1. INTRODUCTION TO THE PLAN 1 2. FMP … FMP.pdfCity of Los Angeles Floodplain Management Plan – November 2001 11. INTRODUCTION TO THE PLAN 1.1. Purpose The Floodplain Management

TABLE OF CONTENTS

City of Los Angeles Floodplain Management Plan – November 2001 i

1. INTRODUCTION TO THE PLAN ....................................................................... 1

1.1. Purpose ........................................................................................................... 1 1.2. Background ..................................................................................................... 1

1.2.1. National Flood Insurance Program (NFIP) ....................................................................... 1 1.2.2. Community Rating System (CRS) .................................................................................... 2 1.2.3. Existing City Regulations .................................................................................................. 4

1.3. Plan Approach ................................................................................................. 4 1.4. Repetitive Loss Properties .............................................................................. 5

2. FMP COMMITTEE AND PUBLIC INVOLVEMENT ............................................ 6

2.1. Committee Membership .................................................................................. 6 2.2. Committee Establishment ............................................................................... 7 2.3. Committee Meetings ....................................................................................... 8 2.4. Public Input ..................................................................................................... 8

2.4.1. Public Meetings ................................................................................................................. 8 2.4.2. Questionnaire .................................................................................................................... 9 2.4.3. Public Review ................................................................................................................. 10

3. COMMUNITY DESCRIPTION .......................................................................... 11

3.1. Area .............................................................................................................. 11 3.2. Population ..................................................................................................... 11 3.3. Climate and Rainfall ...................................................................................... 12 3.4. Drainage........................................................................................................ 12 3.5. Land Use ....................................................................................................... 13 3.6. Historical Flooding in Los Angeles ................................................................ 13

4. FLOOD CONTROL SYSTEM DESCRIPTION ................................................. 18

4.1. Los Angeles County Drainage Area (LACDA Project) ................................... 18 4.2. City Drainage System ................................................................................... 21 4.3. Natural Resources and Beneficial Functions of Floodplains ......................... 21

4.3.1. Significant Ecological Areas ........................................................................................... 23 4.3.2. Watershed Management ................................................................................................ 25 4.3.3. Wetlands ......................................................................................................................... 25

5. HAZARD IDENTIFICATION ............................................................................. 26

5.1. Basic Hazard Definitions ............................................................................... 26 5.1.1. Atmospheric Hazards...................................................................................................... 26 5.1.2. Geologic Hazards ........................................................................................................... 27 5.1.3. Hydrologic Hazards ......................................................................................................... 27 5.1.4. Seismic Hazard ............................................................................................................... 27 5.1.5. Fire Hazard ..................................................................................................................... 29 5.1.6. Technological (Man-Made) Hazard ................................................................................ 29

5.2. Flood Hazards for the City of Los Angeles .................................................... 29 5.2.1. FEMA Special Flood Hazard Areas ................................................................................ 31

5.2.1.1. Areas of Shallow Flooding ........................................................................................................ 31 5.2.1.2. Regulated Floodways ............................................................................................................... 31 5.2.1.3. Alluvial Fans ............................................................................................................................. 32 5.2.1.4. Coastal Areas ........................................................................................................................... 32

5.2.2. Other Non-Hillside Hazards ............................................................................................ 32 5.2.2.1. Areas of Shallow Flooding ........................................................................................................ 32

5.2.3. Other Hillside Hazards .................................................................................................... 33 5.2.3.1. Floodways and Watercourses .................................................................................................. 33 5.2.3.2. Mud and Debris Flow Areas ..................................................................................................... 33

TABLE OF CONTENTS

City of Los Angeles Floodplain Management Plan – November 2001 ii

5.2.4. Other Coastal Hazards ................................................................................................... 34 5.2.4.1. Areas of Shallow Flooding ........................................................................................................ 34 5.2.4.2. Coastal Erosion and Storm Surge Areas .................................................................................. 34 5.2.4.3. Tsunami Hazard Areas ............................................................................................................. 35

5.2.5. Geologic Hazards ........................................................................................................... 38 5.2.5.1. Subsidence Areas .................................................................................................................... 38 5.2.5.2. Landslide Areas ........................................................................................................................ 38

5.2.6. System Failure Related Hazards .................................................................................... 43 5.2.6.1. Dam, Reservoir and Storage Tank Inundation Areas ............................................................... 43 5.2.6.2. Power Failure Induced Flooding Areas..................................................................................... 44

6. HAZARD AND PROBLEM ASSESSMENT ..................................................... 45

6.1. Basic Assessment Approach ......................................................................... 45 6.1.1. List of Primary Hazards................................................................................................... 45 6.1.2. List of Major Affected Categories .................................................................................... 45

6.2. Assessment Methodology ............................................................................. 45 6.2.1. Identified Hazard Areas .................................................................................................. 45 6.2.2. Major Affected Categories and Definitions ..................................................................... 48

6.3. Tools and Available Data .............................................................................. 50 6.3.1. Public Works/Bureau of Engineering .............................................................................. 50 6.3.2. Public Works/Bureau of Sanitation ................................................................................. 51 6.3.3. Department of Building and Safety ................................................................................. 51 6.3.4. Planning Department ...................................................................................................... 51 6.3.5. Community Re-Development Agency & Community Development Department ............ 52 6.3.6. Fire Department .............................................................................................................. 52 6.3.7. Department of Emergency Preparedness ...................................................................... 52 6.3.8. Los Angeles County Department of Public Works .......................................................... 52

6.4. Hazard and Problem Assessment Summary................................................. 52 6.4.1. Assessment of Problems ................................................................................................ 53 6.4.2. Economic Impacts of Flooding ........................................................................................ 56

6.5. Repetitive Loss Properties ............................................................................ 61 6.5.1. Los Angeles River (Hillside) ............................................................................................ 64 6.5.2. Los Angeles River (Non-Hillside) .................................................................................... 68 6.5.3. Ballona Creek (Hillside) .................................................................................................. 70 6.5.4. Ballona Creek (Non-Hillside) .......................................................................................... 75

7. GOALS, OBJECTIVES AND POLICIES .......................................................... 79

7.1. Setting Goals ................................................................................................. 79 7.2. Goals, Objectives, and Policies ..................................................................... 79 7.3. Review Possible Activities ............................................................................. 84

8. IMPLEMENTATION PLAN ............................................................................... 87

8.1. Programs ....................................................................................................... 87 8.2. Recommended Repetitive Loss Property (RLP) Activities .......................... 106

8.2.1. RLP Action Plan for Property Protection – Los Angeles River (Hillside) ...................... 108 8.2.2. RLP Action Plan for Property Protection – Los Angeles River (Non-Hillside) .............. 110 8.2.3. RLP Action Plan for Property Protection – Ballona Creek (Hillside) ............................. 111 8.2.4. RLP Action Plan for Property Protection – Ballona Creek (Non-Hillside) ..................... 113

9. ADOPTION, REPORTING, EVALUATING, AND REVISING ......................... 118

9.1. Plan Adoption Process ................................................................................ 118 9.2. Reporting Process ....................................................................................... 118 9.3. Evaluation Process and Revision Process .................................................. 118

ACRONYMS AND GLOSSARY ................................................................................. I

TABLES

City of Los Angeles Floodplain Management Plan – November 2001 iii

EXHIBITS Tables TABLE 1 NFIP COMMUNITY RATING SYSTEM – CLASS SUMMARY ............................................... 2 TABLE 2 RELATIONSHIP BETWEEN CRS PLANNING PROCESS AND FMP DOCUMENT ............. 4 TABLE 3 FMP COMMITTEE MEMBERSHIP LIST ................................................................................. 7 TABLE 4 FMP PUBLIC REVIEW LOCATIONS .................................................................................... 10 TABLE 5 FLOOD-FIRE HAZARD AREAS FOR FEBRUARY 1978 STORM ....................................... 16 TABLE 6 MAJOR RESERVOIRS BENEFITING THE CITY OF LOS ANGELES ................................ 20 TABLE 7 FLOOD CONTROL SYSTEM FEATURES WITHIN LOS ANGELES ................................... 22 TABLE 8 SIGNIFICANT ECOLOGICAL AREA CLASSIFICATION ..................................................... 23 TABLE 9 PRIMARY HAZARDS AND IDENTIFIED HAZARD AREAS ................................................ 46 TABLE 10 MAJOR AFFECTED CATEGORY, SUB-CATEGORY AND DEFINITIONS ........................ 47 TABLE 11 RESIDENTIAL STRUCTURES WITHIN FEMA DESIGNATED FLOOD ZONES ................. 49 TABLE 12 CRITICAL FACILITIES WITHIN FEMA DESIGNATED FLOOD ZONES ............................. 49 TABLE 13 DAMAGES INDICATED IN QUESTIONNAIRE RESPONSES (TIER 1 PRIORITY) ............ 54 TABLE 14 EFFECTS INDICATED IN QUESTIONNAIRE RESPONSES (TIER 2 PRIORITY) .............. 54 TABLE 15 INITIAL RESULTS OF PROBLEM ASSESSMENT (LEVEL 1) ............................................ 55 TABLE 16 REPETITIVE LOSS PROPERTIES – LOS ANGELES RIVER (HILLSIDE) ......................... 65 TABLE 17 FLOODING CAUSES – LOS ANGELES RIVER (HILLSIDE) .............................................. 66 TABLE 18 “POTENTIALLY AFFECTED PROPERTIES” LOS ANGELES RIVER (HILLSIDE) ........... 67 TABLE 19 REPETITIVE LOSS PROPERTIES – LOS ANGELES RIVER (NON-HILLSIDE) ................ 69 TABLE 20 FLOODING CAUSES – LOS ANGELES RIVER (NON-HILLSIDE) ..................................... 69 TABLE 21 “POTENTIALLY AFFECTED PROPERTIES” LOS ANGELES RIVER (NON-HILLSIDE) .. 70 TABLE 22 REPETITIVE LOSS PROPERTIES – BALLONA CREEK (HILLSIDE) ................................ 72 TABLE 23 FLOODING CAUSES – BALLONA CREEK (HILLSIDE) ..................................................... 73 TABLE 24 “POTENTIALLY AFFECTED PROPERTIES” BALLONA CREEK (HILLSIDE) .................. 75 TABLE 25 REPETITIVE LOSS PROPERTIES – BALLONA CREEK (NON-HILLSIDE) ....................... 76 TABLE 26 FLOODING CAUSES – BALLONA CREEK (NON-HILLSIDE) ............................................ 77 TABLE 27 “POTENTIALLY AFFECTED PROPERTIES” BALLONA CREEK (NON-HILLSIDE) ......... 78 TABLE 28 RECOMMENDED SOLUTIONS - LOS ANGELES RIVER (HILLSIDE) RLPS .................. 109 TABLE 29 SUMMARY – LOS ANGELES RIVER (HILLSIDE) RLPS .................................................. 110 TABLE 30 RECOMMENDED SOLUTIONS - LOS ANGELES RIVER (NON-HILLSIDE) RLPS ......... 111 TABLE 31 SUMMARY – LOS ANGELES RIVER (NON-HILLSIDE) RLPS ......................................... 111 TABLE 32 RECOMMENDED SOLUTIONS - BALLONA CREEK (HILLSIDE) RLPS ......................... 112 TABLE 33 SUMMARY - BALLONA CREEK (HILLSIDE) RLPS .......................................................... 113 TABLE 34 RECOMMENDED SOLUTIONS - BALLONA CREEK BASIN (NON-HILLSIDE) RLPS .... 113 TABLE 35 SUMMARY - BALLONA CREEK (NON-HILLSIDE) RLPS................................................. 114

FIGURES

City of Los Angeles Floodplain Management Plan – November 2001 iv

EXHIBITS

Figures FIGURE 1 CRS COMMUNITIES BY CLASS ....................................................................... 3 FIGURE 2 LOCATION OF COMMITTEE MEMBERS .......................................................... 6 FIGURE 3 FLOOD HAZARD ASSESSMENT QUESTIONNAIRE DISTRIBUTION .............. 9 FIGURE 4 CITY OF LOS ANGELES POPULATION ......................................................... 11 FIGURE 5 ANNUAL RAINFALL FOR LOS ANGELES CIVIC CENTER ............................ 12 FIGURE 6 CITY OF LOS ANGELES MAJOR CHANNELS AND WATERSHEDS ............ 13 FIGURE 7 PHOTOS OF 1938 FLOOD ............................................................................... 14 FIGURE 8 PHOTOS OF 1938 FLOOD ............................................................................... 15 FIGURE 9 PHOTOS OF FLOOD CONTROL SYSTEM CONSTRUCTION ........................ 18 FIGURE 10 PHOTOS OF FLOOD CONTROL SYSTEM CONSTRUCTION ........................ 19 FIGURE 11 SIGNIFICANT ECOLOGICAL AREAS ............................................................. 24 FIGURE 12 FAULT RUPTURE STUDY AREAS .................................................................. 28 FIGURE 13 WILDFIRE HAZARD AREAS ........................................................................... 30 FIGURE 14 INUNDATION AND TSUNAMI HAZARD AREAS ............................................. 37 FIGURE 15 LANDSLIDE AREAS ........................................................................................ 40 FIGURE 16 AREAS SUSCEPTIBLE TO LIQUEFACTION .................................................. 41 FIGURE 17 OIL FIELD AND OIL DRILLING AREAS .......................................................... 42 FIGURE 18 LANDUSE WITHIN FEMA DESIGNATED FLOOD ZONES .............................. 48 FIGURE 19 RESPONSES TO QUESTIONNAIRE ............................................................... 53 FIGURE 20 INITIAL RESULTS OF PROBLEM ASSESSMENT (LEVEL 1) ........................ 58 FIGURE 21 FLOOD CASE STUDY AREA - EXAMPLE ...................................................... 59 FIGURE 22 MUD FLOW CASE STUDY AREA – EXAMPLE ............................................... 60 FIGURE 23 REPETITIVE LOSS PROPERTIES ................................................................... 63 FIGURE 24 RETAINING WALL AND DRAINAGE LAYOUT ............................................. 115 FIGURE 25 BERM AND SUMP LAYOUT .......................................................................... 116 FIGURE 26 INLET/FRENCH DRAIN AND DRAINAGE LAYOUT ...................................... 117

APPENDICES

City of Los Angeles Floodplain Management Plan – November 2001 v

APPENDICES APPENDIX A MAPS

A-1. CURRENT RISK AREAS/WATERSHEDS ............................................................................................. I A-2. FLOOD LOSS THROUGHOUT CITY – RLPS AND FEMA PAID CLAIMS........................................... II A-3. CRITICAL FACILITIES ........................................................................................................................ III A-4. MAJOR CHANNELS AND MAIN STORM DRAINS (CITYWIDE) ....................................................... IV A-5. MAJOR CHANNELS AND MAIN STORM DRAINS (BURROUGHS MIDDLE SCHOOL) ................... V A-6. MAJOR CHANNELS AND MAIN STORM DRAINS (REED MIDDLE SCHOOL) ................................ VI A-7. MAJOR CHANNELS AND MAIN STORM DRAINS (REVERE MIDDLE SCHOOL) .......................... VII A-8. MAJOR CHANNELS AND MAIN STORM DRAINS (STONEHURST RECREATION CENTER) ..... VIII A-9. FMP PUBLIC REVIEW LOCATIONS .................................................................................................. IX

APPENDIX B LETTERS

INCLUDES LETTERS TO REPETITIVE LOSS PROPERTY OWNERS, POTENTIAL FMP COMMITTEE MEMBERS, RESIDENTS IN HIGH RISK AREAS, AND OTHER AGENCIES

APPENDIX C QUESTIONNAIRES INCLUDES REPETITIVE LOSS PROPERTY QUESTIONNAIRE AND FLOOD HAZARD ASSESSMENT QUESTIONNAIRE

APPENDIX D FMP COMMITTEE INFORMATION INCLUDES COMMITTEE BY-LAWS, MEMBERSHIP LIST, MEETING SCHEDULES, AND MEETING MINUTES

APPENDIX E FMP CREDIT CALCULATION

TECHNICAL APPENDICES 1 THROUGH 4 (Tetra Tech, Inc.)

City of Los Angeles Floodplain Management Plan – November 2001 1

1. INTRODUCTION TO THE PLAN

1.1. Purpose

The Floodplain Management Plan (FMP) has been developed to (1) identify the City’s known flood problem areas, (2) establish goals, objectives, policies and implementation programs to reduce flooding and flood related hazards, and (3) ensure the natural and beneficial functions of our floodplains are protected. Achievement of this purpose is accomplished through the maximum utilization of existing programs and resources, involving those most affected by flood hazards in the planning process, and ensuring that the policies and programs identified in the implementation plan are carried out.

1.2. Background

In 1968, the U.S. Congress passed the National Flood Insurance Act which established the National Flood Insurance Program (NFIP). The NFIP was broadened and modified with the passage of the Flood Disaster Protection Act of 1973 and later, the Flood Insurance Reform Act of 1994. The NFIP is a federal program administered by the Federal Emergency Management Agency (FEMA) with the purpose of reducing future flood losses. The mechanism to accomplish this is the requirement that communities participating in the program commit to the adoption and enforcement of minimum floodplain management standards.

1.2.1. National Flood Insurance Program (NFIP)

The NFIP makes Federally-backed flood insurance available in communities that adopt and enforce floodplain management ordinances to reduce future flood damage. Flood insurance is available in more than 19,000 communities across the United States. FEMA’s Federal Insurance Administration and Mitigation Directorate manage the NFIP. The Federal Insurance Administration manages the insurance component of the NFIP, and works closely with FEMA’s Mitigation Directorate, which oversees the floodplain management aspect of the program. The NFIP, through partnerships with communities, the insurance industry, and the lending industry, helps reduce flood damage by nearly $800 million a year. Further, buildings constructed in compliance with NFIP building standards suffer 77 percent less damage annually than those not built in compliance. In addition, every $3 paid in flood insurance claims saves $1 in disaster assistance payments.1 The City of Los Angeles joined the regular phase of the NFIP on December 2, 1980. Compliance and ongoing participation in the NFIP ensures that all City residents can purchase flood insurance. Compliance with the NFIP also required the City to adopt and enforce a Specific Plan for the Management of Flood Hazards (Section 1.2.3 on page 4 describes the Specific Plan in more detail).

Source:

1 FEMA

INTRODUCTION TO THE PLAN


1.2.2. Community Rating System (CRS)

The NFIP/CRS was implemented in 1990 as a program for recognizing and encouraging community floodplain management activities that exceed the minimum NFIP standards. The National Flood Insurance Reform Act of 1994 codified the CRS in the NFIP. Under the CRS, flood insurance premium rates are adjusted to reflect the reduced flood risk resulting from community activities that meet the three goals of the CRS: (1) reduce flood losses; (2) facilitate accurate insurance rating; and (3) promote the awareness of flood insurance. The CRS recognizes 18 creditable activities, organized under four categories (numbered 300 through 600): Public Information, Mapping and Regulations, Flood Damage Reduction, and Flood Preparedness. Accumulation of credit points results in the assignment of a CRS classification. Flood insurance premium rates are reduced as the CRS classification decreases. There are a total of ten CRS classes: Class 1 requires the most credit points and gives the largest premium reduction; Class 10 receives no premium reduction. Table 1 below shows the CRS class levels, corresponding credit points, and premium reductions. Table 1 NFIP COMMUNITY RATING SYSTEM – CLASS SUMMARY

Insurance Premium Reduction

Class Credit Points SFHA* Non-SFHA**

1 4,500+ 45% 5%

2 4,000 – 4,499 40% 5%

3 3,500 – 3,999 35% 5%

4 3,000 – 3,499 30% 5%

5 2,500 – 2,999 25% 5%

6 2,000 – 2,499 20% 5%

7 1,500 – 1,999 15% 5%

8 1,000 – 1,499 10% 5%

9 500 – 999 5% 5%

10 0 – 499 0% 0% *Special Flood Hazard Area **Preferred Risk Policies are available only in B, C, and X zones for properties that are shown to have a minimal risk of flood damage. The Preferred Risk Policy does not receive premium rate credits under the CRS because it already has a lower premium than other policies.

As of October 1, 2000, there were 926 communities participating in the CRS program. Figure 1 below shows the distribution of CRS-participating communities by Class.



Figure 1 CRS COMMUNITIES BY CLASS

The 926 CRS communities account for 66% of all NFIP policies. Of all the CRS Communities, the City of Tulsa, Oklahoma has the highest-rated program. Their Class 3 rating is the best in the nation. By continuing to implement more than the minimum required NFIP standards for flood hazard planning, the City of Los Angeles has been a voluntary participant in the CRS since 1991. Floodplain management planning is a principal activity of the City’s compliance with the CRS. FEMA made a significant change to the CRS floodplain management planning activity in July 1996. This change requires the development and implementation of a FMP. When adopted, the FMP will replace the existing Repetitive Loss Plan as a credited activity under the CRS. (Refer to Section 1.4 for more discussion regarding inclusion of Repetitive Loss properties in this FMP). The City’s current CRS classification is 9, which provides for a 5% insurance premium reduction for all City residents. At this time, the City has actually accumulated enough credit points to qualify for a classification of 8, however the classification upgrade can not occur until FEMA has approved the FMP. The CRS class upgrade will provide for an additional 5% flood insurance premium reduction for all policies issued within Special Flood Hazard Areas.

27

110

352

431

0 150

50

100

150

200

250

300

350

400

450

500

Class 9 Class 8 Class 7 Class 6 Class 5 Class 4 Class 3

CRS Classification

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1.2.3. Existing City Regulations

The City Charter sets forth the authority for the establishment of specific plans as may be required to ensure the implementation of the General Plan and to comply with programs such as the NFIP. The City’s Specific Plan for the Management of Flood Hazards (Specific Plan) was originally established by Ordinance No. 154,405 and amended most recently in July 1998 by Ordinance No. 172,081. Ordinance No. 172,081 designates the City Engineer as the Flood Hazard Mitigation Coordinator for the City. The Flood Hazard Mitigation Coordinator is responsible for coordinating the implementation of this ordinance among the Planning, Building and Safety, and Public Works Departments. The Specific Plan is the key component of the City’s participation in the NFIP. The City Engineer has primary responsibility for implementing and managing the activities required within the NFIP. This authority is delegated to the City’s NFIP-CRS Coordinator, who is also certified as a Floodplain Manager. In addition, FEMA continually modifies and updates NFIP requirements for local agencies with the long-range goal of public safety and reduced flood damage.

1.3. Plan Approach

The development of the FMP follows the 10-step planning process identified in Section 511 of the CRS Coordinator’s Manual, January 1999. The City has covered each of the 10 steps in developing the plan but has not organized the plan according to the 10 steps. To simplify the FMP review and evaluation process we have developed the following cross-reference table that indicates the FMP sections that relate to each of the 10 planning steps. Appendix E summarizes the FMP credit calculation as estimated by City staff. Table 2 RELATIONSHIP BETWEEN CRS PLANNING PROCESS AND FMP DOCUMENT

CRS 10-Step Planning Process Floodplain Management Plan Sections Subsection Step

a. Organize to prepare the plan 1.1,1.3,2.1,2.2,2.3,2.4

b. Involve the public 2.1,2.2,2.3,2.4

c. Coordinate with other agencies 2.1,2.2,2.3,7.2

d. Assess the hazard 5.1,5.2,6.1,6.2,6.3,6.4,6.5

e. Assess the problem 6.1,6.2,6.3,6.4,6.5

f. Set goals 7.1,7.2

g. Review possible activities 7.3

h. Draft an action plan 8.1

i. Adopt the plan 9.1

j. Implement, evaluate, and revise 9.2, 9.3



1.4. Repetitive Loss Properties

In July 1994, the City of Los Angeles adopted a “Repetitive Loss Plan” as a part of our compliance with the National Flood Insurance Program Community Rating System. The plan was approved by FEMA in September 1994. The development and implementation of the FMP will replace the existing Repetitive Loss Plan and corresponding implementation activities related to repetitive loss properties. A Repetitive Loss Property (RLP) is one for which two or more claims of $1,000 or more have been paid by the NFIP within any given 10-year period since 1978. The objective of the FMP is to provide programs with specific guidance for potential mitigation measures and activities to best address the problems and needs associated with RLPs. There are currently 117 RLPs within the City of Los Angeles. The RLPs have been identified and grouped by watershed area and flood hazard. The two watersheds that contain RLPs are the Los Angeles River and Ballona Creek. Flood hazards are described by hillside and non-hillside areas. The four groups of RLPs are Los Angeles River Hillside, Los Angeles River Non-Hillside, Ballona Creek Hillside and Ballona Creek Non-Hillside. The summary of the hazard and problem assessment for RLPs is contained in Section 6.5. Figure 23 on page 63 shows the distribution of the RLPs by watershed. The City has developed the FMP with the intent that the goals, objectives, policies and implementation programs apply to all properties within the City. However, RLPs also have a specific objective, policies and programs to address the problems unique to these individual parcels or areas. Refer to Section 7.2 for the Goals, Objectives and Policies, and Section 8.1 for the Implementation Programs.


Figure 2 LOCATION OF COMMITTEE MEMBERS

2. FMP COMMITTEE AND PUBLIC INVOLVEMENT

The development, modification and revision of the FMP are accomplished through the direction and oversight of a FMP Committee and under the supervision of a professional planner. FEMA places a high priority on the establishment of a planning committee that consists of residents, businesses and property owners that are most affected by flood hazards, as well as the involvement of a professional planner. The City has maximized the involvement of the public and the professional planner throughout the FMP Committee process.

