approximately 100 miles of levees in Santa Clara County. About 50 miles provide 100-year flood protection and nearly 18 miles were constructed in partnership with the Corps (SCVWD, 2008). The Corps' National Levee Data base lists seven levees in Santa Clara County, as shown in Table 6-3.
FREQUENCY
Dam and levee failure events are infrequent and usually coincide with events that cause them, such as earthquakes, landslides and excessive rainfall and snowmelt. There is a "residual risk" associated with dams that remains after safeguards have been implemented. The residual risk is associated with events beyond those that the facility was designed to withstand. However, the probability of occurrence of any type of dam or levee failure event is considered to be low in today's regulatory and safety oversight environment.
TABLE 6-2. HIGH HAZARD DAMS IN THE SANTA CLARA COUNTY OA NationallD lwater I Year Dam Crest IHelght!storage Drainage Name # I Course Owner Built T e Length (feet) Capacity area I yp feet acre-feet) sq . ml )
Almaden 72.004 Alamitos Creek SCVWD 1936 Earth 500 110 62 12.50 Leroy Anderson, CA00294
"Anderson Reservoir" Coyote River SCVWD 1950 Earth 1,430 235 1,271 194.40 Austrian 622.013 Los Gatos San Jose 1950 Earth 700 185 96 9.80 Creek Water Co.
Calero 72.003 Calero Creek SCVWD 1935 Earth 840 90 337 7.14 Cherry Flat CAOO158 Penitencia City of San 1936 Earth 230 60 25 2.41 Creek Jose Columbine CA00682 Offstream San Jose 1963 Earth 1,480 24 3 nfa Water Co.
Coyote CA00287 Coyote Creek SCVWD 1936 Earth and 980 . Rock 140 635 120 DeBell CA00686 Bodfish Creek P' tEn Tributary (Iva e n I y 1952 Earth '580 53 18 0.72 Elmer J Chesbro CA00806 Llagas Creek SCVWD 1955 Earth and 690 Rock 95 328 19.50
Felt Lake CA00670 Trail Los
Trancos Creek Santa Clara 1930 Earth 590 67 40 0.20
Foothill Park CA00868 Trail Los City of Palo 1988 Earth 600 86 11 0.11 Trancos Creek Alto Guadalupe CA00290 Guadalupe SCVWD 1935 Earth 695 142 75 6.00 Creek Higuera CA00687 South Calera Private Entity 1953 Earth
1 525 44 4 0.60 Creek
James J. Lenihan, CA00293 Los Gatos SCVWD 1953 Earth 810 208 450 27.70 "Lexington Reservoir" Creek Kuhn CA00683 Trail Dry Creek Private Entity 1947 Earth 312 67 5 0.10 Lake Ranch CA00676 Beardsley San Jose 1877 Earth 160 38 18 0.70 Creek Water Co. 90 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17
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National 10 I Water Year Dam Crest Height Storage Drainage Name # ICourse Owner BUilt Type ~:~rt (feet) ~:~~~t a~~a mi.
North Fork CA00299 Pacheco Pass ! Pacheco Creek Water District 1939 Earth 600 100 197 67.20 Peabody CA00685 Trail Llagas Private Entity 1950 Earth 295 63 .76 5.50 Creek Stevens Creek CA00292 . Stevens Creek SCVWD 1935 Earth 1,080 132 95 17.50 Upper Howell CA00678 San Jose , Rundell Creek W t C 1878 , a er o. Earth 640 36 243 13.00 Uvas CA00807 Uvas Creek SCVWD 1957 Earth 1,100 118 280 32.00 Vasona Percolating CA01516 Pickle Canyon p ' t E fty Creek nva e n I 1935 [Earth 1,00 34 58 44.20 Sources: California Division of Safety of Dams, 2017; Stanford University National Performance of Dams Program, 2017 TABLE 6-3. LEVEES IN SANTA CLARA COUNTY
I I
Segment Corps Counties Where S stem Levee Name Ltd Y Levee Owner Length Program IS oca e miles Levee
Uvas Creek-Left Bank
King & Lyons
Guadalupe River - Right Bank
Guadalupe River - Left Bank
Santa Clara
Alameda and Santa Clara
Santa Clara
Santa Clara
SCVWD 2.19
Alameda Flood Control and 3 5
Water Conservation District .
SCVWD 6.9
SCVWD
cBoyote Creek, Santa Clara - Right Bank Alameda and Santa Clara SCVWD ypass .
8.48 0.43
4.9 6.72
Coyote Creek, Santa Clara - Right Bank Santa Clara SCVWD Coyote Creek, Santa Clara - Left Bank i Santa Clara SCVWD Source: U.S. Army Corps of Engineers, 2016c
SEVERITY
Yes
Yes
No
No
Yes
Yes
Yes
Dams upstream of towns and cities create a high risk potential for life and property, particularly in seismically active states such as California. Measure of extent or severity of a dam failure is through the classification of the dam. Two additional factors influence potential severity of a full or partial dam failure: the amount of water impounded; and the density, type, and value of downstream development and infrastructure. The SCVWD conducts seismic stability evaluations on its dams and applies recently adopted, more stringent, earthquake standards. The U.S. Army Corps of Engineers developed the classification system shown in Table 6-4 for the hazard potential of dam failures. This rating system is based only on the potential consequences of a dam failure; it does not take into account the probability of such failures.
TABLE 6-4. CORPS OF ENGINEERS HAZARD POTENTIAL CLASSIFICATION Hazard I I EnVIronmental
C t a Direct Loss of lIfeb lifeline Lossesc Property Lossesd L e a e or osses
Low
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None (rural location, no permanent
structures for human habitation)
No disruption of services
(cosmetic or rapidly
repairable damage)
Private agricultural lands,
equipment, and isolated
buildings
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Minimal incremental
damage
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Significant Rural location, only transient or day- Disruption of essential High
use facilities facilities and access
Certain (one or more) extensive
residential, commercial, or industrial Disruption of essential facilities and access , development
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Major public and private
facilities
Extensive public and
private facilities
Major mitigation required
Extensive mitigation cost
or impossible to mitigate
a. Categories are assigned to overall projects, not individual structures at a project. b. Loss of life potential based on inundation mapping of area downstream of the project. Analyses of loss of life potential should take into account the population at risk, time of flood wave travel, and warning time. c. Indirect threats to life caused by the interruption of lifeline services due to project failure or operational disruption; for example, loss of critical medical facilities or access to them.
d. Damage to project facilities and downstream property and indirect impact due to loss of project services, such as impact due to loss of a dam and navigation pool, or impact due to loss of water or power supply. e. Environmental impact downstream caused by the incremental flood wave produced by the project failure, beyond what would normally be expected for the magnitude flood event under which the failure occurs.
Source: U. S. Army Corps of Engineers, 1995
In the event of a levee failure, floodwaters may ultimately inundate the protected area landward of the levee. The extent of inundation is dependent on the flooding intensity. Failure of a levee during a 1- percent annual chance flood will inundate the 100-year floodplain previously protected by the levee.
Residential and commercial buildings nearest the levee overtopping or breach location will suffer the most damage from the initial embankment failure flood wave. Landward buildings will be damaged by inundation (FEMA, 2004).
WARNING TiME
Warning time for dam failure varies depending on the cause of the failure. In events of extreme precipitation or massive snowmelt, evacuations can be planned with sufficient time. In the event of a structural failure due to earthquake, there may be no warning time. A dam's structural type also affects warning time. Earthen dams do not tend to fail completely or instantaneously. Once a breach is initiated, discharging water erodes the breach until either the reservoir water is depleted or the breach resists further erosion. Concrete gravity dams also tend to have a partial breach as one or more monolith sections are forced apart by escaping water. The time of breach formation ranges from a few minutes to a few hours (U.S. Army Corps of Engineers, 1997).
Santa Clara County and its planning partners have established protocols for emergency warning and response through the County's adopted emergency operations plan. The SCVWD Dam Safety Program maintains the operation of its dams and works with Santa Clara County Emergency Management to provide copies of the most recent dam emergency action plans and inundation maps, and uses this information to plan notification needs for downstream areas in the event of a failure.
Warning time for levee failures depends on the cause of the failure. A levee failure caused by structural failure can be sudden and occur with little to no warning. If heavy rains are impacting a levee system, communities located in the immediate danger zone can be evacuated before a failure occurs. If the levee failure is caused by overtopping, the community mayor may not be able to recognize the impending failure and evacuate. If a levee failure occurs suddenly, evacuation may not be possible.
SECONDARY HAZARDS
Darn and levee failures can cause severe downstream flooding, depending on the magnitude of the failure. Other potential secondary hazards are landslides, bank erosion, and destruction of downstream 92 I Page Santa Clara County Operational Area Mitigation Plan 10/lS/17
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habitat. Levee failures can also cause environmental incidents due to hazardous materials releases when floodwaters infiltrate facilities that store these types of materials.
EXPOSURE
Exposure and vulnerability to the dam failure hazard were assessed by use of spatial analysis. The consistency of the data available to support this risk assessment varied greatly within the OA. The Level of analyses varied based on available data. A detailed exposure and vulnerability analysis was done for the Andersen Dam and for areas protected by levees.
Exposure-only analyses were completed for the James J. Lenihan Dam, Searsville Dam, and Stevens Creek Dam. This data was provided to the planning partnership for informational risk ranking purposes, but is not included in this comprehensive assessment due to data age and inaccuracies. The Working Group has identified acquisition of detailed information and data for additional dams as a priority need.
POPULATION
All populations in a dam failure inundation zone would be exposed to the risk of a dam failure. The potential for loss of life is affected by the capacity and number of evacuation routes available to populations living in areas of potential inundation. The estimated population living in the mapped Anderson, Lexington, Searsville, and Stevens Creek Dam inundation areas is summru·ized in Table 6-5 and Table 6-6. The population within a levee failure inundation area is 1,775, which represent only 0.09 percent of the OA population (see Table 6-7).
PROPERTY
Based on assessor parcel data, the Hazus model estimated the Anderson Dam inundation area, which is the largest reservoir. The inundation boundaries for this dam cover a large portion of the OA. There are 91,601 structures within the mapped dam failure inundation areas in the OA. The value of exposed buildings in the OA was generated using Hazus and is summarized in Table 6-8. This methodology estimated $136 billion worth of building-and-contents exposure to dam failure inundation, representing
28.5 percent of the total replacement value of the OA. The number of exposed structures by land use type is summarized in Table 6-9.
Structures located in Lexington, Searsville, and Stevens Creek Dam inundation areas also were evaluated based on assessor parcel data, but the only available inundation boundary data for these dams-from ABAG (2006)-does not provide a detailed boundary. The approximate value of exposed buildings is summarized in Table 6-10, Table 6-11 and
Table 6-12. The approximate number of exposed structures by land use is summarized Table 6-13, Table 6-14 and Table 6-15.
TABLE 6-5. POPULATION WITHIN ANDERSON AND LEXINGTON DAM FAILURE INUNDATION AREAS IAnderson Dam ____ !Lexington Dam _ _ __
JUrisdiction Pit E ntage of Total l Pit E d Percentage of Total opu a Ion xp t opu a Ion xpose P it a lon , opu a Ion
Campbell 0 0.0% 27,502 64.58%
Cupertino 0 0.0% 0 '0:00%
Gilroy 9,220 16.7% 0 0.00%
Los Altos 0 0.0% 0 0.00%
Los Altos Hills 0 0.0% iO 0.00%
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~n~r!)on Dam __ _ __ J=exington ~am___ _ _ _ __ _
JUriSdiction I Percentage of Total , Percentage of Total Population Exposed Pit Population Exposed Pit o u a Ion opu a Ion
Los Gatos 0. 0..0.% 3,127 9.97%
Milpitas 4,40.6 5.8% 0. 0..0.0.%
Monte Sereno 0. 0. .0.% 0. 0..0.0.%
Morgan Hili 26,584 60..9% 0. 0..0.0.%
Mountain View 0. 0. .0.% 0. 0..0.0.%
Palo Alto 0. 0..0.% 0. 0..0.0.%
San Jose 316,294 30..4% 94,40.5 9.0.6%
Santa Clara (city) 21,10.9 17.1% 71,413 57.71%
Saratoga 0. 0. .0.% 0. 0..0.0.%
Sunnyvale 366 0..2% 0. 0..0.0.%
Unincorporated County 5,232 6.0.% 7,454 8.53%
tUtal 383210 19.9% 10.58%
Note: The Anderson and Lexington Dam's inundation areas overlap in a small area in the Cities of Santa Clara and San Jose.
