Geotechnical, Geologic, and Seismic Impacts Technical Report

April 2013

Prepared by

Geotechnical, Geologic and Seismic Impacts Technical Report April 2013

Prepared by: The San Diego Association of Governments (SANDAG)

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Geotechnical, Geologic and Seismic Impacts Technical Report Table of Contents

Table of Contents

1.0 INTRODUCTION ...... 1-1 1.1 Purpose of the Report ...... 1-1 1.1.1 Organization ...... 1-1 1.1.2 Impact Evaluation ...... 1-2 1.2 Description of the Mid-Coast Corridor ...... 1-3 1.3 Alternatives under Consideration ...... 1-5 1.3.1 No-Build Alternative ...... 1-5 1.3.2 Build Alternative ...... 1-13 2.0 REGULATORY CONTEXT ...... 2-1 2.1 Federal ...... 2-1 2.1.1 National Environmental Policy Act ...... 2-1 2.1.2 Federal Water Pollution Control Act ...... 2-2 2.1.3 National Engineering Handbook ...... 2-2 2.1.4 American Railway Engineering and Maintenance-of-Way Association Manual for Railway Engineering ...... 2-2 2.2 State ...... 2-2 2.2.1 California Environmental Quality Act ...... 2-2 2.2.2 California Government Code ...... 2-3 2.2.3 Alquist-Priolo Earthquake Fault Zoning Act ...... 2-4 2.2.4 Seismic Hazard Mapping Act ...... 2-4 2.2.5 California Building Code ...... 2-4 2.2.6 California Department of Transportation ...... 2-4 2.3 Local ...... 2-5 2.3.1 City of San Diego Building and Fire Codes ...... 2-5 2.3.2 City of San Diego Municipal Code ...... 2-5 2.3.3 City of San Diego Public Facilities, Services and Safety Element (Hazard Reduction) ...... 2-5 2.3.4 City of San Diego Seismic Safety Element (Geologic and Seismic Hazards) ...... 2-6 3.0 METHODOLOGY ...... 3-1 3.1 Study Area ...... 3-1 3.2 Data Sources ...... 3-1 3.2.1 Aerial Photography Analysis ...... 3-1 3.2.2 Literature Review ...... 3-2 3.2.3 Consultant Reports and Geotechnical Borings ...... 3-2 3.2.4 Topographic Analysis ...... 3-2 3.2.5 Field Reconnaissance ...... 3-3 3.2.6 Fault Rupture Analysis...... 3-3 3.3 Impacts Assessment ...... 3-4 3.4 Impact Determination ...... 3-5 3.4.1 NEPA Guidance...... 3-5 3.4.2 CEQA Guidance ...... 3-5 4.0 EXISTING CONDITIONS ...... 4-1 4.1 Geology and Soils ...... 4-1

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4.1.1 Regional Geology ...... 4-1 4.1.2 Mid-Coast Corridor Geology ...... 4-3 4.1.3 Corridor Soils ...... 4-9 4.1.4 Ground Water ...... 4-10 4.2 Geologic and Seismic Hazards ...... 4-15 4.2.1 Regional Faulting ...... 4-16 4.2.2 Seismicity...... 4-22 4.2.3 Local Faulting and Surface Fault Rupture Hazard ...... 4-25 4.2.4 Strong Ground Shaking ...... 4-46 4.2.5 Liquefaction and Seismic Settlement ...... 4-47 4.2.6 Lateral Spread ...... 4-48 4.2.7 Tsunami and Seiche ...... 4-48 4.2.8 Landslides, Mudslides, and Slope Stability ...... 4-49 4.2.9 Compressible Soils ...... 4-53 4.2.10 Subsidence ...... 4-53 4.2.11 Corrosive Soils...... 4-53 4.2.12 Expansive Soils ...... 4-53 4.2.13 Erosion Potential...... 4-54 5.0 ENVIRONMENTAL IMPACTS ...... 5-1 5.1 Direct and Indirect Impacts ...... 5-1 5.1.1 No-Build Alternative ...... 5-1 5.1.2 Build Alternative ...... 5-1 5.2 Cumulative Impacts ...... 5-6 5.3 Construction Impacts ...... 5-7 6.0 MITIGATION ...... 6-1 7.0 CALIFORNIA ENVIRONMENTAL QUALITY ACT DETERMINATION ...... 7-1 7.1 Significance Criteria and Significance Criteria Application ...... 7-1 7.2 Significance after Mitigation ...... 7-4 7.3 Cumulative Impacts ...... 7-4 8.0 REFERENCES ...... 8-1 9.0 LIMITATIONS AND PREPARER SIGNATURES ...... 9-1

List of Appendices

APPENDIX A FAULT INTERPRETATION FROM AERIAL PHOTOGRAPHY ...... A-1

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List of Figures

Figure 1-1. Mid-Coast Corridor ...... 1-4 Figure 1-2. No-Build Alternative Transportation Improvements ...... 1-7 Figure 1-3. No-Build Alternative Major Bus Routes ...... 1-9 Figure 1-4. No-Build Alternative Bus Route 150 ...... 1-11 Figure 1-5. No-Build Alternative Trolley Operating Plan in 2030 ...... 1-12 Figure 1-6. Mid-Coast Corridor Transit Project ...... 1-14 Figure 1-7. Conceptual Plan and Profile of Mid-Coast Corridor Transit Project ...... 1-17 Figure 1-8. Genesee Avenue Design Concepts ...... 1-22 Figure 1-9. Visual Simulation of Genesee Avenue with Center Columns ...... 1-23 Figure 1-10. Visual Simulation of Genesee Avenue with Straddle Bents ...... 1-23 Figure 1-11. Site Concept for Tecolote Road Station ...... 1-25 Figure 1-12. Site Concept for Clairemont Drive Station ...... 1-26 Figure 1-13. Site Concept for Balboa Avenue Station ...... 1-27 Figure 1-14. Site Concept for Nobel Drive Station ...... 1-28 Figure 1-15. Site Concept for Optional VA Medical Center Station ...... 1-29 Figure 1-16. Site Concepts for UCSD West Station (Build Alternative and VA Medical Center Station Option) ...... 1-30 Figure 1-17. Site Concept for UCSD East Station ...... 1-31 Figure 1-18. Site Concepts for Executive Drive Station, with and without Genesee Avenue Design Option ...... 1-32 Figure 1-19. Site Concepts for UTC Transit Center, with and without Genesee Avenue Design Option ...... 1-34 Figure 1-20. Existing Traction Power Substation at Mission Valley Center Station ...... 1-35 Figure 1-21. Traction Power Substation Layout...... 1-35 Figure 1-22. Mid-Coast Corridor Transit Project Opening Year Trolley Operating Plan ...... 1-39 Figure 1-23. Mid-Coast Corridor Transit Project 2030 Trolley Operating Plan ...... 1-40 Figure 4-1. Geomorphic Subzones of San Diego County ...... 4-2 Figure 4-2. Regional Geologic Map ...... 4-5 Figure 4-3. Soils in Study Area ...... 4-11 Figure 4-4. Geologic Hazards in Study Area ...... 4-17 Figure 4-5. Tectonic Plates and Faults in Southern California ...... 4-21 Figure 4-6. Regional Faults and Seismicity within 60 Miles of Project ...... 4-23 Figure 4-7. Rose Canyon Fault Zone ...... 4-26 Figure 4-8. Study Area Fault Map ...... 4-29 Figure 4-9. Detail Fault Map (South of Old Town Transit Center) ...... 4-33 Figure 4-10. Detail Fault Map (Approximate Stations 185–295) ...... 4-35 Figure 4-11. Detail Fault Map (Approximate Stations 260–418) ...... 4-37 Figure 4-12. Detail Fault Map (Approximate Stations 370–535) ...... 4-39

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Figure 4-13. Detail Fault Map (Approximate Stations 532–773) ...... 4-41 Figure 4-14. Maximum Tsunami Inundation (La Jolla and Del Mar Quadrangles) ...... 4-50

List of Tables

Table 1-1. No-Build Alternative Bus Operating Plan in 2030 ...... 1-8 Table 1-2. No-Build Alternative Trolley Operating Plan ...... 1-13 Table 1-3. Traction Power Substations Locations ...... 1-36 Table 1-4. Trolley Operating Plans ...... 1-38 Table 1-5. Build Alternative Bus Routes Serving Trolley Stations ...... 1-42 Table 3-1. Aerial Photographic Plates, Western San Diego County, 1928 ...... 3-2 Table 3-2. Aerial Photographic Plates, 1953 ...... 3-2 Table 4-1. NRCS Soil Map Units ...... 4-10 Table 4-2. Summary of Faults within 60 Miles of Project ...... 4-22 Table 4-3. Faulting Hazards ...... 4-43

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Abbreviations and Glossary

The following acronyms, initialisms, and short forms are used in this report.

2030 RTP 2030 San Diego Regional Transportation Plan: Pathways for the Future 2050 RTP 2050 Regional Transportation Plan: Our Region, Our Future AASHTO American Association of State Highway and Transportation Officials Active fault A fault which has had surface displacement within Holocene time, about the last 11,000 years. (Special Paper 42, California Geological Survey, 2007). Also referred to as a “Holocene fault.” ADA Americans with Disabilities Act Alluvium A general term for clay, silt, sand, gravel or similar unconsolidated detrital material (sediment), deposited during comparatively recent geologic time by stream or other body of running water. A-PA Alquist-Priolo Earthquake Fault Zoning Act AREMA American Railway Engineering and Maintenance-of-Way Association AtE2 Altamont clay, 15 to 30 percent slopes AtF Altamont clay, 30 to 50 percent slopes bgs below ground surface BP before present BRT bus rapid transit C&S communications and signaling Cal EMA California Emergency Management Agency Caltrans California Department of Transportation CBC California Building Code CCR California Code or Regulations CDMG California Division of Mines and Geology CEQA California Environmental Quality Act CfB Chesterton fine sandy loam, 2 to 5 percent slopes CfC Chesterton fine sandy loam, 5 to 9 percent slopes CFR Code of Federal Regulations CGC California Government Code CgC Chesterton-Urban land complex, 2 to 9 percent slopes CGP Construction General Permit CGS California Geological Survey

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Cretaceous Geologic period ranging between 56 and 146 million years before present CsB Corralitos loamy sand, 0 to 5 percent slopes CWA Clean Water Act DARs direct-access ramps EFZ Earthquake Fault Zone En echelon Geologic features that are aligned in an overlapping arrangement Eocene Geologic epoch ranging in age between 3.9 to 55.8 million years before present EPA U.S. Environmental Protection Agency FTA Federal Transit Administration GaF Gaviota fine sandy loam, 30 to 50 percent slopes GIS geographic information system Holocene Current geologic epoch between the present to approximately 11,000 years ago HOV high-occupancy vehicle HrE2 Huerhuero loam, 15 to 20 percent slopes HuC Huerhuero-Urban land complex, 2 to 9 percent slopes HuE Huerhuero-Urban land complex, 9 to 30 percent slopes I- Interstate IBC International Building Code Inactive fault A fault which has ceased activity at sometime prior to the beginning of the Quaternary period. Also referred to as a “pre-Quaternary fault.” Jurassic Geologic period ranging in age between 146 and 202 million years before present Lineament An extensive linear surface feature; can be differentiated by tonal contrasts, sharp changes in vegetation type or density, or slight topographic variations. Liquefaction In cohesion less soil, the transformation from a solid to a liquid state as a result of increased pore pressure and reduced effective stress, most often brought on by shaking from a seismic event. LOSSAN Los Angeles—San Diego—San Luis Obispo Rail Corridor Agency LRFD Load and Resistance Factor Design LRT light rail transit LRV light rail vehicles m meters Md made land

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Mesozoic Geologic era encompassing the Cretaceous, Jurassic, and Triassic periods Miocene Geologic Epoch prior to Pleistocene between 5.3 and 23 million years before present mm/yr millimeters per year MSL mean sea level MTD Memo to Designers MTDB Metropolitan Transit Development Board MTS Metropolitan Transit System NCSS National Cooperative Soil Survey NCTD North County Transit District NEPA National Environmental Policy Act NPDES National Pollutant Discharge Elimination System NRCS Natural Resources Conservation Service OCS overhead catenary system OTTC Old Town Transit Center PE Preliminary Engineering Pleistocene Geologic epoch prior to Holocene between 11,000 years to 2.6 million years before present Pliocene Geologic epoch prior to Pleistocene ranging in age from 2.6 to 5.3 million years before present Potentially active A fault which has undergone surface displacement sometime during fault Pleistocene time, approximately 2.6 million years to 11,000 years before present; but not within Holocene time, the last 11,000 years. Also referred to as a “pre-Holocene fault.” PRC Public Resources Code PSHA Probabilistic Seismic Hazard Analysis Quaternary Geologic period encompassing the Holocene and Pleistocene epochs RCFZ Rose Canyon Fault Zone RTP Regional Transportation Plan SAFS San Andreas Fault System SANDAG San Diego Association of Governments SbC Salinas clay loam, 2 to 9 percent slopes SCB Southern California Batholith SDC Caltrans Seismic Design Criteria

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Seiche A surface water wave oscillation in an enclosed basin such as a lake or bay, usually caused by an earthquake. SEIS/SEIR Supplemental Environmental Impact Statement and Subsequent Environmental Impact Report SR State Route Strike-slip fault A fault on which the movement is parallel to the strike (horizontal alignment) of the fault SWRCB State Water Resources Control Board TeF terrace escarpment TPSS traction power substation Triassic Geologic period ranging in age between 202 and 251 million years before present UCSD University of California, San Diego Ur urban land USC United States Code USCGS U.S. Coast and Geodetic Survey USDA U.S. Department of Agriculture USGS U.S. Geological Survey USN U.S. Navy UTC University Towne Centre VA Veterans Administration

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1.0 INTRODUCTION

The Federal Transit Administration (FTA) and the San Diego Association of Governments (SANDAG) have prepared a Supplemental Environmental Impact Statement and Subsequent Environmental Impact Report (SEIS/SEIR) for the Mid-Coast Corridor Transit Project in San Diego, California. The SEIS/SEIR supplements the following environmental documents: the Mid-Coast Corridor Alternatives Analysis/Draft Environmental Impact Statement/Draft Environmental Impact Report (Metropolitan Transit Development Board [MTDB], 1995a); the Final Environmental Impact Report for the Mid-Coast Corridor (MTDB, 1995b); and the Mid-Coast Corridor Project Balboa Extension and Nobel Drive Coaster Station Final Environmental Impact Statement (MTDB, 2001). The FTA is serving as lead agency for the SEIS in accordance with the National Environmental Policy Act (NEPA) of 1969, and SANDAG is serving as lead agency for the SEIR in accordance with the California Environmental Quality Act (CEQA) of 1970.

The Draft SEIS/SEIR includes an analysis of the affected environment and potential impacts on the social, economic, cultural, and natural environment that would result from constructing and operating the alternatives under consideration within the Mid-Coast Corridor. The alternatives being considered and analyzed for potential impacts include a No-Build Alternative and a Build Alternative.

The Build Alternative is the Mid-Coast Corridor Transit Project, or project, as it is planned to operate in 2030. The project consists of extending the existing San Diego Trolley (Trolley) Blue Line from the Santa Fe Depot north to the Old Town Transit Center (OTTC), via the existing Trolley tracks, and then north along new tracks to the University Towne Centre (UTC) Transit Center in University City, with eight new stations at Tecolote Road, Clairemont Drive, Balboa Avenue, Nobel Drive, University of California, San Diego (UCSD) West Campus, UCSD East Campus, Executive Drive, and the UTC Transit Center.

The Build Alternative includes two options for consideration. One option provides an additional station at the Veterans Administration (VA) Medical Center and the other is a design option for the aerial alignment along Genesee Avenue in University City. 1.1 Purpose of the Report This technical report describes the affected environment and evaluates the potential impacts of the Build and No-Build Alternatives. It also describes the regulatory framework and methodologies used for the impact analysis. The analysis evaluates short term, long term, and cumulative effects, both direct and indirect. If the project would result in adverse effects, this technical report identifies measures to reduce or eliminate the impacts, which are additionally carried forward and included in the Draft SEIS/SEIR.

1.1.1 Organization This technical report contains the following chapters:

 Introduction  Regulatory Context

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 Methodology  Existing Conditions  Environmental Impacts  Mitigation Measures  CEQA Determination  References  Limitations and Preparer Signatures

1.1.2 Impact Evaluation Projects can result in either beneficial or adverse impacts to the environment. Both NEPA and CEQA require an evaluation of the project impacts. This report uses the Mid- Coast Corridor Transit Project Draft SEIS/SEIR Plan Set (SANDAG, 2013a) in describing the project. The analysis uses several different approaches to identify the potential impacts of the Mid-Coast Corridor Transit Project. Together, these approaches provide an accurate disclosure of the Mid-Coast Corridor Transit Project impacts in compliance with NEPA and CEQA requirements.

1.1.2.1 National Environmental Policy Act Pursuant to NEPA regulations (40 Code of Federal Regulations 1500-1508), project impacts are evaluated based on the criteria of context and intensity. Context means the affected environment in which a proposed project occurs. Intensity refers to the severity of the impact, which is examined in terms of the type, quality, and sensitivity of the resource involved, location and extent of the effect, duration of the effect (short- or long-term), and other consideration of context. Beneficial effects are also identified and described. Impacts are described in terms of beneficial, not adverse, or adverse. This report characterizes the project’s short term, long term, and cumulative effects, both direct and indirect, in accordance with the requirements of NEPA in Chapter 5.0.

The No-Build Alternative serves as the NEPA “No Action” alternative in the Draft SEIS/SEIR. The No-Build Alternative represents what the Mid-Coast Corridor would be like in 2030 without the Mid-Coast Corridor Transit Project. For NEPA purposes, the No- Build Alternative identifies the anticipated conditions for the analysis of impacts under 2030 conditions.