2.1. Committee Membership

The FMP Committee consists of 37 members, with over 50 percent of the members from the general public. There are 20 citizen members from different geographic areas of the City representing owners and renters located within 100-year floodplains, homeowner/ neighbor associations, local businesses, real estate agents, engineers, developers, planners, politicians, and concerned citizens. Table 3 below lists the FMP committee members. There are 14 members representing City departments including Planning, Emergency Preparedness, Building and Safety, Recreation and Parks, Office of the City Administrative Officer, Public Works (Sanitation, Engineering, Public Information Office, Board of Public Works), Fire Department, Community Development, and Harbor. Other committee members include a representative from the Los Angeles County Department of Public Works (Watershed Management Division), a

FMP COMMITTEE


professional planner (City sub-consultant from PCR Services Corporation), and the NFIP-CRS Coordinator (representing the Flood Hazard Mitigation Coordinator). The NFIP-CRS Coordinator will be the primary designee of the City Engineer in the implementation of the FMP. Table 3 FMP COMMITTEE MEMBERSHIP LIST

Citizen Members City/Agency Members

ID Name Business, Occupation or Interest Name Department/Bureau/Office

1 Elliott Agurs Self-employed Mark Davis Emergency Preparedness Department

2 Maria Amaya Interested Citizen Ana Day Emergency Preparedness Department

3 Joann Deutch Interested Citizen Jim Doty Bureau of Engineering

4 Stewart E. Fliege Brentwood Homeowner's Association John Duggan Department of Recreation and Parks

5 Mike Greenspan Citizen Tonya Durrell Board of Public Works

6 Jose Gutierres City of Los Angeles, Planning Department

Craig Fry Fire Department

7 Virginia ("Ginny") Hatfield

California Sate Assembly Robert Hertzerg's Office

Laurie Hancock Community Development

8 Joel Henderson Laurel Canyon Neighborhood Association

Michael Kantor Bureau of Engineering

9 Richard Higashi Interested Citizen Alfredo Magallanes Bureau of Sanitation

10 Marcia Hobbs Interested Citizen Tom Grant Office of the City Administrative Officer

11 Tom Horn Real Estate Agent Siavosh Poursabahian Department of Building and Safety

12 Dan Lafferty LACDPW-Water Resources Lucia Ruta Board of Public Works

13 Elizabeth McClellan 8th District Empowerment Congress Roque Nino Department of Planning

14 Theresa Miller Interested Citizen Daryl Raasch Harbor Department

15 Elzora Ransom Interested Citizen Special Members

16 Maria Rodriguez Union Elementary Luci Hise Professional Planner

17 Brad Rosenheim Rosenheim & Assoc., Development Consultant

Vik Bapna LACDPW

18 Charles Segal Interested Citizen Technical Staff / Coordinator

19 Douglass Staheli Bel-Air Bay Club, Assistant General Manager

Rosalia Rojo NFIP / CRS Coordinator

20 Frank Wein URS Corportation, Urban Planner

2.2. Committee Establishment

To identify potential FMP Committee members, the NFIP-CRS Coordinator conducted a public outreach program to residents in areas that were believed to be high-risk in relation to flood hazards and who were most likely to participate on the FMP Committee. High-risk areas were identified as those with multiple historical drainage complaints, historical flood claims, proposed capital improvement projects, Special Flood Hazard Areas, Repetitive Loss Properties and adjacent properties, hillside areas (where slope is greater than or equal to six-percent), and proximity (within 500 feet) to the coast. For a more detailed description of the identification of high-risk areas, refer to Section 6.3.1. Likeliness to participate was based on the City’s Department of Neighborhood Empowerment (DONE) database of residents involved in community issues. The DONE database consists of a variety of community groups, community activists, homeowner associations and interested individuals.

FMP COMMITTEE


The combination of high-risk data and community data was then evaluated utilizing a Geographic Information System (GIS). The GIS analysis provided a list of approximately 10,000 residents who met both sets of criteria. These residents were then contacted by letter to solicit interest in participation on the FMP Committee and the development of the FMP. Copies of the original solicitation letter and various follow-up letters are contained in Appendix B. Each of the respondents (122 total) was interviewed to verify their interest and to further explain the FMP process, the role of the FMP Committee and the commitment necessary to participate on the FMP Committee. We then selected 20 citizens who we felt would provide the broadest representation of geographic areas and flood hazards. Figure 2 on page 6 shows the geographic distribution of the 20 citizen FMP Committee members.

2.3. Committee Meetings

FMP Committee meetings were held for the five required steps in the planning process. The five key steps are (1) assess the hazard; (2) assess the problem; (3) set goals; (4) review possible activities; and (5) draft an action plan. A total of seven FMP Committee meetings (one meeting was a subcommittee) were held to cover the five required planning steps. The additional meetings were added to allow the Committee more time to discuss the assessment of hazards and problems, the setting of goals and the identification of programs. The FMP Committee membership list, by-laws, meeting schedule, meeting minutes, and other relevant information are contained in Appendix D.

2.4. Public Input

Public input to the FMP development process was obtained through the distribution of a questionnaire and by conducting public meetings at various stages in the process.

2.4.1. Public Meetings

Because Los Angeles represents over 400 square miles of area, we knew that multiple public meetings were necessary to reasonably accommodate the community. A total of eight public meetings were conducted as part of the FMP development and adoption process. Four public meetings were conducted at the beginning of the FMP process to obtain input on flood problems and possible solutions. The four meetings were scheduled in different geographic locations to maximize accessibility to the public. To obtain additional input, we relied on the questionnaire that is discussed in Section 2.4.2 below. To obtain public input on the draft FMP, four public meetings were conducted prior to its submittal to the Mayor and City Council for consideration and approval. These four public meetings were conducted in the same locations as the earlier FMP process input meetings.

FMP COMMITTEE


2.4.2. Questionnaire

As discussed in Section 2.2 above, the GIS was used to identify high-risk areas throughout the City. Areas were identified as high-risk because of multiple historical drainage complaints, historical flood claims, proposed capital improvement projects, Special Flood Hazard Areas, Repetitive Loss Properties and adjacent properties, hillside areas (where slope is greater than or equal to six-percent), and proximity (within 500 feet) to the coast. For a more detailed description of the identification of high-risk areas, refer to Section 6.3.1. The GIS analysis resulted in the identification of approximately 60,000 addresses in areas suspected of flooding risks. A Flood Hazard Assessment Questionnaire was mailed to each of these residents. The questionnaire is included in Appendix C. Figure 3 below shows the distribution of the questionnaires. The intent of the questionnaire was to identify current problems that have been experienced by the residents, businesses and community groups within high-risk areas. It also provided the opportunity for the public to provide input at the beginning of the planning process as an alternative to attending a public meeting. Repetitive Loss Properties were excluded from the risk area identification process discussed above (although, all properties adjacent to RLPs were included). A more specific version of the questionnaire was sent exclusively to the 117 identified Repetitive Loss Properties. The Repetitive Loss Property Questionnaire is also included in Appendix C.

Figure 3 FLOOD HAZARD ASSESSMENT QUESTIONNAIRE DISTRIBUTION

Other

0.01%Citizens Selected

for FMP

Committee

0.04%

Potential

Citizen FMP

Committee

Members

0.11%

Homeowners

Association

0.23%

DONE

Participants

3.25%

500 feet from

Beach Front

0.67%

Churches

0.53%

Neighborhood

Association/

Block Club

0.45%

Hillside

(Slope >= 6%)

74.98%Special Flood

Hazard Areas

10.49%

Proximity to

Repetitive Loss

Property

9.23%

FMP COMMITTEE


2.4.3. Public Review

In addition to the public meetings and the questionnaire described in the previous sections, a 30-day public review period was conducted between July 16, 2001 and August 15, 2001. During this public review period the FMP was made available at 15 locations citywide. The locations are shown in Table 4 below and a map is included in Error! Reference source not found.. Table 4 FMP PUBLIC REVIEW LOCATIONS Address Phone

Engineering District Offices

A Central 201 N. Figueroa St. Los Angeles (213) 977-6032

B Harbor 638 S. Beacon St. San Pedro (310) 732-4680

C Valley 14410 Sylvan St. Van Nuys (818) 756-8946

D West Los Angeles 1828 Sawtelle Bl West Los Angeles (310) 575 8384

Libraries

1 Eagle Rock 5027 Casper Av Los Angeles (323) 258-8078

2 Chatsworth 21052 Devonshire St. Chatsworth (323) 341-4276

3 Exposition Park Regional 3665 S. Vermont Av. Los Angeles (323) 732-0169

4 Goldwyn Hollywood Regional 1623 Ivar Av. Los Angeles (323) 467-1821

5 Lincoln Heights 2530 Workman St. Los Angeles (213) 226-1692

6 Mid-Valley Regional 16244 Nordhoff St. North Hills (818) 895-3650 7 Donald B Kaufman (Brentwood) 11820 San Vicente Bl Brentwood (310) 575-8273

8 Robertson 1719 S. Robertson Bl Los Angeles (310) 840-2147

9 Sunland-Tujunga 7771 Foothill Bl. Tujunga (323) 352-4481

10 Malabar Branch 2801 Wabash Ave Los Angeles (323) 263-1497

11 Wilmington 1300 N. Avalon Bl. Wilmington (310) 834-1082

12 Encino - Tarzana 18231 Ventura Bl Tarzana (818) 343-1983

13 Central Library 630 W. Fifth Street Los Angeles (213) 228-7000

14 Westchester 8946 Sepulveda Los Angeles (310) 645-6082

15 Abbot-Kinney / Venice Beach 501 S. Venice Bl Venice (310) 821-1769

The public review period was advertised in local newspapers and notifications were directly mailed to a large number of homeowner associations, community groups and interested individuals. Also, over 60 agencies were notified of the availability of the FMP for public review and comment. Agencies that are identified in the Implementation Plan as a “ responsible agency”, were provided a copy of the FMP for review and comment.


The City of Los Angeles 468 square miles mild climate 75% alluvial plain 25% rugged canyons & hills nearly all precipitation

occurs from December through March

historical (since 1877) rainfall has ranged from 5 to 38 inches annually

Figure 4 CITY OF LOS ANGELES POPULATION

3. COMMUNITY DESCRIPTION

3.1. Area

The City of Los Angeles is located along the southern coast of the State of California. The City is 468 square miles and has an irregular shape with the most expansive areas being in the northern part of the city and tapering down to a strip in the southern portion. The City of Los Angeles is the largest of 88 incorporated cities within the County of Los Angeles. The City contains approximately 215 square miles of hills and mountains and 22 square miles of parkland, including the largest urban park in the world Griffith Park. Los Angeles is surrounded by the San Gabriel Mountains and Santa Susana Mountains to the north, Santa Monica Mountains to the northwest (which extend into the City), Santa Monica Bay to the west, and San Pedro Bay to the south.

3.2. Population

According to the 2000 Federal Census of Population and Housing, the City of Los Angeles is the second largest city in the United States, with an estimated population of 3,694,820. Los Angeles also has the sixth highest population density, with an average of 8,000 people per square mile. Since the previous census in 1990, Los Angeles’ population increased by 6%. The largest numerical increases were in Central Los Angeles and the Northern San Fernando Valley (each had an increase of approximately 24%). The City's population is projected to further increase to 4,543,000 in 2020 according to the Southern California Association of Governments (SCAG). Figure 4 shows how the population of Los Angeles has increased over the past forty years.2

Source:

2 Department of City Planning

2,479,015

2,811,801

2,966,850

3,485,398

3,694,820

1960 1970 1980 1990 2000

Po

pu

lati

on

(U

S C

en

su

s)

COMMUNITY DESCRIPTION


Figure 5 ANNUAL RAINFALL FOR

LOS ANGELES CIVIC CENTER 3.3. Climate and Rainfall

In general, the Los Angeles area has a mild climate characterized by warm, dry summers and cool, wet winters. Both temperature and precipitation vary considerably with elevation, topography, and distance from the Pacific Ocean. A storm producing moderate rainfall on the coast (1” during a 24-hour period) may produce very heavy rainfall in the mountains (up to 10-20” during the same 24-hour period). Nearly all precipitation occurs from December through March. Precipitation during the summer months is infrequent, and rainless periods of several months are common. Precipitation usually occurs as localized cloudburst and general heavy rains, although snow occurs in the higher elevations. In general, the quantity of precipitation increases with elevation. Over 100 years of rainfall records are available for locations throughout Los Angeles County. Figure 5 to the left shows the total annual rainfall for the Los Angeles civic center for the past 30 years3.

3.4. Drainage

The City terrain can be classified as 75 percent alluvial plain and 25 percent rugged canyons and hills. Elevations range from 5,074 feet at Sister Elsie Peak in the San Gabriel Mountains to nearly mean sea level in the southwestern part of the City. With the cooperation of City, County, and Federal agencies, Los Angeles has an extensive drainage system to protect its citizens and property from flood damage. The City, County, and Federal facilities have capacities for a 10-year event, a 50-year event, and a 100-year event, respectively. This system includes open flood control channels, flood control basins, storm drains, debris basins, detention basins, and spreading grounds (see Chapter 4).

Source:

3 National Weather Service

Inches of Rainfall

9.1

31.0

12.4

12.4

24.4

8.1

27.4

21.0

12.0

7.4

8.1

12.5

7.7

17.9

12.8

10.4

31.3

10.7

9.0

27.0

19.7

33.4

12.3

7.2

14.4

14.9

21.3

7.2

12.3

7.7

27.5

0 10 20 30 40

1998-1999

1997-1998

1996-1997

1995-1996

1994-1995

1993-1994

1992-1993

1991-1992

1990-1991

1989-1990

1988-1989

1987-1988

1986-1987

1985-1986

1984-1985

1983-1984

1982-1983

1981-1982

1980-1981

1979-1980

1978-1979

1977-1978

1976-1977

1975-1976

1974-1975

1973-1974

1972-1973

1971-1972

1970-1971

1969-1970

1968-1969



3.5. Land Use

Los Angeles County increased population by almost 270% between 1940 and 19904. This growth and urbanization has increased stormwater runoff by creating impermeable foundations and surfaces which decrease the amount of water percolating into the soil. In turn, more runoff enters local storm drains and flood channels.

Figure 6 CITY OF LOS ANGELES MAJOR CHANNELS AND WATERSHEDS

3.6. Historical Flooding in Los Angeles

The major causes of flooding in Los Angeles are short-duration, high-intensity storms. The Spanish Mission Fathers who traveled between San Diego and San Francisco in 1769-70 first recorded flooding in the Southern California Area. In the 1800’s, major floods occurred in 1810, 1825, 1862, 1884, 1889, and 1891. The Los Angeles River has altered its point of discharge to the ocean numerous times in the distant past, which is consistent with the alluvial nature of the Los Angeles basin. The flood of 1825 was severe enough to change the course of both the Santa Ana and Los Angeles Rivers. The most recent relocation occurred in the

Source:

4 City of Los Angeles, General Plan Framework, 1999

2 3

5

12



Figure 7 PHOTOS OF 1938 FLOOD

flood of 1862 when the mouth of the Los Angeles River moved from Ballona Creek to its present location in Long Beach Harbor. In the 1900’s, significantly damaging flood flows occurred in 1914, 1916, 1927, 1934, 1938, 1941, 1943, 1952, 1956, 1969, 1978, 1980, and 1983. While the largest flood was probably in the 1800’s (1862), the most damaging flood took place in the 1900’s (1969). The historical record indicates that large floods occur infrequently in Los Angeles, but the magnitude of their destruction is enormous, especially as development in the floodplain dramatically increased. Although a flood with a 100-year or greater frequency has not occurred in the 20th century, floods of near this magnitude have occurred in the past and caused extensive damages throughout the basin. Historical records of the United States Geological Survey indicate that the 1-in-100 year flood flow has been exceeded in the Los Angeles River Basin at the Tujunga Canyon in March 1938, and Topanga and Malibu Creeks in January 1969. The February 1938 flood caused an estimated $40 million in damages and the loss of 113 lives throughout Los Angeles County. A large volume of floodwater, predominately originating in the San Gabriel Mountains, caused significant flooding in the cities of Glendale and Burbank. Extreme flood flows eroded the banks of the Tujunga Wash, damaging residential and commercial structures and washing out bridges and roads. Figure 7 and Figure 8 show photos that were taken after the 1938 flood.



Figure 8 PHOTOS OF 1938 FLOOD

Major storms in 1969 and 1978 demonstrated that the Los Angeles area is especially susceptible to disasters from sequential fire/flood cycles. The floods of January-February 1969 resulted from precipitation that approached six-times-normal in certain areas. The most affected areas experienced flooding as great as that of 1938 with rainfall rates actually surpassing those experienced during the 1938 storm. Prior to the 1969 storm, the Little Rock brush fire consumed 1,760 acres of watershed cover in the Little Tujunga Canyon drainage area and 1,090 acres of watershed cover in the Pacoima Canyon drainage area, causing severe denudation of these watersheds during the summer of 1968. After the saturation of the soil mantle by the first 4 days of the storm, the high-intensity rainfall that occurred on January 22, 1969, caused severe erosion and heavy runoff in most watersheds. Damage in Los Angeles from the 1969 storms was confined almost exclusively to the foothills and canyons. In the San Fernando Valley, on February 25, 1969, flows in Big Tujunga Wash reached a maximum of over 17,000 cubic feet per second, washing out the Oro Vista Avenue dip crossing and eroding the south bank farther downstream. In Sunland, seven homes were destroyed on Bengal Street, and several others on Le Berthon Street and Wescott Avenue were inundated. These flows also undermined and destroyed the southern Foothill Boulevard and Wentworth Place bridges. In the West Los Angeles area, a great deal of damage was caused in 1969 by the saturated condition of the Santa Monica Mountains watershed. In Rustic Canyon, high flows severely eroded the



natural watercourses, which had been protected somewhat with pipe and wire revetment. These flows battered the revetment and damaged homes, garages, and yards. On January 25, 1969, numerous earthslides and an abundance of eroded material caused Mandeville Canyon channel to silt up and overflow, destroying or badly damaging numerous residences and Mandeville Canyon Road. A mudslide destroyed a home along Mandeville Canyon road, killing a man and injuring a fireman who was attempting to rescue him. Record peak flows in Topanga Creek swept away bridges and washed out sections of Topanga Canyon Boulevard. Canyon roads between San Fernando Valley and the Hollywood-West Los Angeles area were closed because of earthslides. At least 10 persons were killed in storm-related accidents in the City of Los Angeles during the 1969 storms. Most notable during the 1969 storm season was the channel flow on the lower half of the Los Angeles River which represented over 80% of the design capacity. However, the Los Angeles County Drainage Area (LACDA) flood control system, which was 99% complete, protected the Los Angeles metropolitan area from what otherwise would have been unprecedented damage. Most of the damages that did occur were caused by mudflows in the foothill areas or by local storm drain inadequacies. In Los Angeles County, seventy-three lives were lost, and damages amounted to $31 million; with $12 million in damages sustained in the LACDA basin alone. The 1978 storms also caused severe damage in the City. Rainfall in the City before these storms was considerably above normal and the watersheds were well saturated; therefore, soil moisture was at or near field capacity in most areas. In addition, several watersheds had been burned by brush fires during the summer of 1977, and other watersheds that had been burned during the summer of 1975 had not fully re-grown their vegetative cover because of the drought conditions that prevailed until the 1977-78 water year. The major fires that affected runoff during the February 1978 storm are listed in Table 5 below: Table 5 FLOOD-FIRE HAZARD AREAS FOR FEBRUARY 1978 STORM

Name of Fire Date Acres Burned

Watershed Location

Pacoima Fire August 9-18, 1975 7,205 Pacoima Canyon

Mill Fire November 22-28, 1975 49,200 Big and Little Tujunga Canyon

Vetter Fire June 25-28, 1977 1,690 Big Tujunga Canyon

Middle Fire July 24-25, 1977 3,860 Mill Creek

La Tuna Fire July 27, 1977 425 La Tuna Canyon

Canyon Fire November 14-15, 1977 1,220 Topanga Canyon



On February 10, 1978, heavy runoff caused hillside erosion in the Verdugo Hills Cemetery located in the Tujunga area and washed debris into residential areas along Parsons Trail, where it accumulated to a depth of 6 feet. The debris-laden flow from Parsons Trail moved 3,400 feet downstream to Tujunga Canyon Boulevard, where it was joined by overflow from Rowley Debris Basin. Floating debris and mud from Zachau Debris Basin, in the Tujunga area, overtopped the spillway and filled the channel downstream, causing extensive damage to residences as far as 8,000 feet downstream. Unimproved reaches of Pacoima Wash and Big Tujunga Wash were eroded by high flows, and homes adjacent to these watercourses were damaged. Flows in Big Tujunga Wash eroded part of Foothill Boulevard and the area downstream. At least three homes were destroyed and one person was killed when debris-laden flows swept through Ebey Canyon, north of Sunland. The San Fernando Valley was hardest hit by the 1978 storm, and this area alone accounted for damage to the Los Angeles Flood Control District facilities estimated at $14.9 million or 28 percent of the total storm damage countywide. As severe, as the damage from the 1969 and 1978 floods were, the LACDA Project facilities prevented more than $2.7 million in further damage. However, about $10 million in damage from mudflows in unprotected, rapidly developing foothill and canyon areas occurred in those years. In addition, about $2 million in damage from landslides occurred in the Pacific Palisades area. The February 16, 1980, flood, estimated to be about a 40-year event, caused near-capacity channel flows in the lower Los Angeles River that deposited debris on the top of the levee which had previously been thought to have a 100-year protection. The 1980 flood damaged and destroyed homes, washed out bridges and roads, eroded beaches, disrupted transportation and closed schools and recreation facilities. Thousands of people were evacuated from their homes, and some communities were without water or natural gas for extended periods of time. Twenty-nine people lost their lives during these storms. President Carter declared Los Angeles, Orange, Riverside, San Bernardino, San Diego, Santa Barbara, and Ventura counties disaster areas. The estimate of damage in the Southern California area was $200 million.


Figure 9 PHOTOS OF FLOOD CONTROL

SYSTEM CONSTRUCTION

4. FLOOD CONTROL SYSTEM DESCRIPTION

With the cooperation of City, County, State and Federal agencies, Los Angeles has an extensive drainage system to protect its citizens and property from flood damage. The system includes open channels, flood control basins, storm drains, catch basins, culverts, low flow diversion structures, pumping plants, debris basins, detention basins, and spreading grounds. The primary agencies that share flood control responsibilities within the City of Los Angeles are the U. S. Army Corps of Engineers (Army Corps), the Los Angeles County Department of Public Works (County), the City of Los Angeles, and Caltrans. Each agency exercises jurisdiction over the flood control facilities they own and operate. Since each agency is responsible for complying with varying regulations, policies, and design standards, flood control facilities throughout the City can differ. Typically, City and County storm drains are designed to carry flow from a 10-year storm within the pipe. Streets and gutters are also considered part of the storm drain system. The combination of storm drain pipe and street (curb to curb) typically provides capacity for a 25-year storm. Army Corps facilities are typically designed for a 100-year storm.

4.1. Los Angeles County Drainage Area (LACDA Project)

In 1914, the State Legislature passed an act creating the Los Angeles County Flood Control District (now known as the Los Angeles County Department of Public Works) to control floods and conserve water. Early bond issues

FLOOD CONTROL SYSTEM DESCRIPTION


Figure 10 PHOTOS OF FLOOD CONTROL

SYSTEM CONSTRUCTION

financed construction of 14 dams in the San Gabriel Mountains. In addition, flood channel modifications were undertaken and debris basins were constructed to trap sediment. In 1936, Federal legislation made the Army Corps a participant in Los Angeles County’s comprehensive flood protection program. The Army Corps’ Los Angeles River, San Gabriel River and Ballona Creek projects included the construction of 5 flood storage reservoirs or basins, 24 debris basins, 95 miles of main channel, 191 miles of tributary channels and two jetties. Together, these two agencies are responsible for all of the major flood control facilities that protect the City of Los Angeles. This regional flood control system, which is known as the Los Angeles County Drainage Area (LACDA) Project, is one of the most extensive flood control systems ever built to protect a metropolitan area. LACDA includes the Los Angeles River, San Gabriel River, Rio Hondo Channel and Ballona Creek. Refer to Figure 6 on page 13 and Appendix Error! Reference source not found. for the general layout of the LACDA system. Flood control improvements to the LACDA system fall into four general categories, as described below:

1. Debris basins, found at the mouth of canyons, are designed to trap debris carried by floodwaters, leaving relatively clean water to flow unimpeded in downstream channels. There are currently 114 debris basins in the watersheds of the Los Angeles and San Gabriel River systems.



2. Flood control reservoirs are designed to control and reduce stream flow so that downstream main channel capacities are not exceeded. The Army Corps operates four major reservoirs as listed on the Table 6 below. Locally operated facilities include 15 flood control and water supply reservoirs in the upper watershed areas of the LACDA basin. Combined, these local reservoirs have a maximum combined capacity of about 102,000 acre-feet5, of which over half is reserved for flood control. In addition to flood protection, these projects also contribute to ground water recharge through spreading grounds, and create extensive recreational opportunities at reservoir facilities developed primarily by the Army Corps in partnership with the cities and the County of Los Angeles. The City of Los Angeles has built recreational facilities at the Hansen Dam and Sepulveda Dam (including golf courses, riding and hiking trails, picnic etc.)

