HomeMy WebLinkAboutMINUTES - 06282011 - SD.7RECOMMENDATION(S):
1) ACCEPT a report on the proposed Contra Costa County Hazard Mitigation Plan Update,
and a related report on a proposed General Plan Amendment to the Safety Element, Contra
Costa County General Plan (2005-2020) involving a minor text amendment adding
reference to the adopted Hazard Mitigation Plan.
2) OPEN the public hearing on the proposed update to Contra Costa County’s Hazard
Mitigation Plan and the related General Plan Amendment (County File: GP#08-0006)
adding reference to the Hazard Mitigation Plan in the Safety Element.
3) CLOSE the public hearing.
4) ADOPT Resolution No. 2011/277, as follows:
a. Contra Costa County Hazard Mitigation Plan Update: APPROVE the Initial
Study/Negative Declaration prepared for the update of the Hazard Mitigation Plan;
APPROVE the Contra Costa County Hazard Mitigation Plan (CCHMP) Update as
recommended by the Office of Emergency Services and Public Works Department;
APPROVE OTHER
RECOMMENDATION OF CNTY ADMINISTRATOR RECOMMENDATION OF BOARD COMMITTEE
Action of Board On: 06/28/2011 APPROVED AS RECOMMENDED OTHER
Clerks Notes:
VOTE OF SUPERVISORS
AYE:John Gioia, District I Supervisor
Gayle B. Uilkema, District II
Supervisor
Mary N. Piepho, District III
Supervisor
Karen Mitchoff, District IV
Supervisor
Federal D. Glover, District V
Supervisor
Contact: Patrick Roche,
925-335-1242
I hereby certify that this is a true and correct copy of an action taken and entered on the minutes of the Board
of Supervisors on the date shown.
ATTESTED: June 28, 2011
David Twa, County Administrator and Clerk of the Board of Supervisors
By: June McHuen, Deputy
cc:
SD. 7
To:Board of Supervisors
From:Catherine Kutsuris, Conservation & Development Director
Date:June 28, 2011
Contra
Costa
County
Subject:Contra Costa County Hazard Mitigation Plan Update and Safety Element GPA
DIRECT the Office of Emergency Services staff to submit the updated Hazard Mitigation
Plan to the Federal Emergency Management Agency (FEMA) and the California Emegency
Management Agency;
RECOMMENDATION(S): (CONT'D)
and, DIRECT the Public Works Department to post the Notice of Determination for this
project with the County Clerk.
b. General Plan Amendment (County File: GP#08-0006): ADOPT finding that the
General Plan Amendment is exempt from CEQA under CEQA Guidelines, Section
15061 (b) (3); ADOPT the minor text amendment to the Safety Element, Contra Costa
County General Plan (2005-2020), as recommended in County Planning Commission
Resolution No. 12-2011, which adds reference to the adopted Hazard Mitigation Plan to
assure compliance with Assembly Bill 2140 and maintain the County’s eligibility to
qualify for state disaster assistance funding, as the 3rd consolidated General Plan
Amendment for calendar year 2011 to the Contra Costa County General Plan
(2005-2020) as permitted by State law; and, DIRECT the Department of Conservation &
Development to post the Notice of Determination for this project with the County Clerk.
FISCAL IMPACT:
Approval of the County’s Hazard Mitigation Plan does not impose any requirement on
the County, which would result in a fiscal impact. On the other hand, failure to adopt the
updated Hazard Mitigation Plan may preclude the County from obtaining FEMA Disaster
Mitigation funds or Disaster Recovery funds in the future, and failure to adopt the
General Plan Amendment to add reference to the Safety Element of the adopted Hazard
Mitigation Plan may disqualify the County from receiving certain disaster assistance
funding.
BACKGROUND:
The Federal Disaster Act of 2000 requires local governments to adopt a comprehensive
Hazard Mitigation Plan (HMP) to receive federal funding after a disaster. By law, a
Hazard Mitigation Plan must describe the type, location, and extent of all natural hazards
that can affect a jurisdiction; describe the jurisdiction’s vulnerability to these hazards;
include a mitigation strategy that provides the jurisdiction’s blueprint for reducing the
potential loses; and, contain a plan maintenance process. The Disaster Mitigation Act of
2000 strongly encourages state and local authorities to work together on pre-disaster
planning, and it promotes “sustainable hazard mitigation”, which includes sound
management of natural resources, local economic and social resiliency, and the
recognition that hazards and mitigation must be understood in the largest possible social
and economic context. The Disaster Mitigation Act of 2000 called for an enhanced
planning network to help local governments accurately assess mitigation needs to enable
a faster allocation of funding for disaster assistance and cost effective risk reduction
projects.
Additionally, at the state level a new law, more commonly known as Assembly Bill (AB)
2140, which became effective on January 1, 2007, places limits on the amount of
additional state funding to local jurisdictions for certain disaster recovery projects funded
by the California Disaster Assistance Act (CDAA). Under AB 2140, unless the local
jurisdiction has an approved Hazard Mitigation Plan and has incorporated that Hazard
Mitigation Plan into the jurisdiction’s General Plan Safety Element, it might not be
eligible to obtain additional funding from the state for certain disaster recovery projects.
Though compliance with AB 2140 is optional, noncompliance limits the County’s ability
to obtain additional disaster assistance recovery funding from the state.
Hazard Mitigation Plan (HMP) Update
Contra Costa County has an adopted local hazard mitigation plan that was the result of
participating in the Association of Bay Area Governments (ABAG) nine-county regional
multi-jurisdictional hazard mitigation planning process initiated in 2005. The County’s
local hazard mitigation plan, which is an annex to the ABAG regional hazard mitigation
plan, was adopted on April 17, 2007 by the Board of Supervisors under Board Resolution
No.2007/13.
The Federal Disaster Mitigation Act of 2000 establishes requirements for local agencies
to maintain current local hazard mitigation plans by updating them every five years.
Seeing the 5-year update as an opportunity to revise and create a hazard mitigation plan
that is more focused on Contra Costa County, rather than the nine-county region, County
staff from the Flood Control Division, Department of Public Works and Office of
Emergency Services secured a FEMA planning grant to prepare a comprehensive and
integrated multi-jurisdictional hazard mitigation plan focused solely on Contra Costa
County.
Once the FEMA planning grant was awarded in Fall 2007, key staff from Department of
Public Works and Office of Emergency Services assembled a planning partnership of 36
Contra Costa agencies, including the County, cities, and special districts. The partnership
collaborated in the development of the update to the hazard mitigation plan in a five
phase planning process over a 24 month period. It resulted in a two volume document that
will provide a comprehensive blueprint for hazard risk reduction in Contra Costa County
for the next five years. Attached for the Board of Supervisors consideration under
Exhibit One are excerpts from the two volume plan, including the Executive Summary
and the County’s annex to the plan which covers the unincorporated area.
The ensuing planning process developed a new Hazard Mitigation Plan for the County
and its planning partners from scratch, using lessons learned from the ABAG regional
planning effort. While this Hazard Mitigation Plan is an update for many of the planning
partners, it is the initial plan for others. The updated Hazard Mitigation Plan (HMP)
differs from the ABAG hazard mitigation plan, as follows:
• The updated HMP has been totally re-structured as a countywide regional plan,
focusing only on Contra Costa County. The risk assessment is not a subset of a
larger regional effort. It is isolated to Contra Costa County and focuses on hazards of
concern for the county.
• The updated HMP was expanded to include special purpose districts as planning
partners.
• The risk assessment has been formatted to better support future grant applications
by providing risk and vulnerability information that will directly support the
measurement of “cost-effectiveness” required under FEMA mitigation grant
programs.
• Newly available data and tools provide for a more detailed and accurate risk
assessment. The ABAG regional hazard mitigation plan did not use tools such as
FEMA’s Hazards U.S. Multi-Hazard (HAZUS-MH) computer model or new data
such as FEMA’s countywide Digital Flood Insurance Rate Maps (DFIRMs).
• The updated HMP will meet program requirements of the Community Rating
System (CRS), providing the additional benefit of reducing flood insurance
premiums in participating jurisdictions.
• The planning process has created an opportunity for all municipal planning partners
to meet the requirements of A.B. 2140, which requires integration of the HMP into
the General Plan Safety Element in order to be eligible for state disaster assistance
funding.
• The updated HMP provided the County and its planning partners an opportunity to
engage local citizens and gauge their perception of risk and support for risk
reduction through mitigation.
An Initial Study/Negative Declaration was prepared for HMP update pursuant to the
California Environmental Quality Act (CEQA) Guidelines. The Initial Study/Negative
Declaration describes the proposed project; it identifies, analyzes, and evaluates the
potential impacts, which may result from the HMP update; and, no significant
environmental effects were found to result from the adoption of the HMP update. The
Initial Study/Negative Declaration was circulated for a 30-day comment period, but no
comments were received.
Safety Element General Plan Amendment – Minor Text Amendment
Assembly Bill (AB) 2140 limits the amount of additional funding for certain disaster
recovery projects funded by the California Disaster Assistance Act (CDAA) unless the
local government has complied with provisions as set forth in AB 2140. Among other
requirements, under AB 2140 a local government must provide a certified copy of the
Resolution of Adoption to the FEMA demonstrating that the approved local hazard
mitigation plan has been adopted and that is has been incorporated into the Safety
Element of the General Plan.
Though compliance with AB 2140 is optional, noncompliance limits the local
government’s ability to obtain additional funding for certain disaster recovery projects.
Specifically, California Government Code Section 8685.9 states:
“… the state share shall not exceed 75 percent of the total state eligible costs unless the
local agency is located within a
city, county, or the city and county that has adopted a local hazard mitigation plan in
accordance with the Federal Disaster
Act of 2000 as part of the safety element of its general plan”.
The General Plan policies which pertain to pre-disaster planning are contained in Chapter
10. Safety Element, Contra Costa County General Plan (2005-2010) in Section 10.11
under the heading “Public Protection Services and Disaster Planning”. This section of the
Safety Element describes essential public protection services which will provide the
major force work, facilities, and equipment for disaster recovery. It generally describes
the function and role of the County Office of Emergency Services as the lead agency in
the County responsible for preparing disaster plans and coordinating emergency services,
rescue, and recovery efforts in the event of a disaster. Although the Board of Supervisors
adopted a local hazard mitigation plan in April 2007, which is consistent with
requirements of AB 2140, there is no reference to it in the text of the Safety Element.
Attached for the Board’s consideration under Exhibit Two, is a May 24, 2011 Report and
Recommendation to the County Planning Commission regarding a General Plan
Amendment for the Safety Element to incorporate reference to the local Hazard
Mitigation Plan consistent with the requirements of AB 2140 and County Planning
Commission Resolution No. 12-2011, which recommends the adoption of the following
minor text amendment beginning at Section 10.11, Public Protection Services and
Disaster Planning, Safety Element, under policies, by adding a new policy statement, as
follows:
“10-83 The County will adopt and implement a comprehensive hazard mitigation plan to
minimize the impacts of natural and
man-made disasters pursuant to the requirements of the federal Disaster Mitigation Act
of 2000.”
Also, at Section 10.11, Public Protection Services and Disaster Planning, Safety Element,
under the listing implementation measures adding a new implementation statement, as
follows:
“ 10-ap The County has adopted hazard mitigation plan pursuant to the requirements of
the federal Disaster Mitigation Act of
2000, and will implement and evaluate the Plan on a regular basis as necessary to
comply with federal and state laws. The
Sheriff’s Office of Emergency Services will be the lead County department responsible
for preparing the hazard mitigation
plan.”
As described in the 5/24/2011 report to the County Planning Commission, the minor text
amendment to the Safety Element which would add policy and implementation language
relating to the County’s local hazard mitigation plan is exempt from California
Environmental Quality Act (CEQA), pursuant to County and State CEQA Guidelines,
Section 15061 (b) (3), where the activity is covered by the general rule that CEQA
applies only to projects, which have the potential for causing a significant effect on the
environment. In this case, it can be seen with certainty that there is no possibility that
adding the new policy and implementation language to reference the County’s adopted
local hazard mitigation plan to the Safety Element will have a significant effect on the
environment.
CONSEQUENCE OF NEGATIVE ACTION:
Failure to approve the Hazard Mitigation Plan update may cause the County to become
ineligble from applying for and receiving FEMA Disaster Mitigation Funds, and failure
to approve the minor text amendment to add reference to the Hazard Mitigation Plan in
the Safety Element may disqualify the County from receiving state disaster assistance
funding.
CHILDREN'S IMPACT STATEMENT:
None.
ATTACHMENTS
Resolution No. 2011/277
Exhibit One: CCCHMP Update: Executive Summary & Co. Annex
Exhibit One: Initial Study/Negative Declaration for CCCHMP Update
Exhibit Two: Report to County Planning Commission on Safety Element GPA
Exhibit Two: County Planning Commission Resolution No. 12-2011
Resolution No. 2011/277
Contra Costa County Hazard Mitigation Plan Update
Volume 1: Planning-Area-Wide Elements
EXECUTIVE SUMMARY
ES-1
EXECUTIVE SUMMARY
Contra Costa County and a partnership of local governments within the county have developed a hazard
mitigation plan to reduce future losses resulting from disasters. Hazard mitigation is the use of long- and
short-term strategies to reduce the loss of life, personal injury, and property damage that can result from a
disaster. It involves planning efforts, policy changes, programs, capital projects, and other activities that
can mitigate the impacts of hazards.
The federal Disaster Mitigation Act (DMA) requires proactive pre-disaster planning as a condition of
receiving certain financial assistance under the Robert T. Stafford Act. The DMA encourages state and
local authorities to work together on pre-disaster planning, and it promotes “sustainable hazard
mitigation,” which includes the sound management of natural resources, local economic and social
resiliency, and the recognition that hazards and mitigation must be understood in the largest possible
social and economic context. The enhanced planning network called for by the DMA helps local
governments accurately assess mitigation needs, resulting in faster allocation of funding and more cost-
effective risk reduction projects.
The responsibility for hazard mitigation lies with private property owners; business and industry; and
local, state and federal government. It is impossible to predict exactly when and where disasters will
occur or the extent to which they will impact an area; but with careful planning and collaboration among
public agencies, stakeholders and citizens, it is possible to minimize losses that disasters can cause.
PLAN UPDATE
Federal regulations require hazard mitigation plans to include a plan for monitoring, evaluating, and
updating the hazard mitigation plan. An update 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. DMA compliance is contingent on meeting the plan update
requirement. A jurisdiction covered by a plan that has expired is not able to pursue funding under the
Robert T. Stafford Act for which a current hazard mitigation plan is a prerequisite.
Initial Response to the DMA in Contra Costa County
In 2004, The Association of Bay Area Governments (ABAG) led a regional effort to address hazard
mitigation planning for jurisdictions within its planning area. This regional template was utilized by
numerous counties and cities within the ABAG planning area to achieve initial compliance under the
DMA. The ABAG process equipped local governments with tools to complete individual planning
processes that met their needs, while pooling resources and eliminating redundant planning efforts.
Seventeen local governments in Contra Costa County used the ABAG tools to achieve DMA compliance.
The Contra Costa County Planning Effort
Recognizing limitations in the ABAG planning effort, Contra Costa County Department of Public Works
and the County Office of Emergency Services (OES) have teamed together to prepare an updated county-
wide hazard mitigation plan that would better suit the needs and capabilities of the County and its
planning partners. The Department of Public Works pursued grant funding under the Federal Emergency
Management Agency’s (FEMA’s) Pre-Disaster Mitigation Grant program, and OES took the lead on
assembling a planning partnership. The grant was awarded in the fall of 2007. The ensuing planning
process developed a new plan for the County and its planning partners from scratch, using lessons learned
Contra Costa County Hazard Mitigation Plan Update; Volume 1—Planning-Area-Wide Elements…
ES-2
from the prior planning effort. While this plan is an update for many of the planning partners, it is the
initial plan for others. The updated plan differs from the initial plan for a variety of reasons:
• The plan has been totally re-structured as a countywide regional plan, focusing only on
Contra Costa County. The risk assessment is not a subset of a larger regional effort. It is
isolated to Contra Costa County and focuses on hazards of concern for the county.
• The plan was expanded to include special purpose districts as planning partners.
• The risk assessment has been formatted to better support future grant applications by
providing risk and vulnerability information that will directly support the measurement of
“cost-effectiveness” required under FEMA mitigation grant programs.
• Newly available data and tools provide for a more detailed and accurate risk assessment. The
initial plan did not use tools such as FEMA’s Hazards U.S. Multi-Hazard (HAZUS-MH)
computer model or new data such as FEMA’s countywide Digital Flood Insurance Rate Maps
(DFIRMs).
• The plan will meet program requirements of the Community Rating System (CRS), providing
the additional benefit of reducing flood insurance premiums in participating jurisdictions.
• This planning process will create the opportunity for all municipal planning partners to meet
the requirements of California Assembly Bill 2140, which requires integration of hazard
mitigation plans into general plans.
• The update gave the County and its planning partners an opportunity to engage local citizens
and gauge their perception of risk and support for risk reduction through mitigation.
PLAN UPDATE METHODOLOGY
A partnership of local governments in Contra Costa County collaborated on the development of this
hazard mitigation plan update. This partnership followed a five-phase planning process over 24 months
that resulted in a document that will provide a blueprint for hazard risk reduction in Contra Costa County
for the next five years.
Phase 1—Organize and Review
A planning team was assembled to provide technical support for the plan update, consisting of key
County staff from the Department of Public Works and OES, as well as a technical consultant. The first
step in developing the plan update was to organize the planning partnership. The County and 10
municipal governments committed to this update process. With special-purpose districts included, plan
coverage was expanded to include 36 planning partners as shown in Tables ES-1 and ES-2. All 36
planning partners committed to the process by providing letters of intent to participate and agreeing to
planning partner expectations.
TABLE ES-1.
MUNICIPAL PLANNING PARTNERS
Antioch Brentwood Danville El Cerrito
Martinez Pinole Pleasant Hill Richmond
San Ramon Walnut Creek Contra Costa County
…EXECUTIVE SUMMARY
ES-3
TABLE ES-2.
SPECIAL-PURPOSE DISTRICT PARTNERS
• Antioch Unified School District
• Bethel Island Municipal Improvement District
• Brentwood Union School District
• Canyon Elementary School District
• Central Contra Costa Sanitary District
• Contra Costa County Fire Protection District
• Contra Costa County Flood Control and Water
Conservation District
• Contra Costa Community College District
• Contra Costa County Office of Education
• Delta Diablo Sanitation District
• Diablo Water District
• East Contra Costa Fire Protection District
• Ironhouse Sanitary District
• Kensington Fire Protection District
• Kensington Police Protection and
Community Services District
• Knightsen Community Services District
• Liberty Union High School District
• Mt. Diablo Unified School District
• Pleasant Hill Recreation and Park District
• Reclamation District 800 (Byron Tract)
• Reclamation District 830 (Jersey Island)
• Rodeo-Hercules Fire Protection District
• San Ramon Valley Fire Protection District
• Walnut Creek School District
• West Contra Costa Unified School District
A 14-member steering committee was assembled to oversee the development of the plan, consisting of
planning partner staff, citizens, and other stakeholders in the planning area. A key function of the Steering
Committee was to confirm a guiding principal, goals and objectives for this updated plan. Full
coordination with other county, state and federal agencies involved in hazard mitigation occurred from
the onset of the plan update process.
A multi-media public involvement strategy centered on a hazard preparedness questionnaire was also
implemented under this phase, as well as a comprehensive review of the previous plan and the State of
California Hazard Mitigation Plan. Additionally, a comprehensive review was performed of existing
programs that may support or enhance hazard mitigation actions.
Phase 2—Update the Risk Assessment
Risk assessment is the process of measuring the potential loss of life, personal injury, economic injury,
and property damage resulting from natural hazards. This process assesses the vulnerability of people,
buildings and infrastructure to natural hazards. It focuses on the following parameters:
• Hazard identification and profiling
• The impact of hazards on physical, social and economic assets
• Vulnerability identification
• Estimates of the cost of potential damage or costs that can be avoided through mitigation.
The risk assessment for this hazard mitigation plan meets requirements outlined in Chapter 44 of the Code
of Federal Regulations (44CFR). Phase 2 occurred simultaneously with Phase 1, with the two efforts
using information generated by one another to create the best possible risk assessment. This was the most
comprehensive phase of the plan update process. All facets of the risk assessment of the plan were visited
by the planning team and updated with the best available data and technology.
Contra Costa County Hazard Mitigation Plan Update; Volume 1—Planning-Area-Wide Elements…
ES-4
Phase 3—Engage the Public
A public involvement strategy was developed by the Steering Committee that maximized the capabilities
of the planning partnership. This strategy was implemented by the planning team and included four public
meetings early in the plan update process, two public meetings to review the draft plan, distribution of a
hazard mitigation survey, a County-sponsored website dedicated to the plan update, and multiple media
releases throughout the process.
Phase 4—Assemble the Updated Plan
The planning team and Steering Committee assembled key information from Phases 1, 2 and 3 into a
document to meet the DMA requirements for all planning partners. Under 44CFR, a local hazard
mitigation plan must include the following:
• A description of the planning process
• Risk assessment
• Mitigation strategy
– Goals
– Review of alternatives
– Prioritized “action plan”
• Plan maintenance section
• Documentation of adoption.
The updated plan contains two volumes. Volume 1 contains all components that apply to all partners and
the broader planning area (plan process, outreach strategy, plan maintenance, risk assessment, goals,
objectives and countywide initiatives). Volume 2 contains all components that are jurisdiction-specific
(ranking of risk, capability assessment, an action plan, prioritization of that action plan and a status report
on prior actions). Each planning partner has a dedicated chapter in Volume 2.
Phase 5—Plan Adoption/Implementation
The final adoption phase will begin once pre-adoption approval is granted by California Emergency
Management Agency (Cal EMA) and FEMA. Each partner will adopt the updated plan individually.
A plan implementation and maintenance section included in this document details the formal process for
ensuring that the plan remains active and relevant. The plan maintenance process includes a schedule for
monitoring and evaluating the plan’s progress annually and producing a plan revision every 5 years.
Throughout the life of this plan, a steering committee representative of the original committee will
provide a consistent source of guidance and oversight.
The plan adoption phase includes strategies for continued public involvement and incorporation of the
recommendations of this plan into other planning mechanisms within the planning area, such as general
plans, capital improvement plans, building codes, and emergency management plans.
MITIGATION GUIDING PRINCIPLE, GOALS AND OBJECTIVES
The following principle guided the Steering Committee and the planning partnership in selecting the
initiatives contained in this plan update:
…EXECUTIVE SUMMARY
ES-5
Guiding Principle—To reduce the vulnerability from natural hazards within the county in a
cost-effective manner, within the capabilities of the partnership.
The Steering Committee and the planning partnership established the following goals for the plan update:
• Goal 1—Save [or protect] lives and reduce injury
• Goal 2—Increase resilience of infrastructure and critical facilities
• Goal 3—Avoid [minimize, or reduce] damage to property
• Goal 4—Encourage the development and implementation of long-term, cost-effective and
environmentally sound mitigation projects
• Goal 5—Build and support capacity to enable local government and the public to prepare,
respond and recover from the impact of natural hazards.