Impacts created by the Build Alternative are compared to the conditions described in the No-Build Alternative to determine the direct and indirect long-term impacts. Impacts are described as they relate to the affected environment. The affected environment can be used to refer to existing conditions as well as future conditions, or both, depending on the environmental topical area that is being analyzed. Generally, the affected environment represents existing conditions and those future conditions described in the No-Build Alternative.

The cumulative analysis considers the incremental impact of the Build Alternative when added to other past, present and reasonably foreseeable actions that affect the resource

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being evaluated. It identifies the aggregate or total impact that results when the impacts of other actions are combined with the direct and indirect impacts of the Build Alternative.

1.1.2.2 California Environmental Quality Act CEQA requires that determinations of significance be made for environmental impacts by measuring project impacts and comparing the project-related impacts to identified topic-specific significance thresholds. This report’s CEQA Determination chapter provides the results of this analysis. Conditions created by the Build Alternative are compared to existing conditions to determine direct and indirect short-term and long- term impacts with project implementation. Existing conditions generally refers to conditions in 2010 when the Notice of Preparation for CEQA was issued.

The No-Build Alternative serves as the CEQA “No Project” alternative in the Draft SEIS/SEIR. The No-Build Alternative represents what the Mid-Coast Corridor would be like in 2030 without the Mid-Coast Corridor Transit Project. The CEQA analysis of the No-Build Alternative focuses on which impacts would be different without the Mid-Coast Corridor Transit Project. One change that is evaluated under CEQA is the continuation and enhancement of bus Route 150.

For CEQA impacts assessment, the level of impact is expressed in terms of whether it is not significant, less than significant, or potentially significant. This determination is based on analysis comparing the impact to the thresholds of significance for each topic. Following identification of appropriate mitigation measures, potentially significant impacts can then be further classified as either less than significant with mitigation incorporated or significant and unavoidable.

Similar to NEPA, the CEQA cumulative analysis identifies the aggregate or total impact that results when the impacts of other actions are combined with the direct and indirect impacts of the Build Alternative. If a cumulatively significant condition is identified, CEQA requires the analysis to determine if the project’s contribution to the significant condition is “cumulatively considerable” and thus, significant. 1.2 Description of the Mid-Coast Corridor The Mid-Coast Corridor is the area centering on Interstate (I-) 5 and extending from Downtown San Diego on the south to UCSD and University City on the north (Figure 1-1). Located entirely within the City of San Diego, the corridor is bounded by the Pacific Ocean on the west and by I-805 and State Route (SR) 163 on the east. The Mid-Coast Corridor is topographically diverse, with terrain ranging from coastal beaches and bays to inland areas containing steep hillsides and narrow canyons.

The Mid-Coast Corridor is characterized by dense urban centers and an abundance of regional activity centers and other major trip generators. Dense population and employment centers currently anchor both the northern and southern ends of the Mid- Coast Corridor. The UCSD campus, the Westfield UTC shopping center, and regional hospitals are clustered in the north part of the corridor and represent the second most dense land uses in the county. At the south end of the corridor is the region’s only identified Metropolitan Center—Downtown San Diego—with the region’s densest land uses and high-rise development.

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Figure 1-1. Mid-Coast Corridor

Source: SANDAG, 2012 Note: The Trolley lines shown represent the 2010 Trolley operating plan.

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Other major land uses within or immediately adjacent to the corridor (Figure 1-1) include:

 Regional hospitals: Scripps Green Hospital, Scripps Memorial Hospital La Jolla (Scripps Hospital), UCSD Thornton Hospital, VA Medical Center, UCSD Medical Center Hillcrest, and Scripps Mercy Hospital  Major colleges and universities: UCSD, University of San Diego, San Diego Mesa College, and San Diego City College  Regional shopping centers: Westfield UTC, Fashion Valley, and Westfield Horton Plaza  Major parks and visitor attractions: Mission Bay Park, San Diego Zoo, SeaWorld San Diego, Old Town San Diego State Historic Park, Balboa Park, the Gaslamp Quarter, San Diego Convention Center, Petco Park, Rose Canyon Open Space Park, and Marian Bear Memorial Park  San Diego International Airport 1.3 Alternatives under Consideration This section describes the No-Build and Build Alternatives, and Build Alternative options that were selected for consideration in this report.

1.3.1 No-Build Alternative This section describes the transportation improvements assumed in the No-Build Alternative within the Mid-Coast Corridor that are evaluated in this technical report and carried forward into the Draft SEIS/SEIR, as well as 2030 horizon year conditions resulting from projected development and changes in population and employment.

1.3.1.1 Highway and Transit Facility Improvements from the 2030 RTP The No-Build Alternative is evaluated in the context of the existing transportation facilities and services in the Mid-Coast Corridor (as characterized in 2010) and other facilities and services identified in the Revenue Constrained Scenario of the 2030 San Diego Regional Transportation Plan: Pathways for the Future (2030 RTP) (SANDAG, 2007). Since the No- Build Alternative provides the background transportation network against which the Build Alternative’s impacts are identified and assessed, the No-Build Alternative excludes the Mid- Coast Corridor Transit Project but does include continued and enhanced bus service on Route 150. The No-Build Alternative that was originally developed for the Draft SEIS/SEIR, and presented during the CEQA and NEPA scoping processes, was derived from the 2030 RTP. In October 2011, the SANDAG Board of Directors adopted a new regional transportation plan that extended the planning horizon from 2030 to 2050, the 2050 Regional Transportation Plan: Our Region, Our Future (2050 RTP) (SANDAG, 2011). However, the 2030 RTP has been retained as the basis for the No-Build Alternative because, as discussed below, no substantive differences exist between the 2030 and 2050 RTPs that would alter the environmental analysis.

The 2050 RTP was reviewed to determine if it includes any additional funded projects planned for implementation in the Mid-Coast Corridor by 2030 and not included in the 2030 RTP. The only major new project in the Mid-Coast Corridor is the extension of the Trolley

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Blue Line from the UTC Transit Center to Mira Mesa via the Sorrento Mesa/Carroll Canyon area. This extension is not an alternative to the Mid-Coast Corridor Transit Project since it is dependent on the Mid-Coast Corridor Transit Project’s implementation. The Mira Mesa/Sorrento Mesa extension has not been considered in a corridor-level alternatives analysis. Future analysis under NEPA and CEQA also would be required. Thus, this extension is not included in either the No-Build Alternative or the Build Alternative.

The 2050 RTP also was reviewed to determine if it includes any Mid-Coast Corridor projects that are assumed in the No-Build Alternative that are not in the 2030 phase of the 2050 RTP. The only major project not in the 2030 phase of the 2050 RTP is the addition of high- occupancy vehicle (HOV) lanes in the segment of I-5 from I-8 to La Jolla Village Drive. The 2050 RTP defers the implementation of the HOV lanes in this segment until the decade ending in 2050. Because the 2050 RTP only defers implementation of the HOV lanes, but still includes them, they are assumed in the design and analysis of the Mid-Coast Corridor Transit Project under the No-Build and Build Alternatives. The other Mid-Coast Corridor projects in the 2050 RTP that are not in the 2030 RTP and that are scheduled for implementation by 2030 are minor projects (e.g., minor adjustments to bus routes, increased bus frequency) and are not expected to have any substantial bearing on the analysis of the Mid-Coast Corridor Transit Project.

Figure 1-2 shows the location of the major projects included in the Revenue Constrained Scenario of the 2030 RTP located within the Mid-Coast Corridor and assumed to exist in the No-Build Alternative. These include the following major improvements from the 2030 RTP:

 Double tracking of the Los Angeles—San Diego—San Luis Obispo Rail Corridor Agency (LOSSAN) tracks and other rail improvements, with an increase in frequency of COASTER service to every 20 minutes during peak periods and to every 60 minutes during off-peak periods in both directions.  HOV lanes on I-5 from I-8 north to Oceanside, with direct access ramps (DARs) at various locations, of which the DARs at Voigt Drive would be located within the Mid- Coast Corridor. The HOV lanes would be restricted to vehicles with two or more occupants.  Combination of HOV and Managed Lanes on I-805 from I-5 to South Bay, with DARs at Carroll Canyon Road and Nobel Drive.  Trolley low-floor system improvements to the Trolley Blue and Orange Lines, including station platform, power, and signaling improvements to allow extension of the Trolley Green Line to the 12th and Imperial Avenue Transit Center and use of low-floor vehicles systemwide.

1.3.1.2 Transit System Improvements The No-Build Alternative transit system within the Mid-Coast Corridor assumes services planned to be in operation in or by 2030. As with the existing transportation system, the No-Build Alternative transit system consists of Trolley services operated by the Metropolitan Transit System (MTS), Amtrak intercity passenger rail services, North County Transit District (NCTD)-operated COASTER commuter rail services, and MTS and NCTD bus transit services. MTS-operated bus services include local, express, limited express, and BRT services.

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Figure 1-2. No-Build Alternative Transportation Improvements

Source: SANDAG, 2013

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Under the No-Build Alternative, the 2030 Trolley operating plan would result in operation of the Trolley Blue Line from the San Ysidro Transit Center at the U.S.–Mexico International Border through Downtown San Diego to the Santa Fe Depot; the Trolley Green Line would operate north and east from the 12th and Imperial Avenue Transit Center through the OTTC and Mission Valley to Santee. The Trolley Orange Line would operate from Gillespie Field through Downtown San Diego to America Plaza.

Figure 1-3 shows the major MTS bus routes serving the Mid-Coast Corridor under the No- Build Alternative. Table 1-1 provides bus route information on fares and service frequency during both peak (i.e., 6:00 to 9:00 a.m. and 3:00 to 6:00 p.m.) and off-peak (i.e., 9:00 a.m. to 3:00 p.m.) periods. Service hours after 6:00 p.m. would be similar to existing operations.

Table 1-1. No-Build Alternative Bus Operating Plan in 2030

Frequency of Service Peak Off-Peak (6:00 to 9:00 a.m.) (9:00 a.m. to Route Description (3:00 to 6:00 p.m.) 3:00 p.m.) Fare 8 OTTC to Garnet and Bayard 15.0 15.0 $2.00 9 Garnet and Bayard to OTTC 15.0 15.0 $2.00 25 Clairemont Mesa to Fashion Valley Trolley Station 15.0 15.0 $2.00 27 Mission and Felspar to Clairemont Mesa 15.0 15.0 $2.00 30 UTC Transit Center to B and 9th Street 10.0 10.0 $2.25 31 Mira Mesa Transit Center to UTC Transit Center 15.0 15.0 $2.00 41 Fashion Valley Transit Center to UCSD West 10.0 10.0 $2.25 44 OTTC to Morena Blvd and Balboa Ave 7.5 7.5 $2.25 50 Park Blvd and Broadway to UTC Transit Center 15.0 15.0 $2.50 105 OTTC to UTC Transit Center 15.0 15.0 $2.25 120 Kearny Mesa Transit Center to 3rd and Market St 15.0 15.0 $2.25 150* 5th and Broadway to UTC Transit Center 15.0 30.0 $2.50 201/202 SuperLoop 7.5 7.5 $2.25** 276 UCSD Route—Voigt Drive Loop 15.0 15.0 ** 284 UCSD Route—UCSD West to Scripps Institution of Oceanography 15.0 15.0 ** 921 Mira Mesa Transit Center to UCSD West 15.0 15.0 $2.25 960 UTC Transit Center to Euclid Avenue Trolley Station 25.0 No service $2.50 Source: SANDAG, 2012 Notes: * Not included in 2030 RTP ** = Free for UCSD students and faculty OTTC = Old Town Transit Center; UCSD = University of California, San Diego; UTC = University Towne Centre

In addition to existing transit services, the No-Build Alternative assumes improvements to existing bus transit and light rail transit (LRT) services operated by MTS. The following sections describe these improvements.

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Figure 1-3. No-Build Alternative Major Bus Routes

Source: SANDAG, 2012

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1.3.1.3 Bus Transit Service Improvements The Mid-Coast Corridor Transit Project is excluded from the No-Build Alternative to represent corridor conditions without the project. Without the Mid-Coast Corridor Transit Project, more direct transit service would be needed to connect Downtown San Diego, the OTTC, and University City. To meet this need, continuing service on the existing Route 150, which provides bus transit services between Downtown San Diego, the OTTC, and University City, was added to the No-Build Alternative to replace the Mid- Coast Corridor Transit Project. Figure 1-4 shows the bus route and station locations for Route 150 under the No-Build Alternative.

Under the No-Build Alternative, the existing Route 150 would be modified to operate along Broadway in Downtown San Diego and along Pacific Highway from Downtown San Diego north to the OTTC. From the OTTC north, Route 150 would be modified to operate within the proposed I-5 HOV lanes north to Nobel Drive. This modification to Route 150 would improve travel times over the existing Route 150, which operates in the general-purpose lanes on I-5 north to Gilman Drive. Route 150 would operate at a frequency of 15 minutes during peak periods and 30 minutes during off-peak and midday periods. The service would be operated using articulated buses. Fares are assumed to be $2.50 for a one-way trip.

1.3.1.4 Trolley Service Improvements In addition to the bus service improvements, the No-Build Alternative assumes service frequency improvements to the existing Trolley system, as identified in the Revenue Constrained Scenario of the 2030 RTP and shown in Figure 1-5. Under the No-Build Alternative, the frequency of service on the Trolley Blue Line would increase from 15 to 7.5 minutes during off-peak periods. Thus, the Trolley Blue Line would operate 7.5- minute service all day, and the Trolley Orange and Green Lines would continue to operate at 15-minute service all day.

Table 1-2 presents a summary of the Trolley operating plans for existing conditions and for the No-Build Alternative. The operating plans identify the service frequency during peak (i.e., 6:00 to 9:00 a.m. and 3:00 to 6:00 p.m.) and off-peak (i.e., 9:00 a.m. to 3:00 p.m.) periods, vehicle type, and fares for the Trolley Green, Blue, and Orange Lines. Service after 6:00 p.m. would be similar to existing operations.

1.3.1.5 Trolley Vehicle Fleet and Maintenance Facilities Operation of the No-Build Alternative Trolley operating plan in 2030 would require a fleet of 142 light rail vehicles (LRVs) including reserve, spare, and special-service vehicles. This represents an increase of eight vehicles over the existing fleet of 134 LRVs.

The maintenance shops located at 1255 Imperial Avenue in San Diego provide service and maintenance to the LRV fleet. The facility has the capacity to store approximately 200 vehicles, or 66 additional vehicles. The maintenance facilities would not require expansion under the No-Build Alternative.

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Figure 1-4. No-Build Alternative Bus Route 150

Source: SANDAG, 2012

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Figure 1-5. No-Build Alternative Trolley Operating Plan in 2030

Source: SANDAG, 2012

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Table 1-2. No-Build Alternative Trolley Operating Plan

Off-Peak Peak Frequency Frequency Fare (6:00. to 9:00 a.m.) (9:00 a.m. to Vehicle (each Route (3:00 to 6:00 p.m.) 3:00 p.m.) Type way) 2010 Operating Plan (Existing Conditions) Trolley Green Line Santee Town Center to OTTC 15.0 15.0 Trolley $2.50 Trolley Blue Line San Ysidro Transit Center to OTTC 7.5 15.0 Trolley $2.50 Trolley Orange Line Gillespie Field to 12th and 15.0 15.0 Trolley $2.50 Imperial Transit Center 2030 Operating Plan (No-Build Alternative) Trolley Green Line Santee Town Center to 12th and 15.0 15.0 Trolley $2.50 Imperial Transit Center Trolley Blue Line San Ysidro Transit Center to Santa 7.5 7.5 Trolley $2.50 Fe Depot Trolley Orange Line Gillespie Field to America Plaza 15.0 15.0 Trolley $2.50 Source: SANDAG, 2012 Note: OTTC = Old Town Transit Center

1.3.1.6 Regional Growth and Development The No-Build Alternative assumes regional growth and development consistent with the 2030 RTP, which uses the Series 11: 2030 Regional Growth Forecast Update adopted by SANDAG. This forecast is used as a basis for land use and demographic information in the transportation and traffic modeling. The Series 11: 2030 Regional Growth Forecast Update: Process and Model Documentation (SANDAG, 2008) presents a basic description of the SANDAG forecast models used in the 2030 Regional Growth Forecast Update. The conditions created by the No-Build Alternative in 2030, as predicted by the Series 11 forecast (adjusted to exclude the Mid-Coast Corridor Transit Project), include the expected effects of development projects consistent with adopted land use plans.

1.3.2 Build Alternative The Build Alternative consists of the Mid-Coast Corridor Transit Project. This section describes the project, including minor modifications to bus services to improve access to stations and eliminate duplication of service with the extension of the Trolley Blue Line.

The Mid-Coast Corridor Transit Project provides for the extension of the Trolley Blue Line from the Santa Fe Depot in Downtown San Diego to the UTC Transit Center in University City. With the extension of the Trolley Blue Line, construction of the project would provide for continuous service on the Trolley Blue Line from the San Ysidro Transit Center at the U.S.–Mexico International Border to University City.

Figure 1-6 shows the project alignment and station locations and the VA Medical Center Station Option and the Genesee Avenue Design Option. The project would use the existing Trolley tracks for approximately 3.5 miles, from the Santa Fe Depot to a point just north of the OTTC and south of the San Diego River. The Trolley Blue Line trains would share the tracks with the Trolley Green Line trains. North of this point, the project

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Figure 1-6. Mid-Coast Corridor Transit Project

Source: SANDAG, 2013

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includes construction of 10.9 miles of new double track extending to the terminus at the UTC Transit Center in University City.

In addition to the new double-track extension, the project includes eight new stations, upgrades to existing systems facilities between the Santa Fe Depot and the OTTC, and the acquisition of new Trolley vehicles for the extended project operation. Stations would be located at Tecolote Road, Clairemont Drive, Balboa Avenue, Nobel Drive, UCSD West Campus, UCSD East Campus, Executive Drive, and the UTC Transit Center. The project also includes an option for an additional station at the VA Medical Center.