Table 6 MAJOR RESERVOIRS BENEFITING THE CITY OF LOS ANGELES

NAME CAPACITY (acre-feet)

Hansen Dam 25,446

Lopez Dam 441

Santa Fe Dam 32,109

Sepulveda Dam 22,493

Whittier Narrows Dam 34,947

3. Improved channels are designed to speed passage of flood flows through the local communities and into the mainstem river system, draining either into a flood control reservoir or directly into one of the two mainstem rivers. Improved tributary channels include Arroyo Seco and Compton Creek.

4. Main channel improvements pass the controlled or partially controlled flows to the ocean. The Los Angeles River is improved for its entire reach below Sepulveda Dam, and the channel has a shape that fluctuates between trapezoidal and rectangular. The sides and invert are lined with either concrete or grouted rock, except for an ungrouted stone invert in the vicinity of Glendale and the reach from Willow Street to the Pacific Ocean where the channel is soft bottomed and the walls have riprap protection. Sepulveda and Hansen Dams (operated and maintained by the Army Corps) regulate flows to the main channel of the Los Angeles River.

In total, the LACDA system has over 100 miles of mainstem channel, over 370 miles of tributary channels, 129 debris basins, 15 flood control and water conservation dams, and 5 flood control dams. In addition, the Los Angeles County Department of Public Works has constructed and is responsible for the operation and maintenance of approximately 1,000 miles of storm drain bond-issue projects within the City of Los Angeles. All of these local drains provide protection to flood-prone areas.

Source:

5 An acre-foot is approximately 326,000 gallons.



As discussed in Chapter 3 of this document, the levee of the Los Angeles River was originally designed to provide protection from a 100-year event. However, the 1980 flood, estimated to be a 40-year event, left debris on the top of the levee. As a result, and based on a feasibility report, the Army Corps is completing a project to raise the parapet walls along the Los Angeles River.

4.2. City Drainage System

The City of Los Angeles has complemented the LACDA drainage system with a comprehensive storm drainage system to prevent local flooding. These local drains collect runoff and carry it to the mainstem river channels rapidly. An inventory of all flood control facilities within the City of Los Angeles and a break down showing the agency responsible for operation and maintenance of the facilities is shown in Table 7 on page 22.

4.3. Natural Resources and Beneficial Functions of Floodplains

A natural flood control system is composed of open spaces that provide natural and beneficial functions. Surface water, floodplains and watersheds are part of an ecological system that exists in a state of dynamic equilibrium. If a disturbance occurs in one part of the system, the entire system will readjust toward a new equilibrium. The geomorphological, hydrological, and biological effects of the system’s readjustments may be evident far upstream and downstream from the disturbance and may last for a long period of time. Therefore, floodplain development and modification should be viewed with caution and with careful assessment of the potential adverse impacts on the natural resources and beneficial functions, including flood protection to existing development. Floodplains in their natural or relatively undisturbed state provide three broad sets of natural and beneficial resources values. These values are (1) water resources values including natural moderation and attenuation of floods, water quality maintenance, and groundwater recharge; (2) biological resource values including large and diverse populations of plants and animals; and (3) societal resource values including historical, archeological, scientific, recreational, and aesthetic.



Table 7 FLOOD CONTROL SYSTEM FEATURES WITHIN LOS ANGELES

Flood Control Facility Feature

Description

Total Quantity

Jurisdictional Responsibility

Open Channel Larger visible concrete lined drainage system

220 miles

City of LA 31 mi

LACDPW 110 mi

US Army Corps 30 mi

Caltrans 49 mi

Storm Drain Pipe Underground pipe or box varying in size from 12” diameter to greater than

10’ diameter

1,900 miles

City of LA 1,200 mi

LACDPW 700 mi

Debris Basin Basin that collects debris (sand, mud, rock,

vegetation) at the point where natural areas

connect with development. Size varies

130 City of LA 86

LACDPW 29

US Army Corps 13

Caltrans 1

Catch Basin Curb inlet structure for directing runoff into the

storm drain system

62,660 City of LA 33,800

LACDPW 22,600

Caltrans 5,660

Private 280

Other 320

Pump Plant Collects runoff in low lying areas and pumps it

to an acceptable discharge location

15 City of LA 11

LACDPW 4

Culvert Open channel crossing at bridges or other

locations where a short pipe or box structure

conveys runoff

3,270 City of LA 2,350

LACDPW 520

Caltrans 290

Private 60

Other 50

Corrugated Metal Pipe (CMP) - City of LA only

Storm drains constructed of corrugated metal pipe. Typically, less desirable

and prone to require excessive maintenance

30 miles*

City of LA 30 mi

Low Flow Drain Conveys low or nuisance runoff short distances to alleviate minor problem

areas

1,315 City of LA 1,250

LACDPW 30

Caltrans 14

Private 20

Other 1

*This is only a preliminary estimate of the number of miles of CMP within City of LA



4.3.1. Significant Ecological Areas

The City of Los Angeles contains Significant Ecological Areas and other open spaces with significant value to habitats, plants and animals of special concern. “Significant Ecological Areas” (SEAs) were defined and mapped by the Los Angeles County Department of Regional Planning in 1976. Figure 11 on page 24 shows the SEAs and Table 8 below describes SEA classification. Table 8 SIGNIFICANT ECOLOGICAL AREA CLASSIFICATION

Class Description

1 The habitat of rare, endangered, and threatened plant and animal species.

2 Biotic communities, vegetative association, and habitat of plant and animal species either one-of-a-kind or restricted in distribution on a regional basis.

3 Biotic communities, vegetative association, and habitat of plant and animal species either one-of-a-kind or restricted in distribution in Los Angeles County.

4 Habitat that at some point in the life cycle of a species or group of species, serves as a concentrated breeding, feeding, resting, or migrating grounds, and is limited in availability.

5 Biotic resources that are of scientific interest because they are either in extreme physical geographical limitations, or they represent unusual variation in a population or community.

6 Areas important as game habitat or as fisheries.

7 Areas that would provide for the preservation of relatively undisturbed example of the natural biotic communities in Los Angeles County.

In addition to SEAs, the City has identified areas that can provide valuable habitat (Environmental Affairs Department, 1998. Draft LA CEQA Threshold Guidelines). (1) Pacoima Spreading Grounds (2) Sepulveda Flood Control Basin (3) Los Angeles River (4) Silverlake Reservoir (5) Stone Canyon Reservoir, and (6) San Pedro Harbor

Projects in these areas are subject to a higher level of review so that their habitat value is protected and potential impacts to the species they contain can be avoided. The City’s goal is to preserve SEAs in an ecologically viable condition for public education, research, and other non-disruptive outdoor uses, however limited compatible development is not precluded. Natural resources and biological resources are more specifically addressed in the City’s General Plan Conservation Element.



Figure 11 SIGNIFICANT ECOLOGICAL AREAS



4.3.2. Watershed Management

During the 1990’s, Federal and state agencies began to collaborate in efforts at coastal watershed planning, in hopes of preserving and enhancing remnant natural resources, particularly in rapidly urbanizing watersheds such as the Los Angeles River Watershed. In 1999, the Lower Los Angeles River and San Gabriel Mountains Conservancy (the Conservancy) was established. One of the Conservancy’s primary interests is to improve recreational, open space opportunities, and habitat values along the Los Angeles River. There are several other local agencies and community groups that are interested in watershed management issues, including the Los Angeles Regional Water Quality Control Board, California Coastal Conservancy, United States Fish and Wildlife Services, Santa Monica Mountains Conservancy, Los Angeles and San Gabriel Rivers Watershed Council, Sun Valley Watershed Stakeholders Group, North East Trees, Tree People, “Heal the Bay,” “Friends of the Los Angeles. River,” ”The River Project,” and the Trust for Public Land. The City of Los Angeles is an active participant in several of these organizations and maintains contact with all. Refer to Figure 6 on page 13 and Appendix Error! Reference source not found. to see the three major watersheds within the City of Los Angeles.

4.3.3. Wetlands

The California Coastal Conservancy has compiled “wetland profiles” distilling the most recent studies documenting physical and biological characteristics of Southern California’s coastal wetlands (Southern California Coastal Wetlands Inventory). Out of the nine wetlands profiled by the Coastal Conservancy, six are located (at least in part) within the limits of the City of Los Angeles. Of these six wetlands, only two areas (Tujunga Wash and Hansen Dam) contain FEMA designated SFHAs. Currently, the Lower Los Angeles River and San Gabriel Mountains Conservancy is examining restoration opportunities in the Los Angeles River watershed to provide a cohesive watershed restoration perspective (Wetlands of the Los Angeles River Watershed, Profiles and Restoration Opportunities). Projects to protect and enhance the flood control and habitat properties of wetlands are on going. In Venice, work is continuing to enhance natural habitat values in Ballona Lagoon and the Venice canals, while protecting adjacent areas from stormwater and stormtide flooding. The City, County, Corps of Engineers, and a private landowner have joined together to improve natural tidal flushing of Ballona Wetlands and to construct artificial wetlands to treat urban stormwater runoff flowing into Ballona Wetlands. The County of Los Angeles purchased 200 acres of Tujunga Wash, just south of the 210 Freeway, to use as a mitigation bank for impacts on riparian and/or wetland habitats. However, there are continued proposals for development of these sites, such as a proposed golf course and clubhouse on over 350 acres within the Tujunga Wash.


5. HAZARD IDENTIFICATION

In keeping with its congressional directives, FEMA established a National Mitigation Strategy that focused on incorporating mitigation as the foundation of emergency management. FEMA also established a National Mitigation Goal to be accomplished by the year 2010. The two components of the goal are (1) to substantially increase public awareness of natural hazards risk so that the public demands safer communities in which to live and work, and (2) to significantly reduce the risk of loss of life, injuries, economic costs, and destruction of natural and cultural resources that result from natural hazards6.

5.1. Basic Hazard Definitions

The first of five objectives set by FEMA to meet the National Mitigation Goal is Hazard Identification and Risk Assessment. The City of Los Angeles has used the basic hazard definitions as the starting point for identifying hazards for the FMP. The FEMA definitions for multi-hazards are provided below.

5.1.1. Atmospheric Hazards

Thunderstorms and Lightning: These events are generated by atmospheric imbalance and turbulence due to the combination of (1) unstable warm air rising rapidly into the atmosphere; (2) Sufficient moisture to form clouds and rain; and (3) Upward lift of air currents caused by colliding weather fronts (cold and warm), sea breezes, or mountains. The number one cause of deaths associated with thunderstorms is flashfloods. Lightning induced fires can also result from thunderstorm activity. Tornadoes: A tornado is a rapidly rotating vortex or funnel of air extending toward the ground from a cumulonimbus cloud. Most of the time, vortices remain suspended in the atmosphere. When the lower tip of the vortex touches earth, the tornado becomes a force of destruction. Other hazards that accompany weather systems that produce tornadoes include rainstorms, windstorms, large hail, and lightning. The most damaging tornado recorded in Los Angeles occurred in 1983. It traveled several miles, moving north from South Central Los Angeles and the vicinity of the Convention Center in the Central City. Vehicles were turned over and many homes and other structures were damaged. Severe Winter Storms: For Southern California, this phenomenon consists of the large winter storms that bring widespread rainfall to the region. These storms are different than typical thunderstorms in that they produce significant rainfall over a large portion of the region and can last for several days. Severe winter storms are associated with other natural hazards, such as coastal flooding and erosion, thunderstorms, tornadoes, and extreme winds. The 100-year rain event that defines

Source:

6 Multi-Hazard Identification and Risk Assessment – A Cornerstone of the National

Mitigation Strategy, Federal Emergency Management Agency, 1997

HAZARD IDENTIFICATION


the Special Flood Hazard Areas would most likely result from an extended duration severe winter storm.

5.1.2. Geologic Hazards

Landslides: Landslides and mudflows are common events in California because of active mountain-building processes, rock characteristics, earthquakes, and intense storms. There are also human factors that may contribute to or influence landslides. The principal human factors are mining and construction of highways, buildings, and railroads. The principal natural factors are topography, geology, and precipitation. The 1994 Northridge earthquake triggered more than 10,000 landslides. See Section 5.2.5.2 “Landslide Areas” on page 38 for more information and a map.

5.1.3. Hydrologic Hazards

Flooding: Flooding is defined as the accumulation of water within a water body and the overflow of excess water onto adjacent floodplain lands. Based on information provided by the Federal Interagency Floodplain Management Task Force, flooding in the South West United States can be separated into several types;

(1) Riverine (overflow from a river, channel, flash floods, alluvial fan floods, and dam-break floods);

(2) Local drainage or high groundwater levels; Groundwater is very close to the surface in the Wilshire District, feeding the La Brea tar pits, which once entrapped pre-historic animals.

(3) Fluctuating lake levels; (4) Coastal flooding (including storm surges and tsunamis); (5) Debris flows; and (6) Subsidence.

5.1.4. Seismic Hazard

Earthquakes: The City of Los Angeles (a major population center) is located in a seismically active area. However, the maximum anticipated earthquake for this area has not been experienced. The principal threat from earthquakes is the damage or collapse of buildings or infrastructure (dams, bridges, overpasses, roads, railways, and water, power, and communication lines). Figure 12 on page 28 shows the Fault Rupture Study Areas for the City of Los Angeles. Tsunamis: A tsunami is a wave or series of waves generated at sea or near shore by an earthquake, volcano, or landslide. Tsunamis often damage or destroy docking and waterfront storage facilities, boats and ships, residential and non-residential buildings, and other infrastructure. According to FEMA, Southern California is one of several areas likely to experience destructive tsunamis due to its location along the Pacific Rim. See Section 5.2.4.3 below for more information including a map of Tsunami Hazard Areas.



Figure 12 FAULT RUPTURE STUDY AREAS



5.1.5. Fire Hazard

Wildfires: There are four categories of wildfires that are experienced throughout the United States:

(1) Wildland fires are fueled by natural vegetation. Typically occurring in national forests and parks.

(2) Interface or Intermis fires are urban/wildland fires in which vegetation and the built-environment provide fuel.

(3) Firestorms are events of such extreme intensity that effective suppression is virtually impossible. Firestorms occur during extreme weather and generally burn until conditions change or the available fuel is exhausted.

(4) Prescribed fires and prescribed natural fires are fires that are intentionally set or selected natural fires that are allowed to burn for beneficial purposes.

The U. S. Forest Service reported in 1990 that 25.7% of wildfires were caused by arson. Other ignition sources include debris burns and lightning. Lightning can present particularly difficult problems when dry thunderstorms move across an area that is suffering from seasonal drought. Watershed areas burned by wildfires create a potential threat to downstream areas, in the event that above normal rainfall falls over burned watersheds, extensive damage to property from water, mud and water-carried debris could occur in the burned and downstream areas. Figure 13 on page 30 shows Selected Wildfire Hazard Areas for the City of Los Angeles.

5.1.6. Technological (Man-Made) Hazard

Dam Failure: Dam failures could result from a significant seismic event or landslide that may or may not be seismically induced. An engineering failure is not likely, but has occurred in the past and is a possibility. See Section 5.2.6 below for more information including a map.

5.2. Flood Hazards for the City of Los Angeles

The identification of flood hazards for the City of Los Angeles uses the framework created by FEMA and presented in Section 5.1. The FEMA framework has been enhanced to correlate to the local conditions experienced in Los Angeles. The hazard assessment contained in Chapter 6 is based on the identified hazards within the five categories. The System Failure Related category includes technological hazards due to the possibility of system failure (e.g., dam failure during a seismic event).



Figure 13 WILDFIRE HAZARD AREAS



5.2.1. FEMA Special Flood Hazard Areas

The Flood Insurance Rate Maps (FIRMs) are the official maps for the City of Los Angeles on which FEMA has delineated the applicable Special Flood Hazard Areas (SFHAs), which include shallow flooding, floodway, alluvial fans, and coastal areas. The SFHAs were determined using statistical analysis of records of river flow, storm tides, and rainfall; information obtained through consultation with the City of Los Angeles, the County of Los Angeles; floodplain topographic surveys; and hydrologic and hydraulic analyses. A detailed Flood Insurance Study (FIS) for the areas subject to flooding was originally completed on September 2, 1980, with updates occurring in 1984, 1987, 1991, 1998 and 1999.

5.2.1.1. Areas of Shallow Flooding

Shallow flooding (zones A, AE, A1-30, AH, AO) occurs in flat areas when there are depressions in the ground that collect "ponds" of water, areas of sloping land and areas of sheet flow where flood depths from one to three feet are indicated. Some SFHAs (zone designation AO) experience a sheet flow hazard, but because detailed hydraulic analyses have not been performed, no base flood elevations or depths are shown. The descriptions of each flood zone designation are as follows:

Zone A: SFHAs subject to inundation by the 100-year flood. Because detailed hydraulic analyses have not been performed, no base flood elevations or depths are shown. Zones AE and A1-30: SFHAs subject to inundation by the 100-year flood determined in a Flood Insurance Study by detailed methods. Base flood elevations are shown within these zones. (zone AE is used on new and some revised maps in place of zone A1-30.) Zone AH: SFHAs subject to inundation by the 100-year shallow flooding (usually areas of ponding) where average depths are between one and three feet. Base flood elevations derived from detailed hydraulic analyses are shown in this zone. Zone AO: SFHAs subject to inundation by types of 100-year shallow flooding (usually sheet flow on sloping terrain) where average depths are between one and three feet. Average flood depths derived from detailed hydraulic analyses requirements apply.

5.2.1.2. Regulated Floodways

The regulated floodway is shown on the FIRM and consists of the river/stream channel plus that portion of the overbanks that must be kept free from encroachment in order to discharge the 100-year event without increasing flood levels. The City is responsible for prohibiting encroachments, including fill, new construction, and substantial improvements, within the regulated floodway unless it has been demonstrated through hydrologic and hydraulic analyses that the proposed encroachment will not increase flood levels. In shallow flooding areas that are outside of the regulated floodway (termed the "floodway fringe"), development is



allowed, provided that it causes no more than a 1-foot increase in the 100-year flood water-surface elevation.

5.2.1.3. Alluvial Fans

An alluvial fan is a sedimentary deposit located at a topographic break such as the base of a mountain front, escarpment, or valley side, that is composed of streamflow and/or debris flow sediments and which has the shape of a fan, either fully or partially extended. Alluvial fan flooding occurs on the surface of an alluvial. Active alluvial fan flooding is a type of flood-hazard that occurs only on alluvial fans. It is characterized by flow path uncertainty so great that this uncertainty cannot be set aside in realistic assessments of flood risk or in the reliable mitigation of the hazard. An active alluvial fan flooding hazard is indicated by three related criteria: (a) flow path uncertainty below the hydrographic apex, (b) abrupt deposition and ensuing erosion of sediment as a stream or debris flow loses its competence to carry material eroded from a steeper, upstream source area, and (c) an environment where the combination of sediment availability, slope, and topography creates an ultra-hazardous condition for which elevation on fill will not reliably mitigate the risk. Inactive alluvial fan flooding is similar to traditional riverine flood-hazards, but occurs only on alluvial fans. It is characterized by flow paths with a higher degree of certainty in realistic assessments of flood risk or in the reliable mitigation of the hazard.

5.2.1.4. Coastal Areas

Coastal areas are SFHAs along coasts subject to inundation by the 100-year flood with the additional hazards associated with storm waves. (Zone VE is used on new and some revised maps in place of zones V1-30.)

5.2.2. Other Non-Hillside Hazards

The only identified flood hazard in non-hillside areas that are not designated as SFHAs, is shallow flooding. The definition of non-hillside areas includes all land that is at a slope less than six percent (6%). Existing data relative to the areas of shallow flooding is inconclusive and additional research will be necessary to identify mitigation programs.


Areas that have been identified as having more than one occurrence of shallow flooding have been targeted for review. Records indicate that flooding is caused by one or more of the following causes: clogged drainage structure (drain, catch basin, or natural watercourse), insufficient drainage system, and poor surface drainage patterns (street or property). Analysis of existing data does not provide sufficient information at this time. Further analysis is necessary to indicate actual causes of flooding, identify the need to regulate certain areas, and to develop programs to mitigate future flood damages.



5.2.3. Other Hillside Hazards

For the purposes of this section, hillside areas are exclusive of the mapped SFHAs identified in Section 5.2.1. The intent of this section is to identify additional hazard areas that are located within hillside areas. A significant number of problems identified in the review of existing data occur in hillside areas. Although not related to the problems, an initial inconsistency that was observed is the official City of Los Angeles definition of hillside areas. Hillside Areas are designated on the Bureau of Engineering Basic Grid Map No. A-13372. The Basic Grid Map No. A-13372 was adopted on April 19, 1965 (Ordinance No. 129,885). The capability that exists today with the use of geographic information systems allows us to designate areas based on slope. The Hillside Areas as delineated on Basic Grid Map No. A-13372 consists of 137,196 acres and 212,153 parcels. Approximately fifty percent (50%) of the Hillside Areas is land with a slope of less than six percent (6%). Definitions of hillside areas obtained from other communities indicate that slopes of 10 percent or more are typically regulated. To remain conservative, yet improve on the Basic Grid Map, hillside areas for the purposes of the FMP consist of all land that is greater than or equal to six-percent slope (>=6%). The FMP designated hillside areas consists of 67,156 acres and 39,353 parcels.

5.2.3.1. Floodways and Watercourses

The regulated floodways are described in Section 5.2.1.2 above. The floodways and watercourses described herein are currently unmapped and unregulated. The intent is to gather additional data related to floodways and watercourses and identify certain reaches of each that should be more prudently and soundly managed to prevent additional damages to property owners. The review of existing data related to unmapped and unregulated floodways and watercourses is inconclusive at this time. The widespread nature of the hazards and associated problems in the hillside areas will require additional review and analysis of data. Based on the additional data review, the City may need to map floodways and watercourses and establish requirements that prohibit encroachments, including fill, new construction, and substantial improvements within them, unless it has been demonstrated through hydrologic and hydraulic analyses that the proposed encroachment will not increase flood levels.

5.2.3.2. Mud and Debris Flow Areas

Mud and debris flow is the hazard most associated with problems within hillside areas. Other than the mapped SFHAs, the City has not officially designated any other hazard areas for mud and debris flow. The Department of Building and Safety currently regulates development in hillside areas in accordance with the Hillside Ordinance (Ordinance No. 129,885). The ordinance is amended periodically based on past lessons learned. Often times, it is violations of the ordinance that lead to the damage or loss of property. Through



site inspections, the Department of Building and Safety identifies violators and requires them to stop work and resubmit grading plans. In some instances, the City constructs temporary erosion control measures where violations have occurred to protect adjacent properties, with the violators being held financially responsible for the City’s efforts. In addition, the Department of Building and Safety also participates in community outreach programs to inform residents and businesses that sand bags are available from the Fire Department during periods of heavy rain.

5.2.4. Other Coastal Hazards


No differentiation has been made between shallow flooding in coastal areas versus shallow flooding in non-hillside areas. Areas that have been identified as having more than one occurrence of shallow flooding have been targeted for review. Records indicate that flooding is caused by one or more of the following causes: clogged drainage structure (drain, catch basin, or natural watercourse), insufficient drainage system, and poor surface drainage patterns (street or property). Analysis of existing data does not provide sufficient information at this time. Further analysis is necessary to indicate actual causes of flooding, identify the need to regulate certain areas, and to develop programs to mitigate future flood damages.

5.2.4.2. Coastal Erosion and Storm Surge Areas

Storm surges, responsible for coastal flooding and erosion, are associated with severe winter low-pressure systems in the North Pacific Ocean and the Gulf of Alaska. In 1982-83, a severe winter storm caused more than $100 million in damage along the California coast. A storm surge occurs when the water level of a tidally influenced body of water increases above the normal astronomical high tide. Factors controlling storm surges include: 1. Wind Speed: In areas with mild slopes and shallow depths, the resulting flooding

can reach greater heights. 2. Low Barometric Pressures: Usually experienced during coastal storms, which

cause water surface to rise. 3. Timing of Storm: Storms can reach the coast during peak astronomical tide. 4. Coastal Shoreline Configuration: Concave features or narrowing bays create a

resonance within the area. Coastal erosion is generally associated with storm surges, hurricanes, windstorms, and flooding hazards, and may be exacerbated by human activities such as construction of seawalls, groins, jetties, navigation inlets, boat wakes, dredging and other interruption of physical processes. Coastal erosion is measured as the rate of change in the position or horizontal displacement of a shoreline over a period of time.



Natural recovery after erosive episodes can take months or years. If a dune or beach does not recover quickly enough via natural processes, coastal and upland property may be exposed to further damage in subsequent events. Although death and injury are not associated with coastal erosion, it can cause the destruction of buildings and infrastructure. Actions to supplement natural coastal processes, such as beach nourishment and dune stabilization, can modify erosion trends. Construction of shore protection structures can mitigate the hazard, but may exacerbate it under some circumstances.