TABLE 6-6. POPULATION WITHIN SEARSVILLE AND STEVENS DAM FAILURE INUNDATION AREAS ISearsvilie Dam __ . ________ ~tevens Creek Dam _______ _ JUrisdiction Pit E d Percentage of Total : Pit E d Percentage of Total opu a Ion xpose Po ulatlon opu a Ion xpose Po ulatlon
Campbell 0. 0..0.0.% 0. ,0..0.0.%
Cupertino 0. :0..0.0.% 4,284 ;7.36%
Gilroy 0. 10..0.0.% 0. io..o.o.%
Los Altos 0. 0..0.0.% 84 '0..27%
Los Altos Hills 0. ;0..0.0.% 0. :0..0.0.%
Los Gatos 0. 0..0.0.% 0. 0..0.0.%
Milpitas 0. .0..0.0.% 0. 0. .0.0.%
Monte Sereno 0. 0.00.% 0. 0..0.0.%
Morgan Hill 0. :0..0.0.% 0. 0..0.0.%
Mountain View 0. 0..0.0.% 0. 0. .0.0.%
Palo Alto 24,70.4 136.22% 0. 0..0.0.%
San Jose 0. '0..0.0.% 0. 0..0.0.%
Santa Clara (city) 0. '0..0.0.% 0. '0..0.0.%
Saratoga 0. 0.0.0.% 0. 0..0.0.%
Sunnyvale 0. 0. .0.0.% 46,901 '31.61 %
Unincorporated County ·14 0..0.2% 10.2 0..12%
Total 2Vif8 ,.j S1371 2,66%
Note: Searsville and Stevens Creek Dam inundation areas do not overlap with any other dam inundation zones.
TABLE 6-7. POPULATION WITHIN LEVEE FAILURE INUNDATION AREA JUrisdiction Po ulatlon Exposed Percenta e of Total Po ulatlon Campbell 0. 0..0.0%
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Cupertino 0 0.00%
Gilroy 0 0.00%
Los Altos 0 0.00%
Los Altos Hills 10 0.00%
Los Gatos 0 0.00%
~ilpitas_ 0 0.00%
Monte Sereno 0 0.00%
Morgan ~m 0 0.00%
Mountain View 10 0.00%
Palo Alto 14 0.01%
San Jose 1,771 0.17%
Santa Clara (city) 10 0.00%
Saratoga 0 0.00%
Sunn}'Vale 0 0.00%
Unincorporated County 0 0.00%
otal 1775 0.09%
TABLE 6-8. EXPOSURE AND VALUE OF STRUCTURES IN ANDERSON DAM FAILURE INUNDATION AREAS Number of Value Exr:>0sed?__ _ _____ ~ Exposed Value as % JUriSdiction BUildings I of Total Replacement
Exposeda Structure Contents Total Valueb
Campbell 0 $0 $0 $0 0.0%
Cupertino ;0 $0 _._$0 $0 0.0%
Gilroy 2,371 . $~,426,314,807 $2,214,963,210 i $4,641 ,278,017 34.6% Los Altos 0 $0 $0 ,$0 0.0%
Los Altos Hills 0 $0 $0 $0 0.0%
Los Gatos 0 '$0 $0 $0 0.0%
Milpitas 1,065 $738,770,581 $631,254,957 $1,370,025,538 7.2% Monte Sereno 0 $0 $0 $0 0.0%
Morgan Hill 7,486 $4,747,494,356 $3,761 ,592,009 $8,509,086,365 76.2% Mountain View ° $0 $0 '$0 0.0%
Palo Alto 0 $0 $0 $0 0.0%
San Jose 73,737 $57,089,646,257 $45,935,355,046 $103,025,001 ,303 48.3% Santa Clara (city) 5,227 $6,577 ,993,232 $6,177,399,001 $12,755,~92,232 29.4% Saratog .. 0 $0 $0 $0 0.0%
Sunnyvale 242
Unincorporated County 1,473
1l0tal 91,601
a. Anderson Dam failure flooding hazard depth grids provided by SCVWD. b. Values based on Santa Clara County tax assessor data received August 2016.
Note: The Anderson and Lexington Dam's inundation areas overlap in a small area in the Cities of Santa Clara and San Jose. 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 95
OFFICE OF EMERGENCY SERVICES
COUNTY OF SANTA CLARA & SANTA CLARA COUNTY FIRE
TABLE 6-9. STRUCTURFS EXPOSED TO ANDERSON DAM FAILURE BY LAND USE TYPE Cupertino 0 0 0 0 0 0
Gilroy 2,064 198 82 8 9 19
Los Altos 0 0 :0 0 0 ,0 0
Los Altos Hills 0 0 0 0 0 ,0 0
Los Gatos 0 0 0 0 0 ,0 0
Milpitas 1,015 25 22 0 1 2 0
Monte Sereno 0 0 0 0 0 0 0
Morgan Hill 6,904 364 181 18 11 4 4 7,488
Mountain View 0 0 ,0 0 0 0 0 0
Palo Alto 0 0 0 0 0 :0 0 0
San Jose 68,750 3,419 1,344 13 139 :25 47 73[73.7
Santa Clara (city) 4,597 236 :388 0 5 1 0 1'.27
Saratoga 0 0 0 0 0 0 0
~unnyvale 75 39 127 1 0 0 0
Unlncor orated County 1,128 93 24 208 10 7 3
• 83
TABLE 6-10. EXPOSURE AND VALUE OF STRUCTURES IN LEXINGTON DAM FAILURE INUNDATION AREAS Number of Value Exposedb Exposed Value as %
JUrisdiction BUildings -8-- - ---r1c-- -~ - ~ of Total Replacement E de tructure ontents E da V I b x ose x ose a ue
Campbell 7,901 $4,_604,158,781 $3,553,103,236 $8,157,262,017 72.95% Cupertino 0 $0 $0 1$0 0.00%
Gilroy 0 $0 $0 $0 0.00%
Los Altos 0 \$0 ,$0 $0 0,00%
Los Altos Hills 0 $0 '$0 $0 0,00%
Los Gatos 1,037 $733,314,896 ,$519,890,010 $1 ,253,204,906 11.50% Milpitas 0 $0 '$0 $0 0.00%
Monte Sereno 0 $0 ·$0 $0 0.00%
Morgan Hill 0 1$0 $O $0 0.00%
Mountain View 0 $0 ,$0 $0 0,00%
Palo Alto 0 $0 '$0 $0 ·0.00%
San Jose 22,313 j $17,615,261 ,921 $13,542,081,898 : $31,157,343,819 14.60% Santa Clara (city) 17,085 $16,609,952.520 1$15,291,520,055 : $31.901 ,472.575 73.51% Saratoga 0 $0 :$0 $0 0.00%
Sunnyvale 0 $0 ~ $0 0.00%
Unincorporated County 1,688 $657,884,576 ,$1 ,169,166.860 4.61% Total OOlOZ'1 171 15.45%
a. Lexington Dam failure flooding hazard zones based on ABAG 2006 data. b. Values based on Santa Clara County tax assessor data received August 2016.
Note: The Anderson and Lexington Dam's inundation areas overlap in a small area in the Cities of Santa Clara and San Jose. 96 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17
OFFICE OF EMERGENCY SERVICES
COUNTY OF SANTA CLARA & SANTA CLARA COUNTY FIRE
TABLE 6-11. EXPOSURE AND VALUE OF STRUCTURES IN SEARSVILLE DAM FAILURE INUNDATION AREAS I Number of alu~E~o~edb _ ~ ________ Exposed Value as % JUrisdiction BUildings S C BUildings of Total Replacement E dB tructure ontents E da V I b X ose I x ose a ue
Campbell 10 $0 '$0 $0 0,00%
Cupertino 0 $0 $0 $0 0,00%
Gilroy 0 $0 $0 $0 0.00%
Los Alios 0 $0 $0 $0 o,gO%
Los Altos Hills 0 $0 $0 $0 0,00%
Los Gatos 0 $0 $0 $0 0,00%
MiJpltas 0 $0 $0 $0 0,00%
Monte Sereno 0 $0 $0 $0 0,00%
Morgan Hill 0 $0 $0 $0 0,00%
Mountain View 0 $0 $0 $0 0.00%
Palo Alto 7,329 . $5,425,794,045 $4,090,819,895 $9,516,613,940 36,92% San Jose 0 ,$0 $0 $0 0.00%
Santa Clara (city) 0 '$0 $0 $0 10.00%
Sarato.ga 0 :$0 $0 $0 0.00%
Sllnl1yvale 0 $0 $0 $0 0,00%
Unincorporated County 27 $251,650,593 $368,421,855 $620,072,448 2.45% ot 7.356 $5,677,444 838 $4 1'. $10136 aaa.389 2.13%
a. Searsville Dam failure flooding hazard zones based on ABAG 2006 data. b. Values based on Santa Clara County tax assessor data received August 2016, Note: Searsville and Stevens Creek Dam inundation areas do not overlap with any other dam inundation zones.
TABLE 6-12. EXPOSURE AND VALUE OF STRUCTURES IN STEVENS CREEK DAM FAILURE INUNDATION AREAS INumber of yal!J~XR9? ~d b ___ ~ _ ~ ___ ~ __ Exposed Value as % JUrisdiction I BUildings S C BUildings of Total Replacement E da tructure ontents E dB V I b I X ose x ose a ue
Campben 0 $0 $0 $0 0,00%
Cupertino 1,207 $722,579,855 $421,324,629 $1,143,904,485 8.23% Gi!ro~ 0 $0 $0 $0 0.00%
Los Altos 29 $26,093,597 $21,653,678 '$47,747,275 0.54% Los Altos Hills ° $0 $0 1$0 0,00%
Los Gatos 0 $0 $0 $0 0,00%
Milpit~s :0 $0 $0 $0 0.00%
Monte Sereno ° $0 $0 $0 0.00%
Morgar:'l Hill ;0 $0 $0 $0 0,00%
Mountain View 1 $17,213,760 $17,213.760 $34,427,520 0,14% Palo Alto 0 $0 $0 $0 0.00%
San Jose 0 $0 $0 $0 0.00%
Santa Clara (city) ,0 $0 $0 $0 0,00%
Saratoga '0 $Q $0 $0 0,00%
Sunnyvale 9,766 $4,197,286,651 $2,425,247.372 $6,622,534,022 15.45% Unincorporated County 22 1 $7,335,970 $3,667,985 $11 ,003,955 ,0.04% Total ~m .. $I tOY 'l 1.85'4
a, Stevens Creek Dam failure flooding hazard zones based on ABAG 2006 data b, Values based on Santa Clara County tax assessor data received August 2016.
Note: Searsville and Stevens Creek Dam inundation areas do not overlap with any other dam inundation zones, 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 97
OFFICE OF EMERGENCY SERVICES
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TABLE 6-13. STRUCTURES EXPOSED TO LEXINGTON DAM FAILURE BY LAND USE TYPE I Number of Structures In Dam Inundations Area
Junsdlctlon ' . Residential Commercial Industnal A nculture Religion Government I Education I Total Campbell 7,179 528
Cupertino 0 0
Gilroy 0 0
Los Altos 0 0
Los Altos Hills 0 0
Los Gatos 974 56
Milpitas 0 0
Monte Sereno 0 0
Morgan Hill '0 0
Mountain View 0 0
Palo Alto 0 0
San Jose 20,520 1,441
Santa Clara (city) 15.552 815
Saratoga 0 0
Sunnyvale 0 0
Unincorporated Coun
Total
'169
o
,0
o
o
o
o
o
o
o
o
279
668
o
0 10
10 0
0 2
0 0
0 0
0 0
0 0
0 0
2 ,22 1
0 0
10 0
0 0
0 0
4 0
0 0
0 0
0 0
0 0
0 0
41 10
21 2
0 0
0 0
2 0
90 13
TABLE 6-14. STRUCTURES EXPOSED TO SEARSVILLE DAM FAILURE BY LAND USE TYPE Cupertino 0 10 0 0
Gilroy 0 0 :0 0 0
Los Altos 0 0 0 ;0 0 0
Los Altos Hills 0 0 0 :0 0 0
Los Gatos 0 0 0 :0 0 0
Milpitas 0 0 0 ,0 0 0
Monte Sereno 0 0 0 :0 0 0
Morgan Hill 0 0 0 10
i 0 0
Mountain View 0 0 0 jO 0 0
Palo Alto 16,858 431 9 11 19 3
San Jose 0 0 0 0 0 0
Santa Clara (city) 0 0 0 !O 0 0
Saratoga 0 0 0 ;0 0 0
Sunnyvale 0 0 0 to 0 0 ,
Unincorporated County 3 10 0 0 0
9 ~ 19 3
98 I Page Santa Clara County Operational Area Mitigation Plan 2 7901
0 0
0 0
0 0
0 0
1 1.037.