The following sections describe the project alignment, stations, vehicles, power system and signaling, operating plan, and schedule for implementation of the project.

1.3.2.1 Alignment The project alignment would follow the LOSSAN tracks within the existing MTS and City of San Diego right-of-way from the Santa Fe Depot to approximately 3,500 feet south of the I-5/Gilman Drive/La Jolla Colony Drive interchange. The alignment would then leave the LOSSAN right-of-way, enter California Department of Transportation (Caltrans) right- of-way, and parallel the east side of the I-5 corridor north to the I-5/Gilman Drive/La Jolla Colony Drive interchange. North of the interchange, the alignment would parallel the I-5 corridor, traveling partially within Caltrans right-of-way and partially on private property. At about 2,500 feet south of Nobel Drive, the alignment would transition to an aerial structure and cross over to the west side of I-5 south of Nobel Drive. From Nobel Drive, the alignment would continue north to the UCSD West Campus, then cross back over to the east side of I-5 along Voigt Drive and terminate on Genesee Avenue at the UTC Transit Center. The alignment’s total length from the south side of the San Diego River to the terminus at the UTC Transit Center is 10.9 miles.

Plan and profile drawings for the project alignment and Genesee Avenue Design Option are provided in the Mid-Coast Corridor Transit Project Draft SEIS/SEIR Plan Set (SANDAG, 2013a), referred to as Draft SEIS/SEIR plan set. Right-of-way plans showing existing and proposed rights-of-way and temporary construction easements for the project and Genesee Avenue Design Option alignment, stations, and supporting facilities also are contained in the Draft SEIS/SEIR plan set. The Mid-Coast Corridor Transit Project Property Acquisitions Technical Report (SANDAG, 2013b) identifies property acquisitions and structures to be demolished as part of the project. The Mid-Coast Corridor Transit Project Construction Impacts Technical Report (SANDAG, 2013c) describes the construction methods, activities, and durations.

Figure 1-7 presents a conceptual plan and profile drawing of the project alignment, stations, and supporting facilities. The alignment for the project with the Genesee Avenue Design Option is basically the same as for the project without the design option. The only difference is that the Genesee Avenue Design Option uses straddle bents1 rather than columns to

1 A straddle bent refers to a type of structure used to avoid a situation where the column would cause an obstruction (such as a fly-over ramp where the column might land in the roadway below). The straddle bent, as its name implies, straddles the roadway or other obstruction. It consists of a beam supported by columns on the outside.

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support the aerial structure and stations, and has different locations of special trackwork on Genesee Avenue.

Alignment North of OTTC to UTC Transit Center North of the OTTC, the project alignment would be located primarily at grade within the existing MTS right-of-way, north to the vicinity of Gilman Drive/La Jolla Colony Drive. This railroad corridor is used by the COASTER commuter rail, Amtrak intercity rail, and Burlington Northern and Santa Fe freight rail. The project alignment would be located east of the existing LOSSAN tracks, from the OTTC to south of SR 52, with at-grade stations at Tecolote Road, Clairemont Drive, and Balboa Avenue.

The project alignment would use bridges to cross the San Diego River, Tecolote Creek, and Rose Creek, and would be grade separated over Friars Road and Balboa Avenue. South of SR 52, the alignment would transition to an aerial structure and would cross the existing LOSSAN tracks, continuing at grade west of the existing LOSSAN tracks. To accommodate the alignment along the westerly right-of-way, the existing LOSSAN tracks would be relocated east but would still be located within the MTS right-of-way. Just south of Gilman Drive/La Jolla Colony Drive, the alignment would leave the MTS right-of-way and enter the I-5 right-of-way. Along the I-5 corridor, the project alignment would be designed so as not to preclude the future widening of I-5.

Upon entering the I-5 right-of-way north of SR 52, the project alignment would extend at grade along the east side of I-5, crossing under La Jolla Colony Drive in an approximately 200-foot-long cut-and-cover underpass. North of that underpass, the alignment would continue at grade along the east side of I-5, generally within or adjacent to the I-5 right-of-way, and transition to an aerial structure to cross to the west side of I-5, south of Nobel Drive. The aerial alignment would continue north along the west side of I-5 to an aerial station at La Jolla Village Square (Nobel Drive Station).

Continuing north from the Nobel Drive Station, the project alignment would remain on an aerial structure, travel for approximately 160 feet along the southeast corner of the shopping center on the north side of Nobel Drive, then enter the I-5 right-of-way and travel along the west side of I-5 within the I-5 right-of-way. It would return to grade just north of the I-5/La Jolla Village Drive interchange. North of this interchange, the alignment would run at-grade for approximately 460 feet along the west side of I-5 and the east side of the VA Medical Center. An optional at-grade station would be located at the VA Medical Center. The station would be within the I-5 right-of-way, with access provided from the VA Medical Center property.

South of Gilman Drive, the project alignment would transition back to an aerial structure and enter the UCSD West Campus, crossing Gilman Drive and the surface parking lot located north of Gilman Drive on the UCSD campus. The aerial alignment would then cross Pepper Canyon and continue to an aerial station on the UCSD West Campus.

North of the UCSD West Station, the project alignment would turn east on an aerial structure on the UCSD campus and cross to the north side of Voigt Drive. It would continue east on the UCSD campus, crossing over I-5 and the corner of the Scripps Hospital surface parking lot located on the east side of I-5 and the north side of Voigt

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Figure 1-7. Conceptual Plan and Profile of Mid-Coast Corridor Transit Project

Source: SANDAG, 2013a

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Figure 1-7. Conceptual Plan and Profile of Mid-Coast Corridor Transit Project (continued)

Source: SANDAG, 2013a

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Drive. Column supports would be required along the west side of Warren Field and along the parking lots on the north side of Voigt Drive, both on the UCSD West Campus and at Scripps Hospital. The alignment would be located north of the existing northerly curb line of Voigt Drive to allow for future widening of Voigt Drive, which is proposed as part of the Caltrans I-5 North Coast Corridor Project currently under environmental review. The I-5 North Coast Corridor Project proposes to construct HOV DARs that connect to the north side of Voigt Drive. Construction of the DARs is scheduled for completion by 2020. To provide the required vertical clearance between the LRT alignment and the future DARs at Voigt Drive, the project alignment crossing I-5 would be located at an elevation higher than Voigt Drive.

On the east side of I-5, the project alignment would continue on aerial structure and cross to the south side of Voigt Drive in the vicinity of the Scripps Hospital driveway entrance, located north of the UCSD baseball field. The aerial alignment would continue on UCSD property to Genesee Avenue, where it would enter the street right- of-way.

Caltrans is proposing to realign Voigt Drive to connect to Genesee Avenue and realign Campus Point Drive to connect to Voigt Drive. Voigt Drive is located on UCSD property. The Mid-Coast Corridor Transit Project’s columns would be placed so as not to preclude the realignment of Voigt Drive and Campus Point Drive. Localized widening of Voigt Drive would be required to minimize use of straddle bents to support the aerial structure along Voigt Drive within the UCSD East Campus.

The aerial alignment would cross the southbound lanes of Genesee Avenue just west of Regents Road and continue south on an aerial structure in the median of Genesee Avenue, following the existing alignment of Genesee Avenue to a station at Executive Drive and a terminal station at the UTC Transit Center. The project’s Genesee Avenue Design Option is located in the segment between Regents Road and the project’s terminus. This design option would use straddle bents rather than some center columns along Genesee Avenue to reduce right-of-way acquisition from adjacent properties.

Figure 1-8 presents a conceptual plan view of the project alignment and Genesee Avenue Design Option showing the location of the center columns and straddle bents under each design concept. The plan set contains cross sections and plans with more detailed information on the location of the columns and straddle bents, including structure dimensions.

Project with Center Column Design on Genesee Avenue Under the project, the support columns generally would be located in the center of the Genesee Avenue median, as shown in the visual simulation in Figure 1-9. The project would require two straddle bents along Genesee Avenue, as shown in Figure 1-8.

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Figure 1-8. Genesee Avenue Design Concepts

Source: SANDAG, 2012

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The first straddle bent would be Figure 1-9. Visual Simulation of Genesee Avenue with located west of Center Columns Regents Road where the alignment would enter Genesee Avenue at an angle. The second one would be located on Genesee Avenue at the Executive Square intersection. The straddle bents would have support columns either in the median of Genesee Avenue, along the south side of Genesee Avenue, or in the median of Executive Square. The remaining support columns would be spaced at approximately 125 to 210 feet apart. Localized widening of Genesee Avenue would be required to accommodate the support columns with necessary clearances and to maintain the number of existing traffic lanes.

Project with Straddle Bent Design Option on Genesee Avenue The Genesee Avenue Design Option, which is visually simulated in Figure 1-10, would use some straddle bents in place of median support columns on Genesee Avenue, thereby reducing the amount of right-of-way acquisitions required by the project. The use of straddle bents along Genesee Avenue is the only change provided by this design option. Figure 1-10. Visual Simulation of Genesee Avenue with Straddle Bents The straddle bents would be located on each side of the right- of-way or in the median of Genesee Avenue to support cross beams that would span the roadway. Approximately 16 straddle bents would be required for this design option (Figure 1-8). The straddle bents would include one at Regents Road, four in the vicinity of Eastgate Mall, six in the vicinity of Executive Square and Executive Drive, and five in the vicinity of Esplanade Court/UTC Driveway and the UTC Transit Center. The guideway and stations would rest on the cross beams with the roadway underneath. Right-of-way acquisitions under this design option would be confined primarily to column locations along the right-of-way edge and

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where the columns cannot fit within the existing right-of-way. The straddle bents would be spaced at approximately the same distances as the project’s center columns without the design option, as shown in Figure 1-8.

1.3.2.2 Stations The project includes eight new stations for passenger access, plus an optional station at the VA Medical Center. All new stations would be side-platform stations with 360-foot- long platforms designed to accommodate up to four-car trains. All platforms would be fully accessible and comply with the Americans with Disabilities Act (ADA).

Canopies would be provided at each station and would cover portions of the platforms and fare collection areas. Fare collection equipment, consisting of ticket/smart card vending machines and Compass Card validators, would be provided at each station. These amenities would be placed as appropriate on the platform where boarding occurs or at station entrances. Other station amenities would include benches, information kiosks, and security features according to SANDAG Design Criteria. Bicycle lockers would be provided at all stations except at the UTC Transit Center. Bicycle lockers at this station would be provided during the planned reconstruction of the bus transit center in the future, which is a separate project from the Mid-Coast Corridor Transit Project. Parking and bus transfer facilities would be provided at five stations, as described later in this section. Lighting would be provided at all station platforms and parking areas.

For the at-grade stations south of Balboa Avenue where the southbound platform would be adjacent to the LOSSAN tracks, a screen wall would be constructed at the back of the platforms to shield passengers from the wind induced by a fast-moving Amtrak or COASTER train. On aerial platforms, a 10-foot-high safety fence or screen would be provided at the back of both platforms.

The new project stations include both at-grade and aerial stations. The project segment along the MTS right-of-way between the San Diego River crossing and Gilman Drive would include three at-grade stations at Tecolote Road, Clairemont Drive, and Balboa Avenue. The site concept plans developed for these stations are described below. More detailed station site plans for each of the stations are provided in the Mid-Coast Corridor Transit Project Draft SEIS/SEIR Plan Set (SANDAG, 2013a).

 Tecolote Road Station—This at-grade station would be located south of the existing Tecolote Road overcrossing (Figure 1-11). Primary access to the station for northbound traffic would be provided via the existing signalized intersection at West Morena Boulevard and Vega Street. A driveway for right turns in and out would be provided on West Morena Boulevard for southbound traffic. A traction power substation (TPSS) would be located immediately north of the station driveway on West Morena Boulevard. The station site would include 280 surface parking spaces, with 180 spaces adjacent to the west side of West Morena Boulevard and another 100 spaces to the south of Vega Street. Short-term parking spaces would be provided for pick up and drop off of passengers (referred to as kiss-and-ride). Bus stops and turnouts for transferring passengers would be provided on both sides of West Morena Boulevard by widening the roadway and removing approximately

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Figure 1-11. Site Concept for Tecolote Road Station

Source: SANDAG, 2013

15 existing on-street parking spaces along the east side of West Morena Boulevard. In the vicinity of the bus stops, a fence would be provided in the median of West Morena Boulevard to prevent passengers from crossing at mid-block. Pedestrian ramps and stairs would be constructed on the east side of West Morena Boulevard for access to the north and south sides of Tecolote Road. Additionally, a new sidewalk would be constructed along the east side of West Morena Boulevard to Knoxville Street.  Clairemont Drive Station—This at-grade station would be located south of the existing Clairemont Drive overcrossing adjacent to Morena Boulevard (Figure 1-12). The station platforms would be located along the west side of Morena Boulevard and a 150-space surface parking lot would be located across the street on the east side. The station parking lot would include a site for a TPSS. Access to the station parking lot would be provided via driveways on Ingulf Street and Clairemont Drive. Pedestrian access from Clairemont Drive to the station would be provided by new stairs and ADA-compliant access ramps located on both sides of Clairemont Drive. A new bus turnout would be provided on the south side of Clairemont Drive. New sidewalks would be constructed along the east side of Morena Boulevard from Ingulf Street to north of Clairemont Drive and along the west side of Morena Boulevard from the north side of the station platform to Gesner Street. Pedestrian crossings between the east and west sides of Morena Boulevard and the station parking lot would be provided by existing crosswalks at the signalized intersections at Morena Boulevard/Ingulf Street and Morena Boulevard/Gesner Street.

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Figure 1-12. Site Concept for Clairemont Drive Station

Source: SANDAG, 2013

 Balboa Avenue Station—This at-grade station would be located in the southwest quadrant of the Balboa Avenue/Morena Boulevard interchange (Figure 1-13). The station site would include a surface parking lot with approximately 220 spaces, five bus bays, and short-term parking for pick up and drop off of passengers. An additional on-street bus turnout would be provided on the west side of Morena Boulevard. To provide for bus and vehicular access to the station, the existing on ramp from eastbound Balboa Avenue to southbound Morena Boulevard would be removed and traffic would be diverted to the loop ramp connecting eastbound Balboa Avenue to Morena Boulevard. The loop ramp would be widened and its intersection with Morena Boulevard would be signalized, allowing traffic to turn south on Morena Boulevard. The westerly leg of this intersection would serve as the entrance to the station for buses and as an entrance and exit for vehicular traffic. Buses would exit the station via a new signalized intersection constructed at the southern end of the station site. Pedestrian access to the station from Morena Boulevard would be provided via new sidewalks on both sides of Morena Boulevard within the station area. Access from Balboa Avenue would be via ramps and stairs on both sides of the street. A pedestrian bridge would be provided across Balboa Avenue for access to the station from the north side of Balboa Avenue.

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Figure 1-13. Site Concept for Balboa Avenue Station

Source: SANDAG, 2013

The project segment along the I-5 corridor between Gilman Drive and the alignment crossing of I-5 at Voigt Drive would include an aerial station at Nobel Drive, an optional at-grade station at the VA Medical Center, and an aerial station on the UCSD West Campus. The UCSD West Station includes two different station concepts depending on whether the VA Medical Center Station is included in the project. The site concept plans developed for these stations are described below.

 Nobel Drive Station—This aerial station would be located within an existing parking area on the west side of I-5 and south of Nobel Drive at the La Jolla Village Square shopping center (Figure 1-14). The station would include a joint-use parking structure with 260 transit parking spaces as well as replacement parking for the surface parking spaces lost as a result of constructing the station and parking structure at the shopping center. Access to the station platform would be provided by stairs and elevators. No bus stops would be constructed at this station as part of the project. Nobel Drive currently has bus stops on both sides of the street in the vicinity of the station.

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Figure 1-14. Site Concept for Nobel Drive Station

Source: SANDAG, 2013

 VA Medical Center Station—This optional at-grade station would be located at the VA Medical Center on the west side of I-5 and north of La Jolla Village Drive (Figure 1-15). The horizontal and vertical track alignment has been designed so as not to preclude this optional station under the Build Alternative. The station would be at approximately the same elevation as the surface parking lot of the VA Medical Center. No new parking or bus stops would be provided at this station. A connection to the hospital would be provided by improvements to the pedestrian paths between the station and the main hospital entrance. A TPSS would be located in Caltrans right-of-way, south of the station.  UCSD West Station—This aerial station would be located at the north end of Pepper Canyon and west of the UCSD student housing complex (Figure 1-16). The station would be located just east of the campus center and the Price Center. No parking would be provided at the station. Because the alignment would have to clear the existing parking lot at the south end of the canyon and Lyman Drive at the north end of the canyon, this station would be constructed at an elevation higher than the elevation of the canyon rim. North of the station, two to three shuttle bus stops and a bus turnaround area would be provided for the UCSD shuttle bus service. The shuttle bus area would be located at grade below the north end of the elevated station platforms. Stairs and an elevator would provide access to the north end of the station platform.

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Figure 1-15. Site Concept for Optional VA Medical Center Station

Source: SANDAG, 2013

Without the Optional VA Medical Center Station, access to the VA Medical Center would be provided by stairs and an elevator at the south end of the station platform (as shown in the top inset in Figure 1-16). These stairs and elevators would descend to the elevation of the westerly canyon rim. A walkway would be constructed to connect to the existing pedestrian walkways on the UCSD West Campus. With the Optional VA Medical Center Station (shown in the bottom inset in Figure 1-16), only stairs for emergency use would be provided at the south end of the platform because access to the VA Medical Center would be provided by the additional station.

The project segment east of I-5, along Voigt Drive, would include an aerial station on the UCSD East Campus west of Campus Point Drive, serving both the UCSD East Campus and Scripps Hospital. The site concept plan for the UCSD East Station is described below.

 UCSD East Station—This aerial station would be located along the south side of Voigt Drive, west of Campus Point Drive and the Preuss School, near Scripps Hospital (Figure 1-17). Station access would be provided by stairs and elevators. A pedestrian bridge would be provided across Voigt Drive for access to the north side of Voigt Drive. New sidewalks would be constructed on both sides of Voigt Drive to connect with the western end of the station. No station parking or new bus stops would be provided. A TPSS would be located to the west of the station platforms.