5.2.4.3. Tsunami Hazard Areas

Tsunamis are large seismic sea waves, typically induced by a rapid, vertical thrust along the subsurface fault line between two tectonic plates of the earth’s crust. Also, when a large mass of earth on the ocean bottom impulsively sinks or uplifts, the column of water directly above it is displaced, forming a tsunami wave on the surface. Volcanic activity and submarine landslides (sometimes the result of earthquakes) can also cause tsunamis. The Great Alaskan Earthquake of 19647 was the largest earthquake in North America (Richter magnitudes reported ranged form 8.4 to 8.6) and second largest ever recorded (the largest occurred in Chile in 1960). It caused 115 deaths in Alaska, all of which were due to tsunamis generated by tectonic uplift of the sea floor and submarine landslides. Impacts from the tsunamis were felt all along the Pacific Region. Thirteen deaths and $10 million in damages were reported in California as a result of an earthquake-induced tsunami. No deaths were reported in Los Angeles, however, a wave increase of 0.6 feet was recorded. Coastal topography defines the landward penetration of tsunami wave runup and flood inundation. Although a subduction-zone tsunami wave event has not occurred in recent history, exposure to potential disaster has increased due to development activities along the coast and the heavily populated coastal area of the West Coast. A subduction-zone earthquake close to the shore could generate a tsunami wave that reaches the shoreline in less than 20 minutes, making evacuation time insufficient. The map illustrating tsunami hazard areas is provided as Figure 14 on page 37. This map also shows areas of potential inundation from water storage facilities (see Section 5.2.6), tsunami hazard areas are indicated in blue. The tsunami hazard portion of this map was originally prepared for the County of Los Angeles by the National Oceanographic and Atmospheric Administration (NOAA) and the University of Southern California under a state/FEMA grant. The map includes the Los Angeles County coastline from Malibu to approximately Long Beach. Completion of the

Source:

7 The Great Alaskan Earthquake of 1964, Thomas J. Sokolowski, West Coast and Alaska Tsunami Warning Center, Palmer Alaska.



second phase of this mapping (down to the southern end of Orange County) is scheduled by October 2002. As part of the international Tsunami Warning System (TWS), NOAA, through the National Weather Service, operates the Alaska Tsunami Warning Center, which serves as the regional warning center for Alaska, British Columbia, Washington, Oregon, and California coastal areas. Tsunami warnings are developed based on seismic data received from NOAA, the United States Geological Survey, and other member agencies. Warnings include predicted tsunami arrival times at selected coastal communities (i.e., those communities within the potentially affected geographic area). Tsunami warning information is disseminated to national, state, and local emergency officials, as well as the general public. The public is alerted over commercial radio and television channels, the NOAA Weather Radio System, US Coast Guard marine radios, and through other local programs. Local authorities are responsible for formulating and executing evacuation plans. Currently, emergency procedures for tsunamis are outlined in the County’s multi-hazard Operation Area Emergency Response Plan. After completion of the second phase of mapping discussed above, the County is planning to develop a specific tsunami emergency response plan.



Figure 14 INUNDATION AND TSUNAMI HAZARD AREAS



5.2.5. Geologic Hazards

There are several maps showing Geologic Related Hazards – Figure 15 on page 40 shows Landslide Areas; Figure 16 on page 41 shows Areas Susceptible to Liquefaction; and Figure 17 on page 42 shows Oil Field and Drilling Areas.

5.2.5.1. Subsidence Areas

The primary causes of most subsidence are human activities: underground mining of coal, groundwater or petroleum withdrawal, and drainage of organic soils. Regional lowering of land elevation occurs gradually over time. It may aggravate flooding potential, particularly in coastal areas. Collapses, such as the sudden formation of sinkholes or the collapse of an abandoned mine, may destroy buildings, roads, and utilities. Generally, subsidence poses a greater risk to property than to life. Damage usually consists of direct structural damage and property loss and depreciation of land values, but also includes business and personal losses that accrue during periods of repair.

5.2.5.2. Landslide Areas

Landslides are often triggered by other natural events such as floods, earthquakes, and volcanic eruptions. Other human factors contributing to landslides, are cut-and-fill, construction of highways, construction of buildings and railroads, and mining operations. During the past 20 years, landslides have resulted in 38 disaster declarations, 15 of them in California. Landslides are classified by type of movement and type of material. The types of movement are slides, flows, lateral spreads, and falls and topples. The types of material are bedrock and soils, where soils are described as predominately coarse or predominately fine. A combination of two or more of the principle types of flows is referred to as a “complex movement”. Slides involve downward displacement along one or more failure surfaces. The material from the slide may be broken into a number of pieces or remain a single, intact mass. Sliding can be rotational, where movement involves turning about a specific point; or translational, where movement is donwslope on a path roughly parallel to the failure surface. The most common example of a rotational slide is a slump, which has a strong, backward rotational component and a curved, upwardly-concave failure surface. Flows are characterized by shear strains distributed throughout the mass of material. Flows are distinguished from slides by high water content and the distribution of velocities resembles that of viscous fluids. These flows are a form of rapid mass movement in which loose soils, rocky, and organic matter, combined with air and water, form a slurry that flows downslope.



Mudflows are flows of fine-grained materials, such as sand, silt, or clay, with a high water content. A subcategory of debris flow, mudflows contain less than 50% gravel. Lateral Spreads can occur in fine grained, sensitive soils such as quick clays, particularly if remolded or disturbed by construction and grading. Loose, granular soils commonly produce lateral spreads through liquefaction (Figure 16 on page 41 shows Areas Susceptible to Liquefaction). Falls and Topples. Falls occur when masses of rock or other material detach from a steep slope or cliff and descend by free fall, rolling, or bouncing. Movements are rapid to extremely rapid. Earthquakes commonly trigger rock falls. Topples consist of the forward rotation of rocks or other materials about a pivot point on a hillslope. Toppling may culminate in abrupt falling, sliding, or bouncing, but the movement is tilting without collapse.



Figure 15 LANDSLIDE AREAS



Figure 16 AREAS SUSCEPTIBLE TO LIQUEFACTION



Figure 17 OIL FIELD AND OIL DRILLING AREAS



5.2.6. System Failure Related Hazards

5.2.6.1. Dam, Reservoir and Storage Tank Inundation Areas

The California Office of Emergency Services (CA OES) dam failure inundation mapping and emergency procedures program applies to dams meeting specific requirements under Sections 6002, 6003 and 6004 of the California Water Code. State law [SB 896 (1972)] requires emergency procedures for the evacuation and control of populated areas below dams that could be used to save lives and reduce injury in the event of a dam failure. Dam owners submit inundation maps to CA OES for review and approval in accordance with guidance issued by CA OES. Inundation maps represent the best estimate of where water would flow if a dam failed completely and suddenly with a full reservoir. The map illustrating areas of potential inundation from water storage facilities is provided as Figure 14 on page 37. This map also shows tsunami hazard areas, inundation areas are indicated in pink. The City’s Department of Water and Power (DWP) has emergency plans with regard to potential earthquake-induced hazards to dams and reservoirs, including measures implemented in the past to minimize potential impacts from seiche action (a seiche is a surface wave created when a body of water is shaken). These measures included water level restrictions and additional retaining wall heights at local reservoirs. As part of DWP’s Emergency Response Plan, reservoir inspection and damage (buildings) inspection teams are dispatched to evaluate and report on the condition of DWP facilities immediately following a natural disaster. DWP also maintains and updates a Dam and Reservoir Emergency Notification List, which provides appropriate agency contact information to be used in the case of an emergency. As an example, DWP’s emergency response plans were implemented following the 1971 San Fernando Earthquake and resulted in the evacuation of approximately 80,000 people in a potential dam inundation area in the San Fernando Valley. In addition to emergency measures, DWP has preventative strategies in place, including a dedicated reservoir surveillance group that routinely monitors and reports on the condition of DWP facilities. Other preventative strategies/programs include the collection and analysis of real-time data by the Los Angeles Water Systems Data Acquisition Center. The U.S. Army Corps owns and operates seven dams in the Los Angeles County Drainage Area, including Sepulveda, Hansen, Lopez, Santa Fe, Whittier Narrows, Brea, and Fullerton Dams (Brea and Fullerton are not related to the City of Los Angeles). In response to a natural disaster such as an earthquake, the Corps inspects the condition of Corps owned and operated dams and relays any pertinent information to the established point-of-contact for the local agency/jurisdiction. In addition, at the request of FEMA and under the Federal Response Plan, the Corps provides emergency engineering services in the case of a catastrophic event.



5.2.6.2. Power Failure Induced Flooding Areas

At this time, the only power failure induced flooding would be from a loss of power at the City’s pumping plants, which drain the low-lying areas. The City operates and maintains 10 stormwater pumping plants. The Bureau of Sanitation maintains an updated inventory of the pumping plants with emergency generators. Most of the pumping plants have permanent backup power generators installed. For pumping plants that do not have permanent backup generators, portable generators located at the nearest District yards can be brought into service rapidly. Portable generators are strategically located at the four District yards (South, Harbor, North, Venice, West Los Angeles, and North Hollywood Districts).


6. HAZARD AND PROBLEM ASSESSMENT

6.1. Basic Assessment Approach

The assessment of both flood hazards and problems is best described through a systematic approach. The basic assessment approach is a strategy for prioritizing flood hazards and problems at a planning level. The City used a systematic approach to allow for a ranking of the primary hazards and to support the identification and assessment of problems. The basic assessment approach consists of the types of hazards (Section 6.1.1) and the categories of items affected (Section 6.1.2). The two components of the basic assessment approach are listed below and are further described in Sections 6.2 and 6.4. The basic assessment approach is intended to allow for the prioritization of the primary hazards, identification of problems, and to guide the development of goals, objectives, policies and implementation programs.

6.1.1. List of Primary Hazards

Shallow Flooding Geologic Dam/Reservoir Inundation Coastal Erosion/Storm Surge Mud/Debris Flow Tsunami

6.1.2. List of Major Affected Categories

Infrastructure People Land Property Natural Resources Structures

The basic assessment approach is the starting point for ranking the primary hazards based on the cause and effect of the hazards on people and property. Utilizing existing data, and following the basic assessment approach, an assessment methodology was developed and applied based on the existing data for the City. For situations where a lack of existing data prevents identifying a problem, additional research and investigation may be recommended.

6.2. Assessment Methodology

The assessment of the impact of flood hazards has been developed based on existing data, and follows the methodology from the basic approach identified above. The components of the basic assessment approach are further defined in the following sections.

6.2.1. Identified Hazard Areas

The identified hazard areas are defined in Section 5.2. Table 9 below provides the breakdown of the primary hazards listed in Section 6.1.1 into the identified hazard areas for the City of Los Angeles. These hazard areas have been identified based on all available data.

HAZARD AND PROBLEM ASSESSMENT


Table 9 PRIMARY HAZARDS AND IDENTIFIED HAZARD AREAS

Primary Hazard Shallow Flooding

Identified Hazard Areas Regulatory Basis Comments

FIRM Shallow Flooding FEMA required GIS mapped SFHAs

Other Shallow Flooding No current requirements Not currently mapped

FIRM Alluvial Fan FEMA required GIS mapped SFHAs

Other Alluvial Fan No current requirements Not currently mapped

Power Failure Induced No current requirements Not currently mapped

Primary Hazard Dam/Reservoir Inundation


Inundation Area Mapped but not regulated State required maps

Primary Hazard Mud/Debris Flow


FIRM Floodway FEMA required GIS mapped SFHAs

Other Floodway No current requirements Not currently mapped

Watercourse Mapped w/no requirements Some areas mapped

Primary Hazard Geologic


Subsidence Mapped w/no requirements Some areas mapped

Landslide Area No current requirements Not currently mapped

Primary Hazard Coastal Erosion/Storm Surge


FIRM Coastal FEMA required GIS mapped SFHAs

Other Coastal No current requirements Not currently mapped

Primary Hazard Tsunami


Inundation Area No current requirements Some areas mapped

Each of the identified hazard areas is an indicator of higher risk based on available data. The analysis of existing data has not resulted in the identification of new high-risk areas for regulatory purposes. The FEMA defined FIRM hazard areas (Special Flood Hazard Areas) will remain the only specially regulated areas for the City of Los Angeles at this time. The identified flood hazard areas will continue to be reviewed in light of new data and this review and data collection process will be supported through the development of goals, objectives and policies. The expansion of the basic assessment approach based on available data is shown in the subsequent sections.



Table 10 MAJOR AFFECTED CATEGORY, SUB-CATEGORY AND DEFINITIONS

Major Affected Category Infrastructure

Sub-Categories Definitions

Roads, bridges, storm drainage facilities, wastewater facilities, water facilities, power facilities, communication facilities

Publicly owned facilities, systems, sub-systems and networks, excluding land, property and structures [as defined herein].

Major Affected Category Land


Private and public owned Real estate/property, excluding structures and property [as defined herein]

Major Affected Category Natural Resources


Agricultural, archaeological, biological, mineral, land forms and scenic vistas

The City’s natural resources are described in the Conservation Element of the General Plan

Major Affected Category People


None All people within the community including residents and visitors

Major Affected Category Property


Privately held or owned: vehicles, equipment, furniture, supplies, animals, roads, and systems (drainage, water, power and communication) Public property: vehicles, equipment, furniture, supplies, etc.

Personal property items, excluding land and structures [as defined herein] Property owned by federal, state and local governmental agencies, excluding infrastructure, land, and structures [as defined herein]

Major Affected Category Structures


Privately owned: homes, commercial buildings, industrial buildings, bridges, accessory buildings, etc. Publicly owned: office buildings, police and fire buildings, libraries, schools, and buildings supporting infrastructure functions

Privately owned structures includes all buildings and support facilities, excluding property [as defined herein] Publicly owned structures includes all facilities not covered in infrastructure and property [as defined herein]



6.2.2. Major Affected Categories and Definitions

The six major affected categories identified in Section 6.1.2 are defined in Table 10 above. The major categories are listed in alphabetical order and do not indicate priority. The existing data is not sufficient to prioritize the major affected categories at this time. The results of the hazard and problem assessment are summarized in Section 6.4 below. As part of the problem assessment process, the number and type of residential structures within high-risk areas were identified. For the purposes of this FMP, high-risk areas consist of the FEMA designated flood zones since these are the only mapped hazard areas at this time. The primary tool used to analyze high-risk areas is the Geographical Information System (GIS). To determine affected categories the FEMA designated flood zones were mapped (refer to Error! Reference source not found.) and compared with other existing mapped data (see Section 6.3 for more information on tools and available data). Utilizing GIS and City Planning Department data, land uses, residential structures, and critical facilities within high-risk areas were all identified. Figure 18 shows the distribution of land use. A breakdown of residential structures within FEMA designated flood zones is included in Table 11 on page 49 and critical facilities within high-risk areas are listed in Table 12.

Figure 18 LANDUSE WITHIN FEMA DESIGNATED FLOOD ZONES



Table 11 RESIDENTIAL STRUCTURES WITHIN FEMA DESIGNATED FLOOD ZONES

Number of Structures within SFHA (by Type)

Flood Zone

Single Family

Duplex 3-9 Units

10-49 Units

50 or more Units

Mobile Home

A 2,466 45 213 360 450 174

A0 9,462 557 2,306 40 0 13

AO(AF) 409 0 5 70 32 55

A2-A24 695 39 177 180 43 43

A2(FW)-A6(FW) 18 0 1 0 0 0

AE 1,006 18 284 232 135 10

AH 1,162 23 166 435 227 1

D 29 0 0 1 3 0

V5-V14 468 19 12 93 16 19

TOTAL 15,715 700 3,164 1,412 907 315

There are approximately 1.4 million single-family structures within the City, therefore, about 1 percent of these are within a FEMA designated flood zone (also known as Special Flood Hazard Areas). Similarly, the percentages for the other types of residential structures are as follows:

Duplex – 700 out of 44,500 – about 1.6%

3 to 9 units – 3,164 out of 222,000 – about 1.4%

10 to 49 units – 1,412 out of 340,000 – about 0.4%

50 or more units – 907 out of 130,000 – about 0.7%

Mobile homes – 315 out of 8,300 – about 4% Table 12 CRITICAL FACILITIES WITHIN FEMA DESIGNATED FLOOD ZONES

11%

3%

4%

8%

22%26%

26%

Single Family (640 acres)

Multi Family (315 acres)

Commercial (240 acres)

Industrial (845 acres)

Transportation (1,670 acres)

Open Space (2,035 acres)

Water (1,970 acres)



Total Critical

Facilities

Within SFHAs (100 yr)

Within SFHAs (500 yr)

Percentage within SFHAs

Transportation 23 1 2 13% Communication 568 3 17 4% Airfields 59 0 0 0% Utilities 66 0 10 15% Health Services 231 2 7 4% Public Order and Safety 119 1 5 5% Education 1,033 2 53 5%

A map showing the distribution of critical facilities throughout the City is included as Appendix Error! Reference source not found.. Analysis indicates that within the City, only 9 critical facilities lie within 100-year flood zones. Two schools, one police station, one health services facility and one communications retail store are situated in AO zones. One railroad facility is located within an AE zone. Two communications retailers and one health service facility are in AH zones.

6.3. Tools and Available Data

The City is utilizing existing data to fully assess the extent that flood hazards cause problems. Using the existing data, combined with analysis tools, we have identified the goals, objectives, policies and implementation programs contained in Chapters 7 and 8. As mentioned above, the primary analysis tool used to identify high-risk areas is the Geographical Information System (GIS). The following sections provide a summary of the data that is currently available to the City of Los Angeles (by Department).

6.3.1. Public Works/Bureau of Engineering

FEMA Flood Insurance Rate Maps: Citywide delineation of Special Flood Hazard Areas. These areas of 100-year flood inundation have been digitized into the Geographic Information System (GIS) and can be queried with other available data.

Hillside Areas: On April 19, 1965 the City Council adopted Ordinance No. 129,885 which established a map of Hillside Areas (Bureau of Engineering: Basic Grid Map A-13372). These designated areas were used as a starting point for determining hillside areas for the purposes of the FMP. Utilizing the GIS, the Basic Grid Map A-13372 was further divided into subareas where land is greater than or equal to six-percent slope (>=6%).

Drainage Complaints: Deficiencies are most often reported directly by concerned individuals and property owners. Complaints are investigated by staff engineers or maintenance crews. Complaints range from local to system wide difficulties and are typically greater during above average wet seasons. Many complaints involve drainage facilities on private property such as



questions about drainage facilities in easements. Complaints have been entered into a database and geo-coded for display on the GIS.

List of Know Deficiencies: The Bureau of Engineering maintains a list of known deficiencies based on each of its four Engineering Districts (Valley District, West Los Angeles District, Central District and Harbor District). A project is identified to address each deficiency and therefore the deficiency list is actually a list of proposed projects. Many of the proposed projects originated from older studies while some come from more recent studies and/or complaints. Projects are also added based on staff expertise or by referral from other City Departments. There are currently over 350 proposed projects contained in the database. The projects can also be displayed on the GIS.

Critical Facilities: Database of critical facilities within the City, based on the American Business Institute 2000 data. Critical facilities include police, fire, hospital, school, transportation, communication and certain industrial facilities. A map showing the distribution of critical facilities throughout the City is included as Appendix Error! Reference source not found..

Assessment of Infrastructure Damage: Field investigations subsequent to major storms.

Geotechnical Reports: Findings related to landslide areas, mudflow prone areas and other geologically unstable areas.

Citywide Flood Hazard Assessment Questionnaire: The questionnaire was mailed to approximately 60,000 residents in areas suspected of flooding risks.

FEMA Claims Database: Flood damage claims paid since 1977. FEMA List of Repetitive Loss Properties: This list contains a total of 117

properties that have received payments from their flood insurance at least twice over a ten-year period.

6.3.2. Public Works/Bureau of Sanitation

Assessment of Infrastructure Damage: Field investigations subsequent to major storms.

Identification of Problem Areas: Areas in need of frequent maintenance of the flood control system, and/or known deficiencies based on field observations.

6.3.3. Department of Building and Safety

Post Storm Inspections: Inspection results following major storms (i.e. El Nino Storms of 1998).

Identification of mud-prone and landslide areas throughout the City. Number of building permits issued in flood risk areas.

6.3.4. Planning Department

Census Data (demographic and type of buildings) Land Use Data Zoning Data Determination of flood protection provided by the General Plan and each

Community Plan.



Tsunami Maps, Dam Inundation Maps and Landslide Hazard Identification Maps from the Safety Element of the General Plan (prepared with input from the State Division of Mines and Geology and the State Office of Emergency Services).

Description of City policy in maintaining open space and discussion of the effectiveness of current regulatory and preventive standards to prevent flood damage.

Description of natural and beneficial areas within the City (i.e. wetlands, riparian areas, sensitive areas, and habitat for rare or endangered species).

6.3.5. Community Re-Development Agency & Community Development Department

Description of development and re-development trends in the City.

6.3.6. Fire Department

Description of current regulatory and fire prevention standards and programs. Identification of hillside fires and their potential threat for mud flows. Identification and location of industrial facilities that use and store significant

quantities of water-reactive chemicals.

6.3.7. Department of Emergency Preparedness

Description of applicability of emergency Plan to respond to flooding events (discuss source of forecast of flood threats, ability to notify residents in threatened areas, evacuation, etc.)

6.3.8. Los Angeles County Department of Public Works

6.4. Hazard and Problem Assessment Summary

The review of existing data identified in Section 6.2.2 above led us to focus on information relative to the past ten years. The majority of historical data relative to this region, although informative, has little bearing on the current floodplain management planning activities. Due to significant development that has occurred within Los Angeles, the area is highly urbanized and the flood control systems are almost completely built out. The City of Los Angeles’ flood hazards, and problems associated with them, are not typical of most CRS communities (except those in Southern California). The majority of flood related problems occur outside of the FEMA designated flood zones (mapped Special Flood Hazard Areas) and are geographically spread out. Many data points were analyzed using the GIS and the wide distribution of problems and their associated hazard(s) can only support a distinction between hillside and non-hillside areas. The distinction between hillside and non-hillside areas is related to shallow flooding and mud/debris flow, respectively.



The assessment of flood hazards included a review of the available data identified in Section 6.2.2. Based on the assessment, two of the six primary hazards, shallow flooding and mud/debris flow, rank higher in priority and represent the area of focus for the development of goals, objectives and policies. The six primary hazards are listed below.

Shallow Flooding Geologic Dam/Reservoir Inundation Coastal Erosion/Storm Surge Mud/Debris Flow Tsunami

The potential effects of dam/reservoir inundation, geologic, coastal erosion/storm surge and tsunami are much more severe and catastrophic in nature. However, the data does not indicate current problems. In addition, these potentially severe/catastrophic hazards are best addressed though the development of early warning systems and emergency response activities.

6.4.1. Assessment of Problems

The data review that was conducted relating to the information sources identified in Section 6.2.2 was supplemented by a Flood Hazard Assessment Questionnaire. The intent of the questionnaire was to identify current problems that have been experienced by the residents, businesses and community groups within high-risk areas. A sample questionnaire is included in Appendix C. The questionnaires were evaluated using the basic assessment approach described in Section 6.1.

Figure 19 RESPONSES TO QUESTIONNAIRE

The following steps describe the methodology used by staff in analyzing the questionnaire responses:

60,000 questionnaires mailed

approximately 1,700 responses

935 responses assessed

68% assessed as no drainage problem

32% assessed as drainage problem



1. Began entering responses to questionnaire into a database (approximately 1,442 out of 1,700 responses have been entered as of May 16, 2001).

2. Began assessing responses to the questionnaire. Respondents who indicated

there was a drainage problem in their area were addressed first. As of May 16, 2001, 935 responses have been assessed. The assessment of the remaining questionnaires will continue on an on-going basis. However, a full assessment will not be ready for inclusion into the FMP.

3. Prioritized the 935 assessed questionnaires into two tiers:

Tier 1 – consisted of those respondents who reported damage to infrastructure, land, people, property, and/or structures (public or private);

Tier 2 – consisted of those respondents who indicated that infrastructure, land,

people, property, and/or structures were affected, but no damage was reported.

Table 13 and Table 14 below summarize the results of the questionnaires and the Tier analysis. The initial analysis indicates no problems related to dam/reservoir inundation, coastal erosion/storm surge and tsunami. The geologic problems that were identified, although limited, relate to the landslide hazard. This information also supports the focus of effort on shallow flooding and mud/debris flow.

Table 13 DAMAGES INDICATED IN QUESTIONNAIRE RESPONSES (TIER 1 PRIORITY)

Primary Hazard(s) Involved Number of Cases*

Affected Category

Total Indicated Damages

Shallow Flooding

Mud/Debris Flow

Geologic

Infrastructure 5 4 1 1

Land 4 3 4 2

People 0 0 0 0

Property 20 15 8 1

Structures 27 24 6 5 *Multiple Primary Hazards may be indicated for a separate report of damage. Therefore, “total” is not the summation of the Hazard columns. Table 14 EFFECTS INDICATED IN QUESTIONNAIRE RESPONSES (TIER 2 PRIORITY)

Response/ Primary Hazard Totals**

Total Number of Responses per Affected Category

Primary Hazard

Infrastructure Land Natural

Resources People Property Structures

Shallow Flooding

179 45 51 * 5 39 86

Dam/Reservoir 0 0 0 * 0 0 0



Inundation

Mud/Debris Flow

82 25 35 * 0 17 19

Geologic 12 3 5 * 0 5 7 Coastal Erosion/ Storm Surge

0 0 0 * 0 0 0

Tsunami 0 0 0 * 0 0 0 Response/Category Totals 73 91 * 5 61 112

* Natural resources were not considered in the questionnaires due to the complexity of the issue. ** There may be multiple affected categories for each primary hazard, therefore the “total” may be

smaller than the sum of the row.

4. In order to identify specific cases of shallow flooding and mudflow problems, the

GIS was used to display the existing data and the newly assessed questionnaire results. Also, to better understand the drainage patterns, the following supporting data was used: topography information, parcel level information and existing drainage system.