Plan objectives were developed via a facilitated exercise that focused on finding objectives that meet
multiple goals. The objectives are listed in Table ES-3.
MITIGATION INITIATIVES
Mitigation initiatives are activities to reduce or eliminate losses resulting from natural hazards. Mitigation
initiatives are the key element of the hazard mitigation plan update. By implementing these initiatives, the
planning partnership will strive to become disaster-resistant through sustainable hazard mitigation.
Although adoption of this plan makes the planning partners eligible for FEMA grant funding, the
purposes of the plan go beyond grant eligibility. It was important to the planning partnership and the
Steering Committee to look at initiatives that will work through all phases of emergency management.
Some of the initiatives outlined in this plan are not grant eligible but were chosen for their effectiveness in
achieving the goals of the plan. A series of countywide initiatives were identified, as summarized in
Table ES-4. Jurisdiction-specific initiatives are listed in Volume 2 of this plan.
IMPLEMENTATION
Full implementation of the recommendations of this plan will require time and resources. Specific
recommendations and plan review protocols are provided to evaluate changes in vulnerability and action
plan prioritization after the plan is adopted. The true measure of the plan’s success will be its ability to
adapt to the changing climate of hazard mitigation. Funding resources are always evolving, as are state
and federal mandates. Contra Costa County and its planning partners have a long-standing tradition of
proactive response to issues that may impact local citizens. Each local government will assume
responsibility for adopting the recommendations of this plan and committing resources toward
implementation. The framework established by this plan identifies a strategy that maximizes the potential
for implementation based on available and potential resources. It commits all planning partners to pursue
initiatives 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.
Contra Costa County Hazard Mitigation Plan Update; Volume 1—Planning-Area-Wide Elements…
ES-6
TABLE ES-3.
OBJECTIVES FOR NATURAL HAZARD MITIGATION PLAN UPDATE
Objective
Number Objective Statement
Goals for
Which It Can
Be Applied
O-1 Increase resilience of (or protect and maintain) infrastructure and critical facilities 2, 3, 5
O-2 Sustain reliable local emergency operations and facilities during and after a disaster 1, 5
O-3 Educate the public on the risk from natural hazards and increase awareness,
preparation, mitigation, response, and recovery activities
1, 3, 5
O-4 Minimize the impacts of natural hazards on current and future land uses by
providing incentives for hazard mitigation
1, 3, 5
O-5 Prevent (or discourage) new development in hazardous areas or ensure that if
building occurs in high-risk areas that it is done in such a way as to minimize risk
1, 3, 5
O-6 At the local government level, continually improve understanding of the location
and potential impacts of natural hazards, utilizing the best available data and
science.
1, 2, 3, 4, 5
O-7 Ensure all structures meet minimum standards for life safety 1, 2, 3, 5
O-8 Monitor plan progress annually to integrate local hazard mitigation plans and the
results of disaster- and hazard-specific planning efforts
1, 2, 3, 5
O-9 Lower cost of flood insurance premiums through CRS program 3, 4, 5
O-10 Provide/improve flood protection with flood control structures, and drainage
maintenance plans
2, 3, 4
O-11 Strengthen codes, and their enforcement, so that new construction can withstand the
impacts of natural hazards and lessen the impact of that development on the
environment’s ability to absorb the impact of natural hazards.
1, 3
O-12 Consider the impacts of natural hazards in all planning mechanisms that address
current and future land uses within the planning area.
1, 3
O-13 Eliminate or minimize disruption of local government operations caused by natural
hazards
1, 3, 4
O-14 Consider open space land uses within identified high-hazard risk zones 1, 2, 3, 4, 5
0-15 Retrofit, acquire or relocate identified high-risk structures, including those known
to experience repetitive losses.
1, 3, 4
0-16 Establish a partnership among all levels of government and the business community
to improve and implement methods to protect property
1, 2, 3, 4, 5
…EXECUTIVE SUMMARY
ES-7
TABLE ES-4.
ACTION PLAN—COUNTYWIDE MITIGATION INITIATIVES
Hazards
Addressed Lead Agency Possible Funding Sources or Resources Time Linea Objectives
CW-1—Continue to maintain a Countywide hazard mitigation website that will house the plan and provide the
public an opportunity to monitor plan implementation progress. Each planning partner can support this initiative by
including an initiative in its action plan of creating a link to the County Hazard Mitigation webpage.
All Hazards OES OES operational budget Short
term/ongoing
3, 6, 16
CW-2—Leverage public outreach partnering capabilities (such as CERT) within the planning area to promote a
uniform and consistent message on the importance of proactive hazard mitigation.
All Hazards OES, CERT OES operational budget Short term/
ongoing
2, 3, 6 ,16
CW-3—Coordinate mitigation planning and project efforts within the planning area to leverage all resources
available to the planning partnership.
All Hazards OES, Public Works FEMA mitigation grant funding will
reimburse for grant application
preparation.
General fund allocations of all planning
partners.
Short term 6, 16
CW-4—Where appropriate, support retrofitting, purchase, or relocation of structures located in hazard-prone areas
to protect structures from future damage, with repetitive and severe repetitive loss properties as a priority. Seek
opportunities to leverage partnerships within the planning area in these pursuits.
All Hazards OES, Public Works FEMA Mitigation Grant funding Long-term/
depends on
funding
7, 15, 16
CW-5—Continue to update hazard mapping with best available data and science as it evolves within the capabilities
of the partnership. Support FEMA’s Risk MAP Initiative.
All Hazards Public Works FEMA Mitigation Grant Funding,
FEMA’s CTP program, County CIP
funding
Long-term/
depends on
funding
3, 6, 16
CW-6—To the extent possible based on available resources, provide coordination and technical assistance in the
application for grant funding that includes assistance in cost vs. benefit analysis for grant eligible projects.
All Hazards OES, Public Works FEMA mitigation grant funding will
reimburse for grant application
preparation.
General fund allocations of all planning
partners.
Short term 6, 16
CW-7—A steering committee will remain as a viable body over time to monitor progress of the hazard mitigation
plan, provide technical assistance to Planning Partners and oversee the update of the plan according to schedule. This
body will continue to operate under the ground rules established at its inception.
All Hazards OES, Public Works Public Works and OES operational
budgets
Short term/
ongoing
8, 16
Contra Costa County Hazard Mitigation Plan Update; Volume 1—Planning-Area-Wide Elements…
ES-8
TABLE ES-4 (CONTINUED).
ACTION PLAN—COUNTYWIDE MITIGATION INITIATIVES
Hazards
Addressed Lead Agency Possible Funding Sources or Resources Time Linea Objectives
CW-8—Amend or enhance the Contra Costa County Hazard Mitigation Plan on an “as needed” basis to seek
compliance with state or federal mandates (i.e., CA. Assembly Bill # 2140) as guidance for compliance with these
programs become available.
All Hazards OES, DCD, Public Works County General Fund Short term/
ongoing
5, 6, 14
CW-9—Utilize information contained within the Contra Costa County Hazard Mitigation Plan to support updates to
other emergency management plans in effect within the planning area.
All Hazards OES Possible DHS funding, General funds of
all planning partners
Long term,
depends on
funding
2, 13, 16
CW-10—Continue to coordinate emergency management and hazard mitigation planning functions with the
Association of Bay Area Governments to leverage resources and information on the planning area to
support/enhance these activities for the Contra Costa County planning partnership.
All Hazards OES OES operational budget Short term/
ongoing
2, 13, 16
CW-11—Sponsor the formation and training of Community Emergency Response Team (CERT) training through
partnerships with local businesses
All Hazards All Municipal Planning
Partners, OES
General Funds Short term/
ongoing
2, 3, 6 ,16
a. Short term = 1 to 5 years; Long Term= 5 years or greater
OES = Sheriff’s Office of Emergency Services; DCD = Contra Costa County Department of Conservation and
Development
Contra Costa County Hazard Mitigation Plan
Volume 2: Planning Partner Annexes
PART 2—
ANNEXES FOR MUNICIPAL PLAN
UPDATES
2-1
CHAPTER 2.
UNINCORPORATED CONTRA COSTA COUNTY ANNEX
2.1 HAZARD MITIGATION PLAN POINT OF CONTACT
Primary Point of Contact Alternate Point of Contact
Susan Roseberry, Senior Emergency Planning Coordinator
50 Glacier Drive
Martinez, CA 94553
Telephone: 925-313-9625
e-mail Address: srose@so.cccounty.us
Rick Kovar, OES Manager
50 Glacier Drive
Martinez, CA 94553
Telephone: 925-313-96216
e-mail Address: rkovar@so.cccounty.us
2.2 JURISDICTION PROFILE
The following is a summary of key information about the jurisdiction and its history:
• Date of Incorporation—1850
• Current Population—1,060,435 as of January 1, 2009
• Population Growth—Contra Costa County should continue to experience a steady rate of
growth, with an estimated population increase of 29 percent by 2035.
• Location and Description—Contra Costa County is major metropolitan area east of San
Francisco. The county has a total area of 802 square miles, of which 720 square miles is land
and 82 square miles is water. It is bounded on the south and west by Alameda County; on the
northwest San Francisco Bay (San Francisco and Marin Counties); on the north by San Pablo
Bay, the Carquinez Strait, and Suisun Bay (Solano and Sacramento Counties); and on the east
by the San Joaquin River (San Joaquin County).
• Brief History—Contra Costa County was incorporated in 1850 as one of the original 27
counties of the state. The County’s Spanish language name translates as “opposite coast,”
indicating its location opposite San Francisco on San Francisco Bay.
Coal was discovered near Pittsburg in the early 1850s. The Mount Diablo Coal Field was the
most extensively mined coal deposit in California. From the 1860s to the beginning of the
20th century, it is estimated that 4 million tons of coal were extracted from the area.
Railroads are also an important part of the County’s history. In 1901, the Santa Fe Railroad,
now BNSF Railway, selected Richmond for its western terminal. During the early 1900s,
industry moved into the county: a U.S. Steel mill opened in Pittsburg in 1910; Standard Oil,
later to become Chevron, moved to Richmond; and Shell Oil built a refinery in Martinez.
Great Western Electro-Chemical, which later became Dow, opened in Pittsburg in 1916.
Contra Costa County played a significant role in World War II. Richmond was a major
shipbuilding center, the U.S. Steel mill in Pittsburg produced casting for the shipyards, Camp
Stoneman (Pittsburg) was a troop staging area from 1942 to 1957, wartime pilots trained at
what is now Concord/Buchanan Field Airport, and Port Chicago was a major munitions
depot. Saint Mary’s College Pre-Flight School trained approximately 15,000 recruits in
Moraga from June 1, 1942, until it was decommissioned on June 30, 1946. Many workers
who migrated to the county to work in the shipyards remained after the war ended. Veterans
who passed through the county during the war returned to become residents.
…2. UNINCORPORATED CONTRA COSTA COUNTY ANNEX
2-3
TABLE 2-1.
CONTRA COSTA COUNTY GROWTH PROJECTIONS
2000 2005 2010 2015 2020 2025 2030 2035
Population 948,816 1,023,400 1,090,300 1,130,700 1,177,400 1,225,500 1,273,700 1,322,900
Household Population 937,479 1,012,100 1,078,800 1,118,900 1,165,300 1,213,300 1,261,500 1,310,700
Households 344,129 368,310 392,680 407,250 424,340 442,330 461,330 480,480
Persons/household 2.72 2.75 2.75 2.75 2.75 2.74 2.73 2.73
Employed Residents 461,992 459,600 490,200 528,000 586,200 631,700 64,900 718,700
Mean Household Income $100,500 $98,400 $102,000 $107,500 $113,500 $119,700 $126,200 $133,200
Employment
Agriculture & Natural
Resources
2,550 2,550 2,550 2,550 2,550 2,550 2,550 2,550
Construction 27,580 29,270 28,340 30,750 33,190 36,510 39,370 42,510
Manufacturing, Wholesale 40,120 34,490 35,110 38,220 41,060 42,950 45,800 48,330
Retail 46,720 46,390 43,870 46,650 50,870 56,740 60,710 64,710
Transportation & Utilities 15,990 18,240 17,690 18,950 20,360 21,090 22,090 23,310
Information 19,760 19,640 19,290 20,970 22,920 25,860 28,430 30,700
Financial & Leasing 40,380 40,930 39,060 41,550 44,470 47,690 50,150 53,870
Professional &
Management Services
49,130 47,580 46,450 51,170 56,040 61,670 67,160 72,160
Health, Education 71,090 78,130 81,190 90,430 99,930 106,170 116,870 126,740
Arts, Recreation & Other 44,840 48,110 50,230 54,740 59,840 62,730 67,590 73,310
Government 13,150 13,700 13,040 13,670 14,320 15,390 16,190 17,460
Total 371,310 379,030 376,820 409,650 445,550 479,350 516,910 555,650
Source: 2000 demographic data taken directly from the U.S. Census. 2000 employment data are derived from the Census
Transportation Planning Package. 2000 income data are from U.S. Census, based on 1999 income and then adjusted to
2005 dollars. ABAG updated these data to 2005 based on the Bay Area CPI and real income growth estimates for each
county from the Bureau of Economic Analysis. All income data are expressed in constant 2005 dollars.
Anticipated development trends are moderate to high, consisting primarily of residential
development. Single-family homes are the predominant housing type in the County,
especially in unincorporated areas, where single-family dwellings make up 80 percent of the
housing stock. The population of every city in the County increased during the 1990s, but
growth has been strongest in the East County, particularly in Antioch, Brentwood, and
Oakley. (East County includes Antioch, Pittsburg, Brentwood, Bay Point, Oakley, and Rural
East Contra Costa County. The San Ramon Valley includes the unincorporated community of
Dougherty Valley, some of which is annexed into the City of San Ramon.) According to the
Association of Bay Area Governments (ABAG), East County and San Ramon will account
for much of the household growth between 2000 and 2020. Substantial growth is also
expected in Bay Point, an unincorporated community within Pittsburg’s sphere of influence,
as the Pittsburg/Bay Point BART station is the new terminus for the Bay Point/Pittsburg line.
ABAG also anticipates noticeable growth for the West County, especially for Richmond and
Hercules. Redevelopable land near the new Richmond Parkway connecting I-80 and I-580
will help fuel growth for the Richmond area. Hercules will most likely grow due to its supply
of vacant land and its location at the junction of Highways 80 and 4.
Contra Costa County Hazard Mitigation Plan; Volume 2—Planning Partner Annexes…
2-4
Central County will continue to absorb new housing growth, despite the diminishing supply
of vacant land. Undeveloped land remains available in pockets and some communities are
experiencing redevelopment in neighborhoods near the downtown and other activity centers,
such as the Walnut Creek and Pleasant Hill BART Stations.
California law requires counties and cities to prepare and adopt a comprehensive long-range
plan to guide community development. The plan must consist of an integrated and internally
consistent set of goals, policies, and implementation measures and must focus on issues of the
greatest concern to the community. County actions such as those relating to land use
allocations, annexations, zoning, subdivisions and design review, redevelopment, and capital
improvements, must be consistent with the plan. Contra Costa adopted its general plan under
this state mandate in January 2005. Future County growth and development will be managed
as identified in the plan.
2.3 JURISDICTION-SPECIFIC NATURAL HAZARD EVENT HISTORY
Table 2-2 lists all past occurrences of natural hazards in the county. Repetitive loss records are as follows:
• Number of FEMA Identified Repetitive Flood Loss Properties: 8
• Number of Repetitive Flood Loss Properties that have been mitigated: Unknown
2.4 HAZARD RISK RANKING
Table 2-3 presents the ranking of the hazards of concern.
2.5 CAPABILITY ASSESSMENT
The assessment of the jurisdiction’s legal and regulatory capabilities is presented in Table 2-4. The
assessment of the jurisdiction’s administrative and technical capabilities is presented in Table 2-5. The
assessment of the jurisdiction’s fiscal capabilities is presented in Table 2-6. Classifications under various
community mitigation programs are presented in Table 2-7.
2.6 HAZARD MITIGATION ACTION PLAN AND EVALUATION OF
RECOMMENDED INITIATIVES
Table 2-8 lists the initiatives that make up the jurisdiction’s hazard mitigation plan. Table 2-9 identifies
the priority for each initiative. Table 2-10 summarizes the mitigation initiatives by hazard of concern and
the six mitigation types.
2.7 STATUS OF PREVIOUS PLAN INITIATIVES
Table 2-11 summarizes the current status of strategies that were adopted by the County for the ABAG
hazard plan. Those that are directly carried over as actions in this hazard plan are also indicated as such in
Table 2-8. Section 1.4 of this volume describes the ABAG strategies and how their status was reviewed
for this plan.
2.8 HAZARD AREA EXTENT AND LOCATION
Hazard area extent and location maps have been generated for the Contra Costa County area and are
included in Volume 1 of this plan. These maps are based on the best available data at the time of the
preparation of this plan, and are considered to be adequate for planning purposes.
…2. UNINCORPORATED CONTRA COSTA COUNTY ANNEX
2-5
TABLE 2-2.
NATURAL HAZARD EVENTS
Type of Event Date Preliminary Damage Assessment
Landslide 4/6/2006 5,500,000 Property
Flooding 12/31/2005–1/1/2006 22,000,000 Property/8,710,359 Crop
Wind 12/31/2002 120,000 Property
Wind 11/7/2002 200,000 Property
Severe Weather 7/10/2002 25,000 Property
Wind 11/24/2001 700,000 Property
Wind (High Wind) 12/18/2000 550,000 Property
Flooding (Flash Flood) 02/14/2000 100,000 Property
Wind (High Wind) 12/21/1999 62,500 Property
Wind (High Wind) 2/9/1999 200,000 Property
Wind (High Wind) 12/16/1998 25,000 Property
Tornado 12/5/1998 200,000 Property
Tornado 02/19/1998 50,000 Property
Landslide (El Nino) 1/1/1997 27,000,000 Property
Severe Weather 12/9/1995 6,000,000 Property/500,000 Crop Damage
Severe Weather 2/21/1994 128,000 Property
Severe Weather 12/11/1993 344,828 Property
Wind (High Wind) 11/14/1993 62,500 Property
Wind (High Wind) 2/19/1993 50,000 Property
Flooding (Flash Flood) 1/20/1993 12,500 Property
Flooding (Flash Flood) 1/13/1993 5,555,556 Property/Crops
Severe Weather 1/10/1993 8,333,333 Property
Flooding/Severe Weather 12/11/1992 131,579 Property
Severe Weather 12/7/1992 1525 Property
Flooding- Severe Weather 02/14/1992 9090.91 Property
Flooding- Severe Weather 02/11/1992 11627.91 Property
Severe Weather 02/09/1992 89286
Severe Weather 12/20/1990 86206 Property/Crops
Flooding (Flash Flood) 5/28/1990 500,000 Property
Earthquake (Loma Prieta) 10/17/1989 25,000.000
Wind 12/14/1988 50000 Property
Flooding (Flash Flood) 2/17/1986 5,000,000 Property
Levee Failure, High Winds, High
Tides, Floods, Storm, Wind
Driven Water
12/9/1983 Public-7,240,785; private- 2,669 million;
agriculture 1 million
Contra Costa County Hazard Mitigation Plan; Volume 2—Planning Partner Annexes…
2-6
TABLE 2-2 (continued).
NATURAL HAZARD EVENTS
Type of Event Date Preliminary Damage Assessment
Severe Weather 12/3/1983 312,500 Property
Flood- Severe Weather 1/25/1983 384,165 Property
Wind 12/22/1982 1,041,666 Property
Flooding 3/30/1982 166,667 Property
Flood- Severe Weather 1/3/1982 7,142,857 Property
Delta Levee Break
Holland & Webb Levee breaks
1/23/1980 Public-11,158,700; private-1,479,500; agriculture-
3,887,195; Total-17,388,013
Drought 2/13/1976 Damage Statewide $888.5 million
Eucalyptus Tree Freeze 4/4/1973 Federal Disaster 2 Counties Contra County &
Alameda- removal of approximately 2 million dead
trees $8-10 million
Flood- Severe Storm/Thunder 1/16/1973 86206 Property
Flood- Severe Storm/Thunder 1/18/1969 862068 Property
a. Drought conditions and Department of Agriculture declared disasters:
• As of May 2009, three consecutive years of drought conditions resulting in approximately $3.6 loss of
forage value and $1.3 million cattle production
• March 2004—Rangeland forage loss $6,564,946 and dryland hay loss $72,425
• Sept 2002—Reduced rangeland due to drought estimated loss $1,114296
b. In the years 1973, 1980, 1982, 1983, and 1986, one or more Delta island levees failed or were overtopped,
and some of these events were summer breaks that did not occur at time of high storm runoff. Some
islands in the Delta have flooded two or three times since 1980.
Sources: Spatial Hazard Events and Losses Database for the United States (SHELDUS); Cal EMA Disasters
1950 – 1999
TABLE 2-3.
HAZARD RISK RANKING
Rank Hazard Type Risk Rating Score (Probability x Impact)
1 Earthquake 54
2 Severe Weather 45
3 Landslide 36
4 Flood 27
5 Wildland Fire 24
6 Drought 15
7 Dam failure 8
…2. UNINCORPORATED CONTRA COSTA COUNTY ANNEX
2-7
TABLE 2-4.
LEGAL AND REGULATORY CAPABILITY
Local
Authority
State or
Federal
Prohibitions
Other
Jurisdictional
Authority
State
Mandated Comments
Codes, Ordinances & Requirements
Building Code Y N N Y California Building Code Ordinance 2007-54
adopted 11/27/2007
Zoning Code Y N N Y County Code Title 8 Zoning Division-84 Land
Use Districts.
Subdivisions Y N N N County Ordinances Code (94-4.2)
Post Disaster
Recovery
N N N N To be addressed in 2010
Real Estate
Disclosure
N N Y Y CA. State Civil Code 1102 requires full
disclosure on Natural hazard Exposure of the
sale/re-sale of any and all real property.
Growth
Management
Y N N Y Growth Management is addressed in the County’s
General Plan 2005 - 2020
Site Plan Review Y N N N County Code Titles 8,9,10
Special Purpose
(flood
management,
critical areas)
Y N N N County Code Title 10 See the Hazard Mitigation
Plan for the Contra Costa Flood Control and
Water Conservation District.
Planning Documents
General Plan Y N N Y Contra Costa County General Plan 2005-2020
adopted in January 2005.
Floodplain or
Basin Plan
N N N N Managed by the Public Works Department/Flood
Control & Water Conservation District
Stormwater Plan Y N N N Managed by the Public Works/Flood Control &
Water Conservation District. SB790 Stormwater
Resources Act effective 1/1/2010.
Capital
Improvement Plan
N N N N Contra Costa County Public Works Department-
Capital Road Improvement Preservation Program
(CRIPP) Fiscal Year 2007/08 to Fiscal Year
2013/2014. Initially adopted by the Board on May
19, 1989. The CRIPP is updated every other year
during the odd years.
Habitat
Conservation Plan
N N N N East Contra Costa County Habitat and
Conservation Plan- adopted 05/09/2007
Economic
Development Plan
Y N N N County Administration
Emergency
Response Plan
Y N N N Emergency Operations Plan (EOP), Adopted by
the County in January 2006. Currently being
revised 2010.