0 0
0 0
0 0
0 0
0 0
22 22.313
27 17.085
0 0
:0 0 ,1 1~88
53 50 24
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 8
0 0
0 0
23 10/15/17
OFFICE OF EMERGENCY SERVICES
COUNTY OF SANTA CLARA & SANTA CLARA COUNTY FIRE
TABLE 6-15. STRUCTURES EXPOSED TO STEVENS CREEK DAM FAILURE BY LAND USE TYPE JUrisdiction I Number_of Sjructures In_ Dar:!1--,nund~tlons ~ea __ ';_ _, ~ __ _ Residential Commercial Industrial A riculture Religion I Government Education Total Campbell 10 10 10 a 'a 0 a 0
Cupertino 1,173 30 1 0 3 0 0 1,207
Gilroy 0 :0 a 10 ,a a :0 0
Los Altos 28 1 a a 'a 0 a 29
Los Altos Hills 0 0 a 10 a 0 0 0
los Gatos 0 0 0 a a 0 0 0
Milpitas 0 10 a a a a 0 0
Monte Sereno 0 0 0 0 a 0 a 0
Morgan Hili 0 0 0 0 a 0 0 0
Mountain View a 1 a a 0 a a 1
Palo Alto a a a a 0 0 0 0
San Jose a a 0 0 a 0 a 0
Santa Clara (city) a a 0 0 0 0 0 0
Saratoga 0 a 0 0 a 0 a ,0
Sunnyvale 9,615 132 a 0 14 ,1 4 9,.
Unincor orated County 22 0 0 a a a a 22
Total 10838 164 1 0 17 1 it 111_
CRITICAL FACILITIES
GIS analysis determined that 1,001 of the OA's critical facilities (28.2 percent) are in the mapped Anderson Dam inundation area, as summarized in Table 6-16.
TABLE 6-16. CRITICAL FACILITIES IN ANDERSON DAM FAILURE INUNDATION AREASA Emergency
J d t R I P bl Infrastructure Military Recovery Socioeconomic Hazardous Ttl UriS IC Ion esponse U IC 0 a Health & Safet lifeline FaCIlities FaCilities FaCIlities Materials Campbell 10 a 0 a 0 0 0
Cupertino 0 0 0 ,0 0 0 0
Gilroy 7 21 0 0 13 3 44
Los Altos 0 0 a 0 0 0 0
Los Altos Hills 0 0 0 0 a 0 0
Los Gatos 0 0 0 0 0 0 0
Milpitas , 0 17 0 0 6 5 28
Monte Sereno a a a a a 0 0
Morgan Hill 5 13 a 0 32 7 87
Mountain View 0 a a a a 0 0
Palo Alto a a a 0 !o a 0
San Jose 45 365 a 1 207 85 70a
Santa Clara (city) 4 128 a a 17 42 91
Saratoga 0 a 0 0 a 0 0
Sunnyvale 1 0 a a a ,6 7
Unincor orated County 3 60 a 0 7 1 71
otll 85, 504 0 1 - HI 1.001
a. Due to data availability and quality, only Anderson Dam was used in this assessment 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 99
ENVIRONMENT
OFFICE OF EMERGENCY SERVICES
COUNTY OF SANTA CLARA & SANTA CLARA COUNTY FIRE
Reservoirs held behind dams affect many ecological aspects of a river. River topography and dynamics depend on a wide range of flows, but rivers below dams often experience long periods of very stable flow conditions or saw-tooth flow patterns caused by releases followed by no releases. Water releases from dams usually contain very little suspended sediment; this can lead to scouring of river beds and banks.
The environment would be exposed to a number of risks in the event of dam failure. The inundation could introduce many foreign elements into local waterways. This could result in destruction of downstream habitat and could have detrimental effects on many species of animals, especially endangered species such as salmon.
VULNERABILITY
POPULATION
Vulnerable populations are all populations downstream from dam failures that are incapable of escaping the area within the allowable time frame. This popUlation includes the elderly and young who may be unable to get themselves out of the inundation area. The vulnerable population also includes those who would not have adequate warning from a television or radio emergency warning system.
PROPERTY
Vulnerable properties are those closest to the dam inundation area. These properties would experience the largest, most destructive surge of water. Low-lying areas are also vulnerable since they are where the dam waters would collect. Transportation routes are vulnerable to dam inundation and have the potential to be wiped out, creating isolation issues. This includes all roads, railroads and bridges in the path of the dam inundation. Those that are most vulnerable are those that are already in poor condition and would not be able to withstand a large water surge. Utilities such as overhead power lines, cable and phone lines could also be vulnerable. Loss of these utilities could create additional isolation issues for the inundation areas.
It is estimated that there could be up to $36.6 billion in loss from an Anderson dam failure affecting the OA. This represents 27 percent of the total exposure within the inundation area, or 7.7 percent of the total replacement value of the OA. Table 6-17 summarizes the loss estimates for dam failure.
TABLE 6-17. LoSS ESTIMATES FOR DAM FAILURE
I Estimated Loss ASSOCiated With Dam Fallurea Estimated Loss as % of JUriSdiction --- .-- -- - . --- - -- Structure Contents 'Total Total Re lacement Value
Campbell $0 $0 $0 0.0%
Cupertino $0. $0 '$0 0.0%
Gjlroy $123,414,912 $264,509,313 $387,924,224 2.9%
Los Altos $0 $0 $0 0.0%
Los Altos Hills $Q $0 $0 0.0%
Los G~tos $0 $0 $0 0.0%
Milpitas $3,264,371 $2,489,545 $5,753,917 0.0%
Monte Sereno $0 $0 $0 0.0%
Mor~an Hill $953,794,167 1$1 ,341 ,152,417 $2,294,946,584 20.6% 100 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17
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Estimated Loss Associated with Dam Fallurea Estimated Loss as % of JUrisdiction - - . -- ----- - Structure Contents ITotal Total Replacement Value Mountain View $0 !$O $0 0.0% ,- Palo Alto '$0 !$O $0 0.0% San Jose I $13,319,?.B5,267 $17,251,673,625 $30,570,958,892 14.3% Santa Clara (city) '$1 ,107,372,297 ! $1 ,474,757,272 $2,582,129,569 59% Saratoga $0 $0 $0 0.0%
Sunnyvale 1 $48,225,722 $.167,939,609 0.4%
Unincorporated County i$271 ,263851 $635,322 709 2.5%
Total $15 826 820 586 $36 844,975,504 7.7%
a. Due to data availability and quality, only Anderson Dam was used in this assessment It is estimated that there could be up to $6.3 billion in loss from a levee failure affecting the OA. This represents only 1.34 percent of the total replacement value of the OA. Table 6-18 summarizes the loss estimates for levee failure.
CRITICAL FACILITIES
Critical facilities in the Anderson Dam's inundation area would receive 13.4 percent damage to structures and 42.3 percent damage to contents during a dam failure event. The estimated time to restore these facilities to 100 percent of their functionality is 612 days. Critical facilities vulnerability was not available for the Lexington, Searsville, or Stevens Creek dam inundation areas.
TABLE 6-18. Loss ESTIMATES FOR LEVEE FAILURE
I Estimated Loss ASSOCiated With Levee Failure Estimated Loss as % of JUrisdiction ---- Structure Contents IT otal Total Re lacement Value Campbell $0 $0 $0 0.00%
Cupertino $0 $0 $0 ;0.00%
Gilroy $0 $0 $0 io.oO%
Los Altos $0 $0 $0 iO.OO%
Los Altos Hills $0 $0 '$0 ;0.00%
Los Gatos $0 1$0 $0 '0.00%
Milpitas $0 1;$0 $0 !O.OO%
Monte Sereno $0 $0 $0 :0.00%
Morgan Hill $0 $0 '$0 iO,OO%
Mountain View $302,501 ,709 $358.394,436 $660,896,145 '2.64% Palo Alto $251 ,765,030 $273,275,,192 i $525,040,223 12.04% San Jose $946,889,058 $906,446,482 $1,853,335,540 .0,87% Santa Clara (city) $144,539,498 $149,199,908 $293,739,407 0.68% Saratoga $0 $0 $0 0.00%
Sunnyval~ _ $1 ,420 5~7 856 $1,619,151,888 7,09%
Unincorporated County $0 $0 0.00%
Tatal 3'01 ~
10/15/17 Santa Clara County Operational Area Mitigation Plan Page 1101
ENVIRONMENT
OFFICE OF EMERGENCY SERVICES
COUNTY OF SANTA CLARA & SANTA CLARA COUNTY FIRE
The environment would be vulnerable to a number of risks in the event of dam failure. The inundation could introduce foreign elements into local waterways, resulting in destruction of downstream habitat and detrimental effects on many species of animals, especially endangered species such as coho salmon.
The extent of the vulnerability of the environment is the same as the exposure of the environment.
FUTURE TRENDS IN DEVELOPMENT
Land use in the OA will be directed by general plans adopted under state law. The safety elements of the general plans establish standards and plans for the protection of the community from hazards. Dam and levee failure are currently not addressed as stand-alone hazards in the safety elements, but flooding is.
Municipalities participating in this plan have established comprehensive policies regarding sound land use in identified flood hazard areas. Most of the areas vulnerable to the more severe impacts from dam and levee failure intersect the mapped flood hazard areas. Flood-related policies in the general plans will help to reduce the risk associated with dam and levee failure hazard for all future development in the OA.
SCENARIO
An earthquake in the region could lead to liquefaction of soils around a dam. This could occur without warning during any time of the day. A terrorist or other intentional attack also could cause a catastrophic failure of a dam that impacts the OA. While the probability of dam failure is very low, the probability of flooding associated with changes to dam operational parameters in response to climate change is higher.
Dam designs and operations are developed based on hydrographs with historical record. If these hydrographs experience significant changes over time due to the impacts of climate change, the design and operations may no longer be valid for the changed condition. This could have significant impacts on dams that provide flood control. Specified release rates and impound thresholds may have to be changed.
This would result in increased discharges downstream of these facilities, thus increasing the probability and severity of flooding.
ISSUES
The most significant issue associated with dam failure involves the properties and populations in the inundation zones. Flooding as a result of a dam failure would significantly impact these areas. There is often limited warning time for dam failure. These ~vents are frequently associated with other natural hazard events such as earthquakes, landslides or s~vere weather, which limits their predictability and compounds the hazard. Important issues associated with dam failure hazards include the following:
• Federally regulated dams have an adequate level of oversight and sophistication in the development of emergency action plans for public notification in the unlikely event of failure.
However, the protocol for notification of downstream citizens of imminent failure needs to be tied to local emergency response planning.
• Mapping for federally regulated dams is already required and available; however, mapping for' non-federal-regulated dams that estimates inundation depths is needed to better assess the risk associated with dam failure from these facilities. Moreover, although mapping is required for federally regulated dams, development downstream of dams and upgrades to older dams may have altered inundation areas; however, these inundation maps may not have been updated for significant periods of time. Encouraging property owners of dams to 102 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17
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update emergency action plans and inundation maps will ensure availability of the most accurate data to assist emergency planners and local officials. • Most dam failure mapping required at federal levels requires determination of the probable maximum flood. While the probable maximum flood represents a worst-case scenario, it is generally the event with the lowest probability of occurrence. For non-federal-regulated dams, mapping of dam failure scenarios that are less extreme than the probable maximum flood but have a higher probability of occurrence can be valuable to emergency managers and community officials downstream of these facilities. This type of mapping can illustrate areas potentially impacted by more frequent events to support emergency response and preparedness.