5. Upon viewing the GIS results, two levels of analysis were identified. As of May 16,

2001, an initial (Level 1) analysis has been performed on approximately 20 (out of 44) Tier 1 questionnaires. A more detailed (Level 2) analysis will be conducted as a part of implementing the FMP.

Level 1: Focused on the quantity and proximity of Tier 1 responses, Repetitive

Loss Properties, and proposed Flood Control Capital Improvement Projects. (The proposed projects are indicators of drainage deficient areas.)

Level 2: Focused on the quantity and proximity of Tier 2 responses and historical

drainage complaints (where flooding to property was reported). 6. Cases were identified based upon an observed pattern of damage defined as

follows: (1) damage to multiple properties by the same or similar problem; and/or (2) one reported damage incident supported by other properties being affected by the same problem. Flood problem cases are indicated with F1, F2, F3, etc. Mudflow problem cases are indicated with M1, M2, M3, etc.

Table 15 INITIAL RESULTS OF PROBLEM ASSESSMENT (LEVEL 1)

No. Flood Cases

F1 22000 Block of Londelius Street. Appears to be a sump area with no subterranean drains. Damage reported to one property and two others affected.



F2 Street appears to carry excessive runoff, concentrated on Tujunga Canyon Ave. Curbs are overtopped which has caused damage to fences and garage.

F3 Hillhaven Avenue and Sundale Dr. Unpaved street. Damage to multiple properties.

F4 Madelia Avenue. Proposed drainage project indicating old problem affecting multiple properties.

F5 Golden Front Walk and Speedway. Area is very flat. Garages flood when runoff overtops the curb. Sanitation responds with pump trucks to drain streets/alleys. Damages reported and impact to many other properties.

F6 1700 block of Chastain Parkway East. No catch basins. Apparent excessive runoff and poor drainage collection cause damages to numerous properties.

F7 North of Sunset Boulevard, South of Marquez Avenue. Apparent poor drainage. No drainage systems. Reported damage to several properties.

No. Mud Flow Cases

M1 Mandeville Canyon Road. Repeated damages to various properties.

M2 Castallamare and Brie. Possible year round flow of natural spring. Area seems to have risk of mudslides and landslides. Report of several properties being removed due to landslides.

M3 Along Stone Canyon Avenue and Loadstone Drive from top of road to Sunny Oak Road. Excessive runoff overtopping curbs specially at intersection of both streets. Repeated damage to properties.

M4 Partially paved road (Sueno Road) behind property on 22400 block of Domingo Road that diverts runoff to properties and causes mudflows and damage.

A map (Figure 20) showing the cases identified to date can be found on page 58. There are also examples of two case study areas – one flooding problem and one mud flow problem that are provided in Figure 21 and Figure 22 respectively.

6.4.2. Economic Impacts of Flooding

The City is aware that FEMA and the National Institute of Building Sciences are currently developing a Flood Loss Estimation Model. Once complete (a preview model is expected in 2002), the model will be incorporated into HAZUS, a nationally applicable standardized methodology and software program for estimating potential losses from earthquakes, floods, and wind. The model is being designed to estimate several elements of potential flooding damage including:

direct damage,

induced damage, such as fire, hazardous materials release, or debris generation

direct economic impacts, such as injuries and cost of repair/replacement, and



indirect losses, such as unemployment and sales decline. City staff and the GIS consultant have provided input during the development of the model by participating in a conference call question and answer session with the technical contractors developing the model, EQE International and Michael Baker Jr. Corporation. At this point, the City will continue to provide input when asked, review the preview model once it is available, and perform pilot testing for eventual use in estimating the economic impacts of flooding.



Figure 20 INITIAL RESULTS OF PROBLEM ASSESSMENT (LEVEL 1)



Figure 21 FLOOD CASE STUDY AREA - EXAMPLE



Figure 22 MUD FLOW CASE STUDY AREA – EXAMPLE



6.5. Repetitive Loss Properties

The 117 Repetitive Loss Properties (RLPs) within the City of Los Angeles (see Figure 23) have been evaluated based on the four RLP areas identified in Section 1.4 - Los Angeles River (Hillside), Los Angeles River (Non-Hillside), Ballona Creek (Hillside) and Ballona Creek (Non-Hillside). The research, investigation and evaluation of the City’s RLP sites was conducted by Tetra Tech, Inc., a consultant to the Los Angeles County Department of Public Works. Each of the four RLP areas is described in more detail in this section. A field visit was conducted for each RLP during the period of January and February 2001. The field visit was an important part of the analysis because it verified the findings of the previous investigations performed by the City of Los Angeles (Bureau of Engineering, Bureau of Sanitation and/or Department of Building and Safety). The visit also identified any new flood-related problems, if present, and the improvements to the known drainage problems. During the field visit, the general layout of each property was drawn with drainage-related features, such as drainage pattern and locations of on-site drains and nearby storm drain systems. Any possible flooding sources and the existing conditions of the site and adjacent grounds found by the previous investigations and this field visit were analyzed. The information gathered during the field visits has been summarized into a separate Technical Appendix (the Technical Appendix will be provided to FEMA and agencies responsible for implementing RLP programs). Some of the RLP sites had been labeled ‘inactive’ during earlier investigations conducted by the City of Los Angeles. The field visit and subsequent engineering analysis were conducted for all RLP sites in order to evaluate the adequacy of the drainage improvements implemented either by the City of Los Angeles or the property owners. The common causes of flooding to the 117 RLPs within the City are summarized as follows:

Hillside drainage/grading deficiency - 50 RLP sites 40 sites with current problems 10 with past problems that were remedied

Street drainage/grading deficiency - 28 RLP sites 22 sites with current problems 6 with past problems that were remedied

On site drainage/grading deficiency - 6 RLP sites (all current problems)

“Other” – 33 RLP sites 13 sites with current identified problems 20 with no current problems



The hydrology and stormwater discharge rates affecting the RLPs were estimated by applying the Modified Rational Method as described in the Los Angeles County Department of Public Works, Hydrology and Sedimentation Manual. The methodology primarily depends on three factors: total drainage area, runoff coefficient of the area, and rainfall intensity. The runoff coefficient and rainfall intensity was determined from the Manual, drainage map, and data gathered from field visits. The drainage area was delineated on the City of Los Angeles drainage map. Determination of drainage areas was dependent on the flooding sources that affect each RLP site. The details of the hydrologic analysis are contained in the Technical Appendix. The information obtained from the research, investigation and evaluation of all RLPs is summarized by RLP Area [i.e. Los Angeles River (Hillside), Los Angeles River (Non-Hillside), Ballona Creek (Hillside) and Ballona Creek (Non-Hillside)] in Table 16 through Table 27. These tables list each of the RLPs by its unique identification number, provide the flooding history and the FEMA-designated flood zone, and identify the type of problem experienced at each site. Table 28 through Table 35 in Chapter 8 provide primary and secondary solutions recommended by Tetra Tech for each of the 81 RLP sites with a current identified problem. While performing their field research, investigation, and evaluation of identified RLPs, Tetra Tech staff also discovered neighboring properties that appear to be affected by the same flooding risks (see Table 18, Table 21, Table 24, and Table 27). Although these neighboring “potentially affected properties” are not RLPs (in other words, they did not file claims more than twice within any given 10-year period since 1978), they are included in this document for discussion purposes. In addition, the City of Los Angeles will monitor these sites for future flood damage reduction efforts.



Figure 23 REPETITIVE LOSS PROPERTIES



6.5.1. Los Angeles River (Hillside)

Thirty-seven (37) out of the 117 RLPs identified by FEMA are within the Los Angeles River Watershed and subject to Hillside hazards. Of the 37 RLPs, none is located within a FEMA designated special flood hazard area. One RLP is located in flood zone B; one is in zone X; and 35 are in zone C. Flood zones B and X indicate the area inundated by a 500-year flood. Table 16 on page 65 provides a list of the 37 RLPs and indicates the flooding history and FEMA designated flood zone for each site. The flood events occurred in 1977/78, 1978/79, 1979/80, 1980/81, 1981/82, 1982/83, 1985/86, 1991/92, 1992/93, 1994/95, and 1997/98 rainy seasons. The majority of the RLPs suffered flooding damages twice in this time period. RLP No. 24 suffered flood damages a total of five times – the worst among the 37 RLPs. Table 17 on page 66 identifies the causes of flooding and whether a current problem exists at each of the RLP sites. At 9 RLP locations (ID Nos. 16, 21, 26, 31, 41, 60, 66, 106, and 107) the current owners/occupants were not aware of any recent flooding problems. Property ID No. 26 had previously reported no problems at a site visit conducted by the City on November 29, 2000. Property ID No. 28 reported some losses during a recent rainstorm event in January 2001. Table 18 on page 67 shows a summary of RLP-neighboring “potentially affected properties” in the Los Angeles River (Hillside) Watershed which may be affected by the same problem sources as the current RLPs. RLP-neighboring “potentially affected properties” were determined by analyzing the nature of the problem and the tract map of each RLP (provided by the City of Los Angeles). Six (6) RLPs seem to have neighboring “potentially affected properties”, which appear to be affected by the same flood risk problem. The remaining 31 of the 37 RLPs in the Los Angeles River (Hillside) Watershed have site-specific flood risks, which, based on current information, do not impact neighboring properties.



Table 16 REPETITIVE LOSS PROPERTIES – LOS ANGELES RIVER (HILLSIDE) ID No. Community Zip Claim Dates FEMA Designated

Flood Zone

3 Los Angeles 90046 3/83, 2/80 X

16 Los Angeles 91040 2/83, 3/79 B

17 Los Angeles 91042 2/80, 2/78 C

18 Los Angeles 91316 2/80, 2/78 C

19 Los Angeles 91316 3/83, 1/86 C

20 Sun Valley 91352 3/83, 1/81 C

21 Sherman Oaks 91403 3/83, 2/80 C

23 Sherman Oaks 91403 3/83, 2/80, 3/78 C

24 Sherman Oaks 91423 1/95, 1/93, 1/80, 3/79, 3/78 C

25 Sherman Oaks 91423 2/93, 3/83, 4/82 C

26 Encino 91436 3/83, 2/80 C

27 Encino 91436 1/83, 11/82, 1/80 C

28 Encino 91436 3/83, 2/80 C

29 Encino 91436 3/83, 2/80 C

31 Studio City 91604 2/80, 1/78 C

32 Studio City 91604 2/80, 3/78 C

41 Sherman Oaks 91423 3/83, 2/80 C

45 Encino 91436 2/80, 3/79 C

47 Los Angeles 91040 1/81, 2/80 C

50 Woodland Hills 90364 2/92, 2/80 C

51 Sherman Oaks 91403 2/83, 3/83 C

55 Sherman Oaks 91423 1/93, 2/92, 3/83, 1/83 C

57 Tarzana 91356 2/86, 11/82, 12/80 C

60 Los Angeles 91040 2/98, 2/92, 3/83 C

65 Tarzana 91356 2/98, 1/95, 2/92, 11/82 C

66 Sherman Oaks 91423 2/92, 2/80 C

67 Chatsworth 91311 3/83, 3/80 C

83 Los Angeles 90068 3/92, 2/92 C

84 Los Angeles 91436 2/80, 3/78 C

94 Sherman Oaks 91403 1/93, 2/92 C

99 Encino 91436 3/83, 2/80 C

104 Sherman Oaks 91403 1/95, 2/92 C

106 Studio City 91604 3/98, 2/98 C

107 Encino 91436 2/98, 2/92 C

110 Encino 91436 2/98, 1/95 C

111 Encino 91316 12/97,1/95 C

115 Encino 91436 2/98, 3/95, 1/95 C



Table 17 FLOODING CAUSES – LOS ANGELES RIVER (HILLSIDE)

R

LP

Id

No

.

Hills

ide

Dra

inag

e/

Gra

din

g D

efi

cie

nc

y

Str

eet

Dra

inag

e/

Gra

din

g D

efi

cie

nc

y

On

sit

e D

rain

ag

e/

Gra

din

g D

efi

cie

nc

y

Oth

ers

Causes

Pro

ble

m

No

Pro

ble

m

3 X Trash in retaining wall gutter, hillside problem X

16 X Storm drain improved, berm at driveway, no more problem X

17 X Street sump, property lower than street X 18 X Street sump, property lower than street X

19 X Clogged area drains, windows open during the rain X

20 X Lack of debris basin, adjacent to watercourse X

21 X Added V-ditch - no more problem X

23 X Slope failure and mudslide X

24 X Street with no curb/berm. Street runoff flow toward property X

25 X Possible onsite hillside drainage problem X

26 X Mudslide in the past - no more problem X


28 X Onsite drainage plugged X

29 X Street/onsite drainage, property lower than street X 31 X Mudslide before - added retaining wall, no more problem X


41 X Abandoned construction site X

45 X House below street grade, berm not adequate X

47 X Abandoned restaurant. Street & channel drainage problem X

50 X Onsite hillside drainage problem X


55 X Street/onsite drainage problem, property lower than street X


60 X Abandoned house X

65 X Onsite hillside drainage problem X 66 X Onsite hillside drainage problem - improved, no more problem X

67 X Onsite backyad drainage problem X


84 X Onsite hillside drainage problem, inlet plugged X


99 X Onsite sideyard hillside drainage problem X

104 X Groundwater seepage through floor X

106 X Installed french drain - no more problem X

107 X Storm drain damaged - repaired, no more problem X

110 X Sideyard grading/drainage problem X

111 X Backyard/sideyard drainage problem X

115 X Frontyard drainage, house lower than street grade X



The specific problems that were identified for each RLP site in Table 17 are further described below.

Hillside Drainage Problem (ID Nos. 3, 20, 21, 23, 25, 26, 27, 31, 32, 50, 51, 57, 65, 66, 83, 84, 94, 99, 110, and 111): The backyards of these properties are located at the bottom of a steep hill and are impacted by hillside runoff. Flooding occurs due to deficient, private on-site drainage. Mudslides from slope failure are also possible.

Street Drainage Problem (ID Nos. 16, 17, 18, 24, 45, 47, 55, 106, 107, and 115):

The building pads of the properties are lower than the street level, and/or the driveway is sloped toward the house and garage. Street runoff can enter the private property if a berm with sufficient height is not placed at the driveway or property boundaries facing the street, especially if the property is located at the street sump area (lowest point of the nearby streets – ID Nos. 17 and 18), where street flow can pond. Storm drain problems include undersized or broken storm drains and debris-clogged catch basins (ID Nos. 16 and 107).

On-Site Drainage Problem (ID Nos. 19, 28, 29, and 67): The on-site, private

drain inlets can be deficient or plugged with debris in the yard, causing water to pond within the property and not drain to the street.

Others (ID Nos. 41, 60, and 104): The properties have site-specific problems

that need special and individual attention. Groundwater seepage enters into the lower level of the house (ID No. 104). Some of the properties were abandoned at the time of the field visit and/or had a new house under construction and a new drainage system being laid out (ID Nos. 41 and 60).

Table 18 “POTENTIALLY AFFECTED PROPERTIES” LOS ANGELES RIVER (HILLSIDE)

RLP Id No.

Number of other properties possibly affected by same

problem

Description of Problem

17 3 Street sump, property lower than street

23 5 Slope failure and mudslide 24 2 Street with no curb/berm. Street runoff

flow toward property 31 1 Mudslide before – added retaining wall,

no more problem 67 3 Onsite backyad drainage problem

106 1 Installed french drain – no more problem

These potential problems for RLP-neighboring sites are further described below. Hillside Drainage Problem (Neighbors of ID Nos. 23, 31): Suspected flooding risks

as a result of unstable hill area and erosion in the backyard.



Street Drainage Problem (Neighbors of ID Nos. 17, 24, and 106): Suspected flooding risks as a result of street flow or sump conditions, usually accompanied by undersized or plugged storm drains.

On-Site Drainage Problem (Neighbors of ID No. 67): The private Railroad property

running behind these houses is a suspected flooding risk.

6.5.2. Los Angeles River (Non-Hillside)

Sixteen (16) out of the 117 RLPs identified by FEMA are within the Los Angeles River Watershed and subject to Non-Hillside hazards. Of the 16 RLPs, two are located within a FEMA designated special flood hazard area AE (RLP Nos. 33 and 54). The remaining fourteen RLPs are located in zone C. Table 19 provides a list of the 13 RLPs and indicates the flooding history and FEMA designated flood zone for each site. The flood events occurred in 1977/78, 1978/79, 1979/80, 1982/83, 1987/88, 1991/92, 1992/93, 1994/95, and 1997/98 rainy seasons. The 1979/80 and 1982/83 seasons were the worst seasons in terms of the number of flood-impacted properties, among the above-listed seasons. The majority of the RLPs suffered flooding damages twice or three times in this time period. Property ID No. 34 suffered flood damages a total of five times – the worst among the 13 RLPs. Table 20 identifies the causes of flooding and whether a current problem exists at each of the RLP sites. At 5 RLP locations (Property ID Nos. 22, 30, 56, 88, and 90) the current owners/occupants were not aware of any recent flooding problems. Among these properties, property ID No. 22 previously reported no problem as shown in the City’s Summary Findings dated November 29, 2000. The property ID No. 22 was confirmed again by the property owners during the recent survey. Table 21 shows a summary of RLP-neighboring “potentially affected properties” in the Los Angeles River (Non-Hillside) Watershed which may be affected by the same problem sources as the current RLPs. RLP-neighboring “potentially affected properties” were determined by analyzing the nature of the problem and the tract map of each RLP (provided by the City of Los Angeles). Three (3) RLPs seem to have neighboring “potentially affected properties, which appear to be affected by the same flood risk problem. The remaining 13 of the 16 RLPs in the Los Angeles River (Non-Hillside) Watershed have site-specific flood risks, which, based on current information, do not impact neighboring properties.



Table 19 REPETITIVE LOSS PROPERTIES – LOS ANGELES RIVER (NON-HILLSIDE) ID No. Community Zip Claim Dates FEMA Designated

Flood Zone

22 Sherman Oaks 91403 3/83, 2/80 C

30 North Hollywood 91602 3/83,1/83, 2/80 C

33 North Hollywood 91605 1/83,2/80,1/80 AE

34 Los Angeles 91605 2/95,2/93,2/92,10/87,3/83 C

54 Los Angeles 91605 2/80,1/80,3/78 AE

56 Woodland Hills 91367 2/80 C

61 Van Nuys 91406 2/92,3/83 C

77 Los Angeles 90015 11/97,12/94, 3/94 C

88 Los Angeles 90014 2/80,1/78,1/78,1/78 C

90 Los Angeles 91604 2/93,2/92 C

100 A-D

Los Angeles 91602 1/80,2/80 C

108 Encino 91316 2/98, 2/98 C

109 North Hollywood 91605 3/83,3/79 C

Table 20 FLOODING CAUSES – LOS ANGELES RIVER (NON-HILLSIDE)

R

LP

Id

No

.

Hills

ide

Dra

inag

e/

Gra

din

g D

efi

cie

nc

y

Str

eet

Dra

inag

e/

Gra

din

g D

efi

cie

nc

y

On

sit

e D

rain

ag

e/

Gra

din

g D

efi

cie

nc

y

Oth

ers

Causes

Pro

ble

m

No

Pro

ble

m

22 X Street flow to underground. parking, Added floodwall - no problem X

30 X Owner (since 1979) has no knowledge of flooding X

33 X Storm drain/channel problem X

34 X Street sump, property lower than street X

54 X Storm drain/channel problem X

56 X Storm drain blocked by construction on street X

61 X Street drainage problem - debris in catch basins X

77 X Street sump, wave from flooding X 88 X Owner said no flood problem X

90 X Under construction w/ basement X

100A X Street sump, property lower than street X

100B X Street sump, property lower than street X

100C X Street sump, property lower than street X

100D X Street sump, property lower than street X

108 X Frontyard drainage, house lower than street X

109 X Street sump, property lower than street X




Street Drainage Problem (ID Nos. 22, 34, 61, 77, 88, 100 A-D, 108, and 109): The building pads of the properties are lower than the street level, and/or the driveway is sloped toward the house and garage. Street runoff can enter the private property if a berm with sufficient height is not placed at the driveway or property boundaries facing the street (ID Nos. 22, 61, 88, and 108), especially if the property is located at the street sump area (lowest point of the nearby streets – ID Nos. 34, 77, 100 and 109), where street flow can pond.

Others (ID Nos. 30, 33, 54, 56, and 90): The properties have site-specific

problems that need special and individual attention. The properties were located near the outlets of Lockheed Channel relief pipes, which were owned and maintained by the railroad company (ID Nos. 33 and 54). Catch basins were blocked by debris from the construction on the street fronting the property (ID No. 56). New owners have remodeled the house and are not aware of any previous flood-related problems experienced by the previous owners (ID No. 30). The new building with new drainage system was under construction during the field visit (ID No. 90).

Table 21 “POTENTIALLY AFFECTED PROPERTIES” LOS ANGELES RIVER (NON-HILLSIDE)

RLP

Id No. Number of other properties possibly affected by same

problem



77 4 Street sump, wave from flooding


These potential problems for RLP-neighboring sites are further described below. Street Drainage Problem (Neighbors of ID Nos. 34, 77, and 109): Neighboring

RLPs were previously damaged by street flow or sump conditions, usually accompanied by undersized or plugged storm drains.

6.5.3. Ballona Creek (Hillside)

Fifty-one (51) out of the 117 RLPs identified by FEMA are within the Ballona Creek Watershed and subject to Hillside hazards. Of the 51 RLPs, four are located within a FEMA designated special flood hazard area AO (shallow flooding with the 100-year flood depth from one to three feet) (RLP Nos. 2, 74, and 75 and 113). One RLP is located within the FEMA designated flood zone AH (RLP ID NO. 11). One is located in Zone B, two are in zone shaded X, seven are in Zone X, and thirty-six are in Zone C.



Table 22 provides a list of the 51 RLPs and indicates the flooding history and FEMA designated flood zone for each site. The flood events occurred in 1977/78, 1978/79, 1979/80, 1980/81, 1981/82, 1982/83, 1985/86, 1991/92, 1992/93, 1994/95, and 1997/98 rainy seasons. The majority of the RLPs suffered flooding damages twice in this time period. Property ID No. 38 suffered flood damages a total of four times – the worst among the 51 RLPs. Table 23 identifies the causes of flooding and whether a current problem exists at each of the RLP sites. At 19 RLP locations (Property ID Nos. 2, 12-15, 35-37, 39, 58, 63, 73, 75, 86, 87, 101, 105, 114, and 117) the current owners/occupants were not aware of any recent flooding problems. Among these properties, property ID Nos. 7-9, 12, 14, 36, and 37 previously reported no problem as shown in the City’s Summary Findings dated November 29, 2000. Property ID Nos. 9, 39, 52, 62, and 114 were confirmed by the property owners during the recent survey. Property ID No. 74 reported some losses during the recent rainstorm event in February 2001.

Table 24 shows a summary of RLP-neighboring “potentially affected properties” in the Ballona Creek (Hillside) Watershed which may be affected by the same problem sources as the current RLPs. RLP-neighboring “potentially affected properties” were determined by analyzing the nature of the problem and the tract map of each RLP (provided by the City of Los Angeles). Seven (7) RLPs seem to have neighboring “potentially affected properties”, which appear to be affected by the same flood risk problem. The remaining 44 of the 51 RLPs in the Ballona Creek (Hillside) Watershed have site-specific flood risks, which, based on current information, do not impact neighboring properties.



Table 22 REPETITIVE LOSS PROPERTIES – BALLONA CREEK (HILLSIDE)

ID No.

Community Zip Claim Dates FEMA Designated Flood Zone

2 Los Angeles 90024 1/83, 2/80 AO 4 Los Angeles 90046 3/83, 2/80 Shaded X 5 Los Angeles 90046 2/80, 2/78 X 7 Los Angeles 90049 2/80, 1/79 C 8 Los Angeles 90049 2/80, 1/79 C 9 Los Angeles 90049 3/83, 2/80, 3/79 C 11 Los Angeles 90049 1/83, 3/80 AH 12 Los Angeles 90049 2/80, 1/79 C 13 Los Angeles 90049 1/83, 2/80 C 14 Los Angeles 90069 3/83, 4/80 X 15 Los Angeles 90272 1/83, 2/80 C 35 Los Angeles 90272 2/80, 1/79 C 36 Los Angeles 90049 3/83, 2/80 C 37 Los Angeles 90210 1/83, 2/80, 3/78 C 38 Los Angeles 90046 1/95, 2/93, 1/93, 2/92 Shaded X 39 Los Angeles 90046 2/98, 2/91, 2/80 X 40 Los Angeles 90210 1/95, 2/93, 2/80 C 42 Los Angeles 90049 3/83,2/80 C 43 Los Angeles 90049 3/83, 2/80, 3/79 C 46 Los Angeles 90049 3/83, 2/80 C 48 Los Angeles 90210 3/83, 2/79 C 52 Los Angeles 90077 3/79, 2/78, 1/78 C 53 Los Angeles 90068 2/80, 2/78 C 58 PacificPalisades 90272 3/83,1/83,2/80 C 59 Los Angeles 90049 3/83,2/80 C 62 Los Angeles 90210 2/93,11/85 C 63 Los Angeles 90077 2/92,2/80 C 68 Los Angeles 90049 4/98,2/92,2/80 C 70 Los Angeles 90046 1/83,2/80 X 71 Los Angeles 90077 2/93, 3/83, 3/80, C 72 Los Angeles 90049 3/95, 2/93, 1/83 C 73 Los Angeles 90077 2/93,2/80 C 74 Los Angeles 90077 2/93, 2/80 AO 75 Los Angeles 90077 3/98,1/95,1/93 AO 76 Los Angeles 90210 1/95,1/93 C 79 Los Angeles 90046 2/86,1/83 X 80 Los Angeles 90068 1/95,3/83 C 81 Los Angeles 90049 3/95,3/93 C 82 Los Angeles 90046 2/93,2/92, 2/78 X 85 Los Angeles 90210 2/80,3/78 B 86 PacificPalisades 90272 3/83,2/80, 3/78 C 87 Los Angeles 90049 2/92,2/80 C 93 Los Angeles 90210 1/95,1/93,2/92 C 98 Los Angeles 90049 2/93,12/92 C 101 Los Angeles 90077 2/96,1/95 C 103 Los Angeles 90069 3/95,2/93 X 105 Los Angeles 90049 3/95,2/93 C 113 Los Angeles 90077 2/98,1/93 AO 114 Los Angeles 90077 2/98,1/95 C 116 Los Angeles 90077 3/98,2/98 C 117 Los Angeles 90069 2/98,12/92 C



Table 23 FLOODING CAUSES – BALLONA CREEK (HILLSIDE)

R

LP

Id

No

.