…2. UNINCORPORATED CONTRA COSTA COUNTY ANNEX
2-7
TABLE 2-4.
LEGAL AND REGULATORY CAPABILITY
Local
Authority
State or
Federal
Prohibitions
Other
Jurisdictional
Authority
State
Mandated Comments
Codes, Ordinances & Requirements
Building Code Y N N Y California Building Code Ordinance 2007-54
adopted 11/27/2007
Zoning Code Y N N Y County Code Title 8 Zoning Division-84 Land
Use Districts.
Subdivisions Y N N N County Ordinances Code (94-4.2)
Post Disaster
Recovery
N N N N To be addressed in 2010
Real Estate
Disclosure
N N Y Y CA. State Civil Code 1102 requires full
disclosure on Natural hazard Exposure of the
sale/re-sale of any and all real property.
Growth
Management
Y N N Y Growth Management is addressed in the County’s
General Plan 2005 - 2020
Site Plan Review Y N N N County Code Titles 8,9,10
Special Purpose
(flood
management,
critical areas)
Y N N N County Code Title 10 See the Hazard Mitigation
Plan for the Contra Costa Flood Control and
Water Conservation District.
Planning Documents
General Plan Y N N Y Contra Costa County General Plan 2005-2020
adopted in January 2005.
Floodplain or
Basin Plan
N N N N Managed by the Public Works Department/Flood
Control & Water Conservation District
Stormwater Plan Y N N N Managed by the Public Works/Flood Control &
Water Conservation District. SB790 Stormwater
Resources Act effective 1/1/2010.
Capital
Improvement Plan
N N N N Contra Costa County Public Works Department-
Capital Road Improvement Preservation Program
(CRIPP) Fiscal Year 2007/08 to Fiscal Year
2013/2014. Initially adopted by the Board on May
19, 1989. The CRIPP is updated every other year
during the odd years.
Habitat
Conservation Plan
N N N N East Contra Costa County Habitat and
Conservation Plan- adopted 05/09/2007
Economic
Development Plan
Y N N N County Administration
Emergency
Response Plan
Y N N N Emergency Operations Plan (EOP), Adopted by
the County in January 2006. Currently being
revised 2010.
Contra Costa County Hazard Mitigation Plan; Volume 2—Planning Partner Annexes…
2-8
TABLE 2-4 (continued).
LEGAL AND REGULATORY CAPABILITY
Local
Authority
State or
Federal
Prohibitions
Other
Jurisdictional
Authority
State
Mandated Comments
Planning Documents (continued)
Shoreline
Management Plan
N N N N The General Plan Land Use Element combined
with zoning ordinances addresses County
Shoreline (unincorporated). East Bay Regional
Park District is responsible for district land use,
the Army Corps of Engineers is responsible for
dredging channels, and the Office of the Sheriff
contracted by the U.S. Army is responsible for the
Marine Ocean Terminal Concord. Also involved
in shoreline management are the Bay
Conservation Development Commission and the
State Lands Commissions.
Post Disaster
Recovery Plan
N N N N To be written 2010
TABLE 2-5.
ADMINISTRATIVE AND TECHNICAL CAPABILITY
Staff/Personnel Resources Available? Department/Agency/Position
Planners or engineers with knowledge of land
development and land management practices
Y Department of Conservation and Development/Public
Works Department
Engineers or professionals trained in building
or infrastructure construction practices
Y Department of Conservation and Development/Public
Works Department/General Services
Planners or engineers with an understanding
of natural hazards
Y Emergency Services Division/Office of Emergency
Services- Senior Emergency Planners, Public Works
Department- Engineers
Staff with training in benefit/cost analysis Y Public Works Department/General Services Department
Floodplain manager Y Public Works Department/Flood Control and Water
Conservation District-Assistant Chief Engineer &
Floodplain/Watershed Manager
Surveyors Y Public Works Department
Personnel skilled or trained in GIS
applications
Y Department of Information Technology (DOIT), Public
Works Department, and the Department of Conservation
and Development
Scientist familiar with natural hazards in local
area
Y Flood Control and Water Conservation Control District-
Hydrologist Department of Conservation and
Development- Geologist
Emergency manager Y Emergency Services Division/Office of Emergency
Services- OES Manager
Grant writers Y Emergency Services Division/Office of Emergency
Services- OES Manager, Public Works Department, Health
Services Department, Contra Costa Fire District
…2. UNINCORPORATED CONTRA COSTA COUNTY ANNEX
2-9
TABLE 2-6.
FISCAL CAPABILITY
Financial Resources
Accessible or
Eligible to Use?
Community Development Block Grants Yes
Capital Improvements Project Funding Yes
Authority to Levy Taxes for Specific Purposes Yes
User Fees for Water, Sewer, Gas or Electric Service Yes
Incur Debt through General Obligation Bonds Yes
Incur Debt through Special Tax Bonds Yes
Incur Debt through Private Activity Bonds Unknown
Withhold Public Expenditures in Hazard-Prone Areas No
State Sponsored Grant Programs Yes
Development Impact Fees for Homebuyers or Developers Yes
Other Yes
TABLE 2-7.
COMMUNITY CLASSIFICATIONS
Participating? Classification Date Classified
Community Rating System
• City of Concord Yes 8 10/1/2008
• Contra Costa County Yes 6 10/1/2006
• City of Pleasant Hill Yes 8 05/01/2008
• City of Richmond Yes 9 10/1/2005
• City of San Ramon Yes 8 10/1/2006
• City of Walnut Creek Yes 7 05/01/2006
Building Code Effectiveness Grading Schedule
• City of Antioch Yes 3/2 N/A
• City of Brentwood — — To Be Rated 2010
• City of Clayton Yes 4/3 N/A
• City of Concord Yes 2/2 N/A
• Town of Danville — — To Be Rated 2010
• City of Hercules Yes 4/3 N/A
• City of Lafayette Yes 4/3 N/A
• City of Martinez No N/A N/A
• Town of Moraga Yes 4/3 N/A
• City of Oakley — — To Be Rated 2010
• City of Orinda Yes 4/3 N/A
• City of Pinole — — To Be Rated 2010
• City of Pittsburg Yes 4/4 N/A
• City of Pleasant Hill No N/A N/A
• City of Richmond No N/A N/A
• City of San Pablo Yes 4/3 N/A
• City of San Ramon Yes 2/2 N/A
• City of Walnut Creek Yes 4/4 N/A
• Contra Costa County Yes 4/3 N/A
Contra Costa County Hazard Mitigation Plan; Volume 2—Planning Partner Annexes…
2-10
TABLE 2-7 (continued).
COMMUNITY CLASSIFICATIONS
Participating? Classification Date Classified
Public Protectiona
• Contra Costa County Fire Protection District Yes 3/8 N/A
• East County Fire Protection District Yes 4/9 N/A
• Moraga/Orinda Fire Protection District Yes 3/9 N/A
• San Ramon Valley Fire Protection District Yes 2/8 N/A
• Richmond Fire Protection District Yes 3/9 N/A
• El Cerrito Fire Protection District Yes 3 N/A
• Pinole Fire Protection District Yes 4/9 N/A
• Hercules/Rodeo Fire Protection District Yes 3/9 N/A
• Crockett Fire Protection District Yes 3/9 No
• East Bay Regional Park District No Not Rated N/A
Storm Ready Yes Currentb 05/26/2004
Firewise Noc N/A N/A
a. Higher classification applies to when subject property is located beyond 1000 feet of a creditable fire hydrant
and is within 5 road miles of a recognized Fire Station.
b. Contra Costa County is listed by the NWS as one of six Storm Ready Counties in California. The county was
first recognized as Storm Ready on May 26, 2004. We anticipate renewing our Storm Ready status in 2010.
c. Contra Costa Fire Districts participate in the Diablo Fire Safe Council planning and outreach efforts.
TABLE 2-8.
HAZARD MITIGATION ACTION PLAN MATRIX
Applies to
new or
existing
assets
Hazards
Mitigated
Objectives
Met
Lead
Agency
Estimated
Cost
Sources of
Funding Timeline
Included
in
Previous
Plan?
Initiative #CCC-1—Support County-wide initiatives identified in Volume 1.
New &
Existing
All Hazards All Planning Low General fund Short-Term,
Ongoing No
Initiative #CCC-2—Continue to support the implementation, monitoring, maintenance, and updating of this Plan,
as defined in Volume 1.
New &
Existing
All Hazards All Planning Low General fund,
FEMA
Mitigation
Grant Funding
for 5-year
update
Short-Term,
Ongoing No
Initiative #CCC-3—Continue to maintain compliance and good standing under the National Flood Insurance
Program
New and
existing
Flood 4, 5, 6, 7,
11, 12
Public
Works
Low General Fund Ongoing
program
No
…2. UNINCORPORATED CONTRA COSTA COUNTY ANNEX
2-11
TABLE 2-8 (continued).
HAZARD MITIGATION ACTION PLAN MATRIX
Applies to
new or
existing
assets
Hazards
Mitigated
Objectives
Met
Lead
Agency
Estimated
Cost
Sources of
Funding Timeline
Included
in
Previous
Plan?
Initiative #CCC-4—Continue to maintain/enhance the County’s classification under the Community Rating
System
New and
Existing
Flood 3, 4, 5, 7, 9 Public
Works
Low General Fund Short Yes,
ECON-
f-1
Initiative #CCC-5—Integrate Local Hazard Mitigation Plan into the Safety Element of the General Plan
New and
Existing
All Hazards 4, 5, 14 OES &
DCD
Low General Fund Early 2010,
Short-Term
No
Initiative #CCC-6—Upgrade Emergency Operations Center (EOC) HVAC
Existing All Hazards 1, 2, 15 OES/Genera
l Service
250,000,
High
Potential
Sources-
General Fund
EOC Grant
Long-Term No
Initiative #CCC-7—Develop and Conduct a Multi-Hazard Seasonal Public Awareness Program to Include
Exercises
New
&Existing
All Hazards 2, 3, 6, 13,
16
OES Low Potential
Sources-Citizen
Prep, UASI
Mid 2010,
Short-Term
No
Initiative #CCC-8—Provide California State Training Institute (CSTI) “Earthquake” Class to Essential County
Personnel. Course to be offered Dec 2009 and Jan 2010, we anticipate offering the course on an annual basis.
Existing Earthquake 2, 3, 6, 13,
16
OES/CSTI 55,000 per
class, High
State Homeland
Security Grant
Program
(SHSGP) Funds
Annual,
Short-Term
No
Initiative #CCC-9—The OES conducts annual Mass Care and Shelter Drills which involve both County
Employees, Non-Government Agencies, CERT volunteers, and the public. Shelter Drills were conducted in June &
October of 2009. The next drill is scheduled for the summer of 2010.
New &
Existing
All Hazards 2, 3, 6, 13,
16
OES 15,000,
Low
Potential
Source- SHSGP
Annual,
Short-Term
No
Initiative #CCC-10—County OES participates in the annual Golden Guardian Statewide Exercise
Existing All
Hazards/2011
Levee Break
2, 3, 6, 13,
16
OES 10,000,
Medium
Potential UASI Annual,
Short-Term
No
Contra Costa County Hazard Mitigation Plan; Volume 2—Planning Partner Annexes…
2-12
TABLE 2-8 (continued).
HAZARD MITIGATION ACTION PLAN MATRIX
Applies to
new or
existing
assets
Hazards
Mitigated
Objectives
Met
Lead
Agency
Estimated
Cost
Sources of
Funding Timeline
Included
in
Previous
Plan?
Initiative #CCC-11—FCC P-25 East Bay Regional Communications System (Alameda & Contra Costa County-
At built out, the East Bay Regional Communications System will be a 36-site, 2 county P-25 compliant
communication system designed to provide fully interoperable communications to all public agencies within
Alameda and Contra Costa counties. refer to website www.ebrcsa.org for complete project description.
New
Assets
All Hazards 1, 2, 13, 16 Sheriff Tech 68 Million,
High
Potential
sources of
funding:
SUASI, UASI,
SHSGP
EARMARK,
PSIC
Long-term,
depends on
funding
No
Initiative #CCC-12—Update existing network in the EOC to support full activation to include Wi-Fi.
Existing All Hazards 1, 2, 13, 16 Sheriffs
Tech
High Potential source
EOC Grant
Long-Term No
Initiative #CCC-13—Retrofit antenna mast to support the addition of additional antennas, and protect from
impacts from seismic and severe weather hazards
Existing Earthquake,
Severe Weather
1, 2, 13, 15,
16
Dept of Info
Tech
15,000,
High
Potential source
EOC Grant
Long -Term No
Initiative #CCC-14—Continue to maintain and develop the existing County-wide Community Warning System
(CWS) by identifying and implementing new technology as it becomes available.
Existing All Hazards 1, 2, 13, 16 CWS
600,000,
Low
Community
Awareness
Emergency
Response
(CAER) non-
profit
organization
Short-Term,
Ongoing
No
Initiative #CCC-15—Community Warning System to continue outreach for their “Cell Phone Alert” program
which allows individuals to register their cell phones with the CWS and to be notified via cell phone during an
emergency incident in their geographic location.
Existing All Hazards 1, 2, 13, 16 CWS Low CAER
Short-Term,
Ongoing
No
Initiative #CCC-16—Update/enhance existing flood hazard mapping to better reflect current conditions.
New &
Existing
Flood 3, 6, 12, 16 Public
Works/Floo
d Control
District
Medium FEMA/Public
Works
Floodplain
Determination
Fees., FEMA
Risk-MAP
program
Short-Term,
Ongoing
No
…2. UNINCORPORATED CONTRA COSTA COUNTY ANNEX
2-13
TABLE 2-8 (continued).
HAZARD MITIGATION ACTION PLAN MATRIX
Applies to
new or
existing
assets
Hazards
Mitigated
Objectives
Met
Lead
Agency
Estimated
Cost
Sources of
Funding Timeline
Included
in
Previous
Plan?
Initiative #CCC-17—Canal Road Bridge Replacement
Existing Flood/
Earthquake
1, 7, 15 Public
Works
Medium Awaiting
Funding-
HBRR, Prop
111 Gas Tax
Long-term,
depends on
funding
No
Initiative #CCC-18—Marsh Creek Road Bridge over Marsh Creek
Existing Flood/
Earthquake
1, 7, 15 Public
Works
Medium Awaiting
Funding
Long-term,
depends on
funding
No
Initiative #CCC-19—Bethel Island Road retrofit-Widen to four lane arterial standard from East Cypress Road to
Gateway Road including realignment of curve, Road elevation, and construction of new bridge.
Existing Flood/Levee
Breach
1, 7, 15 Public
Works
12 Million,
Medium
HBRR, Prop
111 Gas Tax
and Bethel
Island Area of
Benefit (AOB)
revenue
Anticipated
completion
date 2011,
Short-Term
No
Initiative #CCC-20—Center Avenue (Pacheco Blvd. To Blackwood Drive) Relocate Fire Station, widen bridge
and construct 2 additional lanes (4 lanes total)
Existing Flood/
Earthquake
1, 7, 15 Public
Works
$7.6
Million,
High
FEMA Hazard
Mitigation
Grant funding
for FS
relocation.
Possible Prop
111 Gas Tax for
road work
Long-term,
depends on
funding
No
Initiative #CCC-21—Boulevard Way at Las Trampas Creek Scour Repair- Bridge on Boulevard Way crossing
Las Trampas Creek- Repair of the scouring is needed to maintain the bridge’s structural integrity.
Existing Flood/
Earthquake
1, 7, 15 Public
Works
$500,000,
Medium
HBRR, Prop
111 Gas Tax
2009/2010,
Short-Term
No
Initiative #CCC-22—Retrofit Marsh Drive Bridge over Walnut Creek
Existing Flood/
Earthquake
1, 7, 15 Public
Works
High HBRR, City of
Concord AOB
Long-term,
depends on
funding
No
Contra Costa County Hazard Mitigation Plan; Volume 2—Planning Partner Annexes…
2-14
TABLE 2-8 (continued).
HAZARD MITIGATION ACTION PLAN MATRIX
Applies to
new or
existing
assets
Hazards
Mitigated
Objectives
Met
Lead
Agency
Estimated
Cost
Sources of
Funding Timeline
Included
in
Previous
Plan?
Initiative #CCC-23—Orwood Road Bridge Replacement- the existing bridge is approaching the end of its useful
life and is not designed to for earthquake loading. Project # 0662-6R4076
Existing Flood/
Earthquake
1, 7, 15 Public
Works
$4 Million,
Medium
HBRR, Prop
111 Gas Tax,
Local Road
Funds, East Bay
Regional Park
District Funds
Construction
Date 2012,
Short-Term
No
Initiative #CCC-24—Pomo Street Arch Culvert Repair
Existing Flood/
Earthquake
1, 7, 15 Public
Works
110,000,
Low
Local Road
Funds
Construction
Date 2010,
Short-Term
No
Initiative #CCC-25—San Pablo Avenue Bridge over Rodeo Creek- Bridge replacement.
Existing Flood/
Earthquake
1, 7, 15 Public
Works
3.6 Million,
Medium
HBRR, Prop
111 Gas Tax,
Local Road
funds
Construction
Date 2013,
Short-term
No
Initiative #CCC-26—Update of four Dam Emergency Action Plans (EAP): Deer Creek, Dry Creek, Marsh Creek,
and Pine Creek
Existing Dam Failure 1, 2, 6, 16 OES/Flood
Control
High Potential
sources of
funding:
SUASI, UASI,
SHSGP
EARMARK,
PSIC-NDSP
(National Dam
Safety Program)
grant
Long-term,
depends on
funding
No
Initiative #CCC-27—Adoption of Fire Hazard Maps-”Very High Fire Zone Severity Maps” currently being
developed. Anticipated date of completion and adoption by the Board of Supervisors late 2009 early 2010
New &
Existing
Wildfire 1, 2, 6, 16 County
OES/Plannin
g-Fire
District
Low General fund Short-Term No
…2. UNINCORPORATED CONTRA COSTA COUNTY ANNEX
2-15
TABLE 2-8 (continued).
HAZARD MITIGATION ACTION PLAN MATRIX
Applies to
new or
existing
assets
Hazards
Mitigated
Objectives
Met
Lead
Agency
Estimated
Cost
Sources of
Funding Timeline
Included
in
Previous
Plan?
Initiative #CCC-28—Enhance/Improve County Code language and enforcement including: County Building
Codes to Increase Compliance with SB 1369 Defensible Space and Other Fire Safe Requirements in the
Unincorporated County
New &
Existing
Wildfire 4, 5, 11, 16 County
OES/Plannin
g-Fire
District
Low General Fund Short-Term,
Ongoing
No
Initiative #CCC-29—Improve, expand and develop new programs that increase awareness of and reduce risk to
wildfires including: Support Fire District Chipper Program
New &
Existing
Wildfire 3, 15, 16 County
OES/Plannin
g-Fire
District
Low General fund,
PDM, DHS-
Citizens Corps
Program
Long-term,
depends on
funding
No
Initiative #CCC-30—Implementation of projects listed in the Community Wildfire Protection Plan (CWFPP)
Existing Wildfire 3, 15, 16 County
OES/Plannin
g-Fire
District
Low Existing
funding-pursue
grant funding
where eligible
Short-Term,
Ongoing
No
Initiative #CCC-31—Participate in Annual Multi-Agency Wildland Fire Drill.
Existing
Assets
Wildfire 2, 3, 6, 13,
16
Fire
Districts/OE
S
Low General Fund
Existing
funding-pursue
grant funding
where eligible
Short-Term,
Ongoing
No
Initiative #CCC-32—Continue and Maintain Noxious Weed Eradication Program- Dept of Ag & CDF
New &
existing
Wildfire/Agricult
ural Hazard
3, 16 Dept. of AG Low CA Dept. of
Agriculture
Short-Term,
Ongoing
No
Initiative #CCC-33—Participate in the bi-annual CAER Group Coastal Region Hazardous Materials Response
Organization (CHMRO) Hazardous Materials Transportation Conference 2011.
Existing All Hazards 2, 3, 6, 13,
16
County
Hazmat/OE
S
50,000,
Low
CAER/
Hazardous
Materials/
Private Industry
Short-Term,
Ongoing
No
Contra Costa County Hazard Mitigation Plan; Volume 2—Planning Partner Annexes…
2-16
TABLE 2-8 (continued).
HAZARD MITIGATION ACTION PLAN MATRIX
Applies to
new or
existing
assets
Hazards
Mitigated
Objectives
Met
Lead
Agency
Estimated
Cost
Sources of
Funding Timeline
Included
in
Previous
Plan?
Initiative #CCC-34—Address deferred maintenance of county owned facilities as identified in the 2007 “Contra
Costa County Facility Condition Analysis (FCA).” The FCA project included the inspection of 93 buildings,
totaling over 2,900,000 square feet. Facilities inspected fall into critical infrastructure/key resources categories.
Existing All Hazards 1, 2, 15 General
Service Dept
251
Million,
High
Grants &
General Funds
when they
become
available
Long-term,
depends on
funding
No
Initiative #CCC-35—Where appropriate, support retrofitting, purchase, or relocation of structures located in
hazard-prone areas to protect structures from future damage, with repetitive loss and severe repetitive loss properties
as priority.
Existing Al Hazards 3, 7, 15 Planning &
building
Departments
High FEMA Hazard
Mitigation
Grant funding
with local
match provided
by property
owner
contribution
Long-term,
depends on
funding
No
Initiative #CCC-36— Sponsor the formation and training of Community Emergency Response Teams (CERT)
training through partnerships with local businesses.
New and
Existing
All Hazards 2,3,13,16 Police, Fire,
County OES
Low Existing County
programs
Ongoing Yes
ECON-j-5
Initiative #CCC-37— Better inform residents of comprehensive mitigation activities, for all hazards of concern
including elevation of appliances above expected flood levels, use of fire-resistant roofing and defensible space in
high wildfire threat and wildfire-urban-interface areas, structural retrofitting techniques for older homes, and use of
intelligent grading practices through workshops, publications, and media announcements and events.
New and
Existing
All Hazards 3,6,7,15 Public
Works,
County
OES,
Medium Existing County
programs
Short-term,
ongoing
Yes
HSNG-k-3
…2. UNINCORPORATED CONTRA COSTA COUNTY ANNEX
2-17
TABLE 2-9.
MITIGATION STRATEGY PRIORITY SCHEDULE
Initiative
#
# of
Objectives
Met Benefits Costs
Do Benefits
Equal or
Exceed Costs?
Is Project
Grant-
Eligible?