• The concept of residual risk associated with structural flood control projects should be considered in the design of capital projects and the application of land use regulations. • Addressing security concerns and the need to inform the public of the risk associated with dam failure is a challenge for public officials.
• Limited financial resources for dam maintenance during economic downturns result in decreased attention to dam structure operational integrity, because available funding is often directed to more urgent needs. This could increase potential for maintenance failures. • Dam failure inundation areas are often not considered special flood hazard areas under the NFIP, so flood insurance coverage in these areas is not common. 10/15/17 Santa Clara County Operational Area Mitigation Plan Page 1103
OFFICE OF EMERGENCY SERVICES
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DROUGHT
GENERAL BACKGROUND
Drought is a significant decrease in water supply relative to what is "normal" in a given location. A normal phase in the climate cycle of most geographical regions, drought originates from a deficiency of precipitation over an extended period of DEFiNITIONS time, usually a season or more. This leads to a water shortage for some activity, group or environmental sector.
Determination of when drought begins is based on impacts on water users and assessments of the available water supply, including water stored in surface reservoirs or groundwater basins. Different water agencies have different criteria for defining drought. Some issue drought watch or drought warning announcements. The California water code does not include a statutory definition of drought; however, analysis of the code indicates that legal matters most frequently focus on drought conditions during times of water shortages (California Code of Regulations (CCR), 2016).
MONITORING DROUGHT
The National Oceanic and Atmospheric Administration (NOAA) has developed several indices to measure drought impacts and severity and to map their extent and locations:
Drought-The cumulative
impacts of several dry years
on water users. It can include
dencienc::iE)s in surface and
s lIbsurface water supplies
and generally impacts health,
wellbeing, and quality of life.
Agricultural Drought-Not
enough soil moisture to meet
the needs of a particular crop
at a particular time.
Hydrological DroughtDefiG1eneles in surface and
subsurface water supplies.
SOCioeconomic DroughtDroug"t irYlPa:.c::ts on health,
well-belng, and quality of life.
• The Palmer Crop Moisture Index measures short-term drought on a weekly scale and is used to quantify drought's impacts on agriculture during the growing season. Figure 7-1 shows this index for the week ending October 1, 2016.
• The Palmer Drought Index measures the duration and intensity of long-term droughtinducing circulation patterns. Long-term drought is cumulative, so the intensity of drought during a given month depends on current weather plus the cumulative weather of previous months. The Palmer Drought Index responds rapidly as weather patterns change quickly.
Figure 7-2 shows this index for October 2016.
• The Palmer Z Index measures short-term drought on a monthly scale. Figure 7-3 shows this index for August 2016.
• The hydrological impacts of drought (e.g., reservoir levels, groundwater levels, etc.) take longer to develop and it takes longer to recover from them. The Palmer Hydrological Drought Index is a long-term index to quantify hydrology effects. The Palmer Hydrological Drought Index responds more slowly to changing conditions than the Palmer Drought Index.
Figure 7-4 shows this index for August 2016.
• While the Palmer indices consider precipitation, evapotranspiration and runoff, the Standardized Precipitation Index considers only precipitation. In the Standardized Precipitation Index, an index of zero indicates the median precipitation amount; the index is negative for drought and positive for wet conditions. The Standardized Precipitation Index is computed for time scales ranging from one month to 24 months. Figure 7-5 shows the 24- month Standardized Precipitation Index map for January 2013 through December 2015. 104 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17
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Note: The following graphics represent snapshots in time of para meters that can change daily. They are provided only as examples of the type and level of detail of mapping available on the drought hazard.
CROP MOISTURE
Crop Moisture Index by Division
Weekly Value for Period Ending Apr OS, 2017
Short Term Need vs. Available Water in a Shallow Soli Profile CCI1CTS~ ,lvtf~f04"(l~
~~QlWrtT"'t$$~KAJa;\Ml.
~llII'ltl'(,UJt,~""~Y,"",,fOWlO:
"'-NDtfIOX,All.\U)JIW.CQ01"(lflJolI rloo(l~»IOthO
CF ~ 1N'J~
1..156.-~ lHMfASlJUHCi T'I1f stt(»T-T~ W!U1t)~ STAlU5
CF ORYME$S 0lI: WE'T"'IES& NnCn.,.. ~ ~ CJQIS N,;) FUI.D OPEMnONS U~U .. I~ H,I."'~IJ(.....nJC,o\lll.l! IOCiL",-,._m.o ~~\ow 1lIXI1fD~ Wi'IlI)oWlNIll rolX1lAC1 'lit owo 011 WiSOtL,..o/1'fV.llf.'.oKaiJ~N SO' .... fTtL.tM'(lflcCOt.RiJl:)'tUOl'J("AOI\UlCwJiU,lTO'.HAAIWiW" .~ .\O".IfO\1fW..rriS'oOtc.'I'i..~"'r~~11<t.~'OH~MO'mcS,,"tM;S1 CItO.,IO'I'r eM; M:J iIOJj w,.:Qoi 1M DCPXl'to'~ ftc. 0IQGift 1inQIJV IMld FIGURE 7-1. PALMER CROP MOISTURE INDEX FOR WEEK ENDING APRIL 8, 2017 10/15/17 Santa Clara County Operational Area Mitigation Plan Page 1105
OFFICE OF EMERGENCY SERVICES
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Drought Severity Index by Division
Weekly Value for Period Ending Apr 08,2017
Long Term Palmer
DROUGHT SEVERITY INDEX (PALMER)
DfPTCTS PROlOMGft) (HO.tffiIs, ~) AllNORfW. OAYNESS OR
WEThESS: RfPONOS SLOWLV; 0WHiE5 UTJLf F1WM IIIIEK TO 'W'EEX< AHl RlR.fCTS ~0f£.JBU4 HOISTVRf IlUOOFF, a.eQWl,Gf, AHO DaP PERCDVtTlOH AS MU AS fVIUIOTJl,ANSfIRATlON
U5ES. _Al'f'Uc.A8I.llN HEASWJNG IHsalA'l'M mKl5 Of PRQ..ON(8) DRYNESS OR MTNESS OH WAoTElt SlMJTNf ECONOMIES,. OESIQlING Df~ AREAS Of DROUGHT OR WETIeS;.-HO AfF\fC1lHGo TH( GEHBUL LONG-TeRM SlATVS OF WATU SUWU5 IN AQUIF~ RESEAVOTRS AND 51RfAHS
UMrTAnONS 1$ hOT CiBiERAUV IfI)lCATlV( OfJSHORT·mtH (fEW WEBS) srATU5 OF DROUGHT 011. MTltfSS SUCH AS FREQUErfTlY AFfECTS CJtOfIS AM) AELD CflfRATIOKS (TH/$ IS lfC)iCAleJ IJY TliE ~OP MOISTURE lNOlX).
• -4.0 or less (Extreme Drought)
. -3.0 to -3.9 (Severe Drought)
-2.0 to -2.9 (Moderate Drought)
--1.9 to +1.9 (Neilr Normal)
+2.0 to +2.9 (Unusual Moist Spell)
+3.0 to +3.9 (Very Moist Spell)
• +4.0 and above (Exbemely MoIst)
FIGURE 7-2. PALMER DROUGHT INDEX FOR APRIL 8.2017
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FIGURE 7-3. PALMER Z INDEX SHORT-TERM DROUGHT CONDITIONS FOR MARCH 2017 10/15/17 Santa Clara County Operational Area Mitigation Plan Page 1107
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FIGURE 7-4. PALMER HYDROLOGICAL DROUGHT INDEX LONG-TERM HYDROLOGIC CONDITIONS FOR MARCH 2017
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• +3. 00 and above (exceptionally WQtl
• +2. 00 to +2.99 (extremely wetl
• +1. 25 to +1. 99 (very .... t)
o +0.75 to +1.2Q (moderately wet)
o -0.7Q to +0.74 (near nom.al)
o -1.2Q to -0.75 (moderately dry)
o -1.99 to -1 .25 (very dry)
• -2.99 to -2.00 (.xtremely dry)
• -3.00 and below (exceptionally dry)
Ii'Qstern Rvgional ClimatQ CentQlDe::iert "'R~:iear ch In::Jt1tute P~eno, t{evada FIGURE 7-5. 24-MoNTH STANDARDIZED PRECIPITATION INDEX THROUGH THE END OF MARCH 2017
NORMAL PRECIPITATION IN CALIFORNIA
Most of California's precipitation comes from storms moving across the Pacific Ocean. The path followed by the storms is determined by the position of an atmospheric high pressure belt that normally shifts southward during the winter, allowing low pressure systems to move into the State. On average, 75 percent of California's annual precipitation occurs between November and March, with 50 percent occurring between December and February. A persistent Pacific high pressure zone over California in mid-winter signals a tendency for a dry water year. A typical water year produces about 100 inches of rainfall over the North Coast, 50 inches of precipitation (combination of rain and snow) over the Northern Sierra, and 15 inches in Santa Clara County. In extremely dry years, these annual totals can fall to as little as one half, or even one third of these amounts.
The Sierra Nevada snowpack serves as the primary agent for replenishing water in the San Francisco Bay area, including Santa Clara County, and for much of the State of California. A reduction in spring snowpack runoff, whether due to drier winters or to increasing temperatures leading to more rain than snow, can increase risk of summer or fall water shortages throughout the region.
WATER SUPPLY STRATEGY
The Bay Area Water Supply Conservation Agency (BAWSCA) is the main water provider for much of the Bay Area, allowing SCVWD to manage the continual water supply necessary to maintain health, safety, and economic wellbeing of residents, businesses, and community organizations. BAWSCA agencies manage two-thirds of water consumption from the Hetch-Hetchy Water System, providing water to 2.4 million people in San Francisco, Santa Clara, Alameda, and San Mateo Counties. The HetchHetchy System was so-named because 85 percent of its water comes from Sierra Nevada snowmelt stored in the Hetch-Hetchy reservoir along the Tuolumne River in Yosemite National Park; the remaining 15 10/15/17 Santa Clara County Operational Area Mitigation Plan Page 1109
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percent of water in this system comes from runoff in the Alameda and Peninsula watersheds (BAW'3C.A, 2016).
BAWSCA developed a two-phase, long-term water supply strategy for customers throughout the Bay Area, as outlined in the 2015 Long-Term Reliable Water Supply Strategy Phase II Final Report. Purposes of its strategy are as follows:
• Quantifying water supply reliability needs of BAWSCA member agencies through 2040. • Identifying water supply management programs or programs that can be developed to meet those regional water reliability needs.
• Developing an implementation plan for the water supply strategy.
This strategy recognized that drought-year shortfalls could be significant, but determined that normal-year water supply would be adequate through at least 2014. Dry years could result in systemwide cutbacks of up to 20 percent, but 10 to 15 percent is the more consistent standard. BAWSCA noted that the impacts of water shortages would be regional and could lead to secondary detrimental economic effects. To address this concern, the strategy focused on identifying options for filling all or part of the drought-year supply shortfall, and investigating and potentially implementing actions that seem most beneficial.
BA WSCA also developed a Water Conservation Implementation Plan, focusing on the following objectives (BAWSCA, 2009):
• Help BA WSCA member agencies evaluate potential water savings and cost-effectiveness associated with implementing additional water conservation measures beyond their commitments of 2004.
• Determine potential water savings in 2018 and 2030 based on a selected range of new conservation measures and the 2004 water conservation commitments. • Determine BA WSCA' s role in helping member agencies achieve individual water conservation goals.
• Develop a coordinated regional plan for water conservation implementation measures to serve as a guideline for member agencies.
The Santa Clara Valley Water District ('3C.VWD) is the wholesale water and groundwater management agency throughout Santa Clara County, relying on local retailers (municipalities and private companies) to deliver water throughout the County (SCVWD, 2016). In the Santa Clara County OA, the following districts and cities are members of BAWSCA: SCVWD, Gilroy, Mountain View, Palo Alto, San Jose, City of Santa Clara, and Sunnyvale ('3C.VWD, 2016). The following are the retailer water providers for each municipal planning partner
• Campbell-San Jose Water Company.