Hil

lsid

e D

rain

ag

e/

Gra

din

g D

efi

cie

nc

y

Str

ee

t D

rain

ag

e/

Gra

din

g D

efi

cie

nc

y

On

sit

e D

rain

ag

e/

Gra

din

g D

efi

cie

nc

y

Oth

ers

Causes

Pro

ble

m

No

Pro

ble

m

2 X Sideyard Hillside drainage, owner said no more problem X 4 X Backyard drainage X 5 X Backyard mudslide X 7 X Debris revetments installed, reduce mudslide/flooding X 8 X Debris revetments installed, reduce mudslide/flooding X 9 X House built too low, grading problem X

11 X Street sump, property at street level X 12 X Current owner not aware of the flood problems X 13 X Remodeled & current owner(11/90) not aware of flood problem X 14 X Previous Mudslide X 15 X Owner (4/97) not aware of old problems X 35 X Gated street, no access to property, outside inspection - no problem X 36 X Property lower than street - City reconstructed the street X 37 X Backyard drainage installed - no more problem X 38 X Slope failure and mudslide X 39 X Improved drainage - no more problem X 40 X Hillside backyard drainage X 42 X Street / frontyard grading/drainage X 43 X Hillside backyard drainage X 46 X Hillside backyard drainage X 48 X Hillside sideyard drainage X 52 X Hillside sideyard drainage X 53 X Hillside sideyard drainage X 58 X Broken pipe, groundwater- no more problem X 59 X Hillside backyard drainage X 62 X Sump inlet outside the property clogged by debris X 63 X Water to underground room, Installed french drains, no more problem X 68 X Hillside backyard drainage X 70 X V-ditch behind the house not sufficient X 71 X Hillside backyard drainage X 72 X No backfill or V-ditch behind the neighbor's new retaining wall X 73 X Add terrace and down drains - no more problem X 74 X Street flooding, Storm drain not adequate X 75 X Remodel, add french drain - no more problem X 76 X Hillside backyard drainage X 79 X Hillside backyard drainage X 80 X Hillside backyard drainage X 81 X Hillside backyard drainage X 82 X Hillside backyard drainage X 85 X Hillside backyard drainage X 86 X Current owner is not aware of any flooding problem X 87 X No problem since 1967 X 93 X Hillside backyard and sideyard drainage X 98 X Gated community - unable to get to the prop X

101 X Broken City storm drain has been fixed X 103 X Hillside backyard and sideyard drainage X 105 X Hillside problem (retaining wall & backyard drainage installed) X 113 X Ditch across the frontyard X 114 X Yard drainage improved - no more problem X 116 X Yard drainage to the garage, roof leak X 117 X Property lower than the street – remodeled X




Hillside Drainage Problem (ID Nos. 2, 4, 5, 14, 15, 36, 37, 38, 40, 43, 46, 48, 52, 53, 59, 68, 71, 73, 75, 76, 79, 80, 81, 82, 85, 87, 93, 98, 103, and 105): The backyards of these properties are located at the bottom of the steep hill and impacted by hillside runoff. Flooding occurs due to deficient private onsite drainage. Mudslide from slope failure is also possible.

Street Drainage Problem (ID Nos. 11, 39, 42, and 74): The properties are

located lower than the street level, and/or driveway is sloped towards the house and garage. Street runoff can enter the private property if a berm with sufficient height is not placed at the driveway or at the property boundaries facing the street (ID No. 42), and especially, if the property is located at the street sump area (lowest point of the nearby streets-ID No. 11), where street flow can pond. Storm drain problems may include the undersized or broken storm drain and debris-clogged catch basins (ID Nos. 39 and 74).

Onsite Drainage Problem (ID No. 12): The onsite private drain inlets can be

deficient or plugged with debris in the yard, causing water to pond within the property and not draining to the street.

Others (ID Nos. 7, 8, 9, 13, 35, 58, 62, 63, 70, 72, 86, 101, 113, 114, 116, and

117): The properties have site-specific problems that need special and individual attention. The house was built too low into the bed of the natural watercourse, and groundwater seepage enters into the lower level of the house, flooding the basement after heavy storm (ID No. 9). A sump inlet, which was connected to storm drain, was installed on the sideyard just outside of the subject property and was clogged by debris and branches (ID No. 62) Flooding from ocean and a break in storm drain pipe (ID No. 58). The v-ditch at the backyard hill was extended all the way to the street but drained into the onsite property (ID No. 70). A new retaining wall constructed by new neighbor removed the existing v-ditch and has no backfill or new v-ditch to drain the water (ID No. 72). New owners have remodeled the house and/or are not aware of any old flood-related problems of the previous owners (ID Nos. 13, 86, and 117). The natural watercourse running across the frontyard. (ID No. 113), yard drainage problems (ID Nos. 114, 116), and roof leak (ID No. 116) were also sources of the problems. The owner claimed that he lived in the property since 1967 and never experienced the problem. (ID No. 87) In some cases, the property with no previous inspection data was gated, and no owner was present, so that no observation was made on site (ID No. 35).



Table 24 “POTENTIALLY AFFECTED PROPERTIES” BALLONA CREEK (HILLSIDE)

RLP Id No.

Number of other properties possibly affected by same

problem


7 5 Debris revetments installed, reduce mudslide/flooding

8 5 Debris revetments installed, reduce mudslide/flooding

9 5 House built too low, grading problem

43 7 Hillside backyard drainage


74 8 Street flooding, storm drain not adequate


These potential problems for RLP-neighboring sites are further described below. Hillside Drainage Problem (Neighbors of ID Nos. 7, 8, 9, 43, 59, and 81):

Suspected flooding risks as a result of unstable and mudslide-prone Mandeville Canyon in their backyards. As a side note, the Mandeville Canyon Road area has been identified as a Mud Flow Case Study Area in Figure 21 of this FMP.

Street Drainage Problem (Neighbors of ID No. 74): The neighboring RLP was

damaged by street flow or sump conditions, usually accompanied by undersized or plugged storm drains.

6.5.4. Ballona Creek (Non-Hillside)

Sixteen (16) out of the 117 RLPs identified by FEMA are within the Ballona Creek Watershed and subject to Non-Hillside hazards. Of the 16 RLPs, only one RLP (RLP No. 64) is located within the FEMA designated flood zone AO (shallow flooding with the 100-year flood depth from one to three feet) and the owner has not experienced any more problems. Two RLPs are located in zone B, five are in zone shaded X, three are in zone X, and five are in zone C. Zone B or X is the area inundated by a 500-year flood. Table 25 provides a list of the 16 RLPs and indicates the flooding history and FEMA designated flood zone for each site. The flood events occurred in 1977/78, 1979/80, 1980/81, 1982/83, 1985/86, 1987/88, 1991/92, 1992/93, 1994/95, and 1997/98 rainy seasons. The 1982/ 1983, 1991/92 and 1992/93 seasons were the worst seasons in terms of the number of flood-impacted properties, among the above-listed seasons. RLP No. 10 suffered flood damages a total of ten times –the worst among the 16 RLPs. Table 26 identifies the causes of flooding and whether a current problem exists at each of the RLP sites. At 8 RLP locations (ID Nos. 6, 64, 78, 89, 91, 95, 97, and 102) the current owners/occupants were not aware of any recent flooding problems.



Among these properties, property ID No. 6 previously reported no problem as shown in the City’s Summary Findings dated November 29, 2000. Property ID Nos. 69 and 112 reported some losses during the recent rainstorm event in January 2001.

Table 27 shows a summary of RLP-neighboring “potentially affected properties” in the Ballona Creek (Non-Hillside) Watershed which may be affected by the same problem sources as the current RLPs. RLP-neighboring “potentially affected properties” were determined by analyzing the nature of the problem and the tract map of each RLP (provided by the City of Los Angeles). Four (4) RLPs seem to have neighboring “potentially affected” properties, which appear to be affected by the same flood risk problem. The remaining 12 of the 16 RLPs in the Ballona Creek (Non-Hillside) Watershed have site-specific flood risks, which, based on current information, do not impact neighboring properties. Table 25 REPETITIVE LOSS PROPERTIES – BALLONA CREEK (NON-HILLSIDE)

ID No. Community Zip Flood History (Claim Dates)

FEMA Designated Flood Zone

1 Los Angeles 90024 1/83, 2/80 C

6 Los Angeles 90048 3/83, 2/80 C

10 Los Angeles 90049 2/93,3/83,1/83,2/80 B

44 Los Angeles 90064 3/81,2/80 C

49 Los Angeles 90005 3/83,1/83 C

64 Los Angeles 90064 2/93, 3/81 AO

69 Los Angeles 90049 2/93,3/83 C

78 Los Angeles 90035 2/93,2/92 Shaded X

89 Los Angeles 90046 2/86,3/78 X

91 Playa Del Rey 90293 1/88,1/83 B



96 Los Angeles 90035 2/93,2/92 X



112 Los Angeles 90036 2/98,3/95, 2/80 X



Table 26 FLOODING CAUSES – BALLONA CREEK (NON-HILLSIDE)

R

LP

Id

No

.

Hills

ide

Dra

inag

e/

Gra

din

g D

efi

cie

nc

y

Str

eet

Dra

inag

e/

Gra

din

g D

efi

cie

nc

y

On

sit

e D

rain

ag

e/

Gra

din

g D

efi

cie

nc

y

Oth

ers

Causes

Pro

ble

m

No

Pro

ble

m

1 X Street sump not adequate X

6 X Storm drain improved 1989 - no more problem X

10 X Water into underground garage X 44 X Street sump, property above street grade X

49 X Possible lack of onsite drainage X

64 X Previously plugged CB - no more problem X

69 X Channel not adequate X

78 X Clogged catch basin on La Cienega causing water ponding X

89 X Owner said no flood problem for more than 30 years X

91 X Owner since 1988, no major flood problem X

92 X Street drainage not adequate X

95 X Street flooding X

96 X Plugged catch basin X

97 X Storm drain improved & removed from flood zone X

102 X Storm drain improved (Hollyhills) X

112 X Street drainage not adequate X

The specific problems that were identified for each RLP site in Table 26 are further described below. Street Drainage Problem (ID Nos. 1, 44, 64, 92, 96, and 112) - The building pads

of the properties are lower than the street level, and/or the driveway is sloped toward the house and garage. Street runoff can enter the private property if a berm with sufficient height is not placed at the driveway or property boundaries facing the street, specially if the property is located at the street sump area (lowest point of the nearby streets – ID Nos. 1 and 44), where street flow can pond. Storm drain problems include undersized or broken storm drains and debris-clogged catch basins (ID Nos. 64, 92, 96, and 112).

On-Site Drainage Problem (ID No. 49) - The onsite private drain inlets can be

deficient or plugged with debris from the yard, causing water to pond within the property and not draining to the street.

Others (ID Nos. 6, 10, 69, 78, 89, 91, 95, 97, and 102) - The properties have

site-specific problems that need special and individual attention. The underground garage was flooded without sufficient drainage (ID No. 10). The LACFCD channel running across the property was not adequate in capacity and flooded regularly (ID No. 69). The property owner lived in the property for 30 years and never had flood-related problem (ID No. 89) The properties were



located within the flood zone of FEMA, but currently removed from it after the new improvements of storm drain system by the City (ID Nos. 78, 95, 97, 102). The new improvement on street drainage in 1989 solved any likely drainage problem. (ID No. 6) New owners have remodeled the house and/or are not aware of any old flood-related problems of the previous owners (ID No. 91).

Table 27 “POTENTIALLY AFFECTED PROPERTIES” BALLONA CREEK (NON-HILLSIDE)

RLP

Id No. Number of other properties possibly affected by same

problem


69 1 Channel not adequate

92 4 Street drainage not adequate

96 2 Plugged catch basin

112 4 Street drainage not adequate

These potential problems for RLP-neighboring sites are further described below.

Street Drainage Problem (Neighbors of ID Nos. 69, 92, 96, and 112): The neighboring RLPs were damaged by street flow or sump conditions, usually accompanied by undersized or plugged storm drains.


7. GOALS, OBJECTIVES AND POLICIES

7.1. Setting Goals

Based on the flood hazards facing the City as well as the initial hazard assessment prepared by City staff, the FMP Committee drafted goals, policies and objectives that would be appropriate for inclusion in the FMP. As part of this process, the Committee reviewed existing City goals, objectives, policies, and programs, regarding flood protection and mitigation as well as goals, objectives, policies and programs that could affect the implementation of the FMP. In establishing the goals, objectives, policies and programs for the FMP, attention was given to ensure that the FMP will not conflict with other goals, objectives, policies, and programs contained in other City documents. In addition, the Committee determined that there are several existing goals, objectives and policies that address several flood hazard issues. The Committee decided that these existing goals should be incorporated in the FMP, as appropriate, and that new goals, objectives and polices should be created if necessary to supplement those that already exist. In assessing the potential hazards from flooding, the Committee determined that catastrophic flooding caused by coastal flooding, tsunamis, and damage to infrastructure, (e.g., dams and reservoirs) are currently addressed in the City’s General Plan Safety Element. These hazards are addressed together in the FMP under a common goal. The primary hazards of concern to the City that are not currently addressed are shallow flooding and mud/debris flow hazards. (Please see Chapter 6 of this document.) In addition, the Committee recognized the interrelationship between flooding and water quality and the preservation of natural resources. Therefore, while not directly addressed in the FMP, references to water quality and natural resource protection are made in the FMP.

7.2. Goals, Objectives, and Policies

GOAL 1 - Protect human life and property, to the greatest extent feasible, from catastrophic events, such as tsunami, coastal flooding, or the rupture of water containing infrastructure, such as dams, reservoirs, and water tanks. Objective 1.a Minimize hazards to life and property from flooding that could occur from catastrophic events. Policies: 1.a.01 Continue participation in the federal tsunami alert program and provide

tsunami warning to the people living and working in tsunami hazard areas. 1.a.02 Future development in coastal zones will comply with the design criteria

established in the City’s Specific Plan for the Management of Flood Hazards (Ordinance No. 172,081).

GOALS, OBJECTIVES AND POLICIES


1.a.03 Ensure that water storage infrastructure is adequately maintained and

provide inspection and repair, as necessary, following a natural disaster. 1.a.04 Ensure that emergency procedures are in place to address catastrophic

events. GOAL 2 – To the greatest extent possible, reduce the risk from flood hazards, including shallow flooding and mud/debris flow, to life, property, public investment and social order in the City. Objective 2.a Minimize impacts from flooding in FEMA designated flood zones. Policies: 2.a.01 Ensure that development complies with the criteria established in Ordinance

No. 172,081. 2.a.02 Review existing regulations in Ordinance No. 172,081 to ensure that

impacts to adjacent properties are minimized to the maximum extent feasible.

2.a.03 Reduce repeated losses in FEMA designated flood zones through land

acquisition and/or relocation when appropriate to increase open space. 2.a.04 Provide flood protection information and assistance to property and

business owners, residents, contractors, realtors, and prospective buyers in FEMA designated flood zones.

2.a.05 Provide technical information regarding floodproofing and retrofitting of

property/structures in FEMA designated flood zones to prevent substantial flood damage.

2.a.06 Assign additional priority to stormwater projects that remove FEMA

designated flood zones. 2.a.07 Provide information about erosion control and landscaping to property

owners and contractors in FEMA designated flood zones. 2.a.08 Ensure that alterations to natural watercourses in FEMA designated flood

zones are made in accordance with City requirements and FMP programs. 2.a.09 Coordinate with the Los Angeles County Department of Public Works to

design and construct stormwater projects necessary to reduce the percentage of FEMA designated flood zones in the City.



2.a.10 Ensure that projects proposed by the Community Development Department and Community Redevelopment Agency minimize or eliminate flood risks without impacting adjacent or downstream properties.

2.a.11 Assign additional priority to stormwater projects that protect critical facilities

in FEMA designated flood zones. 2.a.12 Update the FEMA designated flood zones based on the best available

technical data and analysis. Objective 2.b Continue to define flood hazard areas in the City.

Policies: 2.b.01 Continue to evaluate specific cases of shallow flooding and mud/debris flow,

recommend solutions to identified problems, and provide assistance to property owners.

2.b.02 Continue to participate in the National Flood Insurance Program and

improve the City’s rating in the Community Rating System. 2.b.03 Review the stormwater system for deficiencies and revise the FEMA

designated flood zones as necessary to best describe system deficiencies. 2.b.04 Coordinate with other departments that have information regarding flooding,

such as the City Fire Department and Building and Safety Department, to ensure that information regarding flooding is shared between appropriate departments or agencies.

2.b.05 Provide information to property owners regarding the process for removal of

property, if appropriate, from a FEMA designated flood zone. 2.b.06 Identify and pursue various forms of funding to implement the programs

identified in the FMP. Objective 2.c Minimize impacts from flooding in unmapped flood hazard areas.

Policies: 2.c.01 Review existing development regulations to ensure that the standards

minimize, to the extent feasible, flooding impacts to adjacent properties (e.g., downstream or downslope).

2.c.02 Reduce repeated losses through land acquisition and/or relocation when

appropriate to increase open space.



2.c.03 Develop and make available flood protection information to property and business owners, residents, contractors, realtors, and prospective buyers.

2.c.04 Develop and make available technical information regarding floodproofing

and retrofitting of property/structures to prevent substantial flood damage. 2.c.05 Assign additional priority to stormwater projects that remove flood hazards

from unmapped flood zones. 2.c.06 Ensure that projects proposed by the Community Development Department

and Community Redevelopment Agency minimize or eliminate flood risks without impacting adjacent or downstream properties.

2.c.07 Assign additional priority to stormwater projects that protect critical facilities

in unmapped flood zones. Objective 2.d Reduce Repetitive Loss Properties throughout the City. Policies: 2.d.01 Conduct outreach, provide flood awareness information, and provide

technical information to property owners. 2.d.02 Maintain a history of flood hazards, flood losses, and mitigation activities. 2.d.03 Conduct site investigations, research available data, and review proposed

modifications to identify and mitigate drainage problems. 2.d.04 Recommend structural and non-structural flood mitigation alternatives. 2.d.05 Provide information regarding Federal Emergency Management Agency

grant and loan programs. GOAL 3 – Minimize flood hazards and protect water quality Citywide by employing watershed-based approaches that balance environmental, economic, and engineering considerations. Objective 3.a Ensure that all properties are protected from flood hazards through the maintenance and installation of stormwater systems in accordance with applicable standards. Policies: 3.a.01 Provide a stormwater system that has adequate capacity to protect its

citizens and property from flooding which results from a 10-year storm (or a 50-year storm in sump areas).



3.a.02 Implement programs to correct existing deficiencies in the stormwater system, including surface and subsurface drainage.

3.a.03 Continuously review the stormwater system for deficiencies and develop

projects to eliminate or reduce deficiencies to the maximum extent practicable.

3.a.04 Require that adequate storm drain, flood control, and pollution abatement

facilities be constructed to mitigate the impacts associated with new development.

Objective 3.b Maintain the existing stormwater system so that the system operates effectively. Policy: 3.b.01 Ensure that the City’s stormwater system is adequately maintained. Objective 3.c Pursue effective and efficient approaches to reducing stormwater runoff and protecting water quality. Policies: 3.c.01 Implement Best Management Practices as required under the National

Pollution Discharge Elimination System. 3.c.02 Ensure that stormwater pollution abatement best management practices

(BMPs) do not increase flood risk beyond acceptable levels. Objective 3.d Ensure that modifications to rivers and channels in the City do not increase flood hazards. Policy: 3.d.01 Participate in efforts regarding modifications to rivers and channels that are

within or impact the City. Objective 3.e Open space and natural resource areas throughout the City will be managed to minimize flood hazards. Policies: 3.e.01 Conserve and manage the undeveloped portions of the City’s watersheds,

where feasible, as open spaces that protect, conserve, and enhance natural resources.



3.e.02 Continue to protect, restore and/or enhance habitat areas, linkages and corridor segments, to the greatest extent practical, within City owned or managed sites.

7.3. Review Possible Activities

The CRS guidelines require the FMP to identify all the activities considered by the Committee and to indicate if an activity is not pursued in Chapter 8, why the activity was not recommended. The Committee discussed various possible ways to reduce flood losses and to attain the goals applicable to the FMP. The Committee considered the current programs to determine if the programs are sufficient and whether new programs were necessary. The following provides a discussion regarding the six primary (FEMA-recommended) categories and the possible activities addressed, but not pursued, by the Committee. Please see Chapter 8 for the programs that will be part of the Implementation Plan of the FMP. Preventive: Activities that include planning and zoning, open space preservation, floodplain regulations, stormwater management, and drainage system maintenance.

The Committee discussed the need to assess the current condition of the City’s drainage system in a systematic manner. The Committee also discussed whether all areas of the City should have storm drains and not rely on the street for the movement of floodwaters. The Committee decided not to pursue the installation or size-increase of storm drains throughout the City for the sole purpose of conveying all stormwater runoff in pipes. The Committee concluded that this approach would be too costly, relative to the benefits.

The Committee also discussed preserving as open space, those areas that are not currently developed. However, the Committee recognized that if a property is under private ownership, the restriction on development could result in a “taking.” In addition, City funds are not currently available to acquire parcels.

Property Protection: These activities include actions undertaken by the property owners on a case-by-case basis, such as floodproofing and flood insurance, but also include acquisition of land and relocation of structures.

At almost every meeting, the Committee discussed the impacts of cumulative development and the impacts of the situations unique to hillside development and water runoff. The Committee expressed concern that the current regulations do not seem adequate to minimize flooding impacts. Also, concern was raised over insufficient results from City inspections following hillside cross-lot drainage complaints. The Committee discussed various known situations of flooding in hillsides, to assess whether a pattern was apparent. Since no pattern was found, and because the City encompasses such a large area, the Committee decided to include programs to review existing regulations and to further assess specific hillside problem situations. While some members wanted to limit development in the hillside, the Committee generally recognized the unfeasibility of restricting development on



private property. However, the Committee did insist that at a minimum, the City should be able to provide technical assistance to property owners who currently live in, or those who want to purchase property in, identified flood hazard areas.

The Committee also discussed the connection between flooding and the loss of vegetation due to fire, especially in the hillside areas. The Committee was informed that the Fire Department responds to the fire emergency and then seeds the fire-affected area afterward, to help control the mudflow. The Fire Department also provides sand bags during the rains, if necessary. The Committee did not identify the need for additional programs to address this issue.

Other than the recommendations offered by Tetra Tech to address flooding at Repetitive Loss Properties, the Committee did not discuss individual properties. The Committee chose to focus on policies and actions that could be applied Citywide. In doing so, the Committee emphasized the need to educate and heighten public awareness regarding flooding in the City and various programs have been included in the Implementation Plan. See the Public Information section below, for a further discussion of the Committee’s findings on public education and increased awareness.

Natural Resource Protection: Activities undertaken to protect the natural and beneficial functions of the floodplain, such as wetland protection. These activities can include erosion and sediment control and best management practices.

The Committee discussed the importance of linking flooding with natural resource protection, including water quality issues (see discussion under Structural Projects section below). As a result of these discussions, the Committee ensured that the Implementation Plan includes goals, objectives, policies, and programs to link the protection of natural resources with the minimization of flooding.

Emergency Services: Activities that are undertaken during a flood to minimize its impact, which include warning and evacuation.

The Committee discussed the City’s flood warning system for catastrophic events and the potential to increase the number of system locations throughout the City. The Committee also discussed existing City emergency preparedness programs. It was determined that additional programs were not appropriate at the present time and policies were included to support the current efforts. In regard to certain, critical, localized problems areas, the Committee discussed the need for early warning systems so that businesses and property owners could take action to protect their property. However, this approach was not pursued because such areas have not been defined in a systematic manner; this would result in a narrow focus rather than the intended City-wide focus of the FMP.

Structural Projects: Activities that keep floodwaters away from an area and include channel modifications, water diversion structures, and reservoirs.



The Committee discussed the fact that some facilities designed to remove pollution from runoff water may actually aggravate flooding risks (e.g. catch basin filters which restrict flow into the system). The Committee felt this issue would be addressed by a program requiring the City continue to “plan and design stormwater projects so that water quality is protected without creating a flood risk through the alteration of water flow.”