Can Project Be Funded
Under Existing
Programs/Budgets? Prioritya
1 16 Medium Low Yes No Yes High
2 16 Medium Low Yes Yes Yes High
3 7 Medium Low Yes No Yes High
4 5 Low Low Yes No Yes High
5 3 Low Low Yes No Yes High
6 3 High High Yes Yes No Medium
7 5 Low Low Yes No Yes High
8 5 High High Yes Yes Yes High
9 5 Medium Low Yes No Yes High
10 5 Medium Medium Yes Yes Yes High
11 4 High High Yes Yes No Medium
12 4 Low High No No No Low
13 5 High High Yes Yes No Medium
14 4 Medium Low Yes No Yes High
15 4 Low Low Yes No Yes High
16 4 Medium Medium Yes Yes No Medium
17 3 High Medium Yes Yes No Medium
18 3 High Medium Yes Yes No Medium
19 3 High Medium Yes Yes Yes High
20 3 High High Yes Yes No Medium
21 3 High Medium Yes Yes Yes High
22 3 High High Yes Yes No Medium
23 3 High Medium Yes Yes Yes High
24 3 High Low Yes Yes Yes High
25 3 High Medium Yes Yes Yes High
26 4 High High Yes Yes No Medium
27 4 Medium Low Yes No Yes High
28 4 Medium Low Yes No Yes High
29 3 Low Low Yes No Yes High
30 3 High Low Yes Yes Yes High
31 5 Low Low Yes No Yes High
32 2 Low Low Yes Yes Yes High
33 5 Low Low Yes No Yes High
Contra Costa County Hazard Mitigation Plan; Volume 2—Planning Partner Annexes…
2-18
TABLE 2-9 (continued).
MITIGATION STRATEGY PRIORITY SCHEDULE
Initiative
#
# of
Objectives
Met Benefits Costs
Do Benefits
Equal or
Exceed Costs?
Is Project
Grant-
Eligible?
Can Project Be Funded
Under Existing
Programs/Budgets? Prioritya
34 3 High High Yes Yes No Medium
35 3 High High Yes Yes No Medium
36 4 High Low Yes No Yes High
37 4 Medium Low Yes Yes Yes High
a. Explanation of priorities
• High Priority: Project meets multiple plan objectives, benefits exceed cost, funding is secured under existing programs, or
is grant eligible, and project can be completed in 1 to 5 years (i.e., short term project) once funded.
• Medium Priority: Project meets at least 1 plan objective, benefits exceed costs, requires special funding authorization
under existing programs, grant eligibility is questionable, and project can be completed in 1 to 5 years once funded.
• Low Priority: Project will mitigate the risk of a hazard, benefits exceed costs, funding has not been secured, project is not
grant eligible, and time line for completion is long term (5 to 10 years).
…2. UNINCORPORATED CONTRA COSTA COUNTY ANNEX
2-19
TABLE 2-10.
ANALYSIS OF MITIGATION INITIATIVES
Initiative Addressing Hazard, by Mitigation Type
Hazard Type
1.
Prevention
2. Property
Protection
3. Public
Education and
Awareness
4. Natural
Resource
Protection
5. Emergency
Services
6.
Structural
Projects
Dam Failure 2, 5, 26 5, 34, 35 1, 2, 7, 15, 26,
36, 37
5, 6, 7, 8, 9, 10, 11, 12, 13,
14, 15, 26, 33, 36
Drought 2, 5, 1, 2, 7, 15, 36, 37 5, 6, 7, 8, 9, 10, 11, 12, 13,
14, 15, 33, 36
Earthquake 2, 5, 5, 13, 17, 18, 20, 21, 22,
23, 24, 25, 34, 35
1, 2 7, 15, 36, 37 5, 6, 7, 8, 9, 10, 11, 12, 13,
14, 15, 33, 36
Flood 2, 3, 4, 16, 3, 4, 5, 17, 18, 19, 20,
21, 22, 23, 24, 25, 34, 35
1, 2, 3, 4, 7, 15,
16, 36, 37
3, 4 4, 6, 7, 8, 9, 10, 11, 12,
13, 14, 15, 33, 36
4, 19
Landslide 2, 5 5, 34, 35 1, 2, 7, 15, 36, 37 5, 6, 7, 8, 9, 10, 11, 12, 13,
14, 15, 33, 36
Severe Weather 2, 5 5, 13, 34, 35 1, 2, 7, 15, 36, 37 5, 6, 7, 8, 9, 10, 11, 12, 13,
14, 15, 33, 36
Wild Fire 2, 5, 27, 28,
30
5, 29, 30, 34, 35 1, 2, 7, 15, 27,
29, 30, 36, 37
5, 30 6, 7, 8, 9, 10, 11, 12, 13,
14, 15, 27, 30, 31, 33, 36
30, 32
1. Prevention: Government, administrative or regulatory actions that influence the way land and buildings are developed to reduce
hazard losses. Includes planning and zoning, floodplain laws, capital improvement programs, open space preservation, and
stormwater management regulations.
2. Property Protection: Modification of buildings or structures to protect them from a hazard or removal of structures from a
hazard area. Includes acquisition, elevation, relocation, structural retrofit, storm shutters, and shatter-resistant glass.
3. Public Education and Awareness: Actions to inform citizens and elected officials about hazards and ways to mitigate them.
Includes outreach projects, real estate disclosure, hazard information centers, and school-age and adult education.
4. Natural Resource Protection: Actions that minimize hazard loss and preserve or restore the functions of natural systems.
Includes sediment and erosion control, stream corridor restoration, watershed management, forest and vegetation management,
and wetland restoration and preservation.
5. Emergency Services: Actions that protect people and property during and immediately after a hazard event. Includes warning
systems, emergency response services, and the protection of essential facilities.
6. Structural Projects: Actions that involve the construction of structures to reduce the impact of a hazard. Includes dams, setback
levees, floodwalls, retaining walls, and safe rooms.
Contra Costa County Hazard Mitigation Plan; Volume 2—Planning Partner Annexes…
2-20
TABLE 2-11.
PREVIOUS ACTION PLAN IMPLEMENTATION STATUS
Action Status
Action # Completed
Carry Over to
Plan Update
Removed; No
Longer Feasible Comments
ECON-b-2 3 California Building Code Ordinance 2007-54
adopted 11/27/2007
ECON-f-1 3 Addressed by Initiative #CCC-4
ECON-f-6 3 Addressed by Initiative #CCC-3
ECON-f-7 3 Addressed by Initiative #CCC-35
ECON-f-8 3 Addressed by Initiative #CCC-35
ECON-j-5 3 Addressed by Initiative #CCC-36
LAND-c-4 3 Addressed by Initiatives #CCC-3 and #CCC-4
HSNG-g-1 3 Addressed by Initiative #CCC-28
HSNG-k-3 3 Addressed by Initiative #CCC-37
GOVT-a-2 3 Addressed by Initiative #CCC-35
GOVT-a-7 3 Addressed by Initiative #CCC-35
GOVT-c-5 3 Addressed by Initiative #CCC-3
Agenda Item # 3
Conservation and Development Contra Costa County
CONTRA COSTA COUNTY PLANNING COMMISSION
TUESDAY, MAY 24, 2011 – 7:00 P.M.
I. INTRODUCTION
GENERAL PLAN AMENDMENT FOR A MINOR TEXT AMENDMENT
TO ADD REFERENCE TO THE COUNTY’S LOCAL HAZARD
MITIGATION PLAN IN THE SAFETY ELEMENT, CONTRA COSTA
COUNTY GENERAL PLAN (2005-2020), COUNTY-INITIATED, (County
File: GP #08-0006). The proposed General Plan Amendment would incorporate
new policy and implementation language into the Safety Element to reference
Contra Costa County’s local hazard mitigation plan. This amendment would
allow Contra Costa County to qualify for additional state funding for certain
disaster recovery projects.
The Federal Disaster Act of 2000 requires local governments to adopt a
comprehensive Hazard Mitigation Plan (HMP) to receive federal funding after a
disaster. By law, a Hazard Mitigation Plan must describe the type, location, and
extent of all natural hazards that can affect a jurisdiction; describe the
jurisdiction’s vulnerability to these hazards; include a mitigation strategy that
provides the jurisdiction’s blueprint for reducing the potential loses; and, contain
a plan maintenance process. A new law, more commonly known as
Assembly Bill (AB) 2140, which became effective on January 1, 2007, places
limits on the amount of additional state funding for certain disaster recovery
projects funded by the California Disaster Assistance Act (CDAA). Under AB
2140, unless the local jurisdiction has an approved local Hazard Mitigation Plan
and has incorporated that Plan into the jurisdiction’s General Plan Safety Element,
it might not be eligible to obtain additional funding from the state for certain
disaster recovery projects. Though compliance with AB 2140 is optional,
noncompliance limits the County’s ability to obtain additional disaster assistance
recovery funding from the state.
The Contra Costa County Board of Supervisors adopted a local hazard mitigation
plan on April 17, 2007, and the Board is due to consider a five-year update in
June 2011 through the adoption of a new countywide multi-agency, multi-hazard
mitigation plan. The purpose of this General Plan Amendment is to make direct
reference in the Safety Element to the County’s adopted local hazard mitigation
plan, and as it may be updated, in order to assure compliance with AB 2140. This
General Plan Amendment would maintain the County’s eligibility to qualify for
additional state funding for certain disaster recovery projects.
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II. RECOMMENDATION
Staff recommends that the County Planning Commission forward a
recommendation to the Board of Supervisors as follows:
a. Find that the minor text amendment to the Safety Element to add policy
and implementation language relating to the County’s adopted local
hazard mitigation plan is exempt from the California Environmental
Quality Act (CEQA), pursuant to County and State CEQA Guidelines,
Section 15061 (b) (3), because the activity is covered by the general rule
that CEQA applies only to projects, which have the potential for causing a
significant effect on the environment. There is no possibility that adding
the new policy and implementation language to reference the County’s
adopted local hazard mitigation plan to the Safety Element will have a
significant effect on the environment.
b. Adopt the General Plan Amendment for the minor text amendment that
would add policy and implementation language to the Safety Element to
reference the County’s local hazard mitigation plan (County File: GP#08-
0006), as explained under Section VII. to this report, and more fully
described under Exhibit “D” to this report.
III. BACKGROUND AND PURPOSE
The Federal Disaster Mitigation Act of 2000 requires proactive pre-disaster
planning by both state and local governments as a condition of receiving cetain
financial assistance from the federal government after a disaster. The intent is to
minimize losses that a disaster can cause by both promoting pre-disaster planning
and assigning and sharing the responsibility for hazard mitigation between private
property owners, business and industry, and local, state, and federal governments.
To that end, the federal law requires local governments to prepare and adopt a
comprehensive hazard mitigation plan for their community. Mitigation in the
context of disaster planning means a sustained action taken to reduce or eliminate
risk to life and property from a hazard event. Hazard mitigation planning is the
systematic process of learning about hazards that can affect the community,
setting clear goals, identifying appropriate actions, and following through with
effective mitigation strategies. The key objectives of the hazard mitigation plan
are to reduce in the long-term hazard vulnerability for a community, to protect
critical community facilities, to reduce the cost of disasters to property owner and
local governments, to reduce exposure to liability, and to minimize post-disaster
community disruption. A hazard mitigation plan must describe the type, location,
and extent of all natural hazards that can affect the jurisdiction; describe the
jurisdiction’s vulnerability to these hazards; include a mitigation strategy that
provides the jurisdiction’s blueprint for reducing the potential losses; and contain
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a plan maintenance process. The hazard mitigation plan is reviewed and approved
by the Federal Emergency Management Agency.
The Contra Costa County Board of Supervisors adopted a local hazard mitigation
plan on April 17, 2007 and is due to consider a significant five-year update to that
plan by adopting a new countywide multi-agency, multi-hazard mitigation plan at
a meeting in June 2011.
Assembly Bill (AB) 2140 limits the amount of additional funding for certain
disaster recovery projects funded by the California Disaster Assistance Act
(CDAA) unless the local government has complied with provisions as set forth in
AB 2140. Among other requirements, under AB 2140 a local government must
provide a certified copy of the Resolution of Adoption to the FEMA
demonstrating that the approved local hazard mitigation plan has been adopted
and that is has been incorporated into the Safety Element of the General Plan.
Though compliance with AB 2140 is optional, noncompliance limits the local
government’s ability to obtain additional funding for certain disaster recovery
projects. Specifically, California Government Code Section 8685.9 states:
“… the state share shall not exceed 75 percent of the total state eligible
costs unless the local agency is located within a city, county, or the city
and county that has adopted a local hazard mitigation plan in accordance
with the Federal Disaster Act of 200 as part of the safety element of its
general plan”.
The purpose of this General Plan Amendment is to make specific reference to the
County’s adopted local hazard mitigation plan, which is soon to be updated, in the
Safety Element in order to assure the County’s compliance with AB 2140, making
the County eligible for additional funding under the California Disaster
Assistance Act (CDAA) . See Exhibit “A” for a copy of AB 2140
IV. EMERGENCY SERVICES AND PRE-DISASTER PLANNING IN
CONTRA COSTA COUNTY
The Office of Emergency Services (OES) is a unit within the Contra Costa
County Sheriff Department. OES is responsible for emergency and disaster
preparedness, and response and recovery planning following an emergency or
disaster. OES coordinates information, resources, and priorities among County
agencies, local governments, and special districts. OES serves as a link between
the Governor's Office of Emergency Services and the County's cities and special
districts. In the event of an emergency or disaster, OES coordinates
communications and resources among responding agencies, and facilitates cost-
recovery coordination with state and federal agencies. Another key function
within the OES is responsibility for overseeing the preparation of the local hazard
mitigation plan.
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V. CONTRA COSTA COUNTY’S LOCAL HAZARD MITIGATION PLAN
Since April 2007, Contra Costa County has had an adopted local hazard
mitigation plan. It was the result of the County’s participation in the Association
of Bay Area Governments (ABAG) nine-county regional multi-jurisdictional
hazard mitigation planning process that was initiated in 2005. The ABAG multi-
jurisdictional local hazard mitigation plan lists nine hazards that have common
impacts on the Bay Area, including Contra Costa County. Five of the hazards are
related to earthquakes (faulting, shaking, earthquake induced landslides,
liquefaction, and tsunamis) and four hazards are related to weather (flooding,
landslides, wildfire, and drought). An annex to the ABAG regional hazard
mitigation plan covered Contra Costa County. The plan annex examined the
hazard exposure of 184,867 urban acres in Contra Costa County, hazard exposure
of key public infrastructure and essential public buildings (such as hospitals,
schools, and public safety buildings) and then assessed the risks associated with
the hazards common to the Bay Area and Contra Costa County. As a participant
in the ABAG process, County staff helped in the development and review of the
comprehensive list of mitigation strategies in the nine-county regional hazard
mitigation plan. The Office of Emergency Services within the Sheriff’s
Department was the lead County department that worked with ABAG in
preparing the Contra Costa County annex to the ABAG multi-jurisdiction hazard
mitigation plan.
The County’s local hazard mitigation plan, which as explained above is an annex
to the ABAG regional hazard mitigation plan, was adopted on April 17, 2007 by
the Board of Supervisors under Board Resolution No. 2007/13. The ABAG
regional hazard mitigation plan was submitted, as required by federal law, to the
Federal Emergency Management Agency (FEMA). The County was notified that
the plan complies with the Federal Disaster Mitigation Act of 2000. A copy of
the County’s existing local hazard mitigation plan is provided under Exhibit “B”.
The Federal Disaster Mitigation Act of 2000 establishes requirements for local
agencies to maintain current local hazard mitigation plans by updating them every
five years. Seeing the five-year update as an opportunity to revise and create a
hazard mitigation plan that is more specifically focused on Contra Costa County,
rather than the nine-county region, County staff from the Flood Control Division,
Department of Public Works and Office of Emergency Services secured a FEMA
planning grant to prepare a comprehensive and integrated multi-jurisdictional
hazard mitigation plan focused solely on Contra Costa.
Beginning in August 2008, a coalition of local Contra Costa agencies, including
the County, 12 cities, and 26 special districts initiated preparation of hazard
mitigation plan under the FEMA grant. This effort has now culminated in a draft
countywide multi-agency, multi-hazard mitiation plan suitable for adoption by
both the Federal Emergency Management Agency and California Emegency
Management Agency. It anticipated that this new multi-agency, multi-hazard
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mitiation plan for Contra Costa County will be presented to the Board of
Supervisors in June 2011 for consideration and approval.
VI. CURRENT COUNTY GENERAL PLAN SAFETY ELEMENT POLICIES
FOR PUBLIC PROTECTION SERVICES AND DISASTER PLAN
The General Plan policies which pertain to pre-disaster planning are contained
in Chapter 10. Safety Element, Contra Costa County General Plan (2005-2010) in
Section 10.11 under the heading “Public Protection Services and Disaster
Planning”. This section of the Safety Element describes essential public
protection services which will provide the major force work, facilities, and
equipment for disaster recovery. It generally describes the function and role of the
County Office of Emergency Services as the lead agency in the County
responsible for preparing disaster plans and coordinating emergency services,
rescue, and recovery efforts in the event of a disaster. At the present time,
although the Board of Supervisors has adopted a local hazard mitigation plan
consistent with requirements of AB 2140, there is no reference to it in the text of
the Safety Element (attached as Exhibit “C” is a copy the Safety Element, see
Section 10.11, “Public Protection Services and Disaster Planning”, beginning at
page 10-42 for the text in the relevant section where reference could be made to
the local hazard mitigation plan).
VII. PROPOSED TEXT AMENDMENT TO THE SAFETY ELEMENT
Beginning at Section 10.11, Public Protection Services and Disaster Planning,
Safety Element, under policies add a new policy statement, as follows:
“10-83 The County will adopt and implement a comprehensive hazard
mitigation plan to minimize the impacts of natural and man-made
disasters pursuant to the requirements of the federal Disaster
Mitigation Act of 2000.”
Also, at Section 10.11, Public Protection Services and Disaster Planning, Safety
Element, under the listing implementation measures add a new implementation
statement, as follows:
“ 10-ap The County has adopted hazard mitigation plan pursuant to the
requirements of the federal Disaster Mitigation Act of 2000, and will
implement and evaluate the Plan on a regular basis as necessary to
comply with federal and state laws. The Sheriff’s Office of Emergency
Services will be the lead County department responsible for preparing
the hazard mitigation plan.”
See Exhibit “D” for the proposed redline/strikeout changes to the relevant text
under Section 10.11 Public Protection Services and Disaster Planning, Safety
Element, which would result from the text amendment.
S-5
VIII. CEQA REVIEW AND DETERMINATION
The minor text amendment to the Safety Element to add policy and
implementation language relating to the County’s local hazard mitigation plan is
exempt from California Environmental Quality Act (CEQA), pursuant to County
and State CEQA Guidelines, Section 15061 (b) (3), the activity is covered by the
general rule that CEQA applies only to projects, which have the potential for
causing a significant effect on the environment. In this case, it can be seen with
certainty that there is no possibility that adding the new policy and
implementation language to reference the County’s adopted local hazard
mitigation plan to the Safety Element will have a significant effect on the
environment.
IX. CONCLUSION
This General Plan Amendment making a minor text amendment to add policy and
implementation language relating to the County’s adopted local hazard mitigation
plan will ensure that Contra Costa County complies with AB 2140 (California
Government Code Section 8685.9) and is eligible to receive disaster assistance
funding from the State of California.
S-6
LIST OF EXHIBITS
Exhibit “A” Assembly Bill 2140
Exhibit “B” Contra Costa County’s Local Hazard Mitigation Plan
Exhibit “C” Safety Element, beginning at page 10-42, see Section
10.11, “Public Protection Services and Disaster Planning,
for relevant text
Exhibit “D” Redline/Strikeout changes to the relevant text under
Section 10.11 Public Protection Services and Disaster
Planning, Safety Element, to incorporate reference of the
County’s adopted local hazard mitigation plan
M:\Safety Element Update\cpcsrptab2140localhazardmitigationplan.doc
S-7
Exhibit “A” Assembly Bill 2140
Assembly Bill No. 2140
CHAPTER 739
An act to add Sections 8685.9 and 65302.6 to the Government Code,
relating to local planning.
[Approved by Governor September 29, 2006. Filed with
Secretary of State September 29, 2006.]
legislative counsel’s digest
AB 2140, Hancock.General plans: safety element.
(1) The California Disaster Assistance Act limits the state share for any
eligible project to no more than 75% of total state eligible costs, except
that the state share shall be up to 100% of total state eligible costs
connected with certain events.
This bill would prohibit the state share for any eligible project from
exceeding 75% of total state eligible costs unless the local agency is
located within a city, county, or city and county that has adopted a local
hazard mitigation plan in accordance with the federal Disaster Mitigation
Act of 2000 as part of the safety element of its general plan, in which case
the Legislature may provide for a state share of local costs that exceeds
75% of total state eligible costs.
(2) The Planning and Zoning Law requires that a city, county, or city
and county general plan contain specified elements, including a safety
element for the protection of the community from any unreasonable risks
associated with the effects of seismically induced surface rupture, ground
shaking, ground failure, tsunami, seiche, and dam failure; slope instability
leading to mudslides and landslides, subsidence, liquefaction, and other
seismic, geologic, and fire hazards.
This bill would authorize a city, county, or a city and county to adopt
with its safety element a federally specified local hazard mitigation plan
that includes specified elements, and require the Office of Emergency
Services to give preference to local jurisdictions that have not adopted a
local hazard mitigation plan with respect to specified federal programs for
assistance in developing and adopting a plan.
The people of the State of California do enact as follows:
SECTION 1.Section 8685.9 is added to the Government Code, to
read:
8685.9.Notwithstanding any other provision of law, including Section
8686, for any eligible project, the state share shall not exceed 75 percent of
total state eligible costs unless the local agency is located within a city,
94
county, or city and county that has adopted a local hazard mitigation plan
in accordance with the federal Disaster Mitigation Act of 2000 (P.L.
106-390) as part of the safety element of its general plan adopted pursuant
to subdivision (g) of Section 65302. In that situation, the Legislature may
provide for a state share of local costs that exceeds 75 percent of total state
eligible costs.
SEC. 2.Section 65302.6 is added to the Government Code, to read:
65302.6.(a) A city, county, or a city and county may adopt with its
safety element pursuant to subdivision (g) of Section 65302 a local hazard
mitigation plan (HMP) specified in the federal Disaster Mitigation Act of
2000 (P. L. 106-390). The hazard mitigation plan shall include all of the
following elements called for in the federal act requirements:
(1) An initial earthquake performance evaluation of public facilities that
provide essential services, shelter, and critical governmental functions.
(2) An inventory of private facilities that are potentially hazardous,
including, but not limited to, multiunit, soft story, concrete tilt-up, and
concrete frame buildings.
(3) A plan to reduce the potential risk from private and governmental
facilities in the event of a disaster.
(b) Local jurisdictions that have not adopted a local hazard mitigation
plan shall be given preference by the Office of Emergency Services in
recommending actions to be funded from the Pre-Disaster Mitigation
Program, the Hazard Mitigation Grant Program, and the Flood Mitigation
Assistance Program to assist the local jurisdiction in developing and
adopting a local hazard mitigation plan, subject to available funding from
the Federal Emergency Management Agency.