• Cupertino-San Jose Water Company and California Water Service Company. • Gilroy - Gilroy Community Services Department.
• Los Altos - California Water Service Company.
• Los Altos Hills-Purissima Hills Water District and California Water Service Company. • Los Gatos-San Jose Water Company.
• Milpitas - City of Milpitas Community Services.
• Monte Sereno-San Jose Water Company.
• Morgan Hill-City of Morgan Hill.
• Mountain View-City of Mountain View Public Works.
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• Palo Alto-City of Palo Alto Utilities Department.
• San Jose-San Jose Water Company, Great Oaks Water Company, and San Jose Municipal Water System.
• Santa Clara City-City of Santa Clara Water Department. • Saratoga-San Jose Water Company.
• Sunnyvale-City of Sunnyvale Public Works Department and California Water Service Company.
The SCVWD has its own water supply strategy outlined in the SCVWD 2012 Water Supply and Instructure Master Plan (Water Master Plan 2012). The Water Master Plan 2012 outlines a water supply strategy with three key elements:
• Secure existing supplies and facilities.
• Optimize the use of existing supplies and facilities. • Expand water use efficiency efforts.
Some County residents have domestic wells on their property. The South Central Regional Office of California DWR monitors wells for Santa Clara County to help protect groundwater quality (DWR, 2016).
Under Ordinance 90-1, as of July 1, 2013, a person must obtain a permit from SCVWD to perform any well activities.
WATER SUPPLY INFRASTRUCTURE
Figure 7-6 shows the SCVWD water supply system. Santa Clara County receives 55 percent of its water supply from the San Francisco Bay-Delta watershed. Of this water, 40 percent comes directly through the Delta watershed or water conveyance systems (State Water Project) and 15 percent is from the HetchHetchy System. Another 30 percent of the County's supply is local, from natural groundwater, reservoirs to groundwater, and reservoirs to drinking water treatment plans. Five percent is recycled water, primarily used for irrigation, industry, and agriculture. The last 10 percent is savings needed. 10/15/17 Santa Clara County Operational Area Mitigation Plan Page 1111 legend
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COUNTY OF SANTA CLARA & SANTA CLARA COUNTY FIRE
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FIGURE 7-6. SANTA CLARA VALLEY WATER DISTRICT SYSTEM WATER SUPPLY The Hetch-Hetchy Water System was approved in 1913 under the Raker Act, which allowed use of federal lands to build that water system. The water system was constructed by San Francisco over the next 20 years, with first delivery of water in 1934. Although the system is owned by San Francisco, it was designed from the beginning to serve as a regional water supply system (BAWSCA, 2016). Figure 7-7 shows the Hetch-Hetchy Water System. Figure 7-8 shows the local, imported, and other water sources for the municipalities (SCVWD, 2016).
l'Aerne
OCEA"
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HETCH HETCHY REGIONAL WATER SYSTEM
---I
... ......... -
"
e-._.
- FIGURE 7-7. HETCH-HETCHY WATER SYSTEM
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A1vi .. 0 0
c. ......... 0 0 0 0 0
Cupertino 0 0 0 0 0
Gi/,.y 0 0 0 0
1.0. Alto. 0 0 0 0 0
1.0. Alto. Hill. 0 0 • 0 0 0
1.0.0. .... 0 0 0 0 0
Mi/";- 0 0 0
Monl. S.rono 0 0 0 • 0
Mo..-Hill 0 0 0
Mountain View 0 0 0 0 • 0 •
Palo AI ... • •
SanJo .. 0 0 0 • 0 0 0
Son M.rrin • 0 •
Sonia Cia ... 0 0 • 0 0 • 0
.. ...,... 0 0 0 0 •
Sunnyva/. 0 • 0 0 0 0 0
Santo (ba Valey WoI8f OisIrictO
FIGURE 7-8. SANTA CLARA COUNTY MUNICIPAL WATER SOURCE
RESPONSES TO DEFINED DROUGHT STAGES
The SCVWD defined drought stages in the 2010 Urban Water Management Plan (Chapter 6.0, Water Shortage Contingency Planning), along with the following outreach and water savings measures associated with each stage:
• Stage 1, Normal-The SCVWD continues ongoing outreach strategies aimed toward achieving long-term water conservation goals. Messages at this stage focus on services and rebate programs the SCVWD provides to facilitate water use efficiency for residents, agricultural operations and businesses. While the other stages are more urgent, success in Stage 1 is vital to achieving long-tertn-water use reduction goals. o Stage 2, Alert-Communication tactics that are employed in Stage 1 may be augmented with additional funding to reach more people with an increased frequency and urgency.
Additional communication tools can be employed to further broaden awareness and promote immediate behavioral changes. Specific implementation plans will be developed when a worsening of the water shortage condition has occurred and up to 10-percent water usage reduction is suggested. Supplemental funding may be identified to augment budgeted efforts, which normally will be set based on an assumption that the county is in Stage 1. Based on historical hydrology and management and operations of SCVWD supplies, it is estimated that groundwater storage would be in Stage 2 one out of every 10 years. o Stage 3, Severe-As the severity of a water shortage increases, the intensity of communications efforts may also increase. Messages are modified to reflect the more dire circumstances. The messages conveyed change to correspond to the call for immediate actions 10/15/17 Santa Clara County Operational Area Mitigation Plan Page 1113
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to save water and a 10- to ZO-percent water usage reduction is suggested. Based on historical hydrology and management and operations of SCVWD supplies, it is estimated that in one out of every 15 years groundwater storage would be in Stage 3. • Stage 4, Critical-In this stage, retailers and cities would be encouraged to enforce their water shortage plans, which could include fines for repeated violations and a 20- to 40-percent water usage reduction would be suggested. Stage 4 strengthens and expands the Stage 3 activities, including further expansion of outreach efforts and opening a drought information center. • Stage 5, Emergency-Stage 5 of the water shortage contingency plan designates and reserves up to 150,000 acre-feet in surface and groundwater storage for emergency conditions to ensure availability of water to meet essential public health and safety requirements. Up to a 50-percent water usage reduction would be suggested and the Emergency Operations Center would be activated.
Participating municipality retail water providers' drought contingency measures are described in the municipal annexes in Volume 2 of this hazard mitigation plan.
HAZARD PROFILE
Droughts originate from a deficiency of precipitation resulting from an unusual weather pattern. Such patterns can be short-term, lasting for a few weeks or months, or long-term, lasting for many months or for years. It is possible for a region to experience a long-term circulation pattern that produces drought, and to have short-term changes in this long-term pattern that result in short-term wet spells. Likewise, it is possible for a long-term wet circulation pattern to be interrupted by short-term weather spells that result in short-term drought. Droughts typically occur after 2 or 3 years of below-average rainfall during the period from November to March, when about 75 percent of California's average annual precipitation falls.
PAST EVENTS
Statewide Droughts
California DWR has state hydrologic data from as far back as the early 1900s. These data indicate occurrences of multi-year droughts from 1912 to 1913, 1918 to 1920, and 1922 to 1924. Between 1954 and 2016, California experienced one FEMA-declared emergency (EM) classified as a drought: FEMA Declaration EM-3023 in 1977, which applied to 58 California counties, including Santa Clara County (FEMA, 2016). During the last 40 years, four prolonged periods of drought in California have impacted Santa Clara County (CaIOES, 2013):
• 1976 to 1977 Drought-California had one of its most severe droughts during the winters of 1976 and 1977.1977 was the driest period on record in California, with the previous winter recorded as the fourth driest in California's hydrological history. The cumulative impact led to widespread water shortages and severe water conservation measures across the state. Only 37 percent of normal Sacramento Valley runoff was received. Over $2.6 billion in crop damage was recorded in 31 counties. Santa Clara County was included in FEMA-3023-EM-CA declaration on January 20, 1977.
• 1987 to 1992 Drought-California received precipitation well below average levels for four consecutive years. While the Central Coast was most affected, the Sierra Nevadas in Northern California and the Central Valley were also affected. Water suppliers did not begin to experience shortages until the third or fourth years of the drought. Reservoir storage provided a buffer against drought impacts during the initial years of the drought. In 1991, the State 1141 Page Santa Clara County Operational Area Mitigation Plan 10/15/17
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Water Project sharply decreased deliveries to water suppliers, including the San Francisco Bay Area. The SCVWD implemented drought contingency measures such as rationing and mandatory conservation to reach its 25 percent reduction goal. By February 1991, all 58 counties in California were suffering under drought conditions that affected urban, rural, and agricultural areas. Some counties had declared local drought emergency, but Santa Clara County was not included.
• 2007 to 2009 Drought-A governor's executive order proclaimed a statewide drought emergency on June 4, 2008 after spring 2008 was the driest spring on record, with low snowmelt runoff. On February 27, 2009, after the largest court-ordered water restriction in state history up to that time, a state of emergency was proclaimed for the entire state as the severe drought conditions continued. Santa Clara County received about half of its water through the Sacramento-San Joaquin River Delta, which was already significantly limited that year because of pumping restrictions mandated under the Endangered Species Act. Water deliveries through the Delta were cut by about 20 to 30 percent. The SCVWD had mandatory water conservation and rationing measures in effect to reduce usage by 15 percent. • 2012 to Present Drought-California's current drought has set several records. From 2012 to 2014, it ranked as the driest three consecutive years for statewide precipitation. New climate records were set in 2014 for statewide average temperatures and for record-low water allocations from State Water Project and Central Valley Project contractors. A statewide drought emergency was declared in January 2014. Minimum annual precipitation records were set for many communities in 2013. Executive orders and regulations called for water conservation and management. A new law requires retail urban water suppliers with more than 3,000 customers to establish rules defining" excessive water use" and impose those rules during drought emergencies.
Reported Local Drought Impacts
The National Drought Mitigation Center developed the Drought Impact Reporter as a national drought impact database for the United States. Information comes from a variety of sources: on-line, droughtrelated news stories and scientific publications, members of the public who visit the website and submit a drought-related impact for their region, members of the media, and members of relevant government agencies. The database is being populated beginning with the most recent impacts and working backward in time.
The Drought Impact Reporter contains information on 144 impacts from droughts that affected Santa Clara County from 2006 through September 2016. The following are the categories and reported number of impacts. Note that some impacts have been assigned to more than one category. • Agriculture - 28.
• Business and Industry-5.
• Energy-2.
• Fire-16.
• Plants and Wildlife-33.
• Relief, Response, and Restrictions-87.
• Society and Public Health-61.
• Tourism and Recreation-6.
• Water Supply and Quality-88.
The following are summaries of incidents from the Drought Impact Reporter that impacted Santa Clara County:
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• April 3, 2009 - A mandatory reduction in water use of 15 percent was ordered for the SCVWD because reservoirs contained only 64 percent of their capacity in March 2009. Residents responded by lowering their water use by 18 percent. Persistent drought spurred the board to extend the mandatory water restrictions through June 30, 2010. • January 30, 2014-The California Department of Fish and Wildlife closed some rivers and streams in Monterey, Santa Cruz and Santa Clara Counties to fishing to protect salmon and steelhead populations while river flows are low.
• March 21, 2014 - The SCVWD informed seven cities and companies that they would receive just 80 percent of their requested treated drinking water through the end of the year. Roughly
1.5 million people in San Jose, Mountain View, Sunnyvale, Cupertino, Milpitas and Santa Clara were affected. The San Jose Water Company responded by pumping more groundwater from its 100 or so wells throughout the county and strongly urged water conservation. • March 23, 2014 - The SCVWD reduced water releases from Anderson Dam from 14 cubicfeet per second (cfs) to 9 cfs, due to drought. With less water, Coyote Creek nearly dried up. • February 29, 2015-Groundwater withdrawals in the SCVWD during 2014 amounted to nearly 84,000 acre-feet, exceeding groundwater use in 2013. The SCVWD's 10 reservoirs hold only 68,000 acre-feet, about 81 percent of what was used in 2014. • May 5, 2015 - About 100 members of city councils, school boards and other local bodies came together at the Santa Clara Convention Center to discuss ways to encourage water conservation by all members of the public.