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Figure 1-16. Site Concepts for UCSD West Station (Build Alternative and VA Medical Center Station Option)

Source: SANDAG, 2013

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Figure 1-17. Site Concept for UCSD East Station

Source: SANDAG, 2013

East of I-5 along Genesee Avenue, the project would include aerial stations at Executive Drive and at the UTC Transit Center. The site concept plans for these two stations, both with and without the Genesee Avenue Design Option, are described below.

 Executive Drive Station—This aerial station would be located in the center of Genesee Avenue, south of Executive Drive, and would span Executive Square (Figure 1-18). Station construction would require removal of the existing pedestrian bridge crossing Genesee Avenue. Pedestrian grade-separated access across Genesee Avenue at this location would be provided through the aerial station platform at Executive Drive via ramps, elevators, and stairway facilities connecting to the existing pedestrian facilities to the west and east sides of Genesee Avenue. Shuttle bus pullouts and passenger drop-off and pick-up areas would be constructed on both sides of Genesee Avenue. No parking would be provided at the station. A TPSS would be located near the southern end of the station site. The station layout and features under the Genesee Avenue Design Option (as shown in the bottom inset in Figure 1-18) would generally be the same as those under the Build Alternative (as shown in the top inset in Figure 1-18). However, under the Genesee Avenue Design Option, there would be no conflict between the existing pedestrian bridge and the proposed LRT guideway allowing the existing pedestrian bridge to remain in place. Minor modifications to the pedestrian bridge would be required to provide pedestrian access to the aerial LRT station.

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Figure 1-18. Site Concepts for Executive Drive Station, with and without Genesee Avenue Design Option

Source: SANDAG, 2013

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 UTC Transit Center—This aerial station would be located in the center of Genesee Avenue, south of Esplanade Court/UTC Driveway, with pedestrian bridges to the Westfield UTC shopping center on the east and the Costa Verde shopping center on the west (Figure 1-19). The station would provide 260 transit parking spaces in a joint-use parking facility at the Westfield UTC shopping center. Access to the station parking facility would be via the intersection of Genesee Avenue and Esplanade Court/UTC Driveway. The station also would include a connection to the new bus transit center, which would be built as part of the expansion of the Westfield UTC shopping center. The Westfield UTC shopping center expansion is scheduled for completion before revenue service begins on the Mid-Coast Corridor Transit Project. A TPSS would be located near the southern end of the station site. Construction of the Build Alternative would require the removal of the pedestrian bridge across Genesee Avenue located mid-block between La Jolla Village Drive and Esplanade Court/UTC Driveway. Pedestrian access across Genesee Avenue would be provided approximately 500 feet to the south of the existing bridge at the intersection of Genesee Avenue and Esplanade Court/UTC Driveway. Grade-separated pedestrian access across Genesee Avenue would also be accommodated through the aerial station platform at the UTC Transit Center to be located just south of Esplanade Court/UTC Driveway via ramps, elevators, and stairway facilities connecting the LRT station to the parkway area along the west side of Genesee Avenue and the UTC Transit Center to the east of the LRT station. The station layout and features under the Genesee Avenue Design Option (as shown in the bottom inset in Figure 1-19) would generally be the same as those under the Build Alternative (as shown in the top inset in Figure 1-19). If the Genesee Avenue Design Option is constructed, the pedestrian bridge would be retained as there would be no conflict between the existing bridge and proposed LRT guideway.

1.3.2.3 Trolley Vehicle Fleet and Maintenance Facilities The Trolley Blue Line extension would require 36 new LRVs to cover peak-period service with spares in 2030. In the opening year of revenue service, 25 of the 36 new LRVs would be required. Fare collection would be the same as the existing proof-of- payment system currently in use on the Trolley. No fare collection equipment would be provided on the vehicle.

The MTS maintenance plan for LRVs, including those for the project, centralizes all functions at the existing maintenance facilities located at 1255 Imperial Avenue in Downtown San Diego. No expansion of existing maintenance facilities would be required for the project.

1.3.2.4 Power System and Signaling The LRVs would receive electrical power from overhead contact wires. Catenary support poles, approximately 25 feet high, would be located at approximately 150- to 180-foot intervals. The catenary poles generally would be located in the center of the project alignment. In some locations, the poles would be located on both sides of the Trolley tracks. The overhead electrical power lines would be suspended above the Trolley tracks.

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Figure 1-19. Site Concepts for UTC Transit Center, with and without Genesee Avenue Design Option

Source: SANDAG, 2013

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Geotechnical, Geologic and Seismic Impacts Technical Report Chapter 1.0 – Introduction

Electricity to power the LRVs would be provided by TPSSs. The TPSSs would be of similar size and design to the existing substations used on the Trolley Green Line. Typical TPSS dimensions would be a 40-foot by 15-foot unmanned equipment enclosure within a 45-foot by 75-foot fenced site. Figure 1-20 shows an example of an existing TPSS.

Figure 1-20. Existing Traction Power Substation at Mission Valley Center Station

Source: SANDAG, 2012

Operation of the project would require 18 TPSSs, including four upgraded substations on three existing sites between Santa Fe Depot and the OTTC and 14 new substations. The TPSS locations and layouts are shown in the Mid-Coast Corridor Transit Project Draft SEIS/SEIR Plan Set (SANDAG, 2013a). Figure 1-21 illustrates the layout of a typical TPSS.

Figure 1-21. Traction Power Substation Layout

Source: SANDAG, 2012

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The project includes improvements and upgrades to three existing TPSS locations between Santa Fe Depot and the OTTC on Olive Street, on Bean Street, and at the OTTC. The site at Olive Street may require two substations. The extension of Trolley Blue Line service proposed on existing tracks between Santa Fe Depot and the OTTC also would require a new substation within the existing MTS Wright Street Yard. The other 13 new substations would be located north of the OTTC. Table 1-3 identifies the location of the existing substations and the proposed substation upgrades between Santa Fe Depot and the OTTC, and the proposed new substations north of the OTTC.

Table 1-3. Traction Power Substations Locations

No. Stationing Location 1, 2 64+00 Olive St, upgrade to an existing substation located along the east side of the right-of-way and addition of a second substation within the same site 3 101+50 Bean St, in City of San Diego right-of-way, may require modification to existing cul-de-sac 4 133+00 Wright Street Yard, within existing MTS property 5 171+00 OTTC, upgrade to an existing substation located along the west side of the right-of-way 6 199+30 South of the San Diego River and north of I-8, in City of San Diego right-of way 7 210+00 North of San Diego River, east of the tracks along Anna Ave 8 240+60 At Tecolote Rd Station, along the east side of the tracks and south of Tecolote Creek 9 312+00 At Clairemont Dr Station, along the east side of Morena Blvd, full acquisition from a shopping center 10 349+50 South of Baker St, in Caltrans right-of-way, along the west side of existing tracks 11 400+00 North of Balboa Ave and south of Jutland Dr, partial take from graded land east of MTS right-of-way 12 456+00 Just north of Jutland Dr, undeveloped parcel east of MTS right-of-way 13 550+50 Just south of La Jolla Colony Dr, in Caltrans right-of-way, along east side of tracks 14 600+50 Undeveloped parcel next to Charmant Dr and east of the alignment, just before the alignment crosses the freeway south of Nobel Dr 15 645+00 In Caltrans right-of-way along the west side of the alignment next to the VA Medical Center. Access would be from the parking lot at the VA Medical Center 16 694+00 Along the south side of Voigt Dr on the UCSD East Campus, next to the baseball field 17 752+50 Along the east side of Genesee Ave, just north of La Jolla Village Dr, partial acquisition of the landscape area in front of a high-rise office building 18 771+00 On Genesee Ave on partially acquired Westfield UTC shopping center property, near the south end of the UTC Transit Center platform Source: SANDAG, 2013a Notes: Caltrans = California Department of Transportation; MTS = Metropolitan Transit System; OTTC = Old Town Transit Center; UCSD = University of California, San Diego; UTC = University Towne Centre; VA = Veterans Administration

Communications and signaling (C&S) buildings centralize train control and communications for Trolley operations at each station. Each facility is an enclosure located within the station site area, typically adjacent to a station platform. Positioning of a C&S building must be selected to provide clearances for maintaining and servicing equipment and to maintain sight lines for LRT operations. Upgrades to the existing C&S system between the Santa Fe Depot and the OTTC would be required as part of the project; however, this would not require additional C&S buildings.

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Other proposed physical improvements to the Trolley system south of the OTTC and north of Santa Fe Depot would include upgrades to existing systems, including the signaling system and the overhead catenary system (OCS) to accommodate all-day 7.5-minute Trolley Blue Line service. These potential improvements would be located within the existing railroad and MTS right-of-way, as described below:

 LRT signaling system improvements would include additional track circuit relays at County Center/Little Italy, Middletown, and Washington Street Stations; upgrades to the block signaling system to accommodate the reduced headways between Santa Fe Depot and the OTTC; and adjustments to the crossing gate controllers to ensure an efficient gate operation also meeting requirements of the Manual on Uniform Traffic Control Devices (23 Code of Federal Regulations, Part 655, Subpart F).  OCS improvements would include the addition of a double messenger wire instead of the existing single messenger wire.  LOSSAN track improvements would provide for the relocation of an existing control point signal from the north side of Taylor Street to the south side of Taylor Street, just north of the existing station platform. The improvements would reduce railroad gate down time for northbound COASTER and Amtrak trains stopping at the OTTC.

1.3.2.5 Operating Plan Operating plans were developed using ridership forecasts. These operating plans were then used to develop the capital and operating cost estimates and to provide the basis for the analysis of potential project impacts.

Table 1-4 presents the existing 2010 Trolley operating plan and the Trolley operating plans developed for the opening year and 2030 revenue service. The 2030 operating plan for the No-Build Alternative (also provided in Table 1-2) is included for comparative purposes.

The 2010 operating plan (existing conditions) does not include the Build Alternative. Therefore, to evaluate project impacts compared to existing conditions, the Build Alternative was added into the 2010 operating plan to provide a basis for comparing project impacts to existing conditions.

At the startup of revenue operations, the project is expected to require 15-minute service during peak and off-peak periods. Figure 1-22 shows the operating plan for the opening year of service.

The proposed Trolley operating plan for the Build Alternative in 2030 presented in Table 1-4 includes the extension of the Trolley Blue Line to the UTC Transit Center. As shown in Figure 1-23, the Trolley Blue Line in 2030 would be operated as a single line with three-car trains from the existing San Ysidro Transit Center in the south to the UTC Transit Center in University City, with stops at all 29 intermediate stations. The Trolley Green and Orange Lines would operate the same as under the No-Build Alternative in 2030. Weekday Trolley Blue Line service in 2030 would operate every 7.5 minutes during peak periods (i.e., 6:00 to 9:00 a.m. and 3:00 to 6:00 p.m.) and during the off-peak midday period (i.e., 9:00 a.m. to 3:00 p.m.). The fare structure would be the same as previously described for the No-Build Alternative.

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Table 1-4. Trolley Operating Plans

Peak Frequency Off-Peak Frequency (6:00 to 9:00 a.m.) (9:00 a.m. to Vehicle Fare Route (3:00 to 6:00 p.m.) 3:00 p.m.) Type (each way) 2010 Operating Plan (Existing Conditions) Trolley Green Line Santee Town Center 15.0 15.0 Trolley $2.50 to OTTC Trolley Blue Line San Ysidro Transit 7.5 15.0 Trolley $2.50 Center to OTTC Trolley Orange Line Gillespie Field to 15.0 15.0 Trolley $2.50 12th and Imperial Transit Center 2010 Operating Plan (Build Alternative) Trolley Green Line Santee Town Center 15.0 15.0 Trolley $2.50 to OTTC Trolley Blue Line San Ysidro Transit 7.5 7.5 Trolley $2.50 Center to UTC Transit Center Trolley Orange Line Gillespie Field to 15.0 15.0 Trolley $2.50 12th and Imperial Transit Center Opening Year Operating Plan* Trolley Green Line Santee Town Center to 15.0 15.0 Trolley $2.50 12th and Imperial Transit Center Trolley Blue Line San Ysidro Transit 7.5 15.0 Trolley $2.50 Center to America Plaza Trolley Blue Line America Plaza to UTC 15.0 15.0 Trolley $2.50 Transit Center Trolley Orange Line Gillespie Field to 15.0 15.0 Trolley $2.50 Santa Fe Depot 2030 Operating Plan (Build Alternative) Trolley Green Line Santee Town Center to 15.0 15.0 Trolley $2.50 12th and Imperial Transit Center Trolley Blue Line San Ysidro to UTC 7.5 7.5 Trolley $2.50 Transit Center Trolley Orange Line Gillespie Field to 15.0 15.0 Trolley $2.50 America Plaza 2030 Operating Plan (No-Build Alternative) Trolley Green Line Santee Town Center to 15.0 15.0 Trolley $2.50 12th and Imperial Transit Center Trolley Blue Line San Ysidro Transit 7.5 7.5 Trolley $2.50 Center to Santa Fe Depot Trolley Orange Line Gillespie Field to 15.0 15.0 Trolley $2.50 America Plaza Source: SANDAG, 2012 Notes: *The Trolley Blue Line would operate as a continuous run from the San Ysidro Transit Center to the UTC Transit Center. During peak periods in the opening year, alternating trains would turn back at America Plaza, resulting in 15-minute headways north of America Plaza and 7.5-minute headways south of America Plaza. OTTC = Old Town Transit Center; UTC = University Towne Centre

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Geotechnical, Geologic and Seismic Impacts Technical Report Chapter 1.0 – Introduction

Figure 1-22. Mid-Coast Corridor Transit Project Opening Year Trolley Operating Plan

Source: SANDAG, 2012

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Figure 1-23. Mid-Coast Corridor Transit Project 2030 Trolley Operating Plan

Source: SANDAG, 2012

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Geotechnical, Geologic and Seismic Impacts Technical Report Chapter 1.0 – Introduction

The Trolley operating plan in 2010 that includes the Build Alternative is the same as the 2010 operating plan except for extension of the Trolley Blue Line from the OTTC to the UTC Transit Center and an increase in service frequency to 7.5 minutes during the off- peak period. Thus, under the Build Alternative in 2010, the Trolley Blue Line would operate at 7.5-minute intervals during both peak and off-peak periods.

With extension of Trolley Blue Line service to the UTC Transit Center, the service provided by bus Route 150 operating between Downtown San Diego and University City would duplicate the new Trolley services and therefore would be eliminated with implementation of the project, consistent with the 2030 RTP. In addition to this modification, minor changes would be made to several bus routes to improve access to the new Trolley stations proposed under the Build Alternative. These modifications consist of rerouting of bus routes to connect to stations. The service frequency of the routes serving the stations would not change. Table 1-5 identifies routes serving the Trolley stations under the Build Alternative and shows which routes would be modified to serve the stations. No changes to other bus routes or the COASTER would be required.

1.3.2.6 Schedule The project is currently in the Project Development phase of the New Starts process, which includes the completion of the NEPA and CEQA processes. Completion of the environmental review process is anticipated in mid-2014, following which SANDAG will seek FTA approval to advance the project to the Engineering phase pursuant to MAP- 21. During the Engineering phase, SANDAG and FTA will negotiate a Full Funding Grant Agreement, which is anticipated in early 2015. Construction is assumed to begin in 2015, and revenue service is expected to start by the end of 2018.

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Table 1-5. Build Alternative Bus Routes Serving Trolley Stations

Frequency of Service Peak Off-Peak (6:00 to 9:00 a.m.) (9:00 a.m. to Build Alternative Modified under Route Description (3:00 to 6:00 p.m.) 3:00 p.m.) Stations Served Build Alternative 8 OTTC to Garnet and 15 15 OTTC, Balboa Ave Yes Bayard 9 Garnet and Bayard to 15 15 OTTC, Balboa Ave Yes OTTC 27 Mission and Felspar to 15 15 Balboa Ave Yes Clairemont Mesa 30 UTC Transit Center to B 10 10 Washington St, OTTC, No and 9th Nobel Dr, UCSD West, UTC Transit Center 31 Mira Mesa Transit Center 15 15 Executive Dr, UTC No to UTC Transit Center Transit Center 41 Fashion Valley Trolley 10 10 UCSD West, Executive No Station to UCSD West Dr, UTC Transit Center 44 OTTC to Morena and 7.5 7.5 OTTC, Balboa Ave No Balboa 50 Park and Broadway to 15 15 Clairemont Dr, UTC No UTC Transit Center Transit Center 105 OTTC to UTC Transit 15 15 OTTC, Tecolote Rd, No Center UTC Transit Center 150* 5th and Broadway to * * Yes—Deleted UTC Transit Center 201 SuperLoop 7.5 7.5 Nobel Dr, VA Medical No Center, UCSD West, UCSD East, Executive Dr, UTC Transit Center 202 SuperLoop 7.5 7.5 Nobel Dr, VA Medical No Center, UCSD West, UCSD East, Executive Dr, UTC Transit Center 276 UCSD Route–Voigt Drive 15 15 VA Medical Center, Yes Loop UCSD West 284 UCSD Route–UCSD 15 15 UCSD West Yes West to Scripps Institution of Oceanography 921 Mira Mesa Transit Center 15 15 UCSD West, Executive No to UCSD West Dr, UTC Transit Center 960 UTC Transit Center to 30 0 Executive Dr, UTC No Euclid Avenue Trolley Transit Center Station Source: SANDAG, 2012 Notes: * Route 150 does not operate under the Build Alternative. OTTC = Old Town Transit Center; UCSD = University of California, San Diego; UTC = University Towne Centre; VA = Veterans Administration

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Geotechnical, Geologic and Seismic Impacts Technical Report Chapter 2.0 – Regulatory Context

2.0 REGULATORY CONTEXT

This chapter describes the federal, state, and local regulations that provide guidance for conducting geotechnical, geologic, and seismic analyses for the Mid-Coast Corridor Transit Project. The specific assessment methodology and criteria for environmental impact analysis, however, are discussed in Sections 3.3 and 3.4, respectively. 2.1 Federal 2.1.1 National Environmental Policy Act The National Environmental Policy Act of 1969 established a national policy for protection of the environment. The purposes of this Act are: “To declare a national policy which will encourage productive and enjoyable harmony between man and his environment; to promote efforts which will prevent or eliminate damage to the environment and biosphere and stimulate the health and welfare of man; to enrich the understanding of the ecological systems and natural resources important to the Nation; and to establish a Council on Environmental Quality” (42 USC § 4321).