O
94
— 2 —Ch.739
Exhibit “B” Contra Costa County’s Local
Hazard Mitigation Plan
Exhibit “C” Safety Element, beginning at page 10-42,
see Section 10.11, “Public Protection
Services and Disaster Planning, for
relevant text
10. SAFETY ELEMENT
10.1 INTRODUCTION
In accordance with the State General Plan Guidelines, the safety element includes maps of
known hazards including seismic and other geologic hazards, and other hazards described
below. It addresses evacuation routes; peak-load water supply requirements; and
minimum road widths and clearances around structures, as they relate to identified fire
and geologic hazards. Other locally relevant safety issues, including hazardous materials
spills and water quality protection are also discussed in this element. The County
Hazardous Waste Management Plan (HWMP) is incorporated herein by reference, and the
goals and policies of the HWMP related to the Safety Element are stated in this section.
LEGAL AUTHORITY
As directed by the State legislature, this element of the General Plan is intended to
further "the protection of the community from any unreasonable risks associated with
the effects of seismically induced surface rupture, ground shaking, ground failure,
tsunami, seiche, and dam failure; slope instability leading to mudslides and landslides,
subsidence and other geologic hazards known to the legislative body; flooding; and
wild land and urban fires (Government Code Section 65302(g))." (Useful Safety
Element definitions and information may be found at the end of this element.) In this
General Plan, flooding and flood control are discussed in more than one element. For
information, goals and policies regarding these issues, the reader is directed to
Sections 7.8, Drainage and Flood Control; and 10.8, Flood Hazards.
This element identifies the hazards that Contra Costa County and its cities must consider
when making land use decisions. Based on analysis of local hazards and an evaluation of
their associated risks to life and property, this element recognizes a degree of acceptable
risk and contains policies for risk management. The element also provides the basis for
planning and coordination of risk management with other divisions of County government,
the incorporated cities, and State and federal agencies in order to ensure that public
projects, plans and programs of other government agencies reflect public safety issues for
Contra Costa County residents.
10.2 RELATIONSHIP TO OTHER ELEMENTS
The Safety Element is expected to affect land use policies and hence is coordinated with
the Land Use Element. Safety considerations may affect the Open Space/Conservation
and Public Facilities/Services Elements, and may present additional justification for
lowering density in conjunction with land use decisions, based partly on seismic and
landslide risk. The Safety Element is also related to the Housing, Transportation and
Circulation; and Public Facilities/Utilities Elements in that it discusses hazards that may
affect decision-making in these issue areas.
10.3 RELATIONSHIP TO OTHER GENERAL PLAN DOCUMENTS
The goals, policies and implementation measures contained in this element are
intended to guide planning for public and private projects that are subject either to
approval of the County planning agency, or to review by County staff, although they
10-1
10. Safety Element
10-2
may be under the jurisdiction of other public agencies operating in the County. Such
goals, policies and implementation measures are intended to be consistent with the
other elements of the General Plan, as well as with other planning documents,
including the County HWMP (1988).
10.4 GENERAL PUBLIC SAFETY ASSUMPTIONS
The concept of public safety expressed in this element, and the proposed policies and programs
to achieve a suitable degree of public protection, are based on the following assumptions:
o Hazards are an unavoidable aspect of life. Not all hazards can be eliminated, nor
can every degree of risk be eliminated for any specific hazard.
o Public policy and action are appropriate measures to mitigate significant hazards to the
general public or to a large part of the population. Such hazards may have a relatively low
risk of occurrence but would be disastrous should they occur, or they may have a
relatively high risk of occurrence, such as minor landslides, but would not be disastrous.
Hazards of the latter type can be due to persistent safety problems in the County.
o Through the dissemination of information and public discussion, satisfactory
judgments can be made as to the levels of monetary, environmental and social
costs appropriate to mitigate hazards to public safety.
The policies of this element are not intended to remove all risks associated with the
specific hazards discussed, but when implemented will reduce risks to life and property
from certain natural and man-made events and conditions, and will lead to greater life
safety in case of general disaster.
The determination of acceptable and unacceptable risk requires judgments based on
weighing several factors including the nature of the hazard, the frequency, or risk, of a
damaging event associated with the hazard, and the relative number of persons
exposed to the risk. The degree or intensity of any specific hazard is a major
consideration in public mitigation efforts. Thus, hazards with a high life-loss potential
are less acceptable than hazards which primarily affect property, and hazards which
could impact entire communities are less acceptable than hazards which may impact
relatively few persons. Only minimal risk to critical facilities and functions (including
water supply, emergency services, evacuation routes, and medical and mass care
facilities) is considered acceptable since these facilities and functions are critical to
disaster recovery for entire communities.
Exposure to the natural hazards considered in the element is often voluntary; persons who
choose to purchase property on unstable ground or subject to wildfire and flooding are usually
aware of the potential hazard. On the other hand, exposure to some risks, such as exposure to
hazardous substances, is usually involuntary. Voluntarily taken risks are not necessarily ac-
ceptable from the public point of view because property owners have expectations that grading
and building regulations, fire services, and flood control works will provide a significant degree
of risk reduction. The greater capital and maintenance costs of public facilities in hazardous
areas, represent a disproportionate share of tax revenues for hazard mitigation.
10.5 SAFETY ELEMENT ORGANIZATION
This chapter of the General Plan is divided into six sections that present background
information, policies, maps, and implementation measures regarding:
o seismic hazards (earthquakes and faults, and the effects of strong earthquakes,
such as liquefaction);
10. Safety Element
10-3
o landslides and associated hazards;
o flooding hazards, including the impacts of the "greenhouse effect," subsidence,
and dam or levee failure;
o hazardous material uses, including the transport and storage of hazardous
materials, pipelines, etc.;
o dangers to water quality and public water supplies; and,
o disaster planning and the provision of public protection services.
10.6 SEISMIC HAZARDS
INTRODUCTION
Earthquakes are sudden releases of strain energy stored in the earth's bedrock. The
great majority of earthquakes are not dangerous to life or property either because they
occur in sparsely populated areas or because they are small earthquakes which release
relatively small amounts of energy. However, where urban areas are located in regions
of high seismicity, damaging earthquakes are expectable if not predictable events.
Seismic risk is assumed by every occupant and developer in Contra Costa County
because the County is within an area of high seismicity; the San Francisco Bay Region
has been impacted by more than ten severe earthquakes during historic time.
The major effects of earthquakes are ground shaking and ground failure. Severe
earthquakes are characteristically accompanied by surface faulting and less commonly by
tsunamis and seiches, further described in the "Flood Hazards" section of this chapter.
Flooding may also be triggered by dam or levee failure resulting from an earthquake, or
by seismically-induced settlement or subsidence. All of these geologic effects are capable
of causing property damage and, more importantly, risks to life and safety of persons.
A fault is a fracture in the earth's crust along which the rocks on opposite sides have
moved relative to each other. By definition, active faults have a high probability of future
movement. With regard to planning and development, two aspects of fault displacement
should be considered: (a) the effects that sudden movement along faults may have on
structures built across their traces, and (b) the relatively slow effects of fault creep on
structures built across their traces. Fault displacement involves forces so great that the
only means of limiting damage to man-made structures is to avoid the traces of active
faults. Any movement beneath a structure, even on the order of an inch or two, could
have catastrophic effects on the structure and its service lines.
Energy release events on an active fault may alternate from one trace to another, and
movement on a master fault may trigger adjustments on minor, subsidiary faults.
Because of these factors, fault traces which intersect or parallel known active faults
warrant special consideration during project review.
For the purpose of this Safety Element, earthquakes are classified according to the
descriptive names listed in Table 10-1.
Earthquake planning and seismic review often use a set of descriptions of predicted
earthquake capabilities called "maximum credible earthquake" and "maximum probable
earthquake." The maximum credible earthquake is the maximum earthquake that appears
capable of occurring. The maximum probable earthquake is the maximum earthquake
believed likely to occur during a 100-year interval. The maximum credible and maximum
probable earthquakes for various faults in the county are defined later in this chapter.
10. Safety Element
10-4
TABLE 10-1
EARTHQUAKE SIZE DESCRIPTIONS
Descriptive Title
Richter
Magnitude Intensity Effects1
Minor Earthquake 1 - 3. 9 Only observed instrumentally or felt
only near the epicenter. Modified
Mercalli Scale, intensity IV or less.
Small Earthquake 4 - 5.9 Surface fault movement is small or
does not occur. Felt at distances of up
to 20 to 30 miles from epicenter. May
cause damage (Modified Mercalli
Scale, VII) in small area.
Moderate earthquake 6 - 6.9 Moderate to severe earthquake
range; fault rupture probable.
Major earthquake 7 - 7.9 Landslides, liquefaction and ground
failure triggered by shock waves.
Great earthquake 8 - 8+ Damage extends over a broad
area, depending on magnitude and
other factors. Maximum intensity
ranges from VIII to XII on the
Modified Mercalli Scale.
Source: Compiled by Contra Costa County Conservation and Development Department.
The overall energy release of an earthquake is its most important characteristic, but
not the only criterion required for seismic safety planning or construction design. Other
important attributes include an earthquake's duration, its related number of significant
stress cycles and its accelerations. Structures capable of withstanding more powerful
earthquakes can fail in a less severe earthquake of long duration or due to especially
high local accelerations.
Local Geology
In order to understand the fault system in Contra Costa County, where earthquakes
are most likely to occur, a brief discussion of the local geology is necessary. Figure 10-
1 illustrates the generalized geology of the County and the accompanying Table 10-2
summarizes the County's "geologic column" and geologic time scale.
The geology of Contra Costa County is dominated by several northwest trending fault
systems which divide the County into large blocks of rock. For example, the Briones Hills
are bounded by the Hayward fault on the west and elements of the Franklin-Calaveras
fault system on the east. Within a particular block the rock sequence consists of (1) a
basement complex of broken and jumbled pre-Tertiary sedimentary, igneous and
metamorphic rocks; (2) a section of younger Tertiary sedimentary rocks and some
volcanic rocks (flows and tuffs) which locally intertongue with and overlie the sedimentary
section; and, (3) surficial deposits including stream alluvium, colluvium (slopewash
deposits at the foot of steeper slopes), slides, alluvial fans, and Bay Plain deposits. The
character of each of these categories of rocks is summarized in Table 10-2.
From the perspective of seismic safety planning, the older, coarser, and well-drained
materials tend to be stable during earthquakes, while younger, fine-grained and water-
saturated deposits tend to be less stable. Colluvium is often marginally stable to
unstable. A disproportionate share of landslides originate in colluvium.
10. Safety Element
10-5
TABLE 10-2
GEOLOGIC TIME SCALE
GENERALIZED STRATIGRAPHIC SECTION
AND LITHOLOGIC CHARACTERISTICS
Generalized Stratigraphic Section
Geologic Age
(Absolute Age)1 Formation Name General Lithologic Description
Quaternary
Holocene & Pleistocene
(0-2)
Alluvium Includes all types of alluvial deposits. In Central
Coast Range, it is separated from Contra Costa
Group by an angular unconformity.
Tertiary
Pliocene
(2-5)
Contra Costa Group
Bald Peak Basalt
Siesta Formation
Moraga Formation
Orinda Formation
Conglomerate, sandstone, siltstone with minor
amounts of limestone and tuff; rapid face changes.
Some basalt and andesite (volcanic) flows. Clastics
are semi-consolidated and contain montmorillonite
clay. Topographic form highly variable.
Miocene
(5-24)
San Pablo Group (Diablo Range)
Neroly Sandstone
Cierbo Sandstone
Briones Sandstone
Predominantly marine sandstone with interbeds
of shale, siltstone and minor conglomerate.
Upper part includes some non-marine beds (e.g.,
Diablo Formation of Weaver, 1944)
Monterey Group (Briones Hills)
Rodeo Shale
Hambre Sandstone
Tice Shale
Claremont Shale
Sobrante Sandstone
Siliceous shale and fine-grained sandstone.
Some zones of rhythmically bedded chert and
shale. Bituminous in places. Underlies
moderately steep-to-steep hillsides in Briones
Hills.
Oligocene
(24-37)
San Ramon Formation Tuffaceous sandstone, tuff, minor conglomerate
and siltstone.
Eocene
(37-58)
Markley Formation
Nortonville Shale
Domengine Sandstone
Meganos Formation
Predominately indurated bedrock including
shale, siltstone and sandstone. Montmorillonitic
clay shales, unstable.
Paleocene
(58-66)
Martinez Formation Marine, Glauconite sandstone and shale. Shale
similar to Ecocene.
Cretaceous
(66-144)
Great Valley Sequence Great Valley Sequence: Massive beds of
sandstone alternating with siltstone and shale.
Minor conglomerate, limestone and lignite.
Complex folding and faulting. Crops out in
Briones Hills and Diablo Range.
Cretaceous-Jurassic
(In part
contemporaneous with
Great Valley Sequence
and Tertiary rocks.)
Franciscan Assemblage Cretaceous-Franciscan: Rhythmically bedded
graywacke Jurassic Assemblage sandstones, shale,
siltstones, radiolarian chert, and greenstone. Minor
amounts of limestone and schist. Partially
recrystallized and intruded by serpentine and
associated igneous rocks. Strongly deformed.
1Units of absolute age are millions of years before present.
Modified after Radbruch (1969). Compiled by Contra Costa County Conservation and Development Department.
Note: This table is generalized from original source materials. It is not an indicator of ground conditions on individual sites.
Faults are seldom-single cracks but are typically a series of quasi-parallel or en-
echelon breaks that comprise zones. These breaks form networks composed of major
and minor faults. A fault having recorded movement, or one which shows evidence of
geologically recent displacement (within about the last 11,000 years), is regarded as
"active" and is more likely to generate a future earthquake than a fault which shows no
signs of recent movement. Along with the criteria for fault activity, the last time of
faulting, based on geologic evidence, is used to access fault activity. The historic
record is so short, and earthquakes are so scattered, that they are used only as the
surest indicator of fault activity.
10. Safety Element
10-6
FIGURE 10-1
Generalized Geology of Contra Costa County
10. Safety Element
10-7
General Inventory of Seismic Faults
Figure 10-2 shows the earthquake faults that have been mapped in the County and categorizes
their recent activity. Further technical information is discussed in the appendix. Table 10-3
summarizes other available data on inferred active faults affecting Contra Costa County.
TABLE 10-3
AVAILABLE DATA ON INFERRED ACTIVE FAULTS
AFFECTING CONTRA COSTA COUNTY
Fault Name
Historic
Damaging
Earthquakes
Historic Surface
Faulting
Known Micro
seismic Activity
Estimated Maximum
Credible Earthquake
Estimated Maximum
Probable Earthquake
Preferred
magnitude
From
literature
Preferred
magnitude
From
literature
San Andreas 1838, 1906 Creep and Surface
Rupture
Yes 8.5 8.51 8.25 8.256
Hayward 1836, 1868 Creep and Surface
Rupture
Yes 7.25 7.0,1 6.9,2
7.25,3 7.0,5
6.8-7.0,6
7.676
6.5 6.756
Calaveras 1861 Surface Rupture None in Contra
Costa County
7.25 7.3,1 6.7,2
7.3,3,4,5 6.5-
7.2,6 7.57
6.255
6.5 6.56
Franklin 1898? None Known No 6.25 6.3,1 7.25,3 N/A N/A
Concord 1955 Creep Yes 6.5 6.5,4,5 6.1-
6.5,6 6.47
6.25,4,5
5.75 5.56
Greenville-
Clayton Segment
None Known None Known No 6.25 6.5,4,5 5.5 N/A
Greenville-
Marsh Creek
1980 Surface Rupture Yes 6.5 6.9,7 5.75 5.56
Greenville-
Segment
Unknown
5.54
Black Diamond
Area
None Known None Known Scattered clusters
in areas near faults
5.5 6.6,1 5.75,4
6.56
N/A
Antioch 1889?, 1965 Reported Creep Yes 6.5 5.75
References:
1Wesson and Others (1975)
2Herd (1979)
3Slemmons and Chung (1982)
4Earth Science Associates (1982)
5Earth Science Associates (1983)
6Woodward-Clyde Consultants (1984)
7Shedlock and Others (1980)
Notes:
(1) The maximum credible earthquake is the maximum earthquake that appears capable of occurring under the presently known tectonic framework. It is
a rational and believable event that is in accord with all known geologic and seismic facts. In determining the maximum credible earthquake, little
regard is given to its probability of occurrence, except that its likelihood of occurring is great enough to be of concern. It is conceivable that the
maximum credible earthquake might be approached more frequently in one geologic environment that in another. (California Division of Mines and
Geology (CDMG) Note 43, 1975)
(2) The maximum probable earthquake is the maximum earthquake that is likely to occur during a 100-year interval. It is to be regarded as a
probable occurrence, not as an assured event that will occur at a specific time. (CDMG Note 43, 1975).
In the context of geologic evidence for activity, those faults which have been active
during the Holocene period, approximately the last 11,000 years, are considered to be
active faults, and those faults which have been active during the Quaternary period,
approximately the last 1.6 million years, are considered to be potentially active faults.
This serves to differentiate faults for which sufficient evidence of recent activity has been
noted to explicitly include them as known geologic hazards, distinct from those faults for
which recent displacement is known or suspected, and whose latest activity has not
been determined, but may have been within approximately the last 11,000 years.
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10-8
FIGURE 10-2
Mapped Earthquake Faults in Contra Costa County
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10-9
FIGURE 10-3
Earthquake Locations in Contra Costa County (1934-1980)
10. Safety Element
10-10
In addition to faults which have been classified as active or potentially active, there are
others whose activity has not been clearly established by presently available information.
Some of these faults are shown on Figure 10-2. Others remain to be studied. Specifically,
there are numerous thrust faults in the County that present an apparently low risk of
surface fault rupture but are potential seismic sources. Perhaps the most significant fault
in this category is the blind thrust fault that defines the boundary between the Great
Valley of California and the Coast Range geomorphic provinces.
The County has been subjected to numerous seismic events, originating both on faults within the
County and in other parts of the region. Six major Bay Area earthquakes have occurred since
1800 that definitely affected the County, and at least two of the faults that produced them run
through or into the County. These earthquakes and the originating faults include the 1836 and
1868 earthquakes on the Hayward fault, and the 1861 earthquake on the Calaveras fault. Two
earthquakes, in 1838 and 1906, originated on the San Andreas fault, west of the county near
San Francisco or to the south, while one earthquake (with two major shocks) that caused some
damage in the County occurred in 1872 and was centered north of Contra Costa County in the
Vacaville-Winters area of Solano County. These latter events likely occurred on a thrust fault and
are not known to have been accompanied by surface fault rupture. A smaller earthquake,
centered near Collinsville in Solano County on a fault of uncertain identity, occurred in 1889.
Existing Policies and Regulations Affecting Seismic Hazards
The major State legislation regarding earthquake fault zones is the Alquist-Priolo Special
Studies Zones Act. The purpose of the Act is to regulate development near active faults
to mitigate the hazard of surface fault rupture. Under the Act, the State Geologist is
required to delineate "earthquake fault zones" along known active faults in California.
Cities and counties affected by the zones must regulate certain development projects
within the zones. They must withhold development permits for sites within the zones
until geologic investigations demonstrate that the sites are not threatened by surface
displacement from future faulting. Within Contra Costa County faults that a currently
zoned include the Hayward, Calaveras, Concord and Greenville faults.
The Seismic Hazards Mapping Act (the Act) of 1990 (Public Resources Code, Chapter 7.8,
Division 2) directs the California Department of Conservation (DOC), Division of Mines and
Geology (DMG) [now called California Geological Survey (CGS)] to delineate seismic hazard
zones. The purpose of the Act is to reduce the threat to public health and safety and to
minimize the loss of life and property by identifying and mitigating seismic hazards. Cities,
counties, and state agencies are directed to use the seismic hazard zone maps in their land-
use planning and permitting processes. Like the Alquist – Priolo Act, projects that fall under
the authority of the Seismic Hazards Act are subject to the outcome of comprehensive
geotechnical studies. Evaluation and mitigation of seismic hazards are to be conducted
under guidelines adopted by the California State Mining and Geology Board (SMGB).
The Act also directs SMGB to appoint and consult with the Seismic Hazards Mapping Act
Advisory Committee (SHMAAC) in developing criteria for the preparation of the seismic
hazard zone maps. SHMAAC consists of geologists, seismologists, civil and structural
engineers, representatives of city and county governments, the state insurance commissioner
and the insurance industry. In 1991, SMGB adopted initial criteria for delineating seismic
hazard zones to promote uniform and effective statewide implementation of the Act. These
initial criteria provide detailed standards for mapping regional liquefaction hazards. They also
directed CGS to develop a set of probabilistic seismic maps for California and to research
methods that might be appropriate for mapping earthquake-induced landslide hazards.
10. Safety Element
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The official Seismic Hazard Maps of Contra Costa County have not yet been issued, but official
maps have been issued for portions of San Francisco, Alameda and Santa Clara Counties, and
the mapping of Contra Costa County is anticipated in the near future. When official maps are
issued, the County would utilize these maps to identify areas that are deemed to present a
risk of liquefaction and seismically triggered landslide hazards that require study.
Projected Probability of Seismic Hazard Occurrences
Using the available data and information, an earthquake probability estimate has been
developed for Contra Costa County and is shown in Table 10-4. Table 10-4 evaluates
the likelihood that earthquakes capable of producing damage in Contra Costa County
will occur on certain faults during a 50-year period. (Fifty years is a rough average
nominal life of a structure.) The forecast shows that a structure built in Contra Costa
County is likely to be subjected to a severely damaging earthquake during its useful
life. Such an earthquake could originate in several locations.
Since a structure built in the region probably will be subjected to a damaging
earthquake during its useful life, it is reasonable that it be designed to survive the
event, or to at least protect its occupants and functions. To do this, architects and
engineers need to have information on earthquake characteristics, such as earthquake
accelerations and duration of strong ground shaking. These characteristics have been
estimated for selected faults in Table 10-5. The data in the table may be used as an
approximation of parameters prevailing over a large area and as a beginning point for
determining the parameters affecting a particular location.
TABLE 10-4
APPROXIMATE PROBABILITY OF OCCURRENCE OF
EARTHQUAKES ON SELECTED BAY AREA FAULTS
(50-YEAR PERIOD)
Causative Fault Magnitude
Approximate Probability of
Occurrence (over a 50-year period)
San Andreas 7.0 - 8.0
8.0 - 8.5
Likely
Intermediate
Hayward 6.0 - 7.0
7.0 - 7.5
Likely
Intermediate
Calaveras 6.0 - 7.0
7.0 - 7.5
Likely
Intermediate - Low
Concord 5.0 - 6.0
6.0 - 7.0
Likely
Intermediate - Low
Antioch 5.0 - 6.0
6.0 - 7.0
Likely
Intermediate - Low
Definition of Terms:
Likely: Greater than a 50% probability of occurrence.
Intermediate: A 15-50% probability of occurrence.
Low: Less than a 15% probability of occurrence.
Source: Contra Costa County Conservation and Development Department estimates
The tabulated earthquake characteristics in Table 10-5 are for "bedrock" for seismic
response purposes, and may differ in the near-surface materials. Solid ground or rock
tends to dampen ground motion while poorly consolidated and water-saturated
materials amplify ground motion. These data should be used only by qualified
personnel in project background evaluations, and by engineers and architects in their
development of structural design criteria.