• August 8,2015- Eight miles of the 14-mile Guadalupe River in San Jose went dry for a few months, contributing to the absence or deaths of fish and other wildlife. Water releases from four upstream SCVWD reservoirs were halved because years of drought had slashed reservoir storage. Twelve of the about 30 primary miles of Coyote Creek were also dry. • August 8, 2015-0ne hundred tons of trash were removed from Los Gatos Creek and the Guadalupe River over a two-year period. Drought lowered water levels, making it easier to access and collect trash along the waterways.
• August 25, 2015 - A large microcystis bloom developed in the Sacramento-San Joaquin Delta.
Microcystis is a type of blue-green algae that can produce toxins that are lethal to fish and people in high concentrations, though such concentrations were not currently present. The algae bloom was observed in the central and north parts of the Delta. Scientists monitoring the bloom were unsure of its cause but suggested that it was produced through a combination of factors related to the warmer, slower water flow due to the drought. Roughly 25 million people from Napa to San Diego to some extent rely on fresh water from the Delta, as do about 3 million acres of irrigated farmland.
• July to November 2015-The SCVWD added $4.6 million to its landscape conversion rebate program. While the expanded budget of $22.8 million had been nearly spent for the year, the district was looking for additional funds to continue the rebates. The SCVWD paid rebates for the removal of 2.9 million square feet in 2015, with another 3.5 million square feet approved and in progress. The added $4.6 million will allow another 2 million square feet to be converted, totaling 8 million square feet.
• July 2016-Coyote Lake was closed on July 18 for the remainder of 2016 after the water level was drawn down below the bottom of the boat ramp. Water from the lake was being used for drinking water in Santa Clara County. The SCVWD would normally be using water from its primary source, the Sacramento-San Joaquin Delta, or the San Luis Reservoir, but both had higher than normal levels of algae, giving the water a taste and smell that customers did not 116 I Page
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appreciate. In late June, the water district turned to Coyote Lake and Anderson Lake. Drought was thought to be playing a role in the presence of algae in the Delta and the San Luis Reservoir.
• September 26, 2016-The Lorna wildfire burned a dozen homes, 16 other structures and near! y 4,500 acres northwest of Morgan Hill in Santa Clara County, according to the California Department of Forestry and Fire Protection.
U.S. Department of Agriculture Disaster Declarations
The U.s. Department of Agriculture (USDA) Farm Service Agency provides assistance for natural disaster losses resulting from drought, flood, fire, freeze, tornadoes, pest infestation, and other natural disasters. The USDA Secretary of Agriculture is authorized to designate counties as disaster areas to make emergency loans to producers suffering losses in those counties and in contiguous counties.
Between 2012 and 2016, the period for which data was available, California has been included in 61 USDA disaster declarations. Santa Clara County was included in 12 of these declarations in relation to drought:
• 53248, S3379 and 53452 in 2012.
• 53547, 53558 and S3569 in 2013.
• S3626, S3637, and 53743 in 2014.
• 53784 and 53943 in 2015.
• 53952 in 2016.
LOCATION
Drought is a regional phenomenon. A drought that affects the OA would affect all aspects of the environment and the community simultaneously and has the potential to directly or indirectly impact every person in the county as well as adversely affect the local economy.
FREQUENCY
Historical drought data regarding Santa Clara County indicate four significant droughts over the last 40 years, with drought occurring in 12 of those 40 years. Based on risk factors and this history, droughts likely will continue to occur in the Santa Clara County OA. Moreover, as temperatures increase, probability of future droughts will likely increase as well. Therefore, droughts likely will occur in 5anta Clara County at varied severities in the future, even after conclusion of the current drought.
SEVERITY
The severity of a drought depends on the degree of moisture deficiency, the duration, and the size and location of the affected area. The longer the duration of the drought and the larger the area impacted, the more severe the potential impacts. Drought can have a widespread impact on the environment and the economy, although it typically does not result in loss of life or damage to property, as do other natural disasters. Drought affects agriculture, business and industry, energy, fire, plants, tourism and recreation, and water supply and quality. The National Drought Mitigation Center uses three categories to describe drought impacts:
• Economic Impacts-These impacts of drought cost people or businesses money. They include farmers' loss of crops, costs for irrigation or drilling new wells to address low water supply, lost business for companies that sell boats or fishing equipment, and water companies' costs for additional water supplies.
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• Environmental Impacts - Plants and animals depend on water. When a drought occurs, their food supply can shrink and their habitat can be damaged. • Social Impacts-Social impacts include public safety, health, conflicts between people when there is not enough water to go around, and changes in lifestyle.
Drought generally does not affect groundwater sources as quickly as surface water supplies, but groundwater supplies generally take longer to recover. Reduced precipitation during a drought means that groundwater supplies are not replenished at a normal rate. This can lead to a reduction in groundwater levels and problems such as reduced pumping capacity or wells going dry. Shallow wells are more susceptible than deep wells. Reduced replenishment of groundwater affects streams. Much of the flow in streams comes from groundwater, especially during the summer when there is less precipitation and after snowmelt ends. Reduced groundwater levels mean that even less water will enter streams when steam flows are lowest.
WARNING TIME
Empirical studies conducted over the past century have shown that meteorological drought is never the result of a single cause. It is the result of many causes, often synergistic in nature; these include global weather patterns that produce persistent, upper-level high-pressure systems along the West Coast with warm, dry air resulting in less precipitation.
Scientists at this time do not know how to predict drought more than a month in advance for most locations. Predicting drought depends on the ability to forecast precipitation and temperature.
Anomalies of precipitation and temperature may last from several months to several decades; California is currently finishing a several-year-long drought, while other areas in the United States may undergo droughts as short as 1 or 2 months. How long droughts last depends on interactions between the atmosphere and the oceans, soil moisture and land surface processes, topography, internal dynamics, and the accumulated influence of weather systems on the global scale.
SECONDARY HAZARDS
The secondary hazard most commonly associated with drought is wildfire. A prolonged lack of precipitation dries out vegetation, which becomes increasingly susceptible to ignition as the duration of the drought extends. Millions of board feet of timber have been lost, and in many cases erosion occurred, which caused serious damage to aquatic life, irrigation, and power production by heavy silting of streams, reservoirs, and rivers.
Drought also is often accompanied by extreme heat, exposing people to the risk of sunstroke, heat cramps and heat exhaustion. Pets and livestock are also vulnerable to heat-related injuries. Crops can be vulnerable as well.
Environmental losses include damage to plants, animals, wildlife habitat, and air and water quality; forest and range fires; degradation of landscape quality; loss of biodiversity; and soil erosion. Some effects are short-term and conditions quickly return to normal following the end of the drought. Other effects linger for some time or may even become permanent. Wildlife habitat, for example, may be degraded through the loss of wetlands, lakes, and vegetation. However, many species will eventually recover from this temporary aberration. The degradation of landscape quality, including increased soil erosion, may lead to a more permanent loss of biological productivity. Although environmental losses are difficult to quantify, growing public awareness and concern for environmental quality has forced public officials to focus greater attention and resources on these effects. 118 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17
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Tree mortality is a key secondary impact of drought. Drought can affect a tree's ability to generate pitch, which it uses to defend itself against infestation by insects such as the bark beetle. Prolonged periods of drought, such as the one just experienced by the State of California, can cause extensive damage to trees.
Since May 2016, the U.s. Forest Service has identified 36 million new dead trees, bringing the total estimate of dead trees in California to 62 million (Tree Mortality Task Force, 2017). Removal of dead trees can be costly and challenging, which can add to the financial impacts of drought. These impacts are not instantaneous, and sometimes are not felt by communities for many years following a drought.
Figure 7-9 shows the extent and location of tree mortality within the planning based on studies by California's Tree Mortality Task Force.
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utll' 140 ""'" flRe': c.oo ....... tGh IUoduIGrNL Drot"OIro:.5ur.a~ Significant depletion of groundwater supplies-from drought, excessive groundwater pumping or both-can lead to subsidence, which is the downward collapse of the land surface when groundwater aquifers lack the water to support the weight of the ground. Compaction of aquifer systems is the greatest cause of subsidence in California. Although this is typically due to groundwater pumping rather than drought, drought creates a need for greater groundwater pumping as freshwater sources disappear.
Drought-induced subsidence is not as common as wildfire or extreme heat, but it can significantly impact the local environment, floodplain/wetlands and water supply, and it typically is irreversible. It may cause wetlands to change size and shape, migrate to lower elevations, or disappear entirely. Rivers may change course, and patterns of erosion and deposition may change (CA Water Science Center, 2016). The 10/15/17 Santa Clara County Operational Area Mitigation Plan Page 1119
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SCVWD has conducted aquifer recharge efforts for years trying to recover groundwater levels and halt subsidence issues (USGS, 2017).
EXPOSURE
Drought can affect a wide range of economic, environmental, and social activities. Its impacts can span many sectors of the economy because water is integral to the ability to produce goods and provide services. The impacts can reach well beyond the area undergoing physical drought. Vulnerability of an activity to drought depends on its water demand and the water supplies available to meet the demand.
California's 2005 Water Plan and subsequent updates indicate that water demand in the state will increase through 2030. The Department of Water Resources predicts a modest decrease in agricultural water use, but an urban water use increase of 1.5 to 5.8 million acre-feet per year (DWR, 2005). The 2013 update to the Water Plan explores measures, benchmarks, and successes in increasing agricultural and urban water use efficiency.
VULNERABILITY
POPULATION
The entire population of the Santa Clara County OA is vulnerable to drought. Drought can affect people's health and safety, including health problems related to low water flows, poor water quality, or dust.
Droughts can also lead to loss of human life (National Drought Mitigation Center, 2016). Other possible impacts include recreational risks; effects on air quality; diminished living conditions related to energy, air quality, and hygiene; compromised food and nutrition; and increased incidence of illness and disease (Centers for Disease Control and Prevention, 2012). Droughts can also lead to reduced local firefighting capabilities.
The SCVWD, BAWSCA, regional water purveyors, and other regional stakeholders have devoted considerable time and effort to protect life, safety, and health during times of consecutive dry years, such as the current drought. Provisions and measures have been taken to analyze and account for anticipated water shortages. With coordination from its cities, the SCVWD has the ability to minimize and reduce impacts on residents and water consumers in the Santa Clara County OA.
PROPERTY
No structures will be directly affected by drought conditions, though some structures may become vulnerable to wildfires, which are more likely following years of drought. Droughts can also have significant impacts on landscapes, which could cause a financial burden to property owners. However, these impacts are not considered critical in planning for impacts from the drought hazard.
CRITICAL FACILITIES
Critical facilities as defined for this plan will continue to be operational during a drought. Critical facility elements such as landscaping may not be maintained due to limited resources, but the risk to the OA's critical facilities inventory will be largely aesthetic. For example, when water conservation measures are in place, landscaped areas will not be watered and may die. These aesthetic impacts are not considered significant.
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ENVIRONMENT
Environmental losses from drought are associated with damage to plants, animals, wildlife habitat, and air and water quality; forest and range fires; degradation of landscape quality; loss of biodiversity; and soil erosion. Some of the effects are short-term and conditions quickly return to normal following the end of the drought. Other environmental effects linger for some time or may even become permanent.
Wildlife habitat, for example, may be degraded through the loss of wetlands, lakes and veg tation.
However, many species will eventually recover from this temporary aberration. The degradation of landscape quality, including increased soil erosion, may lead to a more permanent loss of biological productivity. Although environmental losses are difficult to quantify, growing public awareness and concern for environmental quality has forced public officials to focus greater attention and resources on these effects.
ECONOMIC IMPACT
Drought causes the most significant economic impacts on industries that use water or depend on water for their business, most notably, agriculture and related sectors (forestry, fisheries, and waterborne activities). In addition to losses in yields in crop and livestock production, drought is associated with increased insect infestations, plant diseases, and wind erosion. Drought can lead to other losses because so many sectors are affected-losses that include reduced income for farmers and red uced business for retailers and others who provide goods and services to farmers. This leads to unemployment, increased credit risk for financial institutions, capital shortfalls, and loss of-tax revenue. Prices for food, energy, and other products may also increase as supplies decrease.