Another related item of discussion was the various proposals to modify the Los Angeles River (de-channelize, soft-bottom, use porous materials, etc.). Since all of these proposals are still in the preliminary stages, the Committee decided to remain involved in the discussions and included a policy “to participate in efforts regarding modifications to rivers and channels that are within, or impact, the City.”

Public Information: Activities that provide information to property and business owners, prospective buyers, residents, contractors, and realtors, about flood hazards and ways to protect people and property from flood damage. These activities include outreach projects and environmental education programs.

The Committee believes that education is a key component of the FMP. Various programs have been included to provide education and to increase awareness. The Committee also discussed various methods of distributing information. While the Committee generally would like to provide mailings to everyone in the City, the Committee recognized that the cost would be too great to the City and did not pursue this approach. A suggestion was made to include informational flyers in Department of Water and Power bills. The Committee concluded that this has not been a successful approach in the City over the past ten years. The Committee did endorse other distribution methods, such as public counters, the City’s Annual Emergency Preparedness Fair, and the Internet, to provide information to the public.

The Committee also discussed the need for departmental coordination to ensure that information is exchanged as needed, so that programs can be implemented effectively.

IMPLEMENTATION PLAN


8. IMPLEMENTATION PLAN

This chapter identifies the programs that are being (or will be) implemented in order to meet the Goals, Objectives, and Policies of Chapter 7. Discussions are divided into two distinct sections. Section 8.1 contains the Citywide programs that address all aspects of the FMP. Section 8.2 consists of the activities specifically related to Repetitive Loss Properties.

8.1. Programs

The primary funding sources for programs are the Stormwater Pollution Abatement Fund and General Fund. Monies from other sources such as grants and fees are not specifically identified, but will be pursued to support the implementation of programs. Each program is described by five fields of information: cost, schedule, policy addressed, responsible agency and financing. The definition for each of these fields is provided below.

Field Name Definition

Cost $ = estimated cost in dollars currently funded

[$] = estimated cost in dollars not funded

FTE = Full Time Equivalent staff currently funded

[FTE] = Full Time Equivalent staff not funded

TBD = Cost information to be determined later

Schedule On Going = a continuous program

Start (MM/YYYY) = estimated program start

Finish (MM/YYYY) = estimated program finish

Not Scheduled = no start date has been established

TBD = Schedule information to be determined later

Policy Addressed Policies that relate to the program

Responsible Agency City Departments/Bureaus and outside agencies

Financing Funding sources for the identified program

IMPLEMENTATION PLAN


P-01 Participate in the Los Angeles County Operational Area Tsunami Mitigation Task Force.

Cost: TBD

Schedule: On Going

Policy Addressed: 1.a.01

Responsible Agency: Harbor Department

Financing: Harbor Department

P-02 Maintain membership in the tsunami warning system.

Cost: TBD

Schedule: On Going


Responsible Agency: Harbor Department

Financing: Harbor Department

P-03 Research and recommend the need to include a Tsunami element to the City’s

Emergency Response Master Plan.

Cost: TBD

Schedule: Start (July/2002)


Responsible Agency: Department of Emergency Preparedness

Financing: General Fund

P-04 Continue to maintain and annually update the Dam and Reservoir Emergency

Notification List.

Cost: TBD

Schedule: On Going


Responsible Agency: Department of Water and Power

Financing: Department of Water and Power

IMPLEMENTATION PLAN


P-05 Provide dam inundation maps to the public.

Cost: TBD

Schedule: Start (July/2002); On Going


Responsible Agency: Department of Public Works, Bureau of Engineering

Financing: Stormwater Pollution Abatement Fund

P-06 Continue to evaluate reservoirs in terms of earthquake safety and implement

necessary mitigation/improvement measures, as required by the California Department of Water Resources, Division of Safety of Dams.

Cost: TBD

Schedule: On Going




P-07 Continue to collect and analyze data regarding water volumes and pumping

capabilities in water storage facilities provided by the Los Angeles Water Systems Data Acquisition Center to prevent catastrophic events.

Cost: TBD

Schedule: On Going




P-08 Continue to dispatch reservoir inspection and damage teams following natural

disasters to inspect and report the condition of facilities.

Cost: TBD

Schedule: On Going




IMPLEMENTATION PLAN


P-09 Continue to routinely monitor the existing structural condition of City-owned water storage facilities.

Cost: TBD

Schedule: On Going




P-10 Identify a flood warning system for properties located downstream of City owned

water tanks.

Cost: TBD





P-11 Submit copies of emergency plans for water tank storage and other non-dam

storage systems to the Flood Hazard Mitigation Coordinator and provide updates as they become available.

Cost: TBD

Schedule: Start (September/2001); On Going



Financing: Department of Water Power

P-12 Continue implementing the City’s Annual Emergency Preparedness Fair.

Cost: TBD

Schedule: On Going

Policy Addressed: 2.a.04, 2.a.05, 2.a.07



IMPLEMENTATION PLAN


P-13 Maintain the City web page to provide emergency preparedness information to the general public and media.

Cost: TBD

Schedule: On Going




P-14 Distribute information regarding flood prevention and flood insurance at emergency

operations and emergency preparedness events.

Cost: TBD

Schedule: On Going

Policy Addressed: 2.c.03



P-15 Maintain the City’s Emergency Operations Master Plan and Procedures.

Cost: TBD

Schedule: On Going

Policy Addressed: 2.a.04, 2.a.05, 2.a.07, 2.c.04



P-16 Make sand and sand bags available to flood risk property owners during the wet

season, provide notifications of the availability of these materials, and track the distribution of the materials.

Cost: TBD

Schedule: On Going

Policy Addressed: 2.a.04, 2.b.01, 2.b.04

Responsible Agency: Fire Department; Department of Public Works, Bureau of Street Services and Bureau of Engineering

Financing: General Fund; Stormwater Pollution Abatement Fund

IMPLEMENTATION PLAN


P-17 Establish and maintain a technically based prioritization methodology for use in developing the stormwater capital improvement program.

Cost: 0.5 FTE

Schedule: On Going

Policy Addressed: 2.a.06, 2.a.09, 2.a.11, 2.c.05, 2.c.07, 3.a.01, 3.a.02, 3.a.03

Responsible Agency: Department of Public Works, Bureau of Sanitation and Bureau of Engineering


P-18 Conduct quarterly coordination meetings with the Los Angeles County Department

of Public Works to communicate the City’s list of priority stormwater projects, to discuss watershed management programs, and to develop Countywide standards.

Cost: 0.1 FTE

Schedule: On Going

Policy Addressed: 2.a.09, 3.a.02

Responsible Agency: Department of Public Works, Bureau of Sanitation and Bureau of Engineering, Los Angeles County Department of Public Works

Financing: Stormwater Pollution Abatement Fund (City); Benefit Assessment for Flood Control (County)

P-19 Maintain regular contact with surrounding cities, the Los Angeles County

Department of Public Works, State and Federal agencies regarding flood hazard mitigation and the National Flood Insurance Program.

Cost: 0.1 FTE

Schedule: On Going

Policy Addressed: 1.a.01, 2.a.09, 2.b.02, 2.b.06, 3.d.01

Responsible Agency: Department of Public Works, Bureau of Engineering; Department of Recreation and Parks

Financing: Stormwater Pollution Abatement Fund; General Fund

IMPLEMENTATION PLAN


P-20 Participate in organizations such as the Association of State Floodplain Managers and the National Association of Flood and Stormwater Management Agencies to network with other agencies and remain current in the field of floodplain management.

Cost: 0.05 FTE

Schedule: On Going

Policy Addressed: 1.a.01, 2.a.03, 2.a.04, 2.a.05, 2.a.07, 2.b.02, 2.b.05, 2.b.06, 2.c.01



P-21 Provide the training and support necessary to maintain a Certified Floodplain

Manager within the Department of Public Works.

Cost: 0.05 FTE

Schedule: On Going

Policy Addressed: 1.a.01, 2.a.03, 2.a.04, 2.a.05, 2.a.07, 2.b.02, 2.b.05, 2.b.06, 2.c.01



P-22 Conduct an annual National Flood Insurance Program seminar for City agencies

responsible for applying and enforcing floodplain management regulations.

Cost: 0.1 FTE

Schedule: On Going

Policy Addressed: 2.a.01, 2.a.08, 2.b.02, 2.b.04



IMPLEMENTATION PLAN


P-23 Based on the annual National Flood Insurance Program seminar, update operational procedures and training materials for staff that apply and enforce floodplain management regulations and provide annual training.

Cost: TBD


Policy Addressed: 1.a.02, 2.a.01, 2.a.02, 2.a.05, 2.a.08, 2.a.10, 2.b.02, 2.b.05, 2.c.06

Responsible Agency: Department of Building and Safety; Department of City Planning; Harbor Department


P-24 Conduct a stormwater facilities condition assessment program to identify the

physical and hydraulic condition of the system and to support infrastructure management needs.

Cost: 7.0 FTE; plus $1,000,000

Schedule: Start (June/2001); Finish (June/2003)

Policy Addressed: 2.a.06, 2.a.11, 2.c.05, 2.c.07, 3.a.01, 3.a.02, 3.a.03



P-25 Develop Geographic Information System mapping and modeling capability to

support the stormwater facilities condition assessment program.

Cost: 4.0 FTE

Schedule: Start (June/2001); Finish (June/2003)

Policy Addressed: 2.a.06, 2.a.11, 2.c.05, 2.c.07, 3.a.01, 3.a.02, 3.a.03



P-26 Continue to maintain precise survey bench marks throughout the City.

Cost: 4.0 FTE

Schedule: On Going

Policy Addressed: 2.b.02, 2.b.05



IMPLEMENTATION PLAN


P-27 Develop and maintain a Citywide list of priority maintenance-related flood problem sites.

Cost: TBD

Schedule: On Going

Policy Addressed: 2.b.01, 2.b.02, 3.a.01, 3.a.02, 3.a.03, 3.b.01



P-28 Based on P-27, conduct necessary inspection and maintenance at priority

maintenance-related flood problem sites prior to the wet season and after significant storms.

Cost: TBD


Policy Addressed: 2.b.01, 2.b.02, 3.a.01, 3.a.02, 3.a.03, 3.b.01

Responsible Agency: Department of Public Works, Bureau of Sanitation


P-29 Provide public education about maintaining the stormwater system free of debris

and reporting violations.

Cost: TBD

Schedule: On Going

Policy Addressed: 2.b.02, 3.a.01, 3.b.01, 3.c.02



P-30 Post “No Dumping” signs at points of entry to the stormwater system.

Cost: TBD

Schedule: On Going

Policy Addressed: 2.b.02, 3.a.01, 3.b.01, 3.c.02

Responsible Agency: Department of Public Works, Bureau of Sanitation; Los Angeles County Department of Public Works

Financing: Stormwater Pollution Abatement Fund (City); Benefit Assessment for Flood Control (County)

IMPLEMENTATION PLAN


P-31 Conduct a systematic evaluation of FEMA designated flood zones and revise/update designated flood zones to reflect current conditions.

Cost: [1.0 FTE]

Schedule: Not Scheduled

Policy Addressed: 2.a.03, 2.a.12, 2.b.01, 2.b.02, 2.b.03



P-32 Revise the Map of Hillside Areas (Bureau of Engineering Basic Grid Map A-13372)

to more accurately reflect areas subject to hillside regulations based on current data and technology.

Cost: TBD

Schedule: Start (September/2001); Finish (September/ 2002)


Responsible Agency: Department of Public Works, Bureau of Sanitation and Bureau of Engineering; Department of Building and Safety; Department of City Planning


P-33 Develop a map of known landslide and mudflow areas.

Cost: TBD

Schedule: Start (September/2001); Finish (September/2003)


Responsible Agency: Department of Building and Safety; Department of Public Works, Bureau of Engineering


IMPLEMENTATION PLAN


P-34 Evaluate current development regulations, including the grading ordinance, to determine whether the standards provide sufficient protection for adjacent (downstream or downslope) development.

Cost: TBD

Schedule: TBD

Policy Addressed: 2.a.02, 2.c.01

Responsible Agency: Department of City Planning; Department of Building and Safety; Department of Public Works, Bureau of Engineering


P-35 Establish a policy for identifying significant (substantial) improvement projects that

is consistent with Federal Emergency Management Agency requirements.

Cost: [0.2 FTE]

Schedule: Start (July/2001); Finish (July/2002)

Policy Addressed: 2.a.01, 2.a.02, 2.b.02

Responsible Agency: Department of Building and Safety


P-36 Verify, through the plan check process, that new development complies with the

regulations in the City’s Specific Plan for the Management of Flood Hazards, Ordinance No. 172,081, including freeboard requirements on new construction and substantial improvements.

Cost: TBD

Schedule: On Going

Policy Addressed: 1.a.02, 2.a.01

Responsible Agency: Department of Building and Safety; Department of City Planning; Harbor Department; Department of Public Works, Bureau of Engineering

Financing General Fund; Stormwater Pollution Abatement Fund

IMPLEMENTATION PLAN


P-37 Require that all land division proposals within FEMA designated flood zones include base flood elevation data.

Cost: TBD

Schedule: On Going

Policy Addressed: 2.a.01, 2.a.08, 2.a.10, 2.c.06, 3.a.01, 3.a.04, 3.e.02

Responsible Agency: Department of Public Works, Bureau of Engineering; Department of City Planning


P-38 Study and recommend solutions to conflicts between height limitations and flood

mitigation elevation requirements for structures.

Cost: TBD

Schedule: Start (July/2002)

Policy Addressed: 2.a.01, 2.a.02, 2.a.05, 2.a.12, 2.c.01, 2.d.01

Responsible Agency: Department of City Planning; Department of Public Works, Bureau of Engineering


P-39 Research and continue to improve Municipal Code regulations regarding soil

stability and erosion abatement.

Cost: TBD

Schedule: TBD


Responsible Agency: Department of City Planning; Department of Building and Safety; Department of Public Works, Bureau of Engineering


IMPLEMENTATION PLAN


P-40 Provide information to the Flood Hazard Mitigation Coordinator for preparation of the Annual FMP Evaluation Report that describes the progress made for each Program and any floodplain management regulatory actions and compliance actions conducted during the reporting period, including (a) the number of permits approved in designated flood hazard areas, (b) the number of waivers applied for, (c) the number of waivers approved. The information shall be provided to the Flood Hazard Mitigation Coordinator on July 1 of each year.

Cost: TBD


Policy Addressed: 1.a.02, 2.a.01, 2.a.08, 2.a.10

Responsible Agency: Department of Building and Safety; Department of City Planning; Fire Department; Harbor Department; Department of Water and Power; Department of Public Works, Bureau of Engineering and Bureau of Sanitation.


P-41 Maintain a filing system for all Elevation Certificates and evaluate and improve the

process for obtaining accurately completed Elevation Certificates.

Cost: 0.1 FTE

Schedule: On Going


Responsible Agency: Department of Public Works, Bureau of Engineering; Department of Building and Safety


P-42 Continue to refine the use of the Plan Check and Inspection System (PCIS) to track

high-risk properties and ensure that drainage is adequately addressed through the plan check process.

Cost: TBD

Schedule: TBD

Policy Addressed: 2.a.01, 2.a.02, 2.a.08, 2.b.01, 2.c.01

Responsible Agency: Department of Building and Safety; Department of Public Works, Bureau of Sanitation and Bureau of Engineering


IMPLEMENTATION PLAN


P-43 Incorporate floodplain management information into the Zoning Information and Map Access System (ZIMAS).

Cost: TBD

Schedule: Start (January/2002); On Going

Policy Addressed: 2.a.01, 2.a.04, 2.a.10, 2.b.02, 2.b.04, 2.d.01

Responsible Agency: Department of City Planning; Department of Public Works, Bureau of Engineering


P-44 Annually transfer electronic data regarding structures damaged due to flooding

caused by catastrophic events to the Flood Hazard Mitigation Coordinator.

Cost: [0.1 FTE]


Policy Addressed: 1.a.04, 2.a.12, 2.b.04

Responsible Agency: Department of Building and Safety


P-45 Annually transfer electronic data regarding hazardous materials storage (including

water reactive chemicals) to the Flood Hazard Mitigation Coordinator.

Cost: [0.1 FTE]



Responsible Agency: Fire Department


IMPLEMENTATION PLAN


P-46 Continue to notify insurance agencies and realtors of the requirement that all lessors or renters give written notice to all prospective and interested parties, including but not limited to, purchasers, lessees and renters, prior to finalization of such a transaction when the subject land and/or structures are located within FEMA designated flood zones. The notice shall contain the following information:

1) The nature and classification of the designated flood zone, 2) The zone designation, 3) Whether waivers have been granted for development located within the

designated flood zone, and 4) That premium rates for flood insurance of new structures built at elevations

below the base flood shall substantially increase as the elevations decrease. Failure to give such notice shall be a basis for rescinding any sale, lease or rental agreement.

Cost: 0.05 FTE

Schedule: On Going

Policy Addressed: 1.a.02, 2.a.01, 2.a.04, 2.b.02, 2.c.03



P-47 Provide flood zone information to all residents; provide notifications when flood

insurance is required; and provide notifications when FEMA designated flood zones changes are made.

Cost: 1.0 FTE

Schedule: On Going

Policy Addressed: 2.a.04, 2.b.02, 2.c.03



P-48 Develop and distribute flood protection information and materials to property

owners and developers in high-risk areas.

Cost: TBD

Schedule: TBD

Policy Addressed: 2.c.03

Responsible Agency: Department of Public Works, Bureau of Engineering; Department of City Planning; Department of Building and Safety; Fire Department; Department of Emergency Preparedness; Library Department

Financing: Stormwater Pollution Abatement , General Fund

IMPLEMENTATION PLAN


P-49 Maintain a list of Critical Facilities throughout the City, provide flood protection information to operators of critical facilities located in FEMA designated flood zones, and encourage the implementation of flood protection measures at such facilities.

Cost: TBD


Policy Addressed: 2.a.04, 2.a.05, 2.a.11, 2.c.03, 2.c.04

Responsible Agency: Department of Public Works, Bureau of Engineering; Department of Emergency Preparedness


P-50 Distribute a revised Flood Hazard Assessment Questionnaire to an additional

sector of the population to gather flood damage data.

Cost: TBD

Schedule: On Going

Policy Addressed: 2.a.03, 2.c.02, 3.a.02, 3.a.03, 3.b.01



P-51 Prepare a list of City owned/leased properties that are located in FEMA designated

flood zones.

Cost: TBD



Responsible Agency: Department of General Services; Department of Public Works, Bureau of Engineering


P-52 Evaluate flood hazards to City owned/leased properties located in FEMA

designated flood zones and develop mitigation recommendations.

Cost: TBD





IMPLEMENTATION PLAN


P-53 Maintain adequate flood insurance on public structures located in FEMA designated flood zones.

Cost: TBD



Responsible Agency: Department of General Services


P-54 Continue to investigate Repetitive Loss Properties, as they are identified by the

Federal Emergency Management Agency (FEMA), annually notify Repetitive Loss Property owners regarding local flood hazards and proper protection activities, provide technical advice regarding flood protection and flood preparedness, and distribute a revised Repetitive Loss Property Questionnaire to new Repetitive Loss Properties.

Cost: 0.4 FTE

Schedule: On Going

Policy Addressed: 2.d.01, 2.d.02, 2.d.03, 2.d.04, 2.d.05



P-55 Repetitive Loss Properties shall be flagged in the Plan Check and Inspection

System (PCIS) database for review and approval of building permit applications by the Flood Hazard Mitigation Coordinator.

Cost: 0.2 FTE

Schedule: On Going

Policy Addressed: 2.d.03

Responsible Agency: Department of Public Works, Bureau of Engineering; Department of Building and Safety


IMPLEMENTATION PLAN


P-56 Request that FEMA modify the Repetitive Loss Property list based on mitigation projects already implemented by the owner or other responsible party.

Cost: 0.1 FTE

Schedule: On Going

Policy Addressed: 2.d.02, 2.d.03, 2.d.04



P-57 Identify possible sources of funding including Increase Cost of Compliance funds

and mitigation grant funds among others, and provide this information to Repetitive Loss Property owners.

Cost: 0.1 FTE

Schedule: On Going

Policy Addressed: 2.d.05



P-58 Identify and maintain a list of high-risk properties that could be acquired for

conversion into open space.

Cost: TBD


Policy Addressed: 2.a.03, 2.c.02



P-59 Establish standards and/or incentives for the use of structural and non-structural

techniques that mitigate flood-hazards and manage stormwater pollution.

Cost: TBD

Schedule: On Going

Policy Addressed: 3.c.01, 3.c.02



IMPLEMENTATION PLAN


P-60 Plan and design stormwater projects so that water quality is protected without creating a flood risk through the alteration of water flow.

Cost: TBD

Schedule: On Going

Policy Addressed: 3.c.02, 3.d.01, 3.a.04



P-61 Continue to require environmental review in the development process to provide for

the protection of natural resources.

Cost: TBD

Schedule: On Going

Policy Addressed: 3.e.01

Responsible Agency: Department of City Planning


P-62 Continue to implement environmentally sensitive property management at City

owned sites.

Cost: TBD

Schedule: On Going

Policy Addressed: 3.e.02

Responsible Agency: Department of Recreation and Parks; Department of Public Works; Harbor Department; Department of Water and Power; Department of Airports

Financing: Various

P-63 The Floodplain Management Committee will meet at least one time during the year

to develop the Annual FMP Evaluation Report and recommend any updates to the Plan.

Cost: 0.1 FTE

Schedule: On Going


Responsible Agency: FMP Committee; Department of Public Works, Bureau of Engineering


IMPLEMENTATION PLAN


8.2. Recommended Repetitive Loss Property (RLP) Activities

As discussed in Section 6.5, RLPs were specifically researched by Tetra Tech, Inc. Based on best engineering judgement and analysis of available information (results of field investigations, interviews with property owners, and other technical information) Tetra Tech identified the likely cause of the flood problem(s) for each RLP and recommended property protection activities geared for the property owner to reduce or eliminate the flood hazard.

NOTE: The following section consists of recommendations made by Tetra Tech, Inc. Both private party and public agency actions are suggested. Several specific public agency programs that address RLPs (P-54 through 57) have already been included in Section 8.1 above. Another applicable program is P-48, under which the City will develop and distribute flood protection information and materials to property owners and developers in high-risk areas. Other relevant (although not specific to RLPs) activities are P-12, 14, 15, 16, 24, 25, 29, 32, 33, 34, 39, 42, 58, 59, and 61. The City is committed to implementing all of the programs in Section 8.1 in accordance with the schedule listed under each. Any additional recommendations for governmental action made in the following section will be implemented based on funding availability and provided that they are in accordance with the committed programs contained in Section 8.1. For example, under Program P-17, the City has committed to establishing and maintaining a technically based prioritization methodology for use in developing the stormwater capital improvement program. The prioritization system awards additional points to storm drain projects that will eliminate Special Flood Hazard Areas and/or address RLPs. In instances where Tetra Tech recommends a storm drain project, the City will add the proposed project location to the prioritization list and proceed in accordance with Program P-17. Locations where street and/or berm construction projects are suggested will be handled in a similar fashion (ranked and constructed based on funding availability) by the Bureau of Street Services. Under Programs P-27 and 28, the City has committed to developing and maintaining a citywide list of priority maintenance-related flood problem sites and conducting regular (prior to the wet season and after significant storms) inspection and maintenance at such sites. In instances where Tetra Tech recommends increased maintenance, the City will add these locations to the priority list. In those instances where Tetra Tech suggests actions by other governmental agencies, the City will convey the suggestions to and regularly coordinate with such agencies as described under Programs 18 and 19.

IMPLEMENTATION PLAN


Furthermore, Tetra Tech conducted an economic assessment of damages and the cost-effectiveness of potential measures for each RLP. This assessment process closely followed the analysis procedures employed in examining Federal water resources projects by the United States Army Corps of Engineers (USACOE). The underlying purpose of the USACOE analytical procedure is to convert the random nature of flood related damages to an expression of equivalent annual damage for comparison to the amortized cost of mitigation. The fundamental factors behind USACOE’s determinations of structural related damages are (1) depreciated structure replacement value, (2) content-to-structure value relationships, (3) inundation levels, (4) inundation depth-to-damage percentages, and (5) cleanup cost relationship to the amount of inundated surface. The results of the analysis of these factors are ultimately incorporated into the USACOE Hydrologic Engineering Center’s Flood Damage Analysis Package (HEC-FDA), for the determination of equivalent annual damages. This detailed economic analysis is included in the Technical Appendix (RLP-FMP prepared by Tetra Tech Inc.), which, because of confidentiality issues, will only be provided to FEMA and agencies responsible for implementing RLP programs. Tetra Tech’s recommended flood protection activities for RLPs are generally small-scale in nature and are meant to be implemented at the discretion of the property owner. The following is a complete list summarizing all activities originally considered for property owner implementation. Only those activities that were found by Tetra Tech to be economically feasible were recommended.

Property Protection Activities Considered – Property Owner Responsibility

A. Construct or modify retaining walls with proper drainage and trash capacity. B. Construct berms to divert water flows. C. Install debris fences or traps. D. Install yard inlets to drain water flows to the street. E. Construct on-site detention basins. F. Improve headwalls for water conveyance. G. Floodproof retaining walls. H. Floodproof entrances. I. Add sump pump to drainage systems and drain to nearest storm drain. J. Construct terrace drain and plant slope to reduce erosion. K. Plant slopes to reduce erosion and water flows. L. Improve on-site grading and add french-drain. M. Convert flood prone living space and replace with new story. N. Lift entire house including floor slab and build a new foundation to elevate the

house. O. Waterproof lower level. P. Extend the walls of the house upward and raise the lowest floor.