10. Safety Element
10-12
TABLE 10-5
ESTIMATED MAXIMUM PARAMETERS FOR KNOWN FAULTS
AFFECTING CONTRA COSTA COUNTY
(BASED ON TABLE 10-3)
Fault San
Andreas Hayward Calaveras Concord
Clayton
/Greenville Antioch
Magnitude1 8.25 - 8.5 6.5 - 7.25 6.5 - 7.25 5.75 - 6.5 5.75 - 6.5 5.75 - 6.5
Duration of Strong Shaking2
(Seconds)
25 -37 18 - 30 18 - 30 7 - 22 7 - 22 7 - 22
Maximum Intensity (M.M.)3 IX - XI VIII - IX VIII - IX VII - VIII VII - VIII VII - VIII
Peak Horizontal Accelerations on
Rock4
Distance from Fault in Miles
5
10
20
30
40
50
.50 - .55
.45 - .50
.25 - .30
.20 - .25
.15 - .20
.10 - .15
.25 - .50
.15 - .40
.10 - .25
.05 - .20
.05 - .10
<.10
.25 - .50
.15 - .40
.10 - .25
.05 - .20
.05 - .10
<.10
.20 - .45
.15 - .30
.05 - .15
.05 - .10
<.05
<.05
.20 - .45
.15 - .30
.05 - .15
.05 - .10
<.05
<.05
.20 - .45
.15 - .30
.05 - .15
.05 - .10
<.05
<.05
Notes:
1 Magnitude Estimates from Table 10-3. The first listed magnitude for each fault is the maximum probable earthquake; the second i s
the maximum credible earthquake. The maximum probable earthquake for the San Andreas Fault is the historic 1906 earthquake.
2 Bracketed duration for ground motions are 0.5g within 10 miles of the fault. Estimates based on relationships developed by Bolt (1973).
3 Estimate based on relationships developed by Richter (1958). Modified Mercalli scale is included in Appendix M.
4 Estimates based on relationships developed by Seed and Idriss (1972), Joyner and Boore (1981), Campbell (1981) and Sadigh (1983).
The ways different areas of the County would react to ground shaking have been
mapped using approximation methods (described in a technical background report
which is an appendix to this document). Figure 10-4 illustrates the estimated seismic
susceptibility to damage based upon this mapping.
Areas situated on hard bedrock (e.g. the Briones Hills, Las Trampas Ridge, Diablo
Range) may be expected to perform satisfactorily under earthquake conditions,
provided that ground materials near the surface do not fail. Areas underlain by weakly
consolidated sedimentary rocks (e.g. Pinole Ridge, the Tassajara Area, Alamo) are
considered to possess a moderately low to moderate damage susceptibility.
The characteristics of ground motion in alluvial areas will differ somewhat from nearby
bedrock areas (e.g., higher amplitudes, longer period, somewhat higher accelerations, etc.),
and these differences may be important in the design of sophisticated structures. Areas
underlain by firm, dry alluvium is considered to possess a moderate damage susceptibility.
Areas underlain by young bay mud and deposits of the Sacramento-San Joaquin delta are
considered to possess the highest damage susceptibility. Most of the County's development
and population are located in areas of moderate to moderately low damage susceptibility.
Liquefaction is a specialized form of ground failure caused by earthquake ground motion.
It is a "quicksand" condition occurring in water-saturated, unconsolidated, relatively clay-
free sands and silts caused by hydraulic pressure (from ground motion) forcing apart soil
particles and forcing them into quicksand-like liquid suspension. In the process, normally
firm, but wet, ground materials take on the characteristics of liquids.
Catastrophic ground failures may result from liquefaction that pose a major threat to the
safety of engineered structures. Major landslides, settling and tilting of buildings on level
ground, and failure of water retaining structures have all been observed as a result of
this type of ground failure. It should be emphasized that great earthquakes anywhere in
the Bay Area are capable of triggering liquefaction in Contra Costa County.
10. Safety Element
10-13
FIGURE 10-4
Estimated Seismic Ground Response
10. Safety Element
10-14
Historically, ground failure in its various forms, including liquefaction, has been a
problem in areas of continually wet, unconsolidated geologic units. In Contra Costa
County, the areas which are most susceptible to ground failure include the geologically
young sediments of the San Francisco Bay estuary, including the Delta lowlands.
Within the area of continually wet, unconsolidated deposits (Zone IV on Figure 10-4), the
degree of seismic risk is closely related to local ground conditions. A site underlain by a
great thickness of potentially unstable material (soft, compressive mud and loose, clay-
free sands, etc.) is extremely hazardous. It should be recognized that such a site has a
very limited development potential. Conversely, a site underlain by a minimum thickness
of soft mud possesses a much better development potential. Utilizing existing knowledge
of foundation engineering, such a site could be made suitable for a variety of land uses.
Liquefaction presents the potential for the most serious consequences in the Delta.
Several pre-development studies have confirmed that a high potential for liquefaction
exists below levees and proposed developments. This potential presents the possibility
that several failures can occur simultaneously on a single levee, possibly preventing
access for repairs. Flooding of protected islands would then be unpreventable and would
make emergency relief and later repair very difficult. (A further discussion of flooding
and liquefaction in the Delta area is included in the "Flood Hazards" section below.)
Figure 10-5 shows the estimated liquefaction potential for the County, based on geologic
conditions (summarized in Figure 10-1), and a review of soils data from a number of sources.
This map will be utilized until the new official seismic hazard maps are published and available.
Areas underlain by hard bedrock are not subject to liquefaction, so these can be eliminated
from consideration when large areas are being evaluated on a generalized basis. In Contra
Costa County, such areas comprise about half of the land area, but almost all of that has hilly
topography. Areas with deep water tables and those underlain by well consolidated ground
materials typically have low or moderate liquefaction potentials. The cities of western, central
and northern Contra Costa County fall into these categories.
Geologically young and water-saturated sandy sediments, such as those found in the
extensive shoreline areas in western and northeastern county locations and the delta,
are highly susceptible to liquefaction. Soil engineering studies for subdivision and other
major land development projects should make a careful appraisal of the liquefaction
potential and the possible consequences of such liquefaction.
SEISMIC HAZARD ISSUES
In areas of substantial risk, geologic conditions should be a primary determinant of land
use. Generally, urban or suburban uses or intensities should not be planned for areas
where geologic conditions would result in unacceptable risks to life and safety, and areas
where the public costs of overcoming geologic deficiencies would exceed public benefits.
It should be recognized, however, that much can be done to mitigate potentially
hazardous conditions. Project approvals in areas of substantial risk should be based on
knowledge of local ground conditions and appropriate mitigation. Because it is
impractical for government to prepare detailed geologic information on a countywide
basis, it is preferable to deal with geologic conditions through project review.
State law (1986) requires that jurisdictions prepare an inventory of un-reinforced
masonry structures and adopt local ordinances to improve or replace this type of
structure. Un-reinforced masonry structures are generally believed to be prone to
collapse in an earthquake with resultant high risk of deaths and injuries. This was
recently confirmed by the Paso Robles earthquake of 2003.
10. Safety Element
10-15
FIGURE 10-5
Estimated Liquefaction Potential
10. Safety Element
10-16
Certain public and institutional services are needed immediately following an
earthquake to aid the injured, prevent additional casualties, and protect property. It is
imperative that these critical and emergency service facilities survive an earthquake
and remain operative. Other public facilities such as emergency shelters and gathering
areas for separated family members are also important facilities that should be
designed to survive any earthquake.
Underground components of utility systems are often extensively damaged during
significant earthquakes. Pipelines for domestic and fire fighting water, sewer service,
gas, and for electrical services and communications can be shattered. Above-ground
transmission and distribution systems are also susceptible to earthquake damage, but
they are usually easier and less expensive to restore than the underground
installations. In addition, utility plants and stations are subject to earthquake damage.
Transportation facilities, especially the bridges, roads and streets of the arterial
network, are "critical" or "essential" facilities for responding to the effects of a
substantial earthquake because they are necessary for the movement of emergency
vehicles, supplies, and evacuation transport. Later, they are necessary to accomplish
reconstruction and restoration of the local economy. For example, airports enable
damage-assessment reconnaissance flights immediately after a disaster, and
accommodate the evacuation of casualties and supplies afterwards. The full range of
transportation facilities, including railroads, ports, and public transportation systems,
have roles to play in the recovery process.
Transportation systems are vulnerable to earthquakes. Road and streets are easily
blocked, and are often buckled and broken, but emergency routes can be readily
improvised. The interchanges of freeways and similar installations (bridges and
overpasses, for example) are often damaged but not readily restored. A major
earthquake impacting Contra Costa County would be expected to cause widespread
damage to its transportation systems. The linear elements of these systems--roads,
railroad tracks, and BART tracks--necessarily cross various earthquake faults as well as
areas susceptible to ground failure. Landsliding from non-earthquake causes is a
recurring problem that would be intensified by ground shaking.
Critical industrial facilities are of special concern because of potential hazardous
materials spillage or critical industrial processes disruption. For critical industrial
facilities, seismic safety considerations must include the location of plants and storage
areas, and the design and construction of industrial structures. As a result of
compliance with out-of-date building codes, some existing installations need to be
evaluated in light of current knowledge.
Opportunities and Constraints
Table 10-6 details the acceptable risks from seismic events relative to various types of
structures by use and occupancy. This scale was developed by the California
Legislature's Joint Committee on Earthquake Planning and has been adopted in most
California building codes and by most California planning agencies.
Following the experience of the San Fernando Earthquake of 1971, building code
provisions have strengthened many structural design criteria. However, a major
deficiency in the code is the lack of strict criteria governing attachment of non-structural
elements which present a danger to persons if they are dislodged during an earthquake.
10. Safety Element
10-17
TABLE 10-6
A SCALE OF ACCEPTABLE RISKS
Level of Acceptable Risk Kinds of Structures
Extra Project Cost Probably
Required to Reduce Risk to
an Acceptable Level
1. Extremely low1 Structures whose continued functioning is
critical, or whose failure might be catastrophic:
nuclear reactors, large dams, power intertie
systems, plants manufacturing or storing
explosives or toxic materials.
No set percentage (whatever is
required for maximum attainable
safety).
2. Slightly higher than under
level 1
Structures whose use is critically needed after a
disaster: important utility centers: hospitals, fire
police, emergency communication facilities; fire
stations, and critical transportation elements such
as bridges and overpasses; also smaller dams.
5 to 25 percent of project cost2
3. Lowest possible risk to
occupants of the
structure2
Structures of high occupancy, or whose use after a
disaster would be particularly convenient: schools,
churches, theaters, large hotels, and other high-
rise buildings housing large numbers of people,
other places normally attracting large
concentrations of people, civic buildings such as fire
stations, secondary utility structures, extremely
large commercial enterprises, most roads,
alternative or non-critical bridges and overpasses.
5 to 15 percent of project cost4
4. An "ordinary" level of risk
to occupants of the
structure3
The vast majority of structures: most
commercial and industrial buildings, small
hotels and apartment buildings, and single-
family residences.
1 to 2 percent of project cost, in
most cases (2 to 10 percent of
project cost in a minority of cases)4
1 Failure of a single structure may affect substantial populations.
2 These additional percentages are based on the assumption that the base cost is the total cost of the building or other facility when
ready for occupancy. In addition, it is assumed that the structure would have been designed and built in accordance with current
California practice. Moreover, the estimated additional cost presumes that structures in this acceptable-risk category are to embody
sufficient safety to remain functional following an earthquake.
3 Failure of a single structure would affect primarily only the occupants.
4 These additional percentages are based on the assumption that the base cost is the total cost of the building or facility when ready for
occupancy. In addition, it is assumed that the structures would have been designed and built in accordance with current California
practice. Moreover, the estimated additional cost presumes that structures in the acceptable-risk category are to be sufficiently safe to
give reasonable assurance of preventing injury or loss of life during any earthquake, but otherwise not necessarily to remain functional.
5 "Ordinary risk": Resist minor earthquakes without damage, resist moderate earthquakes without structural damage, but with some
non-structural damage; resist major earthquakes of the intensity or severity of the strongest experienced in California, without
collapse, but with some structural as well as non-structural damage. In most structures, it is expected that structural damage, even
in a major earthquake, could be limited to repairable damage. (Structural Engineers Association of California).
Source: Meeting the Earthquake Challenge, Part 1, p. 9.
The major technical impediment to the development of programs to correct hazardous
structural conditions or "dangerous buildings" is the lack of a comprehensive and
systematic inventory. Conventional sources of generalized structural information, such as
the Federal Census of Housing and Land Use inventories for the general plan, are not
adequate to make even large-area policy planning assessments of where problem
structures are located, what their problems are, and how many structures are involved.
Similarly, normal sources of information on individual structures are inadequate to provide
the kinds of information needed for implementation and enforcement programs. In both
cases, special inventories and specialized reviews of existing data sources are necessary
to prepare seismic safety programs dealing with structures.
10. Safety Element
10-18
The Post-Earthquake Recovery and Redevelopment Advisory Group to the Legislature's
Joint Committee on Seismic Safety has made a series of recommendations which
suggest control mechanisms that can be instituted prior to an earthquake, and which
will go into effect automatically in the post-earthquake period to provide a framework
for reconstruction and redevelopment. The objectives of these recommendations are to
minimize recovery problems and maximize the degree of seismic safety afforded to
future generations inhabiting the affected area.
Evaluation Of Existing Plans, Policies and Regulations
This advisory group has recommended that counties and cities provide for post-disaster
conditions in the General Plans. First, jurisdictions need to ensure that proper consideration be
given to changes in land use in areas that are heavily damaged by future earthquakes. The
planning staff should develop contingency procedures for immediate updating of the General
Plan for areas that are heavily damaged by a severe earthquake. Additionally, it is suggested
that contingency redevelopment be considered in preparing or updating area plans.
The most expeditious results from this program can be gained through the process of
public reviews for both public and private projects because they rely to a substantial
extent on the project sponsor to respond to the findings of studies prepared for the
project. The basic recommendation is that the Safety Element be utilized to its fullest in
performing project reviews. It is intended to guide public and private planning for
development and public works, emergency operations, post-disaster recovery assistance,
and redevelopment. The policies are suggested for consideration by all public, private, and
utility agencies in the County which impact on, or can improve the state of public safety,
guide public and private planning for development and for public works, emergency
operations, post-disaster recovery assistance, and redevelopment. The policies are
suggested for consideration by all public, private, and utility agencies in the County which
impact on, or can improve, public safety.
The purpose of the preceding discussion has been to make observations and preliminary
estimates of the prevalence, location and degree of hazard posed by certain types of existing
structures and facilities. Furthermore, it is intended to indicate the scope, direction and
magnitude of the subsequent review of individual facilities. It is apparent that the highest pri-
ority should be given to (a) critical structures (including industrial facilities and high occupation
buildings) that are sited in hazardous fault zones, in areas subject to seismically-triggered
flooding, and in marshland areas; (b) building types that are know to be hazardous; (c) older
structures which have not had the benefit of seismic design provisions.
SEISMIC HAZARD GOALS
10-A. To protect human life and reduce the potential for serious injuries from earthquakes;
and to reduce the risks of property losses from seismic disturbances which could
have severe economic and social consequences for the County as a whole.
10-B. To reduce to a practical minimum injuries and health risks resulting from the
effects of earthquake ground shaking on structures, facilities and utilities.
10-C. To protect persons and property from the life-threatening, structurally and financially
disastrous effects of ground rupture and fault creep on active faults, and to reduce
structural distress caused by soil and rock weakness due to geologic faults.
10-D. To reduce to a practical minimum the potential for life loss, injury, and economic
loss due to liquefaction-induced ground failure, levee failure, large lateral land
10. Safety Element
10-19
movements toward bodies of water, and consequent flooding; and to mitigate
the lesser consequences of liquefaction.
SEISMIC HAZARD POLICIES
10-1. Contra Costa County, as part of an area with high seismicity, shall recognize
that a severe earthquake hazard exists and shall reflect this recognition in its
development review and other programs.
10-2. Significant land use decisions (General Plan amendment, rezoning, etc.) shall be
based on a thorough evaluation of geologic-seismic and soils conditions and risk.
10-3. Because the region is seismically active, structures for human occupancy shall be
designed to perform satisfactorily under earthquake conditions (see Table 10-6).
10-4. In areas prone to severe levels of damage from ground shaking (i.e., Zone IV
on Map 10-4), where the risks to life and investments are sufficiently high,
geologic-seismic and soils studies shall be required as a precondition for
authorizing public or private construction.
10-5. Staff review of applications for development permits and other entitlements,
and review of applications to other agencies which are referred to the County,
shall include appropriate recommendations for seismic strengthening and
detailing to meet the latest adopted seismic design criteria.
10-6. Structures for human occupancy, and structures and facilities whose loss
would substantially affect the public safety or the provision of needed
services, shall not be erected in areas where there is a high risk of severe
damage in the event of an earthquake.
10-7. The County should encourage cooperation between neighboring government agencies
and public and private organizations to give appropriate attention to seismic hazards
to increase the effectiveness of singular and mutual efforts to increase seismic safety.
Groundshaking Policies
10-8. Ground conditions shall be a primary consideration in the selection of land use
and in the design of development projects.
10-9. In areas susceptible to high damage from ground shaking (i.e., Zone IV on Map
10-4), geologic-seismic and soils studies shall be required prior to the authorization
of major land developments and significant structures (public or private).
10-10. Policies regarding liquefaction shall apply to other ground failures which might result
from groundshaking but which are not subject to such well-defined field and
laboratory analysis.
Faults and Fault Displacement Policies
10-11. Classify as active those faults which have ruptured the ground surface during
Holocene geologic time, roughly the last 10,000 years. Classify as potentially
active faults which displace Quaternary geologic units, those formed during
approximately the last 2 to 3 million years.
10-12. Prohibit construction of structures for human occupancy, and structures whose
loss would affect the public safety or the provision of needed services, over
the trace of an active fault.
10. Safety Element
10-20
10-13. In areas where active or inactive earthquake faults have been identified, the
location and/or design of any proposed buildings, facilities, or other development
shall be modified to mitigate possible danger from fault rupture or creep.
10-14. Preparation of a geologic report shall be required as a prerequisite before
authorization of public capital expenditures or private development projects in
areas of known or suspected faulting.
10-15. To the extent practicable, the construction of structures requiring a high
degree of safety and other critical structures shall not be allowed in an active
or potentially active fault zone.
10-16. When such a critical structure must be located in a fault zone, the structure shall
be carefully sited, designed and constructed to withstand the anticipated
earthquake stresses.
10-17. Locate roads, particularly those which carry important utilities or large volumes
of traffic, over active faults only where other alternatives are impractical.
Liquefaction Policies
10-18. This General Plan shall discourage urban or suburban development in areas
susceptible to high liquefaction dangers and where appropriate subject to the
policies in 10-20 below, unless satisfactory mitigation measures can be
provided, while recognizing that there are low intensity uses such as water-
related recreation and agricultural uses that are appropriate in such areas.
(For the Bethel Island Area, the adopted specific plan policies will apply.)
10-19. To the extent practicable, the construction of critical facilities, structures
involving high occupancies, and public facilities shall not be sited in areas
identified as having a high liquefaction potential, or in areas underlain by
deposits classified as having a high liquefaction potential.
10-20. Any structures permitted in areas of high liquefaction danger shall be sited,
designed and constructed to minimize the dangers from damage due to
earthquake-induced liquefaction.
10-21. Approvals to allow the construction of public and private development projects
in areas of high liquefaction potential shall be contingent on geologic and
engineering studies which define and delineate potentially hazardous geologic
and/or soils conditions, recommend means of mitigating these adverse
conditions; and on proper implementation of the mitigation measures.
SEISMIC HAZARD IMPLEMENTATION MEASURES
10-a. Require that structures intended for human occupancy are adequately set back
from active and potentially active fault traces. Ensure that minimum setbacks take
into account the varying degrees of seismic risk and the consequences of failure.
10-b. Utilize the land in the setback zones along active and potentially active fault
traces for open forms of land use that could experience displacement without
endangering large numbers of people or creating secondary hazards. Examples
are yards, greenbelts, parking lots, and non-critical storage areas.
10-c. Require comprehensive geologic and engineering studies for any critical
structure, whether or not it is located within a Special Studies Zone.
10. Safety Element
10-21
10-d. Through the environmental review process, require geologic, seismic, and/or
soils studies as necessary to evaluate proposed development in areas subject to
groundshaking, fault displacement, or liquefaction.
10-e. Evaluate and, where necessary, upgrade water distribution, sewage disposal, gas and
electricity, communications and other service facilities in areas subject to seismic hazards.
10-f. Evaluate and upgrade hospitals, bridges, major roads, and other essential
structures to be able to withstand seismic hazard.
10-g. Establish a clearinghouse for vital service records and distribution system design plans.
10-h. In areas that could become isolated in the event of a major earthquake, ensure
that adequate medical aid, water supply, waste disposal, and other public health
and safety services are available.
10-i. Adopt ordinance code provisions related to the repair or replacement of
unreinforced masonry structures.
10-j. Prepare an inventory of post-disaster public facilities to be used for emergency
shelter and gathering places.
10-k. Authorize the Conservation and Development Department to immediately begin
updating the general plan in areas which are heavily damaged by a severe
earthquake.
10-l. Develop ordinances incorporating existing Board of Supervisors' policy on
administering the Alquist Priolo Special Studies Zone Act.
10.7 GROUND FAILURE AND LANDSLIDE HAZARDS
INTRODUCTION
The major geologic hazards in Contra Costa County, aside from earthquake rupture and
direct effects of ground shaking, are unstable hill slopes and reclaimed wetlands and marsh
fill areas. Slopes may suffer landslides, slumping, soil slips, and rockslides. Reclaimed
wetlands, whether filled or not, experience amplified lateral and vertical movements which
can be damaging to structures, utilities, and transportation routes and facilities.
Landslides and other ground failures occur during earthquakes, triggered by the strain
induced in soil and rock by the groundshaking vibrations, and during non-earthquake
conditions, most frequently during the rainy season. Both natural and man-made
factors contribute to these slope failures. Contra Costa County's damage costs after a
large earthquake could be high in proportion to the State as a whole because of its
large area of hilly terrain and high proportion of recent, poorly consolidated geologic
formations which are prone to slope failure.
Ground failure occurs when stresses in the ground exceed the resistance of earth
materials to deformation or rupture. This instability can be triggered by earthquake
shaking, which instantaneously places high stresses on earth materials by loss of soil
strength due to saturation or seismic shaking. Ground failure can also be triggered by
man-made changes, such as loading a steep slope or unstable soils.
The manifestations of ground failure are complex and highly variable; they include
numerous varieties of landslides, sloughing, liquefaction, ground cracking, lurching, lateral
10. Safety Element
10-22
spreading, subsidence and differential settlement. Whether ground failure may occur, and
the type of ground failure that may develop, depend on the topographic, geologic, and
hydrologic characteristics of the ground, as well as the extent of ground shaking.
Important effects of ground failure in addition to direct life and structure loss and
injuries, include loss of access for emergency services and repairs at important
facilities which are accessed by traversing unstable ground, and the potential release
of hazardous materials from containment facilities.