When a drought occurs, the agricultural industry faces greatest risk of economic impact and damage.
During droughts, crops do not mature, resulting in smaller crop yields, undernourishment of wildlife and livestock, decreases in land values, and ultimately financial losses to farmers (FEMA, 1997).
Agriculture production has been a significant and growing factor in Santa Clara County, especially as agricultural effects on the economy start to normalize (after a period of decline).
Evaluation of direct effects (i.e., excluding indirect and induced spending benefits) can occur based on information conveyed in USDA reports. According to the 2012 Census of Agriculture, 1,003 farms were present in Santa Clara County, encompassing 229,927 acres of total farmland, including 38,398 acres of cropland and 165,547 acres of pastureland. The average farm size was 229 acres.
Santa Clara County farms had a total market value of products sold of $243.8 million ($233.4 million in vegetable crops including nursery and greenhouse; and $10.4 million in cattle, layers, and horses, and related pl'oducts), averaging $243,100 per farm. The Census indicated that 562 farm operators reported farming as their primary occupation (USDA, 2012).
A prolonged drought can affect a commwlity's economy significantly. Increased demand for water and electricity may result in shortages and higher costs of these resources. Industries that rely on water for business may be impacted the most (e.g., landscaping businesses). Although most businesses wiU still be operationaJ, tl1ey may be affected aesthetically -especially the recreation and tourism industry.
Moreover, dJ'oughts within anoth.er area could affect food supply/price of food for residents within the Santa Clara County OA.
FUTURE TRENDS IN DEVELOPMENT
Land use planning is also directed by general plans adopted under California's General Planning Law.
Municipal planning partners are encouraged to establish General Plans with policies directing land use and dealing with issues of water supply and protection of water resources. These plans increase 10/15/17 Santa Clara County Operational Area Mitigation Plan Page 1121
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capability at the local municipal level to protect future development from impacts of drought. All planning partners reviewed their general plans under the capability assessments undertaken for this effort. Deficiencies revealed by these reviews can be identified as mitigation actions to increase capability to deal with future trends in development.
SCENARIO
Continuation or exacerbation of the current situation across the State of California (i.e., an extreme, multiyear drought associated with record-breaking rates of low precipitation and high temperatures) is the worst-case scenario for Santa Clara County. Low precipitation and high temperatures increase possibility of wildfires throughout the County, increasing need for water when water is already in limited supply. Surrounding counties, also under drought conditions, could increase their demand for the water supplies on which Santa Clara County also relies, triggering social and political conflicts. The higher density population of the Bay Area increases likelihood of such conflicts. Additionally, the longer drought conditions last in or near the OA, the greater the effect on the local economy; water-dependent industries especially will undergo setbacks.
ISSUES
The Core Planning Group has identified the following drought-related issues:
• Identification and development of alternative water supplies. • Utilization of groundwater recharge techniques to stabilize the groundwater supply. • The probability of increased drought frequencies and durations due to climate change. • The promotion of active water conservation even during non-drought periods. • Monitoring of implementation and benefits of the Long-Term Reliable Water Supply Strategy projects, Water Conservation Implementation Plan projects, and water system capital improvement upgrades.
• Application of alternative techniques (groundwater recharge, water recycle, local capture and reuse, desalination, and transfer) to stabilize and offset Sierra Nevada snowpack water supply shortfalls.
• Regular occurrence of drought or multiyear droughts that may limit the Operationa l Area's ability to successfully recover from or prepare for more occurrences-particularly noteworthy due to longevity of the current ongoing drought.
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EARTHQUAKE
GENERAL BACKGROUND
An earthquake is the vibration of the earth's surface following a release of energy in the earth's crust.
This energy can be generated by a sudden dislocation of the crust or by a volcanic eruption. Most destructive quakes are caused by dislocations of the crust. The crust may first bend and then, when the stress exceeds the strength of the rocks, break and snap to a new position. In the process of breaking, vibrations called "seismic waves" are generated. These waves travel outward from the source of the earthquake at varying speeds.
Geologists have found that earthquakes tend to reoccur
along faults, which are zones of weakness in the earth's crust. Even if a fault zone has recently experienced an earthquake, there is no guarantee that all the stress has been relieved. Another earthquake could still occur.
Aftershocks are common after a large earthquake. In
fact, relieving stress can increase stress in other parts of the affected fault and other faults.
California is seismically active because of movement of the North American Plate, east of the San Andreas Fault, and the Pacific Plate to the west, which includes the
state's coastal communities. Movement of the tectonic
plates against one another creates stress, which is
released as energy that moves through the earth as
seismic waves.
DEFINITIONS
Earthquake-The shaking of the ground caused by
an abrupt shift of rock along a fracture in the earth
or a contact zone between tectonic plates.
Epicenter-The point on the earth's surface directly
above the hypocenter of an earthquake. The
location of an earthquake is commonly described by
the geographic position of its epicenter and by its
focal depth.
Fault-A fracture in the earth's crust along which
two blocks of the crust have slipped with respect to
each other.
Hypocenter-The region underground where an
earthql;la~ '5 energy originates
Liquefaction-Loosely packed, water-logged
ilTrlents losing their strength in response to strong
shakln§. causing major damage during
earthquakes.
Active faults have experienced displacement in historical time. However, inactive faults, where no such displacements have been recorded, also have the potential to reactivate or experience displacement along a branch sometime in the future. An example of a fault zone that has been reactivated is the Foothills Fault Zone. The zone was considered inactive until evidence of an earthquake (approximately 1.6 million years ago) was found near Spenceville, California. Then, in 1975, an earthquake occurred on another branch of the zone near Oroville, California (now known as the Cleveland Hills Fault). The State Division of Mines and Geology indicates that increased earthquake activity throughout California may cause tectonic movement along currently inactive fault systems.
DAMAGE FROM EARTHQUAKES
A direct relationship exists between a fault's length and location and its ability to generate damaging ground motion at a given site. Small, local faults produce lower magnitude quakes, but ground shaking can be strong and damage can be significant in areas close to the fault. In contrast, large regional faults can generate earthquakes of great magnitudes but, because of their distance and depth, they may result in only moderate shaking in an area.
Earthquakes can last from a few seconds to over five minutes; they may also occur as a series of tremors over a period of several days. The actual movement of the ground in an earthquake is seldom the direct cause of injury or death. Casualties generally result from falling objects and debris, because earthquakes shake, damage or demolish furnishings and buildings and other structures. Disruption of 10/15/17 Santa Clara County Operational Area Mitigation Plan Page 1123
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communications and internet, electrical power, gas, sewer and water services should be expected in the affected area. Earthquakes may trigger dam failures and landslides. Their damage may cause fires and releases of hazardous material, compounding the disastrous effects.
EARTHQUAKE CLASSIFICATIONS
Earthquakes are typically classified in one of two ways: by the amount of energy released, measured as magnitude; or by the impact on people and structures, measured as intensity.
Magnitude
An earthquake's magnitude is a measure of the energy released at the source of the earthquake. It is commonly expressed by ratings on either of two scales (Michigan Tech University, 2016):
• The Richter scale measures magnitude of earthquakes based on the amplitude of the largest energy wave released by the earthquake. Richter scale readings are suitable for smaller earthquakes; however, because it is a logarithmic scale, the scale does not distinguish clearly the magnitude of large earthquakes above a certain level. Richter scale magnitudes and corresponding earthquake effects are as follows:
.:. 2.5 or less- Usually not felt, but can be recorded by seismograph . • :. 2.5 to 5.4-0ften felt, but causes only minor damage . • :. 5.5 to 6.0-Slight damage to buildings and other structures . • :. 6.1 to 6.9-May cause a lot of damage in very populated areas . • :. 7.0 to 7.9-Major earthquake; serious damage .
• :. 8.0 or greater-Great earthquake; can totally destroy communities near the epicenter. • A more commonly used magnitude scale today is the moment magnitude (Mw) scale. The moment magnitude scale is based on the total moment release of the earthquake (the product of the distance a fault moved and the force required to move it). Moment magnitude roughly matches the Richter scale but provides more accuracy for larger magnitude earthquakes. The scale is as follows:
.:. Great-Mw ~ 8 .
• :. Major-Mw == 7.0 -7.9 .
• :. Strong-Mw = 6.0 - 6.9 .
• :. Moderate-Mw = 5.0 - 5.9 .
• :. Light-Mw = 4.0 - 4.9 .
• :. Minor-Mw == 3.0 - 3.9 .
• :. Micro-Mw < 3.
Intensity
For an earthquake, intensity varies across the area. Intensity will be larger near the fault rupture, in the direction of the rupture, and in sedimentary basins. Currently the most commonly used intensity scale is the modified Mercalli intensity scale, with ratings defined as follows (USGS, 1989):
• I - Not felt except by a very few under especially favorable conditions. • II - Felt only by a few persons at rest, especially on upper floors of buildings. 124 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17
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• III - Felt quite noticeably by persons indoors, especially on upper floors of buildings. Many people do not recognize it is an earthquake. Standing cars may rock slightly. Vibrations similar to the passing of a truck. Duration estimated.
• IV - Felt indoors by many, outdoors by few during the day. At night, some awakened.
Dishes, windows, doors disturbed; walls make cracking sound. Sensation like a heavy truck striking building. Standing cars rocked noticeably.
• V - Felt by nearly everyone; many awakened. Some dishes, windows broken. Unstable objects overturned. Pendulum clocks may stop.
• VI - Felt by all; many frightened. Some heavy furniture moved; a few instances of fallen plaster. Damage slight.
• VII - Damage negligible in buildings of good design and construction; slight in well-built ordinary structures; considerable in poorly built or badly designed structures. Some chimneys broken.
• VIII - Damage slight in specially designed structures; considerable damage in ordinary buildings with partial collapse. Damage great in poorly built structures. Fall of chimneys, factory stacks, columns, monuments, walls. Heavy furniture overturned. • IX - Damage considerable in specially designed structures; well-designed frame structures thrown out of plumb. Damage great in substantial buildings, with partial collapse.
Buildings shifted off foundations.
• X - Some well-built wooden structures destroyed; most masonry and frame structures destroyed with foundations. Rails bent.
GROUND MOTION
Earthquake hazard assessment is also based on expected ground motions. During an earthquake when the ground is shaking, it experiences acceleration. The peak ground acceleration (PGA) is the largest increase in velocity recorded by a particular station during an earthquake. PGA indicates the severity of an earthquake and is a measure of how hard the earth shakes, or accelerates, in a given geographic area.
It is measured in g (the acceleration due to gravity), expressed as a percentage of that acceleration (%g).
Horizontal and vertical PGA varies with soil or rock type. Instruments called accelerographs record levels of ground motion due to earthquakes at stations throughout a region. These readings are recorded by state and federal agencies that monitor and predict seismic activity. Earthquake hazard assessment involves estimating the annual probability that certain ground motion accelerations will be exceeded, and then summing the annual probabilities over the time period of interest.
National maps of earthquake shaking hazards, which have been produced since 1948, provide information for creating and updating seismic design requirements for building codes, insurance rate structures, earthquake loss studies, retrofit priorities and land use planning. After thorough review of the studies, professional organizations of engineers update the seismic-risk maps and seismic design requirements contained in building codes (Brown et a1., 2001). The USGS updated the National Seismic Hazard Maps in 2014. New seismic, geologic, and geodetic information on earthquake rates and associated ground shaking were incorporated into these revised maps. The 2014 map, shown in Figure 8-1, represents the best available data as determined by the USGS.
Building codes that include seismic provisions specify the horizontal force due to lateral acceleration that a building should be able to withstand during an earthquake. Buildings, bridges, highways and utilities built to meet modern seismic design requirements are typically able to withstand earthquakes better, with less damage and disruption. PGA values are directly related to these lateral forces that could damage "short period structures" (e.g. single-family dwellings). Longer-period response components 10/15/17 Santa Clara County Operational Area Mitigation Plan Page 1125
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determine the lateral forces that damage taller structures with longer natural periods (apartment buildings, factories, high-rises, bridges). Table 8-1 lists damage potential and perceived shaking by PGA factors, compared to the Mercalli scale.