To assist federal agencies in fulfilling the goals and effectively implementing the requirements of NEPA, in 1978 the Council on Environmental Quality (CEQ) issued regulations for implementing the procedural aspects of NEPA (40 CFR Part 1500 -1508). The Federal Transit Administration (FTA) responded to the NEPA and CEQ regulations by issuing its own implementing environmental regulations and guidance (23 CFR 771) that relate to the NEPA process in more specific terms.

Through NEPA, Congress directed all federal agencies to:

“include in every … report on proposals for … major federal actions significantly affecting the quality of the human environment, a detailed statement by the responsible official on —

(i) the environmental impact of the proposed action, (ii) any adverse environmental effects which cannot be avoided should the proposal be implemented, (iii) alternatives to the proposed action, (iv) the relationship between local short-term uses of man’s environment and the maintenance and enhancement of long-term productivity, and (v) any irreversible and irretrievable commitments of resources which would be involved in the proposed action should it be implemented.” (42 USC § 4332(C))

The FTA is the lead agency under NEPA and is responsible for review of the environmental impacts of the Mid-Coast Corridor Transit Project. In that capacity, the FTA must assess the potential for adverse direct, indirect, and cumulative impacts on the environment that may result from approval and implementation of the project.

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2.1.2 Federal Water Pollution Control Act The federal Water Pollution Control Act of 1972, commonly referred to as the Clean Water Act (CWA), establishes requirements for discharges of storm water or wastewater from any point source that would affect the beneficial uses of waters of the United States (U.S. Environmental Protection Agency, 2009a). Section 401 of the CWA requires state Water Quality Certification to show that the project will comply with state water quality standards for any activity that results in a discharge to a water body. Section 402 of the CWA establishes the National Pollutant Discharge Elimination System (NPDES) permit process that applies to storm water discharges associated with construction, industrial, and municipal activities (e.g., soil erosion). In the State of California, the State Water Resources Control Board (SWRCB) and Regional Water Quality Control Boards (RWQCB) are responsible for issuance of Water Quality Certifications pursuant to Section 401 of the CWA and implementation of the CWA 402 NPDES General Permit. In accordance with the General Permit, areas of soil erosion would be properly controlled during construction, through the preparation and execution of erosion control plans and measures for soil disturbance (San Diego RWQC, 2009).

Detailed Clean Water Act and San Diego RWQCB regulations for this project are identified in the Mid-Coast Corridor Transit Project Water Impact Analysis Technical Report (SANDAG, 2013d).

2.1.3 National Engineering Handbook The National Engineering Handbook (Natural Resources Conservation Service, 1983) Sections 2.0 and 3.0 provide standards for soil conservation during planning, design, and construction activities. The project would be required to conform to these standards during construction to limit soil erosion. These measures would be defined and outlined within the project’s specific storm water plans.

2.1.4 American Railway Engineering and Maintenance-of-Way Association Manual for Railway Engineering The American Railway Engineering and Maintenance-of-Way Association (AREMA) Manual for Railway Engineering (AREMA, 2011) is an annually updated publication that explains the development and advancement of both technical and practical knowledge and recommended practices pertaining to the design, construction, and maintenance of railway infrastructure. The publication is used as a guideline for design of the project. The manual applies to project structures that cross over or otherwise would affect operations of the Los Angeles—San Diego—San Luis Obispo Railroad Corridor, unless superseded by San Diego Association of Governments Design Criteria. 2.2 State 2.2.1 California Environmental Quality Act The California Environmental Quality Act (CEQA) of 1970 requires state, local, and other agencies to evaluate the environmental implications of their decisions and to avoid or reduce, when feasible, the significant environmental impacts of their decisions (Public Resources Code [PRC] § 21000 et seq.; the CEQA Guidelines [California Code of

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Regulations (CCR) §15000 et seq.). This technical report is being prepared in support of that impact evaluation. When avoiding or minimizing environmental damage is not feasible, CEQA requires agencies to prepare a written statement of overriding considerations when they decide to approve a project that will cause one or more significant impacts on the environment (PRC §21002; the CEQA Guidelines [CCR §15021(a)]). Under the direction of CEQA, the California Natural Resources Agency has adopted regulations known as the CEQA Guidelines, which provide detailed procedures that agencies must follow to implement the law.

CEQA policy encourages environmental protection by establishing that state, local, and other agencies take actions necessary to provide the people with clean air and water and the enjoyment of aesthetic, natural, scenic, and historic qualities. CEQA further identifies the need to maintain ecological systems and the general welfare of the people. CEQA requires that governmental agencies at all levels consider qualitative factors as well as economic and technical factors and long-term benefits and costs, in addition to short-term benefits and costs (PRC §21000(c,g), §21001(g)).

SANDAG is the lead agency under CEQA and is responsible for review of the environmental impacts of the Mid-Coast Corridor Transit Project. In that capacity, SANDAG must assess the potential for significant direct, indirect, and cumulative impacts on the environment that may result from approval and implementation of the project.

2.2.2 California Government Code California Government Code (CGC) §65300 states the following:

Each planning agency shall prepare and the legislative body of each county and city shall adopt a comprehensive, long-term general plan for the physical development of the county or city, and any land outside its boundary which in the planning agency’s judgment bears relation to its planning. Chartered cities shall adopt general plans which contain the mandatory elements specified in Section 65302.

The intent of the safety element, one of the mandatory elements referenced in CGC §65300, as stated in CGC §65302(g)(1), is to protect the community from the following:

…any unreasonable risks associated with the effects of seismically induced surface rupture, ground shaking, ground failure, tsunami, seiche, and dam failure; slope instability leading to mudslides and landslides; subsidence, liquefaction, and other seismic hazards identified pursuant to Chapter 7.8 (commencing with Section 2690) of Division 2 of the Public Resources Code, and other geologic hazards known to the legislative body; flooding; and wildland and urban fires.

CGC §65302(g)(1) also states that the safety element should include mapping of known seismic and other geologic hazards. In accordance with the CGC, the project would identify any unreasonable risks associated with the impacts of seismically induced surface rupture, ground shaking, ground failure, tsunami, seiche, and dam failure; slope instability leading to mudslides and landslides; subsidence, liquefaction, and other seismic hazards.

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2.2.3 Alquist-Priolo Earthquake Fault Zoning Act The Alquist-Priolo Earthquake Fault Zoning Act (A-PA) was enacted in 1975 and amended in 1993. The A-PA provides policies and criteria to assist cities, counties, and state agencies in the exercise of their responsibility to prohibit the location of developments and structures for human occupancy across the strand of active faults. An active fault is a fault that has undergone movement within the past 11,000 years (the Holocene geologic period). The A-PA addresses only the hazard of surface fault rupture and is not directed toward other earthquake hazards. The intent of the A-PA was to provide the citizens of California with increased safety and to minimize the loss of life during and immediately following earthquakes (California Geological Survey [CGS], 2003). In accordance with the A-PA, the project would identify active faults within the study area and any hazards of surface fault ruptures relative to those faults.

2.2.4 Seismic Hazard Mapping Act The Seismic Hazard Mapping Act was enacted by the California Legislature in April 1997, primarily as a result of the Northridge earthquake of 1994. This act requires the creation and publication of maps showing areas where earthquake-induced liquefaction or landslides would occur (CGS, 2003). If a property is located in a Seismic Hazard Zone, as shown on a map issued by the State of California Geologist, the seller or the seller's agent must disclose this fact to potential buyers (CGS, 2007). The Seismic Hazard Mapping Act would be used as a resource for identifying areas of potential earthquake-induced liquefaction or landslides.

2.2.5 California Building Code The California Building Standards Commission published a series of amendments to the International Building Code (IBC) in 2010, which is the building code used throughout California and is known as the California Building Code (CBC). Local codes, however, may be more restrictive than the CBC (Fennie, 2005). The CBC standards would be applied to the project design of buildings and shelters.

2.2.6 California Department of Transportation The project would follow California Department of Transportation (Caltrans) standards as the basis of design of bridge and viaduct structures for the Mid-Coast Corridor Transit Project. The primary Caltrans document governing bridge and viaduct design is the American Association of State Highway and Transportation Officials (AASHTO) Load and Resistance Factor Design (LRFD) Bridge Design Specifications (AASHTO, 2008) with California Amendments (Caltrans, 2010a). The Caltrans Seismic Design Criteria (Caltrans, 2010b) governs the earthquake engineering aspects of project design. Other design requirements are provided through various Bridge Memos to Designers (MTDs) (Caltrans, 2011a) and include the following:

 Surface fault rupture impacts on bridges are addressed in MTD 20-10, Surface Fault Rupture Displacement Hazard Investigations.  Soil liquefaction and lateral spreading are addressed in MTD 20-14, Quantifying the Impacts of Soil Liquefaction and Lateral Spreading, and in MTD 20-15, Soil Liquefaction and Lateral Spreading Analysis Guidelines. Liquefaction lateral

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Geotechnical, Geologic and Seismic Impacts Technical Report Chapter 2.0 – Regulatory Context

spreading design for bridge foundations is provided in Guidelines on Foundation Loading and Deformation Due to Liquefaction Induced Lateral Spreading (Caltrans, 2011b).  Mitigation of tsunami hazard in bridge design is addressed in MTD 20-13, Tsunami Hazard Guidelines. Caltrans and AASHTO update these documents periodically, and the updated versions may be adopted for the Mid-Coast Corridor Transit Project in the future. The project would be designed in accordance with the Caltrans guidelines and design requirements to avoid or minimize potential impacts from surface fault ruptures, soil liquefaction, lateral spreading, and tsunami hazards. 2.3 Local 2.3.1 City of San Diego Building and Fire Codes The 2010 CBC was adopted by the City of San Diego on January 1, 2011. This code is based on the 2009 IBC. These codes establish site-specific investigation requirements, construction standards, and inspection procedures so that development does not pose a threat to the health, safety, and welfare of the public. The city also adopted the 2009 International Fire Code, as amended by the State of California and published as the 2010 California Fire Code. Together, these codes contain minimum baseline standards to guard against unsafe development. The CBC standards would be applied to the project design of building and shelters.

2.3.2 City of San Diego Municipal Code The San Diego Municipal Code contains all ordinances of the City of San Diego. These codes include regulations governing health and sanitation, public safety, public works and property, public utilities, transportation, planning and zoning, and land development. The safety requirements of the Municipal Code with respect to seismic hazards would be applied to the project.

2.3.3 City of San Diego Public Facilities, Services and Safety Element (Hazard Reduction) Within the City of San Diego General Plan (City of San Diego, 2008b), the Public Facilities, Services and Safety Element addresses both services and public facilities that have a direct effect on the location of land uses. These include police and fire protection, all wet-type utilities, waste management, libraries, schools, information infrastructure, disaster preparedness, and seismic safety. These policies also apply to transportation improvements. Hazard reduction programs are designed to improve the overall safety in the community through planning and managed growth. For example, older structures that were built before code standards may need seismic upgrading. Other examples include planning for emergency response at the government and individual level to reduce public risks from hazards and identifying unsafe structures. The project would be design in accordance with City of San Diego Public Facilities, Services and Safety Element seismic requirements.

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2.3.4 City of San Diego Seismic Safety Element (Geologic and Seismic Hazards) The City of San Diego first adopted a Seismic Safety Element in 1974. It was later renamed the City of San Diego Seismic Safety Study (City of San Diego, 2008a). This study has been periodically updated, with the most recent edition released in 2008. The City of San Diego Seismic Safety Study sets forth policies and practices governing development on lands with potential hazard. In accordance with these policies, the project would identify seismic and geologic hazards and to provide appropriate mitigation measures.

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Geotechnical, Geologic and Seismic Impacts Technical Report Chapter 3.0 – Methodology

3.0 METHODOLOGY

This chapter defines the study area and describes the data sources and methodologies used to identify and analyze the potential geotechnical, geologic, and seismic impacts of the Mid-Coast Corridor Transit Project. 3.1 Study Area As described in Chapter 1.0, construction of new tracks and facilities for the extension of the San Diego Trolley (Trolley) system would be limited to the 10.9-mile-long corridor between the Old Town Transit Center (OTTC) and the University Towne Centre Transit Center area. South of the OTTC to the Santa Fe Depot, the project improvements would be limited to signaling, communications, and traction power substation (TPSS) upgrades. Because of the limited nature of the improvements within the segment of the Mid-Coast Corridor south of the OTTC, the study area for the analysis of geotechnical, geologic, and seismic impacts of the project is confined to the corridor north of the OTTC and the area around the TPSS sites between the Santa Fe Depot and the OTTC.

The width of the study area along most of the corridor is a several-hundred-foot-wide band along each side of the project alignment. The assessment of geologic hazards, such as landslides, requires a much broader study area to include adjacent slopes that rise high above the alignment, such as within Rose Canyon. For these geologic hazards within Rose Canyon, the study area was extended up to 800 feet to include the entire slope height on the east side of the alignment. The total study area width for faulting extended up to 2,000 feet along several portions of the alignment. This larger area was needed because a comprehensive study had not been performed encompassing these areas and the broader assessment was needed to decipher fault trends and their potential effect on the project. 3.2 Data Sources Numerous sources of information were reviewed to obtain an understanding of the existing conditions and potential geologic hazards within the study area. The resources consisted of vintage aerial photographs, geologic and topographic maps, research literature, project plans, and consultant reports.

Information from in-house documents was gathered and reviewed, and research for pertinent documents was performed at the offices of the City of San Diego, the County of San Diego, and the California Department of Transportation (Caltrans). As-built plans also were provided by North County Transit District. After initial review and analysis of these data, a field reconnaissance of the project alignment was performed to check the initial findings. The final step was a reappraisal of all the data and an assessment of the potential impacts of the various hazards.

3.2.1 Aerial Photography Analysis Stereoscopic analysis was performed on two sets of historical aerial photographs taken of the study area during surveys conducted in 1928 and 1953. These sets were chosen both for their comprehensive coverage and the fact that they were taken at a time when

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land development was limited, which enabled assessment of landforms in their original condition. Stereoscopic aerial photographic analysis allows observations of landforms on a regional scale, improving the ability to interpret extensive or wide-ranging geologic features such as landslides or faults.

The 1928 aerial photograph survey was performed by the U.S. Navy (USN) and covers most of the western portion of the county. Digitally scanned copies at 1,200 dots per inch resolution were obtained from the cartographic department of the County of San Diego. The 1953 aerial survey was conducted in the San Diego metropolitan area by the U.S. Department of Agriculture (USDA). A listing of the photographic plates reviewed during this study is provided in Table 3-1 and Table 3-2.

Table 3-1. Aerial Photographic Plates, Western San Diego County, 1928

52A5 52 A6 52 B1 52 B2 52 BX4 52 BX5 52 C3 52 C4 59 C5 59 C6 59 D5 59 D6 59 E5 59 E6 59 E7 59 F5 59 F6 59 F7 Source: USN, 1928

Table 3-2. Aerial Photographic Plates, 1953

AXN-3M-215 AXN-3M-216 AXN-3M-217 AXN-3M-218 AXN-4M-85 AXN-4M-86 AXN-4M-87 AXN-4M-88 AXN-4M-89 AXN-4M-90 AXN-4M-91 AXN-4M-92 AXN-7M-187 AXN-7M-188 AXN-7M-189 AXN-8M-1 AXN-8M-2 AXN-8M-3 AXN-8M-4 ------Source: USDA, 1953

3.2.2 Literature Review Published reports and maps produced as part of government and/or academic research were reviewed. These documents included geologic maps, seismic hazard studies, and local and regional studies concerning the geologic, seismic, and tectonic framework of the region. These documents are listed in Chapter 8.0.

3.2.3 Consultant Reports and Geotechnical Borings A review was performed of unpublished consultant geotechnical reports prepared for various projects nearby and/or within the study area. These reports contain geotechnical boring logs, geologic data, and previous fault investigations, and were obtained from the archives of the City of San Diego Department of Development Services and Caltrans. Pertinent data from these sources were used to aid in the interpretation of subsurface conditions and to identify areas of potential geotechnical, geologic, and/or fault hazards. These sources are listed in Chapter 8.0.

3.2.4 Topographic Analysis Topographic (landform) analysis was performed by examining four topographic map sets published between 1889 and 1967. These vintage maps were selected because they

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were produced prior to major development within the study area, and thus show landforms prior to human modification. They were produced by the U.S. Geological Survey (USGS) and the U.S. Coast and Geodetic Survey. All are listed in Chapter 8.0. The topographic analytical method is similar to aerial photograph analysis and allows characterization of landform features, such as landslides and faults, by identifying specific landform features related to a geomorphic process.

3.2.5 Field Reconnaissance Reconnaissance-level field observations of the geologic and geotechnical conditions of the study area were performed by an engineering geologist during several site visits between March 22 and May 5, 2011. Field reconnaissance was performed to make preliminary field assessments of the project site conditions and to check findings from the document review and analysis.

The final phase of the study was to reexamine all of the data in light of new information from the field reconnaissance and to reappraise the hazard potentials within the study area.

3.2.6 Fault Rupture Analysis A comprehensive “desktop-level” study of possible active faults within the study area was performed. This work was accomplished largely by identifying landforms that may be interpreted as recent, fault-generated features on vintage aerial photography related to activity within the Rose Canyon Fault Zone (RCFZ). Data also were obtained from previous mapping projects (Kennedy, 1975; City of San Diego, 2008a; and California Division of Mines and Geology, 1993), previous consultant reports, and recent field observations.