Table 28 through Table 35 list the recommended activities under the four RLP areas - Los Angeles River (Hillside), Los Angeles River (Non-Hillside), Ballona Creek (Hillside) and Ballona Creek (Non-Hillside). Each table lists the primary and alternate recommended flood prevention activity, as identified by Tetra Tech Inc. In some instances, where the

IMPLEMENTATION PLAN


recommended activity involves public agency involvement the recommended activity is shaded in gray. Example design diagrams of the recommended activities are shown in Figure 24 through Figure 26 at the end of this section.

8.2.1. RLP Action Plan for Property Protection – Los Angeles River (Hillside)

As indicated earlier, there are 37 RLPs located in the Los Angeles River (Hillside) area, out of these, 9 RLPs have already addressed their flooding problems and removed the flood risks. Table 28 lists all RLPs in this area (indicating if flood problems still exists) and Tetra Tech’s identified potential solutions to flood risks based on preliminary hydrologic/hydraulic data and basic engineering analysis. Both the primary solution and alternatives were examined for their technical appropriateness, affordability, ability to be implemented, and their regulatory compliance under local, state, and federal regulations. Detailed economical analyses were also conducted and are included in the Technical Appendix (RLP-FMP prepared by Tetra Tech Inc.).

IMPLEMENTATION PLAN


Table 28 RECOMMENDED SOLUTIONS - LOS ANGELES RIVER (HILLSIDE) RLPS

RLP

ID Pro

ble

m

No

Pro

ble

m

Primary Potential Solution Alternate Solution

3 X Raise wall, add V-ditch and trash rack (A) Clean debris, install fence upstream ditch to trap trash

16 X

17 X *Construct berm at high point of driveway, enlarge inlet (B) Improve street drainage or storm drain

18 X Construct berm at high point of driveway (B) Improve street drainage or storm drain

19 X Install inlets in the backyard & drain to the street (D) Improve on-site grading and add french-drain

20 X Construct berm to divert water away from the property (B) Improve street drainage or storm drain

21 X

23 X Raise the retaining wall, increase size of V-ditch (A) Construct terrace drain & plant slope to reduce erosion

24 X *Construct berm in street to keep water in the street Improve street drainage or storm drain


26 X

27 X Add V-ditch, trash rack, drain to the street (A) Construct terrace drain & plant slope to reduce erosion


29 X Construct berm at high point of driveway, drain to street (B) Improve street drainage or storm drain

31 X

32 X Raise wall, enlarge V-ditch and add trash rack (A) Improve street drainage or storm drain

41 X


47 X *Improve headwall at end of channel and add berm (B) Construct terrace drain & plant slope to reduce erosion

50 X Raise wall, enlarge V-ditch and add trash rack (A) Construct terrace drain & plant slope to reduce erosion

51 X Raise wall, enlarge V-ditch and add trash rack (A) Construct terrace drain & plant slope to reduce erosion

55 X Construct berm at edge of shoulder to keep water in the street (B)

Improve street drainage or storm drain

57 X Install inlets in the yard & drain to the street (D) Improve on-site grading and add french-drain

60 X

65 X Raise wall, enlarge V-ditch and add trash rack (A) Const. terrace drain and plant slope to reduce erosion

66 X

67 X Floodproof wall in the backyard (G) Construct terrace drain & plant slope to reduce erosion


84 X Install the inlets in the backyard & drain to the street (D) Improve on-site grading and add french-drain


99 X Install inlets in the yard & drain to the street (D) Improve on-site grading and add french-drain

104 X Install inlets/french drain in the yard & drain to the street (D) Add sump pump, drain to nearest storm drain

106 X

107 X



115 X Construct. berm at front of door, enlarge inlets in driveway (B)

Improve on-site grading and add french-drain

*Solutions will be implemented based on funding availability and in accordance with the citywide (or where applicable, countywide) prioritization system.

IMPLEMENTATION PLAN


Table 29 SUMMARY – LOS ANGELES RIVER (HILLSIDE) RLPS

Property Protection Activities

Recommended Solution RLPs

A. Construct or modify retaining walls with proper drainage and trash capacity

3, 23, 27, 32, 50, 51, 65, and 83

B. Construct berms to divert water flows 18, 20, 29, 45, 55,

and 115

D. Install yard inlets to drain water flows to the street

19, 25, 28, 57, 84, 94, 99, 104, 110,

and 111

G. Floodproof retaining walls 67

B. & Public Agency Involvement

Construct berms to divert water flows and improve storm drains

17 and 47

Public Agency Involvement

Construct berms to divert water flows and improve street drainage capacity

24

Tetra Tech suggests that for two RLPs (Nos. 17 and 47), governmental action is recommended in addition to private party actions to fully mitigate flood hazards. For one RLP (No. 24) governmental action is the sole recommendation to mitigating the flood risks.

8.2.2. RLP Action Plan for Property Protection – Los Angeles River (Non-Hillside)

As indicated earlier, there are 16 RLPs located in the Los Angeles River (Non-Hillside) area, out of these, 5 RLPs have already addressed their flooding problems and removed the flood risks. Table 15 lists all RLPs in this area (indicating if flood problems still exists) and Tetra Tech’s identified potential solutions to flood risks based on preliminary hydrologic/hydraulic data and basic engineering analysis. Both the primary solution and alternatives were examined for their technical appropriateness, affordability, ability to be implemented, and their regulatory compliance under local, state, and federal regulations. Detailed economical analyses were also conducted and are included in the Technical Appendix (RLP-FMP prepared by Tetra Tech Inc.).

IMPLEMENTATION PLAN


Table 30 RECOMMENDED SOLUTIONS - LOS ANGELES RIVER (NON-HILLSIDE) RLPS

RLP

ID P

rob

lem

No

Pro

ble

m


22 X

30 X

33 X *Lower storm drain inlet & backflow valve at outlet storm drain

Improve Lockheed Channel

34 X *Enlarge inlet with trash rack, add berm at driveway (B) Improve street drainage or storm drain

54 X *Lower storm drain inlet & backflow valve at outlet storm drain

Improve Lockheed Channel

56 X

61 X *Keep catch basins and pipe free of debris Add trash rack at catch basin

77 X *Enlarge inlet with trash rack Improve street drainage or storm drain

88 X

90 X

100A X Construct berm at high point of driveway (B) Improve street drainage or storm drain

100B X Construct berm at high point of driveway (B) Improve street drainage or storm drain

100C X Construct berm at high point of driveway (B) Improve street drainage or storm drain

100D X Construct berm at high point of driveway (B) Improve street drainage or storm drain

108 X Construct berm at front of door (B) Add sump pump, drain to nearest storm drain



Table 31 SUMMARY – LOS ANGELES RIVER (NON-HILLSIDE) RLPS



B. Construct berms to divert water flows 34, 100A, 100B,

100C, 100D, 108, and 109

B. & Public Agency Involvement

Construct berms to divert water flows and improve storm drains

34

Public Agency Involvement Improve storm drains and inlet structures 33, 54, 61, and 77

Tetra Tech suggests that for one RLP (No. 34), governmental action is recommended in addition to private party actions to fully mitigate flood hazards. For four RLPs (Nos. 33, 54, 61, and 77) governmental action is the sole recommendation to mitigating the flood risks.

8.2.3. RLP Action Plan for Property Protection – Ballona Creek (Hillside)

As indicated earlier, there are 51 RLPs located in the Ballona Creek (Hillside) area, out of these, 21 RLPs have already addressed their flooding problems and removed the flood risks. Table 32 lists all RLPs in this area (indicating if flood problems still exists) and Tetra Tech’s identified potential solutions to flood risks based on preliminary hydrologic/hydraulic data and basic engineering analysis. Both the primary solution and alternatives were examined for their technical appropriateness, affordability, ability to be implemented, and their regulatory compliance under local, state, and federal regulations. Detailed economical analyses were also conducted and are included in the Technical Appendix (RLP-FMP prepared by Tetra Tech Inc.)

IMPLEMENTATION PLAN


Table 32 RECOMMENDED SOLUTIONS - BALLONA CREEK (HILLSIDE) RLPS

RLP

ID

Pro

ble

m

No

Pro

ble

m


2 X

4 X Install inlets in the yard & drain to the street (D) Add sump pump, drain to nearest storm drain

5 X Raise wall, add V-ditch and trash rack (A) Construct terrace drain & plant slope to reduce erosion



9 X Floodproof wall, add drainage system (G,D) Add sump pump, drain to nearest storm drain


12 X

13 X

14 X

15 X

35 X

36 X

37 X


39 X


42 X Construct berm to keep water in the street (B)

43 X Raise wall, add V-ditch & trash rack, drain to street (A)

Construct terrace drain & plant slope to reduce erosion

46 X Install inlets in backyard & drain to the street (D) Add sump pump, drain to nearest storm drain




58 X


62 X *Construct debris rack at inlet to reduce clogging Improve street drainage or storm drain

63 X


70 X Extend the V-ditch to the street (A) Add sump pump, drain to nearest storm drain


72 X Backfill retaining wall and add V-ditch (A) Construct terrace drain & plant slope to reduce erosion

73 X

74 X *Increase storm drain capacity Improve street drainage or storm drain

75 X







86 X

87 X



101 X


105 X

113 X *Improve storm drain capacity Improve street drainage or storm drain

114 X

116 X Construct berm , enlarge inlets in driveway (B) Add sump pump, drain to nearest storm drain

117 X


IMPLEMENTATION PLAN


Table 33 SUMMARY - BALLONA CREEK (HILLSIDE) RLPS



A. Construct or modify retaining walls with proper drainage and trash capacity

5, 7, 8, 38, 43, 52, 53, 68, 70, 72, 76, 79, 80, 81, 85, 93,

and 103

B. Construct berms to divert water flows 9, 11, 42, and 116


4, 9, 40, 46, 48, 59, 71, 82, and 98

G. Floodproof retaining walls 9


Improve storm drains and inlet structures 62, 74, and 113

Tetra Tech suggests that for three RLPs (Nos. 62, 74, and 113), governmental action is the sole recommendation to mitigating the flood risks.

8.2.4. RLP Action Plan for Property Protection – Ballona Creek (Non-Hillside)

As indicated earlier, there are 16 RLPs located in the Ballona Creek (Non-Hillside) area, out of these, 9 RLPs have already addressed their flooding problems and removed the flood risks. Table 19 lists all RLPs in this area (indicating if flood problems still exists) and Tetra Tech’s identified potential solutions to flood risks based on preliminary hydrologic/hydraulic data and basic engineering analysis. Both the primary solution and alternatives were examined for their technical appropriateness, affordability, ability to be implemented, and their regulatory compliance under local, state, and federal regulations. Detailed economical analyses were also conducted and are included in the Technical Appendix (RLP-FMP prepared by Tetra Tech Inc.) Table 34 RECOMMENDED SOLUTIONS - BALLONA CREEK BASIN (NON-HILLSIDE) RLPS

RLP

ID

Pro

ble

m

No

Pro

ble

m


1 X Construct berm at high point of driveway, enlarge inlet (B,D) Improve street drainage or storm drain

6 X

10 X Floodproof entrances, add drainage system/pump (D) Add sump pump, drain to nearest storm drain

44 X *Improve storm drain capacity Improve street drainage or storm drain

49 X *Construct berm at high point of driveway, enlarge inlet (B) Improve street drainage or storm drain

64 X

69 X *Improve channel capacity

78 X

89 X

91 X

92 X *Improve street drainage capacity Improve street drainage or storm drain

95 X

96 X *Enlarge catch basin to reduce clogging Improve street drainage or storm drain

97 X

102 X

112 X *Improve street drainage capacity Improve street drainage or storm drain


IMPLEMENTATION PLAN


Table 35 SUMMARY - BALLONA CREEK (NON-HILLSIDE) RLPS



B. Construct berms to divert water flows 1 and 49


1 and 10

B & Public Agency Involvement

Construct berm and improve storm drains and inlet structures

49


Improve storm drains and inlet structures 44 and 96


Improve channel capacity 69


Improve street drainage capacity 92 and 112

Tetra Tech suggests that for one RLP (No. 49), governmental action is recommended in addition to private party actions to fully mitigate flood hazards. For five RLPs (Nos. 44, 69, 92, 96, and 112) governmental action is the sole recommendation to mitigating the flood risks.

IMPLEMENTATION PLAN


Figure 24 RETAINING WALL AND DRAINAGE LAYOUT

IMPLEMENTATION PLAN


Figure 25 BERM AND SUMP LAYOUT

IMPLEMENTATION PLAN


Figure 26 INLET/FRENCH DRAIN AND DRAINAGE LAYOUT

ADOPTION, REPORTING, EVALUATING, AND REVISING


9. ADOPTION, REPORTING, EVALUATING, AND REVISING

9.1. Plan Adoption Process

The FMP adoption process consisted of several steps. The first step after completion of the FMP by the Committee was to provide the FMP, in final draft form, to the public and interested agencies for review and comment. Following public review from July 16, 2001 to August 15, 2001, the FMP was revised accordingly by staff and was submitted to the Board of Public Works for review and approval. The Board of Public Works approved and forwarded the FMP to the Mayor and City Council on October 3, 2001. During a joint meeting of the Public Works and Environmental Quality & Waste Management Council Committees session on November 5, 2001 at which several FMP Committee members and supporters were in attendance, the FMP was approved. The City Council adopted the FMP during its November 9th session. Subsequently, the Mayor approved the FMP on November 13, 2001.

9.2. Reporting Process

The Department of Public Works, Bureau of Engineering, will maintain the FMP. The Bureau of Engineering, and more specifically the City’s Flood Hazard Mitigation Coordinator (through the NFIP-CRS Coordinator), will coordinate with other City departments as needed regarding the implementation of programs. The Flood Hazard Mitigation Coordinator will prepare the Annual FMP Evaluation Report, which will include an overview of the FMP and the progress made over the preceding 12 months. To facilitate preparation of the Annual FMP Evaluation Report, the Flood Hazard Mitigation Coordinator will obtain quarterly reports from the various City departments regarding the progress made on the implementation and the status of the programs under their jurisdiction (see Chapter 8, Program P-40).

9.3. Evaluation Process and Revision Process

Any necessary revisions to the FMP will be included in the Annual FMP Evaluation Report. The FMP Committee will review the Annual FMP Evaluation Report before its submittal to the Board of Public Works, the City Council, FEMA and its release to the general public.

TECHNICAL APPENDIX

City of Los Angeles Floodplain Management Plan – November 2001 TA-I

ACRONYMS AND GLOSSARY

ACRONYMS ASFPM – Association of State Floodplain Managers BMP – Best Management Practice CA OES – California Office of Emergency Services CFM – Certified Floodplain Manager CMP – Corrugated Metal Pipe CRS – Community Rating System DONE – Department of Neighborhood Empowerment DWP – Department of Water and Power FEMA – Federal Emergency Management Agency FIA – Federal Insurance Administration FIRM – Flood Insurance Rate Map FIS – Flood Insurance Study FMP – Floodplain Management Plan GIS – Geographic Information System LACDA – Los Angeles County Drainage Area LACDPW – Los Angeles County Department of Public Works NFIP – National Flood Insurance Program NOAA – National Oceanographic and Atmospheric Administration RLP – Repetitive Loss Properties SFHA – Special Flood Hazard Area


City of Los Angeles Floodplain Management Plan – November 2001 II

GLOSSARY Acre-Feet—A measurement of water volume. One acre-foot equals 325,851 gallons. Act—The National Flood Insurance Act of 1968 and Flood Disaster Protection Act of 1973, both as amended. Alluvial Fan—A sedimentary deposit located at a topographic break such as the base of a mountain front, escarpment, or valley side, that is composed of streamflow and/or debris flow sediments and which has the shape of a fan, either fully or partially extended. Annual FMP Evaluation Report—A report prepared by the City Engineer and based on information compiled from other agencies responsible for implementing programs identified in Chapter 8 of the FMP. This report will identify the progress toward the objectives and identify needed changes to the FMP. This report will be submitted to FEMA during the City’s Annual CRS credit recertification. Association of State Floodplain Managers (ASFPM)—The ASFPM is a national organization of professionals (in both the public and private sector) involved in floodplain management, flood hazard mitigation, the National Flood Insurance Program, and flood preparedness, warning and recovery. Association of State Floodplain Managers (ASFPM) Certified Floodplain Manager Program—A national program for professional certification of floodplain managers established by the ASFPM. The primary goal of this program is to help reduce the nation’s flood losses and protect and enhance the natural resources and functions of its floodplains by improving the knowledge and abilities of floodplain managers in the United States. Base Flood (100-year flood)—The flood having a 1 percent chance of being equaled or exceeded in any given year. Catch Basin—An opening in the street adjacent to the curb that allows water from the street to flow into an underground drainage pipe. Certified Floodplain Manager (CFM)—This certification is granted by the ASFPM directly to individuals who demonstrate knowledge of the basic national standards and programs of floodplain management, but who reside or work in states where ASFPM-accredited certification is not available. Community Rating System (CRS)—A program developed by Federal Insurance Administration (FIA) to provide incentives for those communities in the Regular Program that have gone beyond the minimum floodplain management requirements to develop extra measures to provide protection from flooding.


City of Los Angeles Floodplain Management Plan – November 2001 III

Critical Facility—Facilities housing or serving many people, which are necessary in the event of an earthquake or flood, such as hospitals, fire, police, and emergency service facilities, utility "lifeline" facilities, such as water, electricity, and gas supply, sewage disposal, and communications and transportation facilities. In addition, critical facilities include manufacturing facilities that store water reactive materials. Dam and Reservoir Emergency Notification List—A list maintained and updated by the City of Los Angeles, Department of Water and Power that contains agency contact names and numbers to be used in the case of an emergency involving dams or reservoirs. Erosion—The process by which soil and rock are detached and moved by running water, wind, ice, and/or gravity. Federal Emergency Management Agency (FEMA)—The federal agency under which the National Flood Insurance Program (NFIP) is administered. Federal Insurance Administration (FIA)—The federal entity within FEMA that directly administers the National Flood Insurance Program (NFIP). FEMA Designated Flood Zones—Darkly shaded area(s) on a Flood Hazard Boundary Map (FHBM) or a Flood Insurance Rate Map (FIRM) that identifies an area that has a 1 percent chance of being flooded in any given year (100-year floodplain). Over a 30-year period, the life of most mortgages, there is at least a 26 percent chance that this area will be flooded. The FIRM identifies these shaded areas as FIRM Zones A, AO, AH, A1-A30, AE, A99, AR, AR/A, AR/AE, AR/A1-A30, AR/AH, AR/AO, V, V1-V30, and VE. Flood—A general and temporary condition of partial or complete inundation of normally dry land areas from such events as the following: overflow of inland or tidal waters; the unusual and rapid accumulation or runoff of surface waters from any source; mudslides (i.e., mudflows) which are proximately caused by flood (see below for definition); or the collapse or subsidence of land along a body of water as a result of erosion or undermining caused by waves or currents of water exceeding the cyclical levels. Flood Area—Areas not identified in FIRM where based on review of existing data, flooding of any source has caused repeated losses to one or more structure(s)/property(ies). Flood Control Channel—An open conduit usually trapezoidal or rectangular in shape used to move extremely large amounts of water through a drainage area.


City of Los Angeles Floodplain Management Plan – November 2001 IV

Flood Hazard Mitigation Coordinator—The City Engineer is designated by Ordinance No. 172,081 as the Flood Hazard Mitigation Coordinator. The Flood Hazard Mitigation Coordinator is responsible for coordinating the implementation of Ordinance No. 172,081 among the Planning, Building and Safety, and Public Works Departments and the submission of all reports required by Federal regulations. Flood Insurance Rate Map (FIRM)—Official map of a community on which the Administrator has delineated both the special hazard areas and the risk premium zones applicable to the community. Floodplain—The relatively level land area on either side of the banks of a stream regularly subject to flooding. That part of the flood plain subject to a one- percent chance of flooding in any given year is designated as an "area of special flood hazard" by the Federal Insurance Administration.

Floodplain Fringe—All land between the floodway and the upper elevation of the 100-year flood. Floodplain Management—The operation of an overall program of corrective and preventive measures for reducing flood damage, including but not limited to, emergency preparedness plans, flood control works, and floodplain management regulations. Floodproofing—Any combination of structural and nonstructural additions, changes, or adjustments to structures, which reduce or eliminate risk of flood damage to real estate or improved real property, water and sanitation facilities, or structures with their contents. Floodway—The channel of a river or other watercourse and the adjacent land areas that must be reserved in order to discharge the "base flood" without cumulatively increasing the water surface elevation more than one foot. No development is allowed in floodways. Grade Elevation—The average or highest natural (pre-construction) ground level that is immediately adjacent to the walls of the building. Hillside(s)—For purposes of the FMP, land that has a slope equal to or greater than six percent. Map Revision—A change in the Flood Hazard Boundary Map (FHBM) or Flood Insurance Rate Map (FIRM) for a community that reflects revised zone, base flood, or other information.


City of Los Angeles Floodplain Management Plan – November 2001 V

Mudflow (Mudslide)—A river of liquid and flowing mud on the surface of normally dry land areas, as when earth is carried by a current of water and deposited along the path of the current. A mudflow down a hillside is usually the result of a dual condition of loss of brush cover and the subsequent accumulation of water on or under the ground, preceded by a period of unusually heavy or sustained rain. Natural Grade—The grade unaffected by construction techniques such as fill, landscaping, or berming. NFIP-CRS Coordinator—City Engineer’s designee for the implementation of the Specific Plan and the adopted Citywide FMP. Non-Hillside(s)—All land with slope of less than six percent. Nuisance Flooding—Flooding that affects people in some way but does not cause damage to property. Ponding Hazard—A flood hazard that occurs in flat areas when there are depressions in the ground that collect "ponds" of water. The ponding hazard is represented by the zone designation AH on the FIRM. Regulated Floodway—The regulated floodway is shown on the FIRM and consists of the river/stream channel plus that portion of the overbanks that must be kept free from encroachment in order to discharge the 100-year event without increasing flood levels. The City is responsible for prohibiting encroachments, including fill, new construction, and substantial improvements, within the regulated floodway unless it has been demonstrated through hydrologic and hydraulic analyses that the proposed encroachment will not increase flood levels. In shallow flooding areas that are outside of the regulated floodway (termed the "floodway fringe"), development is allowed, provided that it causes no more than a 1-foot increase in the 100-year flood water-surface elevation. Repeated Loss—Indicates multiple incidents of flood damages (refers to properties not included in the City’s Repetitive Loss Property list). Repetitive Loss Properties—Those properties suffering two or more losses within a 10-year period (since 1978) that exceed $1000 each. FEMA has identified a total of 117 Repetitive Loss Properties with the City. Repetitive Loss Plan—A mandatory activity for the City to participate in the CRS was to develop this RLP Plan. Originally prepared and adopted by the City on September 2, 1994, it will now be superceded by the Citywide FMP when adopted by City Council. The RLP Plan identifies reasonable and cost effective mitigation measures to be implemented by the City to help reduce damages to RLPs.


City of Los Angeles Floodplain Management Plan – November 2001 VI

Runoff—That portion of rain (or snow) that does not percolate into the ground and is discharged into streams instead. Sheet Flow Hazard—A type of flood hazard with flooding depths of 1 to 3 feet that occurs in areas of sloping land. The sheet flow hazard is represented by the zone designation AO on the FIRM. Significant (Substantial) Improvement (FEMA definition)—Any reconstruction, rehabilitation, addition, or other improvement of a building, the cost of which equals or exceeds 50 percent of the market value of the building before the "start of construction" of the improvement. Substantial improvement includes buildings that have incurred "substantial damage," regardless of the actual repair work performed. The term does not, however, include either any project for improvement of a building to correct existing state or local code violations or any alteration to a "historic building," provided that the alteration will not preclude the building's continued designation as a "historic building." Special Flood Hazard Area (SFHA)—See definition for FEMA designated flood zones. Specific Plan for the Management of Flood Hazards—The City of Los Angeles Ordinance No. 172,081 which provides regulations for properties in the FEMA designated flood zones. Stormwater System—A system composed of pipes, catch basins, gutters, channels, and pump stations designed to transport stormwater to a larger body of water e.g., lake, bay, ocean. Velocity—The rate of water flow measured in feet per second. Watercourse (Waterway)—Natural or once natural flowing (perennially or intermittently) water (mapped and unmapped) including rivers, streams, and creeks. Includes natural waterways that have been channelized, but does not include manmade channels, ditches, and underground drainage and sewage systems. Watershed—The total area above a given point on a watercourse that contributes water to its flow; the entire region drained by a waterway or watercourse that drains into a lake, or reservoir. Wetlands—Transitional areas between terrestrial and aquatic systems where the water table is usually at or near the surface, or the land is covered by shallow water. Under a "unified" methodology now used by all federal agencies, wetlands are defined as "those areas meeting certain criteria for hydrology, vegetation, and soils.

Documents

1. INTRODUCTION TO THE PLAN 1 2. FMP … FMP.pdfCity of Los Angeles Floodplain Management Plan – November 2001 11. INTRODUCTION TO THE PLAN 1.1. Purpose The Floodplain Management