Source: USGS, 2014
110
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Note: The black circle indicates the approximate vicinity of Santa Clara County FIGURE 8-1. PEAK ACCELERATION (%G) WITH 10% PROBABILITY OF EXCEEDANCE IN 50 YEARS TABLE 8-1. MERCALLI ScALE AND PEAK GROUND ACCELERATION COMPARISON Modified Potential Structure Damage I Estimated PGAB
Mercalll Scale Perceived Shakin ReSistant BUlldin s Vulnerable BUlidm s %) I Not Felt None None <0.17%
II-III Weak 'None None 0.17%- 1.4%
IV Light : None iNone 1.4%- 3.9%
V Moderate ! Very Light Light 3.9%- 9.2%
VI Strong • Light Moderate 9.2%-18%
VII Very Strong • Moderate Moderate/Heavy 18% - 34%
VIII Severe Moderate/Heavy Heavy 34% -65%
IX Violent !Heavy Very Heavy 65%- 124%
X-XII Extreme IVery Heavy Very Heavy >124%
a. PGA measured in percent of g, where g is the acceleration of gravity 126 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17
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Sources: USGS, 2008; USGS, 2010
EFFECT OF SOIL TYPES
The impact of an earthquake on structures and infrastructure is largely a function of ground shaking, distance from the source of the quake, and liquefaction, a secondary effect of an earthquake in which soils lose their shear strength and flow or behave as liquid, thereby damaging structures that derive their support from the soil. Liquefaction generally occurs in soft, unconsolidated sedimentary soils and shallow water table.
A program called the National Earthquake Hazard Reduction Program (NEHRP) creates maps based on soil characteristics to help identify locations subject to liquefaction. Table 8-2 summarizes NEHRP soil classifications. NEHRP Soils Band C typically can sustain ground shaking without much effect, dependent on the earthquake magnitude. The areas that are commonly most affected by ground shaking have NEHRP Soils D, E and F. In general, these areas are also most susceptible to liquefaction.
TABLE 8-2. NEHRP SOIL CLASSIFICA nON SYSTEM
NEHRP lOt Mean Shear VelOCity to
SOil T e escnp Ion 30 m m/s
A
B
C
D
E
Hard Rock
Firm to Hard Rock
Dense Soil/Soft Rock
Stiff Soil
Soft Clays
F Special Study Soils (Iiguefiable soils, sensitive clays, organic soils, soft clays >36 m thick) 1,500
760-1,500
360-760
180-360
< 180
The USGS has created a soil type map for the San Francisco Bay area that provides rough estimates of site effects based on surface geology. NEHRP soil types were assigned to a geologic unit based on the average velocity of that unit, and the USGS notes that this approach can lead to some inaccuracy. For instance, a widespread unit consisting of Quaternary sand, gravel, silt, and mud has been aSSigned as Class C soil types; however, some of the slower soil types in this unit fall under Class D. USGS does not have any way of differentiating units for slower-velocity soils in its digital geologic dataset (USGS, 2016e).
HAZARD PROFILE
The Bay region is located within the active boundary between the Pacific and the North American tectonic plates. The western edge of the Santa Clara County OA is on the Pacific Plate, which is constantly moving northwest past the North American Plate at a rate of about 2 inches per year (CaIOES, 2013).
Earthquakes in the San Francisco Bay region result from strain energy constantly accumulating across the region because of the motion of the Pacific Plate relative to the North American Plate. The San Andreas Fault, on which earthquakes of magnitude 7.8 and 7.9 have occurred in historical time, including the 1906 San Francisco earthquake, is the fastest slipping fault along the plate boundary.
PAST EVENTS
The last major earthquake with an epicenter in the Santa Clara County OA was the 1984 Morgan Hill Earthquake (Magnitude 6.2). The epicenter of the 1989 Lorna Prieta Earthquake (Magnitude 7.1) was just a few miles outside the OA. Since then, there have been no significant seismic events in Santa Clara County (ABAG, 2016). Other significant earthquakes in California include the 1906 earthquake in San 10/15/17 Santa Clara County Operational Area Mitigation Plan Page 1127
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Francisco, the 1971 San Fernando Earthquake, the 1994 Northridge earthquake, and the 2014 Napa earthquake.
The Morgan Hill Earthquake of April 24, 1984, was a moderate size earthquake on the Calaveras Fault.
It caused moderate damage that extended southward from the epicenter. In the Santa Clara County OA, where most of the damage occurred, more than 550 structures experienced minor damage. Major structural damage was mainly confined to a small area on two streets in the Jackson Oaks subdivision east of Morgan Hill. There were numerous reports of fires resulting from the earthquake. Minor damage was also reported in San Martin and Coyote. Twenty seven people were injured (ABAG, 2010). This event led to a FEMA major disaster declaration (DR-845).
The Lorna Prieta Earthquake on October 17, 1989, occurred near Lorna Prieta in the Santa Cruz Mountains along the San Andreas Fault. Thousands of landslides across the area blocked roads and highways, impacting rescue efforts and damaging structures. In Santa Clara County, collapsed and damaged buildings were reported in Gilroy, Los Gatos, and San Jose (Santa Clara HMP, 2011).
California has been included in 12 FEMA major disaster (DR) or emergency (EM) declarations for earthquakes. Santa Clara County was included in only one declaration: DR-845 for the Lorna Prieta Earthquake, which occurred in 1989. The declaration for this event covered Alameda, Contra Costa, Marin, Monterey, Sacramento, San Benito, San Francisco, San Joaquin, San Mateo, Santa Clara, Santa Cruz, and Solano Counties. Figure 8-2 and Table 8-3 summarize recent earthquakes of magnitude of 5.0 or greater within a 100-mile radius of the OA.
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M 5.4 - Northern California
8/8/1989
M 7 2 - Northern California
10/18/1989
FIGURE 8-2. RECENT EARTHQUAKES WITHIN 100-MILE RADIUS OF THE OA Source:
M 5 4 - Central California
1/26/1986
M 5.2 - Central California
8/12/1998
TABLE 8-3. RECENT EARTHQUAKES MAGNITUDE 5.0 OR LARGER WITHIN 100-MILE RADIUS OF THE OA Date Magnitude Epicenter Location
8/24/2014 6.0 South Napa Earthquake
10/21/2012 5.3 28 km east-northeast of King City, CA
10/31/2007 5.6 San Jose, California
5/14/2002 5 Northern California
9/3/2000 5 Northern California
8/12/1998 5.2 Central California
4/18/1990 5.4 Northern California
10/18/1989 7.2 Northern California
8/8/1989 5.2 Central California
6/27/1989 5.3 : Northern California
6/13/1988 5.3 San Francisco Bay area, California
2/20/1988 5.1 Central California
3/31/1986 5.6 Northern California
1/26/1986 5.4 Central California
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LOCATION
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Santa Clara County is exposed to major regional faults: Hayward, Calaveras, and San Andreas. The Hayward and Calaveras faults are in the central portion of Santa Clara County and present the greatest earthquake threat to the OA. The San Andreas Fault is on the northwestern boundary of the OA and runs through hills separating Santa Clara County from Santa Cruz County. The primary seismic hazard for the OA is potential ground shaking from these three large faults (ABAG, 2016). The Greenville fault in the northeastern portion of the county presents less risk than these three major faults. Figure 8- provides location and probability of area fault lines. Specific probabilities associated with the three major faults are described in the following sections.
Hayward Fault
The Hayward Fault runs parallel to and east of the San Andreas Fault. It extends from San Jose about 74 miles northward along the base of the East Bay Hills to San Pablo Bay. The Hayward Fault extends through some of the Bay Area's most populated areas. Communities on or near the fault include San Jose, Oakland, Fremont, Richmond, Berkeley, Hayward, San Leandro, San Lorenzo, El Cerrito, Emeryville, Kensington and Milpitas. Among other sites, the fault runs directly under the now-abandoned old city hall in downtown Hayward, the University of California-Berkeley football stadium, the Mira Vista Golf Course near Berkeley, Lake Temescal, Contra Costa College, and Port Pinole Shoreline Regional Park.
The Hayward Fault is a right-lateral slip fault.
The Hayward Fault is becoming a hazard priority throughout the Bay Area because of its increased chance for activity and its intersection with multiple highly populated areas and critical infrastructure.
The probability of experiencing a Magnitude 6.7 or greater earthquake along the Hayward Fault in the next 30 years is 33 percent. An earthquake of this magnitude has regional implications for the entire Bay Area, as the Hayward Fault crosses transportation and resource infrastructure, such as multiple highways and the Hetch-Hetchy Aqueduct. Disruption of the Hetch-Hetchy system has the potential to severely impair water service to the Santa Clara County OA.
An important difference between the Hayward and San Andreas faults is 1/ aseismic creep." The San Andreas Fault is locked in many places; much of its energy is released in the form of earthquakes.
However, creep occurs in spots alcmg the Hayward Fault. The ground moves a few millimeters each year, pulling apart sidewalks, pipelines and other structures that sit astride the fault. At Memorial Stadium at the University of California Berkeley, which was built in 1923, creep has caused the two sides of the stadium to be offset more than a foot, requiring retrofitting with expansion joints. Creep accounts for a small part of the total motion that takes place on a fault over geologic time; earthquakes account for the rest. (California Department of Conservation, 2017).
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FIGURE 8-3. SIGNIFICANT KNOWN FAULTS IN THE BAY AREA
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10/15/17 Santa Clara County Operational Area Mitigation Plan Page /131 Calaveras Fault
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The Calaveras Fault is a major branch of the San Andreas Fault, located to the east of the Hayward Fault.
It extends 76 miles from the San Andreas Fault near Hollister to Danville at its northern end. The Calaveras Fault is one of the most geologically active and complex faults in the Bay Area (USGS, 2003).
The probability of experiencing a Magnitude 6.7 or greater earthquake along the Calaveras Fault in the next 30 years is 26 percent.
San Andreas Fault
The San Andreas Fault extends 810 miles from the East Pacific rise in the Gulf of California through the Mendocino fracture zone off the shore of northern California. The fault is estimated to be 28 million years old. The San Andreas Fault is an example of a transform boundary exposed on a continent. It forms the tectonic boundary between the Pacific Plate and the North American Plate, and its motion is right-lateral strike-slip.
The San Andreas Fault is typically referenced in three segments. The southern segment extends from its origin at the East Pacific Rise to Parkfield, California, in Monterey County. The central segment extends from Parkfield to Hollister, California. The northern segment extends northwest from Hollister, through Santa Clara County, to its ultimate junction with the Mendocino fracture zone and the Cascadia subduction zone in the Pacific Ocean. The probability of experiencing a Magnitude 6.7 or greater earthquake along the San Andreas Fault within the next 30 years is 22 percent.
Maps of Earthquake Impact on the OA
The impact of an earthquake is largely a function of the following components:
• Surface fault rupture
• Ground shaking (ground motion accelerations)
• Liquefaction (soil instability).
Impacts vary with distance from the source (both horizontally and vertically). Mapping that shows the impacts of these components was used to assess the risk of earthquakes within the OA, as described in the sections below.
PROBABILISTIC SEISMIC HAZARD MAP
A probabilistic seismic hazard map shows the hazard from earthquakes that geologists and seismologists agree could occur. The maps are expressed in terms of probability of exceeding a certain ground motion, such as the 10-percent probability of exceedance in 50 years. This level of ground shaking has been used for designing buildings in high seismic areas.
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/
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10/15/17
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Santa Clara County Operational Area Mitigation Plan
Figure 8-4.
100-Year Probabalistic
Earthquake Scenario Peak
Ground Acceleration
CJ SonlO Clam County Boundory
o Counly Boundnries
Waler Bodies & ChannelS
Modified Mercalli Scale,
Potential Shaking
I (NoIFell)
11 ·111 (Weok)
IV (Lighl,
V (Moderale)
VI (Slrong)
I VII (Very Sirong)
VIII (Severe)
l IX (V101l1Ot)
x .. (Extreme)
~nue of Model Resulls
IlIstd Plltnnlng Areu
~TETRATECH
Map Data Sourets: Santa Clara County,
CarTrans, USDA. Hazus·MH 3.1