Landslides are perhaps the most common form of ground failure that is not caused by
earthquakes. In areas where a severe slope stability problem exists, landslide damage
can best be avoided by simply not building on the unstable ground. In some landslide-
prone areas, landslides can be totally removed or stabilized. Through good planning
and careful, controlled design, landslide losses can be all but eliminated.
Although landslides due to slope failure are most frequent in "wet years" with above-
average rainfall, they can occur at any time. Landslides may also occur on slopes of 15
percent or less; however, the probability is greater on steeper slopes, with old
landslide deposits being the most likely to experience failure.
Slope failures are not expected to produce a disaster affecting hundreds or thousands of
persons in the County. Rather, there is a persistent risk of damage to public and private
property including individual residences, roads, canals and reservoirs, and other facilities. On a
county-wide basis, the two most important factors influencing the performance of slopes are
the nature of the bedrock or surficial deposits and the slope angle. However, there are a
number of other factors which have a profound effect on the stability of a particular hillside. For
example, the presence or absence of deep-rooted vegetation; surface and subsurface drainage
conditions; thickness and engineering characteristics of soils and underlying weathered,
partially decomposed rock; orientation of bedding; or locally high rainfall can exert a controlling
effect on the intensity of natural processes occurring on a particular hillside.
County General Plans historically have recognized that major slope areas in excess of 26
percent are "not readily developable" and "undevelopable," recognizing the cost and
engineering difficulties of grading steep slopes as well as their inherent unsuitability. This
development limit in general agrees with customary limits throughout the Bay Area, and
varies only slightly from the 30 percent standard reference developed by the State Division of
Mines and Geology as the maximum developable slope. This is a state-wide reference which
does not reflect special conditions such as clayey soils prevalent in Contra Costa County.
Landslides and ground slippages are another form of ground failure which may be
precipitated by significant ground motion produced by earthquakes. Areas that are
subject to slides and slippages from other natural causes may be very hazardous under
earthquake conditions. This is also to say that earthquake effects will be more
extensive if a major earthquake occurs during the rainy season when ground
conditions are favorable to landsliding and ground slippage.
Whether a landslide will or will not occur at any specific, presently stable slope usually
cannot be predicted under "natural conditions" because of the range of natural
conditions and changes which occur with time. However, land which has experienced
landsliding in the past is believed to be generally more slide-prone, and also is more
sensitive to man-induced changes, such as grading, watering, removing or changing
the type of vegetation, and changing drainage patterns, among many possible factors.
10. Safety Element
10-23
Many old landslides reach a position of static stability that may be lost as a result of
earthquake shaking. The nearer to "equilibrium" condition the land is during normal
conditions, the more likely the equilibrium (stable condition) will be lost during
earthquake shaking. It should be noted again, however, that equilibrium may prevail
under natural conditions at some times, yet be reduced to marginal stability or
instability with different, natural or changed, conditions. Slight changes in equilibrium
may result in slow, barely recognizable, landslide movement, and/or movement which
periodically occurs under unfavorable conditions. Some landslides can be "turned on
and off" by allowing groundwater levels to rise or fall, or by changing the mass of
material in a particularly sensitive part of the landslide.
Map of Slopes and Landslide Hazard Areas
Maps showing degree of slope, landslides, landslide deposits, and relative slope
stability (or instability) have been produced by several State, regional, and federal
agencies; several such maps cover parts of Contra Costa County, and others, cover
areas as large as the entire nine-County Bay Area. These maps and studies are
referenced in the bibliography. When they are issued the Seismic Hazard Map will be
the official landslide maps. Until that time all available landslide maps should be
utilized. The only Countywide surficial deposits map is that prepared by Nilsen (1975).
Figure 10-6 shows the general locations where landslide deposits are prevalent, based on
U.S. Geological Survey landslide maps. Figure 10-7 illustrates in a general fashion the areas
of the County where the prevailing slopes are 26 percent or over. Neither of the maps is
definitive on a site-specific basis, but they do present an overview of stability and slope
conditions for large areas. They are not a substitute for site-specific engineering geology
and soils investigations. Nevertheless, several of the maps, especially those that are based
on field-checked aerial photograph study, are valuable tools for preliminary assessments of
the intensity or type of more detailed future investigations required for site development.
GROUND FAILURE AND LANDSLIDE HAZARD GOALS
10-E. To minimize the risk of loss of life or injury due to landslides, both ordinary
and seismically-induced.
10-F. To reduce economic losses and social disruption from landslides, both ordinary
and seismically-induced.
GROUND FAILURE AND LANDSLIDE HAZARD POLICIES
10-22. Slope stability shall be a primary consideration in the ability of land to be
developed or designated for urban uses.
10-23. Slope stability shall be given careful scrutiny in the design of developments
and structures, and in the adoption of conditions of approval and required
mitigation measures.
10-24. Proposed extensions of urban or suburban land uses into areas characterized by
slopes over 15 percent and/or generally unstable land shall be evaluated with
regard to the safety hazard prior to the issuance of any discretionary approvals.
Development on very steep open hillsides and significant ridgelines throughout the
County shall be restricted, and hillsides with a grade of 26 percent or greater shall
be protected through implementing zoning measures and other appropriate actions.
10. Safety Element
10-24
Figure 10-6
Geologic (Landslide) Hazards
10. Safety Element
10-25
Figure 10-7
Slopes Over 26%
10. Safety Element
10-26
10-25. Subdivision of rural lands outside planned urban areas down to the allowed
minimum parcel size shall be discouraged, if the parcels are within, or only
accessible through, geologically unstable areas.
10-26. Approvals of public and private development projects in areas subject to slope
failures shall be contingent on geologic and engineering studies which define and
delineate potentially hazardous conditions and recommend adequate mitigation.
10-27. Soil and geological reports shall be subject to the review and approval of the
County Planning Geologist.
10-28. Generally, residential density shall decrease as slope increases, especially
above a 15 percent slope.
10-29. Significant very steep hillsides shall be considered unsuitable for types of
development which require extensive grading or other land disturbance.
10-30. Development shall be precluded in areas when landslides cannot be adequately repaired.
10-31. Subdivisions approved on hillsides which include individual lots to be resold at
a later time shall be large enough to provide flexibility in finding a stable
buildable site and driveway location.
10-32. The County shall not accept dedication of public roads in unstable hillside
areas, or allow construction of private roads there which would require an
excessive degree of maintenance and repair costs.
GROUND FAILURE AND LANDSLIDE HAZARD IMPLEMENTATION MEASURES
10-m. Encourage the State Geological Survey to make preparation of Seismic
Hazards maps of Contra Costa County a priority.
10-n. Analyze the slope failure records of the Conservation and Development
Department and U.S. Geological Survey and recommend any needed
improvements in the County's grading ordinance.
10-o. Consider adoption of a hillside preservation ordinance in order to implement
the policies of the Safety Element and other elements of the General Plan.
10-p. Refer development proposals in areas of potential land instability or geologic
hazards to a registered engineering geologist for review and recommendation.
10-q. Through the environmental review process, require geologic and engineering
studies as necessary to evaluate proposed development in areas subject to
potential landslide hazards.
10-r. General Plan amendment requests which involve parcels with slopes of over
15 percent shall be accompanied by a geological/soils report.
10.8 FLOOD HAZARDS
INTRODUCTION
Substantial areas within Contra Costa County are subject to flooding. According to records
maintained by the Federal Emergency Management Agency (FEMA), the majority of the
County's creeks and shoreline areas lie within the 100-year flood plain, i.e., an area subject
to flooding in a storm that is likely to occur (according to averages based upon recorded
measurements) once every 100 years. The FEMA records are maintained as a means of
determining flood insurance rates through the National Flood Insurance Program.
10. Safety Element
10-27
In the West and Central County, these areas include portions of the shoreline in the
vicinity of Richmond, Hercules, Rodeo, Crockett, Port Costa, and Martinez; most creeks
in urbanized areas, including Concord, Walnut Creek, and the San Ramon Valley; and
reservoirs and creeks located on undeveloped East Bay Regional Park District (EBRPD)
and East Bay Municipal Utility District (EBMUD) lands. In the East County, substantial
acreage lies within the 100-year flood plain, including Bethel Island, the Veale Tract,
Holland Tract, Franks Tract, Jersey Island, and the area in the Byron vicinity. Portions of
the Pittsburg, Antioch, and Brentwood areas, as well as a number of creeks in East
County, are also subject to flooding.
The most serious flood hazard that exists in Contra Costa County relates to the system
of levees that protect the islands and adjacent mainland in the San Joaquin-
Sacramento River Delta area in eastern Contra Costa. Levees are basically long,
continuous dams that keep water out of a lower area, such as the Delta islands, many
of which are at an elevation just above or below sea level.
The islands in the California Delta were drained during the nineteenth century to create
high quality agricultural land. Since then, the peat-laden soil of many of the islands has
oxidized, resulting in a sinking of their island floors and consequently requiring the
construction of higher and heavier levees. Levee failure occurs in some areas where
levees rest on soft mud, silt, or peat.
The islands continue to flood. In general, the islands have been reclaimed after each
flood. However, Franks Tract State Park, essentially a lake east of Bethel Island, and
the Big Break area of water north of Oakley, are visible reminders that it is not always
practical or economical to reclaim flooded lands. Flooding problems in the Delta area
have also been exacerbated by boat movement (primarily recreational) on the
waterways which causes waves that accelerate the natural process of levee erosion.
The threat of levee failure during periods of high water is constant. In the years 1973,
1980, 1982, 1983, and 1986, one or more Delta island levees failed or were overtopped,
and some of these events were summer breaks that did not occur at times of high storm
runoff. Some islands in the Delta have been flooded two or three times since 1980.
The possibility that flooding will occur on the islands in the Delta is greatly increased
by two ongoing, natural processes, which compound the dangers that periodic high
tides or strong winter storms may breach a portion of the existing levee system. The
two natural processes which impact the integrity of the levee are rising sea levels,
caused by the world-wide "greenhouse effect," and "subsidence."
The greenhouse effect is a phenomenon that is projected to cause a rise in sea level over
the next century, thus creating potential flooding problems. Hydrologists estimate the rate
of rise may increase from the present one-half foot per century to approximately two to
eight feet. The anticipated rise is believed to be caused by warming of the global climate
due to accumulation in the atmosphere of gases such as carbon dioxide, methane, and
chlorofluorocarbons which result from fossil fuel burning and deforestation of tropical rain
forests. Since many factors affect global climates, the rate of change over a relatively
short time-period, even a century, is very difficult to establish. The U.S. Environmental
Protection Agency suggests that a rate of four feet per century be assumed for planning
purposes for the San Francisco Bay Area. It is important to note that the existing FEMA
flood hazard maps do not include the greenhouse effect in their potential flooding analysis.
10. Safety Element
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In Contra Costa County, subsidence is caused by the natural process of oxidation of island
peat soils, resulting in a gradual sinking of the ground. As many of the islands in the Delta
(along with their levees) sink in elevation, the levees that protect the island's agricultural
and/or residential uses must be raised and reinforced by adding more earth fill to the top
of the levees. Recent evidence indicates that many islands have experienced significant
subsidence over the last several decades. For example, it is estimated that Webb Tract in
Contra Costa County has subsided up to 17 feet, and Bacon Island adjacent to Contra
Costa County has subsided approximately 14 feet. Most reclaimed portions of the Delta in
the County have subsided at least 10 feet. Areas that have experienced a measurable
amount of subsidence are illustrated in Figure 10-8, Flood Hazards Map included in a later
section of this chapter. These areas are highly susceptible to flooding.
A number of causes for subsidence have been identified. The oxidation-decay and
shrinkage of peat and other soils which are rich in organic matter and fine clay
particles may be the largest contributor to the problem. However, the withdrawal of
shallow ground water for surface drainage may also cause surface compaction and/or
soil shrinkage, which results in a loss of elevation. There is also evidence that the
pumping of groundwater, oil, or gas supplies from underneath several of the islands
may be contributing to the natural consolidation and subsidence. Natural "tectonic"
subsidence may also be contributing to the problem.
There are great difficulties involved in estimating the amounts and rates of subsidence
from island to island in the Delta, since subsidence changes the elevation of bench
marks, the survey points from which elevations are determined. It is first necessary to
establish elevation control from stable areas outside the Delta, which requires very
long survey lines. Recent work is concentrating on the use of an unmanned space
satellite as a "survey platform" from which to study changes in elevations.
The consequence of subsidence and the possibility of sea levels rising due to the
greenhouse effect is the increased potential that levees will fail and tidewater and high river
water will inundate farmed and populated areas in the Delta. The California Delta in Contra
Costa and in the adjoining counties has historically been devoted to agriculture and its
population has remained small. However, growing commercial recreation and residential
uses, as evidenced by the success of year-round subdivisions such as Discovery Bay, are
leading to increases in the permanent population of the area. It will become increasingly
more important, but also more difficult, for the County to provide adequate flood protection
to residents and businesses in the Delta area. New urban development should be allow only
if long term, year-round flood protection can be provided to the area.
Allowing more residential and commercial development on or near the islands of the Delta
increases the disaster potential of subsidence and flooding when levees fail. Approving land
uses in the Delta area that support significant new populations must be carefully measured
in terms of the potential loss of lives and property that could occur in the event of a major
flood. The economic consequences of certain development should also be studied.
Seismicity presents additional special problems in the Delta. Delta levees are, in
places, underlain by sands that are susceptible to ground failures including liquefaction
during an earthquake. Strong earthquake shaking can cause the entire levee
foundation to lose strength, leading to levee failure. Many levees are themselves
constructed of liquefiable sand.
10. Safety Element
10-29
Figure 10-8
Flood Hazard Areas
10. Safety Element
10-30
According to a report prepared for the East Bay Municipal Utility District, whose aqueduct
pipes cross the Delta, twelve separate faults are capable of causing ground motion sufficient
to cause liquefaction, requiring accelerations on the order of 7 to 27 percent of gravity (0.07
to 0.27g), with shaking lasting from about 5 to 23 seconds. A 1985 study by a State
Department of Water Resources geologist noted levee slips and cracks from five recent
earthquakes, some as distant as 150 miles away from Contra Costa County. A large nearby
earthquake could cause a number of simultaneous levee failures, making repairs difficult
because the levees are the only land access to many points following a levee break.
In addition to the flooding hazards associated with levee failure caused by an
earthquake, fault ruptures or ground shaking during an earthquake can cause the
collapse of dams, as well as seiche and tsunami ("tidal waves").
Dam safety is regulated by the State Department of Water Resources, Division of Safety
of Dams. All large reservoirs in the County have been investigated and many have been
strengthened. Further, the Office of Emergency Services has produced inundation maps
and emergency plans covering various scenarios of dam failure in the County.
The safety of small dams, which are mostly used for stock watering and other
agricultural activities, is largely a private concern, with present standards set by the
County Grading Ordinance. Many small dams predate even this regulation. However,
seismic activity is not considered a significant hazard to small dams.
Tsunamis are sea waves created by undersea fault movement. Traveling through the deep
ocean, a tsunami wave is a broad, shallow, and fast moving wave. When it reaches the
coastline, the wave form pushes upward from the ocean bottom and becomes a high swell of
water that breaks and washes inland with great force. The waves may reach fifty feet in
height on unprotected coasts, and one recorded tsunami (in Japan in 1896) killed nearly
30,000 people and destroyed over 10,000 homes. Several people were drowned in Crescent
City, California, in 1964 by the tsunami generated by the "Good Friday" Alaska earthquake.
Historic records of the Bay Area used by one study indicate that 19 tsunamis were
recorded in San Francisco Bay during the period of 1868-1968. The maximum wave
height recorded at the Golden Gate Tide Gage was 7.4 feet, which may be regarded as
a reasonable maximum for future events.
The available data indicate a systematic diminishment of wave height from the Golden
Gate to about half that height on the shoreline near Richmond, and to nil at the head of
the Carquinez Strait. Thus, the damage potential of a tsunami will tend to be greater in
the Richmond area and show a general decrease toward the head of Carquinez Strait.
Flooding can also result from seiche, which is a long wave-length, large-scale wave action
set up in a closed body of water such as a lake or reservoir. Seiche is known to occur during
earthquakes, but is not well understood. No occurrences have been recorded in the Bay
Area. Elongated and deep (relative to width) bodies of water seem most likely to be
affected, and earthquake wave orientation may also play a role in seiche formation. Seiche
can temporarily flood a shoreline in a manner similar to tsunami; however, its destructive
capacity is not as great. Seiche may cause overtopping of impoundments such as dams,
particularly when the impoundment is in a near-filled condition, releasing flow downstream.
Maps of Flood Hazard Areas
Figure 10-8 depicts the general location of the FEMA flood hazard areas throughout
Contra Costa County. Flood Hazard Areas are those areas which have statistical chance
of flooding once in 100 years. This map is not intended to be used to locate parcel-
10. Safety Element
10-31
specific sites in relation to Flood Hazard Areas, but to convey the general extent and
location of such areas. The map also indicates areas of subsidence in the County, but
does not presently include consideration of the greenhouse effect.
FLOOD HAZARD GOALS
10-G. To ensure public safety by directing development away from areas which may
pose a risk to life from flooding, and to mitigate flood risks to property.
10-H. To mitigate the risk of flooding and hazards to life, health, structures,
transportation and utilities due to subsidence, especially in the San Joaquin-
Sacramento Delta area.
GENERAL POLICIES
10-33. The areas designated on Figure 10-8 shall be considered inappropriate for
conventional urban development due to unmitigated flood hazards as defined by
FEMA. Applications for development at urban or suburban densities in areas where
there is a serious risk to life shall demonstrate appropriate solutions or be denied.
10-34. In mainland areas affected by creeks, development within the 100-year flood
plain shall be limited until a flood management plan can be adopted, which
may include regional and local facilities if needed. The riparian habitat shall be
protected by providing a cross section of channel suitable to carry the 100-
year flow. Flood management shall be accomplished within the guidelines
contained in the Open Space/Conservation Element.
10-35. In mainland areas along the rivers and bays affected by water backing up into
the watercourse, it shall be demonstrated prior to development that adequate
protection exists either through levee protection or change of elevation.
10-36. On islands in East County, development shall not be allowed until a study is
performed to resolve issues and determine appropriate locations for development.
This study shall be a high priority for the County and should include the following:
o a risk assessment of development in that area; and
o an analysis of flooding due to runoff and tides, settlement of shallow soils,
deep subsidence, liquefaction, and adequacy of insurance programs.
10-37. A uniform set of flood damage prevention standards should be established by the
cooperative efforts of all County, State, and federal agencies with responsibilities
for flood control works and development in flood-prone areas in the County.
10-38. Flood-proofing of structures shall be required in any area subject to flooding; this shall
occur both adjacent to watercourses as well as in the Delta or along the waterfront.
10-39. In developing areas which are subject to the provisions of the Flood Insurance
Program, for which there is no reasonable expectation of flood control project
participation by the Corps of Engineers and where a significant number of properties
will be affected, the Flood Control District shall be permitted to construct 100-year
flood protection works when so directed by the Board of Supervisors.
10-40. Planning Agency and Flood Control District review of any significant project
proposed for areas in the County which are not presently in Flood Zones shall
include an evaluation of the potential downstream flood damages which may
result from the project.
10. Safety Element
10-32
FLOOD HAZARD POLICIES
10-41. Buildings in urban development near the shoreline and in flood-prone areas
shall be protected from flood dangers, including consideration of rising sea
levels caused by the greenhouse effect.
10-42. Habitable areas of structures near the shore line and in flood-prone areas shall be
sited above the highest water level expected during the life of the project, or shall
be protected for the expected life of the project by levees of an adequate design.
10-43. Rights-of-way for levees protecting inland areas from tidal flooding shall be
sufficiently wide on the upland side to allow for future levee widening to
support additional levee height.
10-44. The County shall review flooding policies in the General Plan on an annual
basis, in order to incorporate any new scientific findings regarding project sea
level rise due to the greenhouse effect.
10-45. The County shall review flooding policies as they relate to properties
designated by FEMA as within both the 100- and the 500-year floodplains.
Policies Regarding Subsidence
10-46. Whenever studies indicate subsidence is or may become a flood-threatening
problem, the County should continue to monitor subsidence until flood
protection is assured.
10-47. In accordance with the following policies, the General Plan shall not permit a
substantial non-agricultural, residential population to be subjected to
increased flood hazard due to subsidence.
10-48. Low density development of lands subject to subsidence shall take into
account and fully mitigate the potential impacts of flooding based on the best
currently available techniques.
10-49. Any development approvals for areas subject to subsidence shall include
conditions which account for the need to support Delta reclamation and irrigation
districts, and to strengthen weak and low levees prior to development.
10-50. The pumping of substantial quantities of water, oil, and gas in an area
protected by levees is inconsistent with new major development approvals.
Policies Regarding Flooding Due to Levee or Dam Failure, or Tsunami
10-51. In order to protect lives and property, intensive urban and suburban
development shall not be permitted in reclaimed areas unless flood protection
in such areas is constructed, at a minimum, to the standards of the Flood
Disaster Protection Act of 1973. Levees protecting these areas shall meet the
standards of the U.S. Army Corps of Engineers.
10-52. Delta levees shall be rehabilitated and maintained to protect beneficial uses of the
Delta and its water. Only those uses appropriate in areas subject to risk of flooding
and seismic activity, such as agriculture and recreation, should be planned and
approved. This policy shall not apply to Bethel Island or Discovery Bay.
10-53. Development of levee rehabilitation plans should consider methods to foster
riparian habitat to the fullest extent possible consistent with levee integrity.
10. Safety Element
10-33
10-54. Agencies whose projects benefit from Delta levee protection, including the
State and federal government (water, highway, fish and wildlife, and
recreational projects), PG&E, and private railroad companies, shall participate
in funding Delta levee improvements and maintenance.
10-55. The potential effects of dam or levee failure are so substantial that geologic
and engineering investigation shall be warranted as a prerequisite for
authorizing public and private construction of either public facilities or private
development in affected areas.
10-56. Development proposals should be reviewed with reference to dam failure inundation
maps, as these become available, in order to determine evacuation routes.
10-57. Dam and levee failure, as well as potential inundation from tsunamis and seiche,
shall be a significant consideration of the appropriateness of land use proposals.
10-58. Dams and levees should be designed to withstand the forces of anticipated
(design) earthquakes at their locations.
10-59. Important dams and coastal levees shall be regarded as critical facilities that
should not be sited over the trace of an active or potentially active fault.
10-60. Structures for human occupancy, and particularly critical structures, and potentially
dangerous commercial or industrial facilities (e.g., plants for the manufacture or
storage of hazardous materials) shall be protected against tsunami hazard.
FLOOD HAZARD IMPLEMENTATION MEASURES
10-s. Revise the creek setback ordinance for residential and commercial structures in
order to prevent property damages from bank failure along natural water courses.
10-t. Encourage the County Flood Control District to proceed with drainage
improvements in areas subject to flooding from inadequate facilities, and to
ensure that additional new drainage facilities, including road culverts and
bridges, are designed to pass the flow specified by County Ordinance Code.
10-u. Develop Flood Control Zone plans based on the concepts found in this General
Plan. As adopted zone plans are revised, they should be brought into
conformity with these concepts.