3.2.6.1 Analysis of Vintage Aerial Photography Vintage aerial photographs were analyzed to assess the landscape for the potential presence and activity of strands of the RCFZ and landslides. Most of San Diego County did not experience much development and alteration of the landscape until after World War II, and in the Rose Canyon area, not until the 1960s or later. Consequently, the 1928 photographs were chosen for the primary analysis and were supplemented by the 1953 USDA AXN-series aerial photographs.

Vintage topographic maps of the La Jolla, Del Mar, and Point Loma USGS quadrangle maps (1:24,000 scale) also were analyzed. These maps were scanned in high resolution, and the individual sections of the maps were cropped to overlap the coverage from the 1928 and 1953 aerial photographs. The 1953 and 1967 topographic maps were used because they appear reasonably accurate and they have a sufficient number of distinct features (roadways, railroad, and other features) to allow them to be superposed.

The aerial photographs and topographic base maps, along with the current Google Earth image, were then superposed in layers in Adobe Illustrator to match all geographic and cultural features such that the mapping could be plotted onto any base map or image and so that the mapping from the different imagery could be compared. The final step

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was to layer in fault data into modern imagery referenced with a geographic information system (GIS), along with GIS-referenced shapefiles from the city’s fault database and the California Geological Survey Alquist-Priolo faults for the northern RCFZ. This composite database forms the platform upon which the fault locations were interpreted.

3.2.6.2 Interpretation of Fault-Related Landforms The RCFZ is considered an active strike-slip fault of the southern San Andreas Plate Boundary System located generally within the Mid-Coast Corridor, although in the past it was considered an inactive fault. Active strike-slip faults produce many distinctive landforms that are typical of this class of fault, and the presence of these landforms can be used to interpret the location and activity of fault strands. Specifically, scarps, deflected and offset drainages, linear side-hill benches and troughs, aligned and deflected ridge notches, and other lineaments that are not associated with anthropogenic (human-related) modification of the landscape all may be indicators of active strike-slip faulting. The presence of several of these types of features that are aligned with or parallel to the mapped strands of the RCFZ is the basis of the resulting interpreted fault locations. It is important to note that minor strands with only minimal recent activity may be completely transparent (i.e., unable to be recognized at the scale of the aerial imagery) in the landscape, but the major strands are commonly sufficiently expressed such that they can be mapped.

The 1928 and 1953 aerial photographs were analyzed for such fault-related landforms. The photographs were studied independently by two geologists, who then compared the maps with the photographs and combined them into a common interpretation. The 1928 photographs were used as the primary mapping base, as they had the least amount of culturally modified landscape and were of sufficiently high resolution. A cross-check to the mapping is to compare the 1928 fault interpretations with those from the 1953 photographs, where the natural landscape is preserved. In all cases, the interpretations from both sets of photographs were similar. The interpreted fault locations do not always coincide with the locations of faults as presented in the City of San Diego General Plan (City of San Diego, 2008b) Seismic Safety Element. Many of these differences are because the city’s fault locations are based on a study prepared for the City of San Diego in 1974. That study identified the Rose Canyon fault as potentially active. The Seismic Safety Element of the City of San Diego General Plan acknowledges that more recent independent studies consider this fault to be active. The current study for this project is based on analysis of the aerial photographs noted above and located the faults based on their inferred presence from their impacts in the landscape. The risk has been conservatively identified for purposes of environmental impact analysis. Additional field investigations will be conducted during the Preliminary Engineering phase to confirm the location of the fault. 3.3 Impacts Assessment The location of geologic hazards in the study area was determined through a review of numerous data resource documents, including vintage aerial photographs, geologic and topographic maps, research literature, project plans, and previous consultant reports. The initial review and analysis of these data were followed by a field reconnaissance of the study area to ground check the initial findings. Following the field reconnaissance, the data were

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reappraised and an assessment was made as to the potential for the following geologic conditions to adversely affect public safety or cause substantial structural damage:

 Local faulting and surface fault rupture  Strong ground shaking  Liquefaction and seismic settlement  Lateral spread  Tsunami and seiche  Landslides, mudslides, and slope stability  Compressible soils  Corrosive soils  Expansive soils  Erosion potential 3.4 Impact Determination The following guidance provided by the National Environmental Policy Act (NEPA) and the California Environmental Quality Act (CEQA) was used to determine whether the Mid-Coast Corridor Transit Project would have an adverse impact under NEPA or a significant impact under CEQA.

3.4.1 NEPA Guidance According to the Council on Environmental Quality regulations (40 CFR 1500 1508), the determination of an impact is a function of both context and intensity. Context means the affected environment in which a proposed project occurs. Both short- and long-term impacts are relevant. Intensity refers to the severity of the effect, which is examined in terms of the type, quality, and sensitivity of the resource involved, location and extent of the impact, duration of the impact, and other consideration of context. Adverse impacts will vary with the setting of the proposed action and the surrounding area. The No-Build Alternative was the primary basis of comparison for the NEPA analysis.

3.4.2 CEQA Guidance Under CEQA, every agency in the state is encouraged to develop and publish thresholds of significance against which to compare the environmental impacts of projects. Based on the CEQA Environmental Checklist (Appendix G of the CEQA Guidelines) and the City of San Diego CEQA Significance Determination Thresholds (City of San Diego, 2011), SANDAG has developed the following thresholds of significance for use in evaluating the impacts of the Mid-Coast Corridor Transit Project.

For project operation and maintenance:

 Would the project expose people or structures to geologic hazards involving earthquakes, landslides, mudslides, ground failures or similar hazards?

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 Would the project result in a substantial increase in wind or water erosion of soils, either on or off the site?

 Would the project be located on a geologic unit or soil that is unstable or that would become unstable as a result of the project, and potentially result in on- or off-site landslide, lateral spreading, subsidence, liquefaction or collapse?

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4.0 EXISTING CONDITIONS

This chapter describes the existing conditions in the study area in 2010 related to geotechnical, geologic, and seismic conditions. Conditions described include geologic materials, structure, faulting, and seismicity at both a regional and local level. 4.1 Geology and Soils 4.1.1 Regional Geology San Diego County is located within the southern portion of California’s Peninsular Ranges Geomorphic Province (Norris and Webb, 1976). This province is characterized as an assemblage of north-to-northwest-trending, high-relief ranges stretching south from the Santa Monica Mountains in Los Angeles, through the county, and well into Baja California, Mexico. Notable ranges of Southern California include the Santa Ana Mountains, the Laguna Mountains, and the Cuyamaca Mountains. The development of this mountainous terrain is closely tied to the transform tectonics of the San Andreas Fault System (SAFS).

The county encompasses three geomorphic subzones (Figure 4-1) that are set in a series of north-to-northwest trending belts, roughly parallel to the Pacific coastline. From west to east, these zones are composed of a relatively narrow, low-relief coastal plain; a central high-relief mountainous zone; and a low-lying desert zone.

The coastal plain subzone ranges from 0.25 mile wide in the northern county to approximately 14 miles wide in the central and southern regions. It is underlain by relatively undeformed near-shore marine sedimentary rocks deposited during intermittent intervals from late-Mesozoic through Quaternary time. The plain steps up in elevation from west to east across 21 marine terrace surfaces uplifted during early- to late-Pleistocene time. The highest terrace attains a maximum elevation of 800 feet at the base of the foothills to the east. A system of late-Quaternary, west-flowing drainages incise the coastal plain, forming steep-sided canyons that outlet at the coastline through broad estuary systems.

The central mountain subzone is 40 to 50 miles wide and is composed mostly of Cretaceous-age granitic rocks of the Southern California Batholith (SCB). The granites are inset with numerous isolated patches of Jurassic to Triassic age metamorphic roof pendants that are remnants of the former sedimentary cover into which the batholith intruded. The batholith surface trends downward toward the west and underlies the sedimentary cover of the coastal plain. The SCB developed during late-Jurassic to Cretaceous time when the Farallon tectonic plate was undergoing subduction beneath the North American Plate. This style of plate tectonic interaction ultimately gave way to the transform tectonics of the current SAFS sometime after the Pacific Plate spreading center was consumed below the North American Plate.

The desert subzone occurs along the extreme eastern edge of the county and extends eastward into Imperial County. This low-lying area is part of the Colorado Desert Geomorphic Province and is commonly referred to as the Salton Trough. The central portion of the desert (east of San Diego County) is up to several hundred feet below sea level and contains several tens of thousands of feet of Pliocene-Quaternary

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Figure 4-1. Geomorphic Subzones of San Diego County

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sediments. This desert basin developed in response to crustal extension and related faulting within the southeastern portion of the SAFS.

4.1.2 Mid-Coast Corridor Geology Geologically, the project alignment is composed of two distinct terrains, divided into southern and northern sections near the Interstate (I-) 5/Gilman Drive interchange (Figure 4-2). The geologic variation of these sections is largely distinguished by active faulting within the Rose Canyon Fault Zone in the southern section. Although there are many faults in the northern section, they are not considered active and likely ceased activity sometime in the early- to mid-Pleistocene era.

The southern section is an approximately 10.5-mile-long stretch between the Santa Fe Depot (13 feet above mean sea level [MSL]) and Gilman Drive at I-5 (up to 150 feet MSL). This section extends along mostly low-relief terrain crossing through various drainages and low-lying coastal terraces. In contrast, the northern section extends the remainder of the alignment north of Gilman Drive to its terminus on Genesee Avenue at the University Towne Centre (UTC) Transit Center. This stretch rises gently up to the top of a mesa of an older marine terrace at 360 feet MSL. The geologic units along this portion of the alignment are composed of consolidated Pleistocene- and Eocene-age sandstones, siltstones, and claystones.

Throughout the project alignment, grading associated with the construction of various transportation, commercial, and residential development projects over the years has modified much of the original topography. This has resulted in the placement of fill soils throughout the project alignment that range from areas with less than two feet (placed for construction of the existing railway) to thicker fill zones that are several tens of feet thick (placed during mass grading of adjacent subdivisions and I-5).

4.1.2.1 Southern Section Just north of Old Town, the project alignment crosses drainages of both the San Diego River and Tecolote Creek. North of Tecolote Creek, the alignment extends along the historic former shore area of Mission Bay (originally known as False Bay) up to Balboa Avenue. North of Balboa Avenue, the alignment enters the south-flowing drainage of Rose Creek and follows this feature for approximately 3.25 miles to an eastward bend in the drainage just south of Gilman Drive. South of Old Town, the existing alignment crosses the southern drainage outlet of the San Diego River, which periodically flowed into San Diego Bay near Washington Street. South of Washington Street, the existing alignment runs along the old eastern shoreline (prior to reclaimed land filling that moved the shoreline farther west) of San Diego Bay.

The geologic materials within the southern terrain are composed primarily of alluvium and late-Pleistocene marine terrace deposits (Figure 4-2). The alluvium is thickest on the south between Old Town and the Morena Boulevard/West Morena Boulevard intersection, where it is up to several hundred feet thick. Alluvium also is present south of Old Town to the Washington Street crossing. Shallow accumulations of alluvium occur in Rose Canyon and consist of coarse deposits only several tens of feet thick. Terrace deposits occur on the low platform between the Morena Boulevard/West

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Morena Boulevard intersection and Clairemont Drive. Similar terrace deposits occur south of Washington Street into Downtown San Diego.

The alluvium is derived from floodplain deposits, stream terraces, and fan deposits. They are composed of unconsolidated gravels, sands, silts, and some clay. From Old Town to north of the mouth of Tecolote Canyon, alluvial sediment from the San Diego River and Tecolote Creek have coalesced to form a large deltaic fan that has spread both into Mission Bay on the north and San Diego Bay on the south. The alluvium is at least several hundreds of feet thick and is interstratified with bay deposits composed of fine sands, organic silts, and clays. Historically, the San Diego River emptied into Mission Bay; only recently was it channelized in its present configuration to outlet directly into the Pacific Ocean. Until the mid-19th century, prior to construction of Derby Dike near Old Town, the river would overflow its banks during flood events and flow south into San Diego Bay. The northern edge of this fan is likely several hundred feet north of the Morena Boulevard/West Morena Boulevard intersection. Similar floodplain deposits are present south of Old Town to approximately Washington Street. These deposits are derived from the San Diego River, which has periodically drained into San Diego Bay during flooding in the past.

North of the Morena Boulevard/West Morena Boulevard intersection, there is a slight rise in the ground surface, where the San Diego Northern Railroad crosses through a small cut composed of Bay Point Formation. The Bay Point Formation is a late-Pleistocene marine terrace deposit composed mostly of medium dense to dense silty and clayey sands. The material in the railroad cut is moderately deformed and faulted, and may represent an active pressure ridge associated with faulting of the Rose Canyon Fault Zone (RCFZ). This slight topographic rise drops to the north and levels out near Asher Street. From Asher Street to Clairemont Drive, the alignment crosses through a nearly flat-lying marine terrace composed of Bay Point Formation. This terrace is most likely interspersed with aggraded drainage channels and small embayments of Mission Bay that previously may have extended eastward into the terrace.

From Clairemont Drive to Balboa Avenue, the alignment rises gently up a higher marine terrace surface also underlain by the Bay Point Formation. The rise in the terrace may be related to uplift along faults through this area. This stretch also is interspersed with several young, west-draining channels and small fans. At Balboa Avenue, there is a large incised old alluvial fan. The large size of this fan reflects the large upstream drainage area of “Balboa Canyon.” The boundaries of the fan can be faintly traced on vintage aerial photography, with the distal edges following the curved configuration of present-day Mission Bay Drive to the west. The northern edge appears to extend up along the eastern edge of Rose Canyon, more than 1,000 feet north of the intersection of Damon Avenue and Santa Fe Street.

North of Balboa Avenue, the alignment enters the south-flowing Rose Canyon drainage and follows it 3.25 miles to Gilman Drive. The geologic units consist mostly of shallow alluvium that was deposited onto consolidated Eocene sandstones, siltstones, and claystones. The alluvium is composed of coarse stream terrace units and fan deposits.

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Figure 4-2. Regional Geologic Map

Source: Kennedy, 1975; SANDAG, 2013

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Figure 4-2. Regional Geologic Map (continued)

Source: Kennedy, 1975; SANDAG, 2013

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Fill occurs throughout this section of the alignment, mostly in areas crossing minor drainage features or shallow surface depressions, along the abutment area of crossings for the major drainages (San Diego River, Tecolote Creek, Balboa Avenue, and Rose Canyon), and along the western edges of slopes such as just north of the Balboa Avenue crossing. Much of this fill is relatively shallow—less than 5 feet deep. There are isolated areas of deeper fill in excess of 10 feet such as along the abutments of the San Diego River. Most of this fill was placed during the original construction of the existing railroad.

4.1.2.2 Northern Section The northern section of the Mid-Coast Corridor is approximately 3.25 miles long, and the elevation differential rises from the south to the north for a total of approximately 225 feet. However, most of this rise occurs within the first mile of this stretch, between Gilman Drive on the south and the La Jolla Village Square shopping center.

The northern terrain area extends north of Gilman Drive, rising up along the I-5 corridor to the top of an older coastal terrace platform to a maximum elevation of approximately 360 feet MSL at the UTC Transit Center. This portion of the alignment is underlain mostly by consolidated Eocene- and Pleistocene-age sandstones, siltstones, and claystones. On the way up the terrace riser, the alignment crosses onto material of the Eocene-aged Ardath Shale. Approximately 0.75 mile north of Gilman Drive, Eocene Scripps Formation is encountered. This unit directly overlies the Ardath Shale and is composed of near-shore marine sandstone. The alignment crosses a moderate-sized drainage at La Jolla Village Drive, where Ardath Shale is again encountered, along the bottom portion of this feature. North of La Jolla Village Drive, the alignment trends along the edges of this drainage and enters a small tributary, where the University of California, San Diego (UCSD) West Station is proposed. This small drainage has a shallow accumulation of alluvium that overlies Ardath Shale, with Scripps Formation on the upper sidewalls. Continuing north from this light rail transit (LRT) station, the alignment reaches the top of the old terrace surface, which is capped by up to several tens of feet of the Pleistocene-aged Lindavista Formation at the UCSD ball field on the west side of I-5. After crossing the freeway cut exposing the Scripps Formation, the surface material from the east side of I-5 to the end of the alignment at the UTC Transit Center is all Lindavista Formation.

Much of the geologic structure in the northern area is relatively flat-lying. Faults are present throughout this area but are mostly contained within the Eocene-aged rocks. The geologic maps do not show faults penetrating the Lindavista Formation in this area, and faulting is likely a pre-Lindavista-age phenomenon (more than 700,000 years in age). No active faults have been observed north of the State Route (SR) 52/I-5 interchange.

4.1.3 Corridor Soils The Natural Resources Conservation Service (NRCS) is a federal agency that performs soil surveys and prepares soil maps throughout the United States. Its original survey of San Diego County was published in 1973 and includes data characterizing the types and distribution of soils within the project area. Soil descriptions and erosion potential were developed from the Web Soil Survey (NRCS, 2008). Soils within the project area have

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been mapped on Figure 4-3. A total of 14 different soil types have been mapped within the project area. The majority of soil types are loam (HrE2), loamy sand (CsB), or sandy loam (CfB, CfC, and GaF). There is one clay loam type (SbC) and two clay types (AtE2 and AtF). Three of the soil types are urban land complexes (HuC, HuE, and Ur) and one is a made land type (Md). One soil type is related to escarpment land (TeF). Specific soils are listed in Table 4-1.