10-v. Draft and adopt a flood management plan for mainland areas affected by
creeks, in accordance with the guidelines contained in the Safety Element and
Open Space/Conservation Element of this General Plan.
10-w. Conduct a study of flooding conditions on islands in East County, including a
risk assessment of development in that area and an analysis of flooding due
to runoff and tides, settlement of shallow soils, deep subsidence, liquefaction,
and adequacy of insurance programs.
10-x. Establish a uniform set of flood damage prevention standards in cooperation
with appropriate County, State, and federal agencies.
10-y. Through the environmental review process, ensure that potential flooding
impacts, due to new development, including on-site and downstream flood
damage, subsidence, dam or levee failure, and potential inundation from
tsunamis and seiche, are adequately assessed. Impose appropriate mitigation
measures (e.g. flood-proofing, levee protection, Delta reclamations).
10. Safety Element
10-34
10-z. Develop and implement Delta levee rehabilitation plans in cooperation with
State and federal agencies and the private sector, in accordance with the
policies of this General Plan.
10-aa. Adopt ordinances implementing the FEMA Flood Insurance Program.
10-ab. Prohibit new structures which would restrict maintenance or future efforts to
increase the height of the levees from being constructed on top or
immediately adjacent to the levees.
10-ac. All analysis of levee safety shall include consideration of the worst case
situations of high tides coupled with storm-driven waves.
10.9 HAZARDOUS MATERIALS USES
INTRODUCTION
Contra Costa County contains extensive heavy industrial development which may be
associated with hazardous materials uses along its west and north coasts, as depicted in
Figures 10-9a and 10-9b. Land uses involving hazardous materials or other hazards
considered in this section include airports, the Concord Naval Weapons Station, petroleum
and chemical processing plants, oil and gas wells, and petroleum product and natural gas
pipelines. In addition, land uses that involve hazards to navigation are considered here.
Heavy industrial land uses centered on the west and north shores of the County have the
potential to present significant risk to public safety because of the hazardous nature of some
petroleum and chemical materials. Potential hazards include explosion and flammability of
petroleum products and other chemicals, and chemical toxicity. Hazardous materials uses are
concentrated in heavy industries along the coasts, and are also present in lesser quantities in
industrial parks in the County's interior. Notwithstanding industrial safety procedures, the
presence of large quantities of hazardous materials in the County, particularly close to and/or
upwind of populated areas, poses a potential safety hazard at all times.
Many industrial uses in the County are located on reclaimed marshland underlain by soft, wet,
unstable mud. However, damage from earth movements are believed to have a low probability
of occurrence because of adequate foundation design of buildings and other structures.
Information is not available on whether or not there are older tanks used to store
hazardous materials that are not sufficiently stabilized. Informal observation of tanks
in the County indicates that there is no requirement to space tanks far enough apart to
prevent a fire or explosion from spreading. In areas in which tanks are closely spaced,
particularly where these are close to population centers, there is a potential for a
disaster affecting a significant population. Although historic accident records suggest
that such a risk is low, the seriousness of the event, should it occur, indicates that
some additional measure of public safety may be advisable.
Hundreds of miles of pipelines for the transportation of natural gas, crude oil, and
refined petroleum products traverse Contra Costa County, including residential and
commercial areas. Such pipelines cross areas with active fault lines, landslide deposits,
unstable slopes, and areas underlain by soft mud and peat. The risk presented to
pipelines by geologic conditions has not been quantified. The public safety hazard from a
pipeline break would depend on the proximity of the accident to populated areas as well
as the nature of the event that produced it (e.g., the landslide or earthquake).
10. Safety Element
10-35
Figure 10-9a
Hazardous Land Uses
10. Safety Element
10-36
Figure 10-9b
Hazardous Land Uses
10. Safety Element
10-37
In general, natural gas is believed to be less hazardous to the public than petroleum
products because it is transported at lower pressures and, when released, rises and
dissipates into the atmosphere. Petroleum products are pumped at pressures up to 200
pounds per square inch and, when released, flow along the ground. Petroleum fires are
also more likely to spread to nearby property than vertical-burning natural gas fires.
Numerous active gas and oil wells are located in the County, most of which are far from
populated areas. Although there is a risk of a well catching on fire, such incidents have
been very few and the risk of such a fire causing a general disaster is remote. North and
east of Brentwood, future parcel splits resulting in a dispersed but sizeable population
could lead to a public safety hazard if rural residential areas are permitted to encroach on
the gas producing area. Further, a concentrated population in proximity to the numerous
wells in peat areas could expose persons and properties to peat fires which are difficult to
control and may smolder for weeks or months before they are completely extinguished.
No particular routes for hazardous materials transportation are designated in the County.
Most of these materials are regularly carried on the freeways and major roads designated
as explosives routes. The proximity of some of these routes to large numbers of people
suggests that an accident involving hazardous materials transportation could reach disaster
proportions. The extreme toxicity of some chemicals used in the County and the specialized
handling and cleanup procedures required during an accident make proper information and
training of local response agencies, such as the police and fire departments, essential.
A unique risk to public safety is presented by transportation in the County of quantities
of various radioactive materials. In the event of an accident, small amounts of
radioactive materials can be dislodged from their protective containers and become
extremely difficult to locate. Emergency response to a spill involving radioactive
materials requires special knowledge and equipment, and persons may be unknowingly
subjected to radiation in traffic accidents or other routine mishaps.
Explosives are defined in the California Health and Safety Code as any substance or
combination of substances the primary purpose of which is detonation or rapid combustion.
Most munitions and some chemical materials are included in the Class A explosives
category regulated by the State and various bridge authorities. There are numerous users
of explosive materials in the County, but by far the largest is the U.S. Army’s Military Traffic
Management Command (formerly Concord Naval Weapons Station), to and from which
munitions are regularly transported by truck, train and ship. Other explosives used for
construction and quarrying are present in smaller amounts throughout the County.
Two major railroad companies serve Contra Costa County – Burlington Northern - Santa Fe and
Union Pacific -- and both transport munitions for the Army’s Military Traffic Management
Command. Truck transportation of explosives through populated areas constitutes a potential
significant public safety hazard. Permitted routes designated by the California Highway Patrol
include the major freeways and other highways in the County. While training requirements
exist for carriers of hazardous materials, including explosives, they may be unable to perform
immediate remediation of emergency conditions under some situations.
The County is responsible for determining land uses and community development configuration
within its jurisdiction, but does not determine the nature of substances used on industrial and
military sites. Nor does the County grant permits for the use or transportation of hazardous
materials, determine appropriate routes for transporting these materials, or require properly
informed emergency personnel. Public safety in regard to the use and transportation of
hazardous substances generally depends on actions by the State and federal governments.
10. Safety Element
10-38
In the case of land uses involving hazardous materials, the County Planning Agency
can minimize public safety risks by ensuring that hazardous materials use areas and
residential populations are separated to the extent that fire or explosions on industrial
and military properties or in gas and oil well areas will not spread to homes or
businesses. Preventing environmental releases of hazardous materials depends
primarily on industrial safety requirements and procedures. By requiring that project
proposals to construct tanks, pipelines, and other facilities be accompanied by
thorough investigations of the natural and man-made hazards potentially affecting the
proper functioning of these facilities, the County can be assured that risks are reduced
to the minimum level that can be achieved by engineering technology.
Since emergency and disaster plans and procedures have been prepared by the County
Office of Emergency Services (OES), it is appropriate for all potentially disastrous events
to be reported to them, so that County emergency services such as traffic control, fire
and medical equipment, and evacuation notification can be available if needed.
Contra Costa County is home to numerous businesses and industries that manufacture,
store, use and dispose of hazardous materials and hazardous waste. These businesses are
neighbors to an increasingly urbanized population. To ensure the protection of public
health and safety and the environment, it is imperative to plan for the safe and effective
use of hazardous materials and the management of hazardous waste. In recent years,
there has been a growing understanding of the widespread use of hazardous materials.
Contra Costa County began planning specifically for the management of hazardous
materials and waste in 1983, with the establishment of the County Hazardous Waste Task
Force. The County has completed the County Hazardous Waste Management Plan, a
comprehensive analysis of all aspects of hazardous waste management from generation
through disposal. The plan establishes goals and policies for the safe management of
hazardous waste, and recommends the establishment of programs designed to reduce
hazardous waste generation by 30 to 40 percent by the year 2000. The plan, which serves
as the primary planning document for hazardous waste management in the County and in
the incorporated cities, projects the need for commercial hazardous waste management
facilities and specifies criteria to determine whether a facility may be established.
The management of hazardous materials is the focus of the Contra Costa County
Hazardous Materials Area Plan, which was adopted in January of 1988. This Plan
outlines the procedures that County regulatory and response agencies will use for
managing, monitoring, containing and removing hazardous materials from the site of
an actual or threatened accidental release. The plan also identifies the agencies within
the County responsible for the effective management of hazardous materials.
Navigational Hazards
With over 70 square miles of water and hundreds of miles of shoreline along the bays, rivers and
sloughs, off-shore waters are particularly important in Contra Costa County for industrial,
commercial, agricultural and recreational uses. The public right to use open water for navigation
is established in the State constitution and State law, but navigation can be hazardous if land-
based activities result in obstructions such as docks, low bridges, or elevated pipelines.
Where waters are shallow for some distance from shore commercial and industrial docks are
usually built out to the shipping channel as a more acceptable plan than continuously dredging
a side channel closer to shore. The Corps of Engineers permit system prevents docks from
encroaching into shipping channels. Small docks for commercial or private recreational use
10. Safety Element
10-39
have proliferated around Bethel Island and on the mainland side of Sand Mound Slough. The
U.S. Department of the Interior, noting "a plethora of uses not associated with commerce
activities" on the State's waterways indicates that controls are necessary to protect the public
right to use navigable waters.
It should also be recognized that because thousands of boaters use the Delta annually,
many of them not skilled, the proliferation of smaller docks may be a hazard to public
safety. The risk would not be of a disastrous single event, but is rather a persistent
hazard probably affecting only a few persons at a time.
As previously mentioned, additional discussion of the County HWMP and related General
Plan goals and policies is provided in the Public Facilities/Services Element of this
document. For a listing of General Plan goals regarding hazardous waste management,
the reader is directed to Section 7.12.
HAZARDOUS MATERIALS GOALS
10-I. To provide public protection from hazards associated with the use, transport,
treatment and disposal of hazardous substances.
HAZARDOUS MATERIALS POLICIES
10-61. Hazardous waste releases from both private companies and from public
agencies shall be identified and eliminated.
10-62. Storage of hazardous materials and wastes shall be strictly regulated.
10-63. Secondary containment and periodic examination shall be required for all
storage of toxic materials.
10-64. Industrial facilities shall be constructed and operated in accordance with up-
to-date safety and environmental protection standards.
10-65. Industries which store and process hazardous materials shall provide a buffer
zone between the installation and the property boundaries sufficient to protect
public safety. The adequacy of the buffer zone shall be determined by the
County Planning Agency.
10-66. To the greatest possible extent, new fuel pipelines should not be routed through
centers of population nor should they cross major disaster evacuation routes.
10-67. In order to provide for public safety, urban and suburban development should not
take place in areas where they would be subject to safety hazards from oil and gas
wells. Development near oil and gas wells should meet recognized safety standards.
10-68. When an emergency occurs in the transportation of hazardous materials, the
County Office of Emergency Services shall be notified as soon as possible.
10-69. Industry should be encouraged to utilize underground pipelines, rail, and
water transportation of hazardous materials to the greatest extent feasible to
take advantage of the greater separation from the general public provided by
these modes of transportation.
10-70. Applications for private or commercial recreation docks which would encroach
into waterways used primarily for recreation boating should be reviewed by
the County to evaluate their aggregate impact upon public safety.
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HAZARDOUS MATERIALS IMPLEMENTATION MEASURES
10-ad. Encourage the State Department of Health Services and the California
Highway Patrol to review permits for radioactive materials on a regular basis
and to promulgate and enforce public safety standards for the use of these
materials, including the placarding of transport vehicles.
10-ae. Request that State and federal agencies with responsibilities for regulating the
transportation of hazardous materials review regulations and procedures, in
cooperation with the County, to determine means of mitigating the public
safety hazard in urbanized areas.
10.10 WATER SUPPLY REQUIREMENTS
INTRODUCTION
This section of the Safety Element focuses on water supply safety issues. For a
discussion of issues related to general domestic water supply, the reader is directed to
the Public Facilities and Services Element of this general plan.
Water supply requirements increase during a disaster, with extra amounts being used
for fire fighting, sanitation, and debris clean up. Damages to this essential supply can
occur in the centralized parts of water supply systems--the intakes, canals, and major
reservoirs--or at the delivery points as a result of disruption of main lines or of the
many subsidiary lines to each home, school, business, or hospital.
Damage to centralized parts of the water supply system has the potential to affect
thousands of persons but can be repaired relatively quickly. Loss of water in localized areas
would affect fewer people, but because repair times could be long, hazards to property and
safety could be greater for inhabitants of such areas. In a general or widespread disaster
the water supply to several parts of the County could be disrupted for days or weeks.
Although the risk of such an event is believed to be low, the seriousness of the impact on
affected communities indicates that citizens, water suppliers and government agencies
should be prepared to supplement water supplies for disaster recovery uses.
Large low-density areas of the County do not use water from large public systems, but
instead rely on wells. These areas would be expected to have less difficulty supplying
water in the event of a disaster such as an earthquake.
WATER SUPPLY GOALS
10-J. To ensure a continuous supply of safe water to county residents.
10-K. To protect the quality, quantity, and productivity of water resources as vital
resources for maintaining the public, ecological and economic health of the region.
10-L. The safety of valuable underground water supplies for present and future
users shall be ensured by preventing contamination.
10-M. All wells and other entrances to aquifers shall be identified and protected.
WATER SUPPLY POLICIES
10-71. The County shall support local, regional, State, and Federal government
efforts to improve water quality.
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10-72. The County shall support water quality standards adequate to protect public
health in importing areas as a priority at least equal in status to support of
Bay/Delta estuary water standards.
10-73. Point sources of pollution shall be identified and controlled to protect adopted
beneficial uses of water.
10-74. Public ownership of lands bordering reservoirs shall be encouraged to
safeguard water quality.
10-75. Prohibit underground discharges of toxic liquid wastes.
10-76. Land use plans and major project proposals that would encourage
development served by wells and septic systems shall be approved only after
there are assurances of the adequacy of the aquifer and that there is
minimum risk of well contamination during the rainy season.
10-77. Annexation of municipal or small service districts into the larger districts shall
be supported when such annexations would result in water supply safety
benefits to the consumers.
10-78. No new water districts shall be established.
10-79. The use of reclaimed water for industrial operations shall be encouraged.
10-80. Because of the public need for water of a quality suitable for domestic,
industrial and agricultural uses, the County shall take an active role in
reviewing regional, State and federal programs which could affect water
quality and water supply safety in Contra Costa County.
10-81. New water storage reservoirs shall be encouraged in appropriate locations
subject to adequate mitigation of environmental impacts.
10-82. Discourage the development of new wells for domestic use in areas with high
nitrite concentrations in the ground water.
WATER SUPPLY IMPLEMENTATION MEASURES
10-af. A permit system shall be required for all future wells or other shafts to aquifers.
10-ag. Monitoring of well water quality shall be required.
10-ah. Develop drilling and sealing ordinances designed for protection of aquifers and
the public health and welfare.
10-ai. Instruct the County Health Department to do a study of the nitrite
groundwater problem for East County including recommendations on
continued approval of new wells for residential use.
10-aj. Prohibit underground discharge of toxic liquid wastes through adoption of a
hazardous materials ordinance or other means.
10-ak. Encourage local, State, and federal agencies to investigate and recommend
methods of maintaining agricultural productivity with reduced amounts of
toxic and nutritive chemicals which can damage water quality.
10-al. Encourage all water districts in their efforts to provide water supply safety for
emergency and disaster uses by the most practicable means.
10-am. Encourage domestic water services to participate in the State Emergency Services
program for county-wide coordination of emergency response planning and to take
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advantage of low cost purchase of auxiliary power equipment where these
programs would result in greater security for domestic water supplies.
10-an. Encourage domestic water suppliers to undertake programs to inform
homeowners, schools, convalescent hospitals, and other institutions of
appropriate and efficient emergency use of available water in an immediate
post-disaster recovery period.
10-ao. Review and evaluate regional, State, and federal programs which could affect
water quality and water supply safety in the County.
10.11 PUBLIC PROTECTION SERVICES AND DISASTER PLANNING
INTRODUCTION
This section of the Safety Element includes a discussion of the essential public
protection services which will provide the major work force, facilities and equipment for
disaster recovery.
The Contra Costa County Office of Emergency Services prepares disaster plans for the
county and coordinates required emergency services and facilities from all agencies
and levels of government to meet emergency and disaster needs. While there is some
overlap between this element and the Public Facilities and Services Element, the
policies contained here are primarily related to disaster situations, rather than to
ongoing facilities and services standards.
Aside from the emergency/disaster situations previously described in this element such as
earthquakes, floods and accidental releases of hazardous materials, the Safety Element
addresses the additional areas of wildfire, emergency medical response and crime prevention.
Wildfire
Fire hazards present a considerable problem to vegetation and wildlife habitats
throughout the County. Grassland fires are easily ignited, particularly in dry seasons.
These fires are relatively easily controlled if they can be reached by fire equipment; the
burned slopes, however, are highly subject to erosion and gullying. While brushlands
are naturally adapted to frequent light fires, fire protection in recent decades has
resulted in heavy fuel accumulation on the ground.
Brush fires, particularly near the end of the dry season, tend to burn fast and very hot,
threatening homes in the area and leading to serious destruction of vegetative cover. While
woodland fires are relatively cool under natural conditions, a brush fire which spreads to a
woodland could generate a destructive hot crown fire. No suitable management technique
of moderate cost has been devised to reduce the risk of brush fires.
Because the natural vegetation and dry-farmed grain areas of the County are extremely
flammable during the late summer and fall, wildfire is a serious hazard in undeveloped
areas and on large lot homesites with extensive areas of un-irrigated vegetation. Several
factors affect the relative degree of wildfire hazard, including atmospheric humidity, slope
steepness, vegetation type, exposure to the sun, wind speed and direction, accessibility to
human activities and accessibility to firefighting equipment. Taking these factors into
consideration, a fire hazard severity scale has been devised which characterizes areas
throughout the County by the number of days of moderate, high and extreme fire hazard.
Mapped information on fire hazard severity is included later in this section.
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Peat fires represent a special hazard in that once ignited, they are extremely difficult to
extinguish. In some instances, islands have been flooded in order to extinguish peat fires.
Any area lying generally east of the mean high water line may be peaty due to the marshy
origin of the soil, although local areas of mineral soil are present within the general area.
Emergency Medical Response
Medical emergency services are provided by hospitals, ambulance companies and fire
districts. Considerable thought and planning have gone into efforts to improve responses
to day-to-day emergencies and planning for a general disaster response capability.
However, certain areas remain which require improvement to enhance public safety.
Identification of streets, house numbers, and townhouse and apartment units remains
a major factor hampering locating patients. Design of multi-story buildings rarely
includes provision for elevators or stairways which can accommodate gurneys, which
are preferred for patient transport because they allow for continuous care. In the event
of a disaster, many persons could be affected.
Although substantial progress has been made in terms of earthquake restrainers being
added to freeway overpasses, cities and communities with limited access to hospitals,
such as Lafayette, Moraga and Orinda, are still at some risk to access blockage due to
the potential for landslides or traffic accidents to temporarily close roads.
Crime Prevention
While it is not a purpose of this element to deal with crime as such, there are planning-
related opportunities to aid in the efficiency of police services and incorporate crime
reducing features into development projects which could enhance public safety at
relatively little public cost.
Response times can be hampered by uncoordinated street naming between
jurisdictions, or by conflicting street numbering between cities and the County on the
same road/street name.
Defensible space is a concept which incorporates crime prevention principles into
development design. This concept has already been discussed in the "Public Protection"
section of the Public Facilities/Services Element.
Maps
In general, the fire hazard severity is related to distance from the marine atmospheric
influences of the Pacific Ocean, intervening topography, slope steepness and
vegetative type and coverage. Figure 10-10 shows these areas.
PUBLIC PROTECTION SERVICES AND DISASTER PLANNING GOALS
10-N. To provide for a continuing high level of public protection services and
coordination of services in a disaster.
PUBLIC PROTECTION SERVICES AND DISASTER PLANNING POLICIES
10-83. The Office of Emergency Services, in cooperation with cities within the
County, shall delineate evacuation routes and, where possible, alternate
routes around points of congestion.
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10-84. The Office of Emergency Services, in cooperation with public protection
agencies, shall delineate emergency vehicle routes for disaster response, and
where possible, alternate routes where congestion or road failure could occur.
10-85. In order to ensure prompt public protection services, dwelling unit numbers
shall be required to be easily seen from the street or road.
10-86. In order to reduce the risk of crime at little public cost, the County shall
encourage the use of citizen action programs such as Neighborhood Alert and
Operation ID.
10-87. The County shall require adequate access for medical emergency equipment
in high-occupancy buildings of over two stories.
10-88. Every high-rise building shall be designed and constructed to provide for the
evacuation of occupants and/or for the creation of a safe environment in case
of a substantial disaster, such as a severe earthquake or fire.
10-89. Policies related to wild land fire risk are contained in the Fire Services section
of the Public Facilities Element.
10-90. Restrict homes built in rural areas or adjacent to major open space areas
from having roofs which are covered with combustible materials.
Figure 10-10 contains the characterization of fire hazard for the County by Fire Weather
Classes, and delineates those areas of the County which are subject to peat fires.
The Fire Weather Classes depicted on Figure 10-10 are defined in terms of the number
of days per year of Critical Fire Weather. Class 1 has 0 to 1 days per year of Critical
Fire Weather, Class II has 1 to 9.5 days and class III has over 9.5 days.
PUBLIC PROTECTION SERVICES AND DISASTER PLANNING IMPLEMENTATION
MEASURES
10-ap. Undertake a program in cooperation with cities within the County to unify
street name and numbering systems.
10-aq. In cooperation with cities within the County and public protection agencies,
delineate evacuation routes, emergency vehicle routes for disaster response and,
where possible, alternative routes where congestion or road failure could occur.
10-ar. Development of areas identified by the criteria of the State Division of Forestry
as having an Extreme Fire Hazard will be avoided where possible. Homes
located in extreme or high fire hazard areas will be constructed with fire-
resistant materials and the surroundings should be irrigated or landscaped with
fire resistant plants.
10-as. Require projects which encroach into areas which are determined to have a
high or extreme fire hazard, or which incorporate wildfire hazard areas, to be
reviewed by the appropriate Fire Bureau to determine if special fire prevention
measures are advisable.
10-at. Major developments will not be approved if fire fighting services are not
available or are not adequate for the area.
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Figure 10-10
Fire Hazard Areas
Exhibit “D” Redline/Strikeout changes to the relevant
text under Section 10.11 Public Protection
Services and Disaster Planning, Safety
Element, to incorporate reference of the
County’s adopted local hazard mitigation
plan