Table 4-1. NRCS Soil Map Units

Map Unit Symbol Map Unit Name with Slope Gradient AtE2 Altamont clay, 15 to 30 percent slopes AtF Altamont clay, 30 to 50 percent slopes CfB Chesterton fine sandy loam, 2 to 5 percent slopes CfC Chesterton fine sandy loam, 5 to 9 percent slopes CgC Chesterton-Urban land complex, 2 to 9 percent slopes CsB Corralitos loamy sand, 0 to 5 percent slopes GaF Gaviota fine sandy loam, 30 to 50 percent slopes HrE2 Huerhuero loam, 15 to 20 percent slopes HuC Huerhuero-Urban land complex, 2 to 9 percent slopes HuE Huerhuero-Urban land complex, 9 to 30 percent slopes Md Made land SbC Salinas clay loam, 2 to 9 percent slopes TeF Terrace escarpment Ur Urban land Sources: Soil Survey of San Diego Area California (USDA, 1973) and National Cooperative Soil Survey Website (NCSS, 2008)

4.1.4 Ground Water Ground-water conditions were evaluated from boring data collected along and nearby the alignment. The majority of these data is north of Old Town. Along the stretch from Old Town to SR 52, Geocon (1991) penetrated numerous borings for a previous investigation along the Mid-Coast Corridor. Boring data by others for the SR 52/I-5 Connector and recent borings performed near the Gilman Drive/La Jolla Colony Drive intersection (Kleinfelder, 2011a), the proposed Nobel Viaduct (Kleinfelder, 2011b), and the proposed Genesee Viaduct (Kleinfelder, 2011c) were reviewed.

Borings in the Old Town area typically encountered ground water between 10 feet to 14 feet below ground surface (bgs), which corresponds to elevations of 1 foot to 4 feet MSL. Similar ground-water conditions occur south of Old Town to approximately the Washington Street crossing. South of Washington Street to the Santa Fe Depot, the existing alignment passes out of alluvial soils and into terrace deposits where it is anticipated that ground-water levels will be more than 15 feet in depth.

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Figure 4-3. Soils in Study Area

Source: NRCS, 2008; SANDAG, 2013

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Figure 4-3. Soils in Study Area (continued)

Source: NRCS, 2008; SANDAG, 2013

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Within the San Diego River drainage, borings by Geocon (1991) encountered ground water at depths of between 24 feet (at higher elevations outside of the river levee) to 5 feet bgs (within the flood channel), which corresponds to approximately 1 foot to -1 foot MSL. Between the northern levee of the San Diego River and Clairemont Drive, ground- water depths are fairly uniform. Eleven borings along this stretch encountered ground water at depths ranging between 5 feet to 13 feet bgs (-4 feet to 9 feet MSL). Only one of several borings between Clairemont Drive and Balboa Avenue encountered ground water. In the boring where it was encountered, it was measured at a depth of 15 feet bgs (29 feet MSL).

Several shallow borings on the order of 10 feet deep were penetrated between Balboa Avenue and the Rose Creek South Bridge, none of which encountered ground water. Five borings between the Rose Creek South and Rose Creek North Bridges encountered ground water at depths between 5 feet to 15 feet bgs (36 feet to 51 feet MSL). Eight shallow borings of 10 feet or less were penetrated between the Rose Creek North Bridge and SR 52, with only one reporting ground water at a depth of 5 feet bgs (62 feet MSL). Based on the similar hydraulic and geomorphological conditions, it is anticipated that ground-water depths along this stretch are similar to the ground-water depth south of the Rose Creek North Bridge, which is less than 20 feet. The same conditions also are anticipated for the stretch north of SR 52 to Gilman Drive, where ground-water data were not available for review.

North of Gilman Drive, the topography steepens up to the top of the mesa and ground- water depth likely increase. Ground water was not encountered in borings by Kleinfelder (2011b) to depths up to 86 feet bgs on both sides of I-5 in the area of the La Jolla Village Square shopping center. Reviews of boring data at sites on the UCSD campus and along Genesee Avenue do not indicate ground water within the drill depths up to 86 feet. Perched ground water can be anticipated in isolated areas, such as along the bottom of canyons or drainage fills.

Ground-water levels are subject to change based on influences of tidal and seasonal effects, irrigation, and rainfall amounts. The ground-water levels reported above should be considered as a general indicator of anticipated conditions. 4.2 Geologic and Seismic Hazards This section describes and considers potential geologic and seismic hazards along the project alignment. The hazards include strong ground shaking, fault ground rupture, landslides, slope instability, liquefaction, lateral spread, compressible soils, and expansive soils. Figure 4-4 depicts potential geologic and geotechnical hazards along the corridor, except for faulting, which is depicted on Figure 4-8 through Figure 4-13. The evaluation is based on review of available geologic maps, topographic maps, published reports, previous geotechnical and geologic investigations, aerial photography analysis, and cursory field mapping. No subsurface investigation was conducted as part of this phase of the study. The following subsections identify specific locations where potential hazards are most likely to exist.

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4.2.1 Regional Faulting As shown in Figure 4-5, Southern California straddles the boundary between two global tectonic plates known as the North American Plate (on the east) and the Pacific Plate (on the west). Active faults associated with this plate boundary cross through some of the most densely populated and developed areas of Southern California. The SAFS is the main boundary between the North American and Pacific tectonic plates and it stretches northwest from the Gulf of California in Mexico, through the desert region of the Imperial Valley, crossing the San Bernardino region, and traversing up into Northern California, where it eventually trends offshore near San Francisco. Within Southern California, the SAFS comprises a complex system of numerous faults that span a 150-mile-wide zone, from the main San Andreas fault in the Imperial Valley, westward to offshore of San Diego. The major faults east of San Diego (from east to west) are the San Andreas fault, the San Jacinto fault, and the Elsinore fault; major faults to the west are the Palos Verdes–Coronado Bank fault, the San Diego Trough fault, and the San Clemente fault. The most dominant zone of faulting within the San Diego region has several faults associated with the RCFZ. Although activity on any of the faults within the SAFS affects the seismicity of the San Diego region, activity within the RCFZ dominates the seismic hazard in the metropolitan San Diego region.

The SAFS is a transform plate boundary dominated by right-lateral fault displacement (Wallace, 1990; Weldon and Sieh, 1985), with the Pacific Plate moving northwest relative to the North American Plate. A transform plate boundary differs from a convergent plate boundary such as that off of the coast of Japan or Oregon (the Cascadia Subduction Zone), where the tectonic plates are “crashing” into each other, with one plate riding under (being subducted below) the other. The significance of this is that the maximum earthquake magnitudes generated by transform plate interactions are typically much smaller than those generated at convergent or subduction plate boundaries.

This is the case in Southern California, where expected maximum moment magnitudes for most faults are typically in the M7.0 to 7.5 range, with only a few faults (San Andreas fault and possibly some thrust faults of the Transverse Ranges) capable of generating earthquakes in the M8 range, such as the 1906 San Francisco and 1857 Fort Tejon earthquakes on the San Andreas fault itself.

Most of the seismic energy and associated fault displacement within the SAFS occurs along the fault structures closest to the plate boundary (i.e., on the Elsinore, San Jacinto, and San Andreas faults). Approximately 49 millimeters per year (mm/yr) (1.9 inches/year) of overall lateral displacement have been measured geodetically and as fault slip across the plate boundary. Combined, the Elsinore, San Jacinto, and San Andreas faults account for up to 41 mm/yr (1.6 inches/year) of the total plate displacement (84 percent), meaning that the remaining 8 mm/year (0.3 inch) (16 percent) is accommodated across the faults to the west (Bennett et al., 1996). At the latitude of San Diego, most of this, about 5–8 mm/yr, is accommodated by the coastal and offshore system of faults, including the Rose Canyon fault. Farther north, a similar amount (6–8 mm/year) is accommodated east of the San Andreas fault in the Eastern California Shear Zone (Rockwell et al., 2000).

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Figure 4-4. Geologic Hazards in Study Area

Source: SanGIS, 2011; City of San Diego, 2008a; SANDAG, 2013

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Figure 4-4. Geologic Hazards in Study Area (continued)

Source: SanGIS, 2011; City of San Diego, 2008a; SANDAG, 2013

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Figure 4-5. Tectonic Plates and Faults in Southern California

Source: CGS, 2010; USGS, 2011

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4.2.2 Seismicity The project is located within one of the most seismically active areas of the United States. Southern California has numerous active faults and, as such, the project alignment is anticipated to be affected by ground motion from seismic shaking within its design lifetime.

Figure 4-6 shows many of the active faults within an approximate 60-mile radius (100 kilometers) of the project alignment, along with the locations of epicenters of historical seismic events.

Table 4-2 lists 11 of the most significant faults within this same radius and also reports other fault parameters, such as fault length, maximum magnitude, slip rate (average amount of relative geologic slip per year), and recurrence interval (average interval in years between earthquakes). These fault data are based on fault parameters developed by the U.S. Geological Survey (USGS) for a probabilistic seismic hazard analysis (PSHA) performed as part of the National Seismic Hazard Mapping Project (Petersen et al., 2008). For most of the faults listed in this table, Petersen et al. provides alternative rupture scenarios involving one or more segments of the fault. For the sake of brevity, this table lists only the rupture scenario producing the longest rupture length and largest magnitude. The California Department of Transportation (Caltrans) (2009a, 2010b) has used the USGS PSHA data and its own fault database parameters (2007) to develop design ground motion parameters. Note that, in some cases, there are minor variations between the Caltrans (2007) and Petersen (2008) databases.

Table 4-2. Summary of Faults within 60 Miles of Project

Approximate Approximate Minimum Fault Distance Maximum Length to Site Moment Slip Rate Fault Name (miles) (miles) Magnitude* (inches/year) Newport Inglewood—Rose 130 0 7.5 0.06 Canyon Connected (alt 2**) Coronado Bank 116 12.8 7.4 0.12 Palos Verdes Connected 62 13.9 7.7 0.12 San Diego Trough 75 23.6 7.49 0.04 Elsinore; W+GI+T+J+CM** 159 38.8 7.85 0.04-0.20 Earthquake Valley 12 44.7 6.80 0.08 San Clemente North 72 48.2 7.47 0.08 San Clemente South 37 49.7 7.10 0.08 Palos Verdes 62 52.8 7.30 0.12 San Joaquin Hills 17 57.8 7.10 0.02 San Jacinto; 161 60.0 7.88 0.04->0.20 SBV+SJV+A+CC+B+SM** Source: Petersen et al., 2008 Notes: * Moment magnitude is an estimate of an earthquake’s size based on rock rigidity, amount of slip, and area of rupture. ** Scenario with fault segments producing the largest magnitude listed.

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Figure 4-6. Regional Faults and Seismicity within 60 Miles of Project

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4.2.3 Local Faulting and Surface Fault Rupture Hazard 4.2.3.1 Rose Canyon Fault Zone The RCFZ occurs both in the offshore (submarine) and onshore (subaerial) areas of San Diego. It stretches north from offshore of Imperial Beach through Coronado, into Downtown San Diego, and northward along the I-5 corridor, where it passes into southern Rose Canyon, then crosses Mount Soledad, and finally passes offshore just south of the La Jolla Beach and Tennis Club (Figure 4-7).

The RCFZ is composed of a complex system of many subparallel fault strands, both active and potentially active, that occupies a band of deformation from 0.5 mile to 3 miles wide (Treiman, 1993; Lindvall & Rockwell, 1995; and Rockwell, 2010). The fault zone is widest in the south, in San Diego Bay, and on Coronado Island, where it is composed of three faults designated as the Silver Strand fault, the Coronado fault, and the Spanish Bight fault. To the north, in Downtown San Diego, numerous potentially active faults have been identified along with two areas of active faulting, one on the west side of downtown near the Federal Courthouse (San Diego fault) and the other on the eastern side of downtown near the City College (Downtown Graben fault). The zone of faulting north of downtown is not clearly defined and is thought to be limited to a narrow band that is roughly parallel to the I-5 corridor, projecting up to the northern end of Mission Bay. North of Mission Bay, the zone of faulting is much better expressed and continues up along the Rose Creek drainage and crosses up onto Mount Soledad.

Faulting within the northern section of the RCFZ from the Old Town area to Mount Soledad has been recognized since geologists first started mapping these areas in the early 20th century. Michael Kennedy (1975) published the first comprehensive map of the La Jolla area, and shows that the RCFZ comprises several subparallel fault strands. Most maps produced since then, including the City of San Diego Seismic Hazard Maps, rely heavily on Kennedy’s work. Kennedy delineated three fault strands in the Old Town and Morena areas and named the most southeastern of these the Old Town fault. East of Mission Bay he delineated two faults: the easternmost is the Rose Canyon fault and the western strand is the Mission Bay fault. Except for the Rose Canyon fault and a few sections of the Old Town fault, which are mapped as “known” structures (solid lines), most of the fault strands through this area are mapped as concealed structures (dotted lines). This means that they are covered by younger unfaulted material, and their locations are conjectured based on interpretation of other known areas of faulting nearby. Concealed faults therefore may or may not be present. Through Rose Canyon and La Jolla, the RCFZ branches into an approximate 1-mile-wide zone of three principal faults. The easternmost of these faults is the Rose Canyon fault, which trends along the eastern side of Rose Canyon and makes a northwestward bend across the north face of Mount Soledad near the SR 52/I-5 interchange. The Mount Soledad fault trends across the western side of Rose Canyon and makes a northwestward bend up Mount Soledad, crossing over just west of the Memorial Cross. The westernmost fault is the Country Club fault. These faults tighten into a 0.5-mile zone on the north, near the shoreline at the La Jolla Beach and Tennis Club, and continue offshore to the northwest.

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Figure 4-7. Rose Canyon Fault Zone

Source: J.A. Treiman, 1993

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Historically, San Diego was long considered a region of negligible seismic hazard. Except for the occurrence of a local event in 1862 (Legg and Agnew, 1979), there has been a lack of significant seismic activity during the recorded history of San Diego. At the time of the publication of Kennedy’s map in 1975 and up until the late 1980s, the RCFZ was thought to be a pre-Holocene structure and was mostly thought to be an inactive or potentially active fault. However, over the past 30 years, fault studies have shown a substantial potential for local seismic activity on certain fault segments within the RCFZ. The most important of these studies was in the southern Rose Creek drainage (east of Mount Soledad, near La Jolla), which uncovered an active strand of the Mount Soledad fault (Rockwell et al., 1991; Lindvall and Rockwell, 1995). Paleoseismic analysis identified a stream channel displaced laterally 30 feet during as many as three discrete earthquake events over the past 8,000 years. Other studies in Downtown San Diego (Testing Engineers et al., 1985; Patterson et al., 1986; and Kleinfelder, 1998) also identified active faulting in both the eastern and western sides of the city core, as previously discussed. Studies farther south in San Diego Bay (Kennedy and Clarke, 1999a and 1999b) and in the City of Coronado (Kleinfelder, 2006 and URS, 2007) have revealed Holocene activity on the Coronado fault, Silver Strand fault, and Spanish Bight fault. Thus, there is ample evidence of recent activity spanning discrete areas of nearly the entire onshore stretch of the RCFZ. Evidence also has been presented that indicates that the RCFZ may be structurally connected to the Newport Inglewood Fault Zone (Grant and Rockwell, 2002; Grant and Shearer, 2004) on the north and the San Miguel–Vallecitos fault or the offshore Descanso fault on the south, all of which are active faults. If this is indeed true, the RFCZ is part of a larger active fault system that stretches more than 150 miles.

The State of California has designated active Alquist-Priolo Earthquake Fault Zones (EFZ) for sections of the RCFZ in Coronado, Downtown San Diego, and the section between the north end of Mission Bay (near De Anza Cove) and the coast in La Jolla. The section of the RCFZ north of Downtown San Diego to De Anza Cove has not been designated as an active EFZ. This is due to the absence of good information on the strand of the fault through this area. As noted earlier, much of the fault through this area is mapped as a concealed (conjectured) feature. However, it should not be construed that active faults are not present along this stretch.

4.2.3.2 Potentially Active Faults Potentially active faults are faults that have undergone movement during the Pleistocene epoch, but ceased their activity sometime prior to the beginning of the present Holocene epoch. They are commonly referred to as “pre-Holocene” faults, which corresponds to an activity period of from 1.6 million years before present (BP) to about 11,000 years BP.

Numerous potentially active faults have been identified within the project alignment north of the SR 52/I-5 interchange (Figure 4-7). Most of these faults are believed to be part of an old system of faulting associated with the incipient development of the early RCFZ (Kern, 1988). This is inferred because they, for the most part, do not displace Pleistocene terraces and because their orientation is generally to the north–northeast, which is strongly misaligned with the northwest structural trend of the active RCFZ. Additionally, it has been recognized that most of these faults are isolated within the Eocene rocks and do not penetrate upward into the overlying Pleistocene-age terrace

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deposits of the Lindavista Formation. It is thought that, as the RCFZ was initially developing, an earlier precursor north-to-northeast system of echelon faults developed first and eventually gave way to the current north–northwest regional structural grain associated with the currently active RCFZ. Three of the largest faults in this earlier fault system are the Scripps fault, the Torrey Pines fault, and the Salk fault. The project crosses several potentially active faults, including those associated with the Scripps and Torrey Pines faults.

It also should be understood that many of the faults within the active RCFZ likely are pre-Holocene, as they were previously active during the early development of the system. The current knowledge (Lindvall & Rockwell, 1995; Testing Engineers et al., 1985; Kleinfelder, 1998; and Kennedy and Clarke, 1999a) shows that active faulting has been delineated only along several isolated segments, including portions of the Mount Soledad fault in Rose Canyon and across Mount Soledad, and faults in Old Town, Downtown San Diego, and to the south in San Diego Bay and Coronado.

4.2.3.3 Fault Surface Rupture Hazard Fault surface rupture is a substantial hazard for the southern section of the project alignment between Downtown San Diego and the SR 52/I-5 interchange because this segment is within the area of influence of the active RCFZ.

Faulting is present north of the interchange, but this region is not within a recognized area of active faulting. Faults in the northern section are considered potentially active, meaning that fault activity ceased prior to the Holocene and likely during the early- to mid-Pleistocene time. Thus the hazard for fault surface rupture in the northern section is considered negligible.

While previous mapping (Kennedy, 1975; City of San Diego, 2008a; and California Division of Mines and Geology [CDMG], 1991) identified many faults within the Southern Geologic Section, the 1991 CDMG study was the only study that identified active faults in this section. This 1991 study, however, was limited to the area north of DeAnza Cove and faults south of this location to the north area of Downtown San Diego were not identified or classified. Consequently, a detailed analysis of vintage aerial photography was undertaken to evaluate the suspected presence of active fault-related features across the entire alignment north of Downtown San Diego to the SR 52/I-5 interchange. The faults from these sources are depicted for the entire alignment on Figure 4-8. Figure 4-9 through Figure 4-13 provide detailed close-ups of the areas of faulting along the alignment.

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Figure 4-8. Study Area Fault Map

Source: SanGIS, 2011; CGS, 2011; Kleinfelder, 2011a, b, c; SANDAG, 2013

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Figure 4-8. Study Area Fault Map (continued)

Source: SanGIS, 2011; CGS, 2011; Kleinfelder, 2011a, b, c; SANDAG, 2013

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Figure 4-9. Detail Fault Map (South of Old Town Transit Center)

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Figure 4-10. Detail Fault Map (Approximate Stations 185–295)

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Figure 4-11. Detail Fault Map (Approximate Stations 260–418)

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Figure 4-12. Detail Fault Map (Approximate Stations 370–535)

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Figure 4-13. Detail Fault Map (Approximate Stations 532–773)

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The standards for indicating faults on a map are as follows:

 Solid lines: Faults that are well-located (known) and usually have been verified visually in the field  Dashed lines: Inferred fault strands that have not necessarily been observed in the field or on aerial photographs, and are thus “inferred,” usually between two locations of known faulting  Dotted lines: Concealed faults that do not break the surface geologic units, but are inferred in the subsurface units across an area

These standards are the basis of the fault strands for the Kennedy, CDMG, and city maps. The CDMG fault strands differ from the other two maps, in that they are all active faults.

The faults mapped in this current study (denoted on Figure 4-8 through Figure 4-13 as “Kleinfelder 2011” faults) employ a similar standard of identification, but have been interpreted almost entirely based on analysis of aerial photography. Some of the Kleinfelder fault strands were confirmed later during limited field reconnaissance activities. Solid lines are used for locations where the surface features observed in aerial photographs strongly indicate the presence of an active fault strand. As an example, the solid line across Balboa Avenue and to the south was drawn based on a series of aligned right-deflected drainages. Dashed lines have a lower confidence level for active faulting and have been drawn based on lesser indicative features, such as lineaments (a geomorphic or tonal linear surface feature—see Abbreviations and Glossary for more detail). The Kleinfelder faults are thus only suspected active features, and additional study would be required to confirm their presence and activity status. Such investigations are planned to occur during Preliminary Engineering.

Table 4-3 identifies 23 “fault hazard” locations where suspected and confirmed faults have been mapped as either crossing the alignment or occurring within 25 feet of the alignment. The table also denotes the station number of the hazard, the type of structure proposed at the location, the source of the fault data, and pertinent comments. Active faults require mitigation at locations where structures are planned. Potentially active faults do not require mitigation.

Table 4-3. Faulting Hazards

Fault Station Proposed Fault Hazard Number1 Structure Fault Data Source Classification Comments 1 239+50 Trolley station Kleinfelder Active (dashed) Fault is 100 feet to east but crosses under Sea World Dr bridge. 2 250+00 - At-grade Kleinfelder Active (dashed) Fault trends parallel to tracks. 265+00 tracks 3 292+00 At-grade City of San Diego Potentially Location of fault is conjectured. tracks Active (concealed) 4 302+25 At-grade Kleinfelder Active (dashed) Fault ends 20 feet west of tracks. tracks 5 314+25 Station Kleinfelder Active (dashed) Fault trends into station below Clairemont Dr overpass.

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Table 4-3. Faulting Hazards (continued)

Fault Station Proposed Hazard Number1 Structure Fault Data Source Fault Class. Comments 6 332+00 – Trolley station Kleinfelder and Active (dashed Fault trends parallel to tracks and 378+00 and At-grade California and solid) Balboa Ave Station. tracks Geological Survey 7 378+00 – Bridge Kleinfelder and Active (solid) Fault trends parallel to bridge. 381+00 City of San Diego 8 389+00 At-grade City of San Diego Potentially active Location of fault is conjectured. tracks (concealed) 9 398+00 At-grade City of San Diego Potentially active Fault is mapped as terminating 20 tracks (solid) feet east of tracks.

10 400+00 At-grade City of San Diego Potentially active Fault is mapped as terminating 20 tracks (solid) feet east of tracks 11 417+75 At-grade City of San Diego Potentially active Location of fault is conjectured. tracks (concealed) 12 427+50 Bridge Kleinfelder Active (dashed) Fault is indicated in previous study and on strike with nearby faults. 13 438+50 At-grade City of San Diego Potentially active Location of fault is conjectured. tracks (concealed) 14 461+00 – At-grade City of San Diego Potentially active Location of fault is conjectured. 469+00 tracks (concealed) 15 475+25 Bridge Kleinfelder Active (dashed) Fault crosses south bridge abutment. 16 485+00 – Bridge City of San Diego Potentially active Fault trends parallel to bridge. 497+00 (concealed) Fault is not identified in trench into bedrock in previous study. 17 580+50 At-grade City of San Diego Potentially active Mapped strand is only 750 feet tracks (solid) long. 18 582+25 At-grade City of San Diego Potentially active Mapped strand is only 1,000 feet tracks (solid) long. 19 587+75 At-grade City of San Diego Potentially active Mapped strand is only 750 feet tracks (solid) long. 20 638+70 Aerial City of San Diego Potentially active Eastern and western sections of structure (solid) fault are mapped as concealed below Pleistocene Lindavista Formation. 21 670+70 Aerial City of San Diego Potentially active Fault is mapped as concealed structure (concealed below Pleistocene Lindavista Formation. 22 696+50 Aerial City of San Diego Potentially active Fault is mapped as concealed structure (concealed below Pleistocene Lindavista Formation. 23 740+25 Aerial City of San Diego Potentially active Fault is mapped as concealed structure (concealed) below Pleistocene Lindavista Formation. Source: SANDAG, 2012

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Field Reconnaissance—Confirmation of Some Lineaments as Faults After preliminary analysis of the 1928 and 1953 aerial photography, a field reconnaissance evaluated whether some fault splays could be identified in the field and searched for possible sites to conduct additional field investigations in critical areas. Interpretations of fault locations were plotted on each of the image and map bases using the Google Earth base to locate field positions.

The modern landscape is heavily modified, and few if any scarps are preserved because of development. As noted previously, in the Morena area, a topographic depression is preserved in an area of commercial development, although some areas have been leveled and others filled. All scarps recognized in the imagery have been destroyed or buried. Road-cut along Morena Boulevard, however, confirmed the presence of a minor, secondary fault near the Balboa Avenue Station, and a railroad cut confirmed a fault near the Morena Boulevard/West Morena Boulevard intersection.

In the southern Rose Creek area where a scarp was mapped across a low terrace, the location of the suspected fault was confirmed by previous trenching by Lindvall and Rockwell (1995). The same imagery and criteria were used in this study as was used by Lindvall and Rockwell (1995) to map and locate suspected active strands of the fault, so it is reasonable to infer that other scarps across the low, Holocene terrace to Rose Creek also are good evidence of fault location and activity in the Rose Creek area.

One major issue is that the fault locations found in this study (for the project alignment) do not always coincide with the locations found in earlier work. This is notable in some cases and probably results from three primary causes, which are described in the following paragraphs.

First, many of the earlier fault locations are a dotted or dashed line, which implies that the fault is buried and only approximately located or inferred. In several of these cases, this current study was able to identify specific geomorphic features, such as scarps, deflected drainages, and offset drainage walls, to locate active fault strands. In contrast, most of the previous investigators either did not have access to the early aerial photographs or did not use them.

Second, the mapping by Kennedy (1975) was based on the distribution of rock units and not interpretation of aerial photography. As such, the mapping is inferred by the presence and approximate location of faults in areas of active alluvium or beneath Mission Bay. Mission Bay is a good example because Kennedy dotted the fault line under the Bay, whereas this current study documents strong geomorphic evidence of the fault onshore through the Morena area.

Third, portions of the map are based on a study prepared for the City of San Diego in 1974 that described the Rose Canyon fault as potentially active. The Seismic Safety Element of the City of San Diego General Plan acknowledges that more recent independent studies consider this fault to be active. This current study is based on analysis of the aerial photographs noted above and located the faults based on their inferred presence from their impacts in the landscape.

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A caveat, however, is that not all of the fault-like features mapped by this current study are necessarily actual faults, so the presence of inferred or suspected faults in critical areas needs to be confirmed in subsequent design-level studies. In fact, additional field investigation is planned during Preliminary Engineering to determine the actual location of faults.

Active Faults Mapped by CDMG (1991) The CDMG map shows an active fault trending nearly coincident with the project alignment for a stretch of nearly 3,500 feet, starting 900 feet south of Balboa Avenue and extending southward to the latitude of DeAnza Cove. There are no other locations on this map where active faults cross the alignment. There are two places where faults occur within several hundred feet of the alignment: one is west of the proposed Balboa Avenue crossing and the other is in the area 700 feet to the north of Jutland Drive.

City of San Diego Faults (2008a) As noted previously, the City of San Diego has mapped numerous faults along the alignment. The city does not, however, identify any of these as active but places them all in a general fault category defined as “inactive, presumed inactive or activity unknown.” Several of the city-mapped faults cross near to or are close to the alignment (Table 4-3). Many of the city faults are mapped as “concealed” (as dotted lines), which are considered hypothetical or highly questionable with respect to their location on the maps. There are no well-defined faults (solid lines) on city maps that cross the alignment. However, two parallel, well-defined faults occur within 25 feet of the eastern side of the alignment in an area approximately 2,000 feet north of Balboa Avenue.

One city fault is of particular interest because of its possible impacts on the Rose Creek LRT Overhead Bridge over the rail tracks of the Los Angeles—San Diego—San Luis Obispo Rail Corridor Agency. The city map shows a concealed fault directly adjacent and parallel to the bridge. Geocon performed two previous fault studies on subdivisions to the east of the proposed bridge in an area crossed by this fault. The 1982 Geocon fault study for the Rose Canyon Business Park excavated a 420-foot-long trench along the eastern bank of Rose Creek that intersected the conjectured strand of this fault. The trench log identifies small shear features in steeply dipping Ardath Shale, but no major faults were located and the stratigraphy is shown as continuous throughout the trench. Another study by Geocon for the View Terrace site in 1978 uncovered a fault trending in a direction away from the northern side of the bridge and toward the south bridge abutment. Thus, the work by Geocon shows that the concealed fault on the city map is not present below the northern side of the bridge and likely was an inaccurate extrapolation of the fault identified by Geocon on the View Terrace site.

4.2.4 Strong Ground Shaking As with all of Southern California, the project area is located in a seismically active area and the project can be expected to experience strong ground shaking from earthquakes during its lifetime. Based on the Caltrans (2010b) methodology for estimating design strong-ground motions, peak ground accelerations along the alignment are expected to range from 0.44 to 0.58 g (peak ground acceleration) resulting from an earthquake on the RCFZ.

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4.2.5 Liquefaction and Seismic Settlement Earthquake-induced soil liquefaction is described as a substantial loss of soil strength and stiffness caused by an increase in pore water pressure resulting from cyclic loading during shaking. Liquefaction is most prevalent in loose to medium-dense, sandy and gravely soils below the ground-water table. The potential consequences of liquefaction to engineered structures include loss of bearing capacity, buoyancy forces on underground structures, ground oscillations (cyclic mobility), increased lateral earth pressures on retaining walls, post-liquefaction settlement, lateral spreading, and “flow failures” in slopes.

Seismic settlement is a related phenomenon in which loose to medium-dense unsaturated soil tends to densify and settle during strong earthquake shaking.

The project alignment from Old Town to Gilman Drive traverses long stretches of liquefaction-prone alluvium. The city designates the area from Old Town to the latitude across from Baker Street as a high liquefaction potential. North of this location to Gilman Drive, the liquefaction potential is designated as low. Review of the project boring data and field reconnaissance indicate that the stretch from Old Town to the Morena Boulevard/West Morena Boulevard intersection is underlain by a thick (up to 200 feet or deeper) deposit of alluvium and bay deposits. As much as the upper 100 feet of this material may be loose enough to be prone to liquefaction. In addition, ground water in this area is typically within 10 feet of the ground surface. Based on these conditions, the potential for liquefaction is considered to range from moderate to high.

South of Old Town, potentially deep alluvium also is present below the Old Town Transit Center traction power substation (TPSS) and the potential for liquefaction is considered moderate to high. The existing alignment crosses out of these deep alluvial deposits on the south near Washington Street. The Wright Street TPSS is depicted on the city hazard maps as being underlain by soils with a low liquefaction potential.

North of the Morena Boulevard/West Morena Boulevard intersection, the alignment crosses onto a low coastal terrace underlain by the Bay Point Formation. This formation appears to underlie the alignment from this intersection to a latitude just south of Balboa Avenue. The Bay Point Formation consists mostly of silty and clayey sands that are typically dense to very dense and weakly to moderately cemented, and therefore is not typically considered a risk for liquefaction. Ground water levels are anticipated to be within 10 feet of the surface to Clairemont Drive, and deepen to the north as the alignment rises up onto the higher terrace level. The liquefaction potential through this stretch of the alignment is considered low. However, areas along the low coastal terrace section may be underlain by isolated areas of stream-deposited alluvium and/or bay deposits laid down in small inlets. The liquefaction potential in these likely small isolated patches would be higher, possibly a moderate or even high level.

From Balboa Avenue north to Gilman Drive, the alignment lies within the Rose Creek drainage and is underlain by relatively shallow alluvial deposits. This alluvium is typically coarse-grained, consisting of discontinuous layers of gravel, sand, and silt. Ground water is usually within 15 feet of the ground surface. The liquefaction potential through this stretch is considered low to moderate.

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North of Gilman Drive to the terminus at the UTC Transit Center, the alignment is located over older consolidated geologic material that is not considered prone to liquefaction.

Areas of potential seismic settlement risk are similar to the same areas of liquefaction risk underlain by alluvium. The risk is considered moderate to high for the deep alluvium north of Old Town, and low to moderate for the stretch from Balboa Avenue to Gilman Drive. North of Gilman Drive, the risk is considered nominal, except for areas where substantial fill exists, which may have a moderate risk of seismic settlement.

4.2.6 Lateral Spread Lateral spread is a liquefaction-related phenomenon in areas of gently sloping and/or a free face condition, such as the slope of a river bank (Kramer, 1996). It horizontally (laterally) displaces large surficial masses of soil, often as intact or broken-up blocks, because of earthquake-induced liquefaction. The path of displacement is typically very low angle, in a downslope direction, and can range from inches to several tens of feet of travel.

With the presence of liquefiable soils and areas of sloping ground and/or free faces (i.e., as in the case of the San Diego River and Tecolote Creek), lateral spreading hazard is considered moderate to high in the area from Old Town to the Morena Boulevard/West Morena Boulevard intersection.

Areas of possible susceptibility for lateral spread are located within the Rose Creek drainage from the southern bridge crossing of Rose Creek (0.75 mile north of Balboa Avenue) to Gilman Drive. The alignment would trend along stream terraces adjacent to the banks of Rose Creek (free face condition) through a large portion of this stretch. The zones where the alignment would follow closer to creek banks would be considered more at risk of being affected by lateral spread. The closest location is an approximate 2,500-foot-long stretch between the Rose Creek South Bridge and the Rose Creek North Bridge. In this location, the alignment would be along the crest of the bank. The alignment would trend near the creek bank at SR 52 where a U-shaped open-channel structure would convey creek flow east of the tracks. Directly north of this location, the alignment trends as close as 30 feet to the crest of the creek bank for a distance of 2,200 feet northward. Because lateral spread is a phenomenon related to liquefaction, the lateral spreading risk is considered low for the areas noted above.

4.2.7 Tsunami and Seiche Tsunamis are large sea waves that are most often generated by displacement of the ocean floor along submarine faults. They also can develop in response to other events, such as submarine landslides. Certain fault types are particularly likely to cause large tsunamis, including subduction faults with vertical displacements, such as those off the coast of Japan and Indonesia. Faults off the coast of California are mostly strike-slip faults with lateral-type displacement and relatively small amounts of vertical displacement. Thus, the near-field tsunami hazard along the California coast is much less severe than that of areas such as Japan.

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The California Emergency Management Agency (Cal EMA) (Cal EMA, 2009) has mapped the tsunami inundation area for the coastal area of the state. These maps are based on the current scientific understanding of tsunami hazard and depict anticipated areas of inundation and the maximum considered run-up (travel distance inland from the shore) from a number of extreme, yet realistic, tsunami sources. Review of these maps for the La Jolla, Point Loma, and Del Mar quadrangles reveals only one location of possible inundation. This location is at the Tecolote Creek Bridge site (Figure 4-14). The bridge site is at the easternmost edge of the inundation line for this area.

A seiche is an oscillatory wave that develops in an enclosed or partially enclosed body of water, such as a bay or lake, in response to seismic shaking from an earthquake. The size of the generated wave depends on several variables such as the intensity and frequency of shaking and the size and shape of the water body. Mission Bay is the closest body of water to the project and lies to the west of the alignment between Tecolote Creek and De Anza Cove. Along this stretch, the edge of the bay ranges from between 350 to 1,300 feet west of the alignment. Based on the distance of the bay from the alignment, inundation from a seiche would be unlikely.

4.2.8 Landslides, Mudslides, and Slope Stability 4.2.8.1 Landslides Landslides are composed of a variety of deep-seated ground failures (several tens to hundreds of feet deep) in which a large mass of a slope becomes unstable, decouples from the underlying intact slope material, and slides downhill under the forces of gravity. The most common landslide types in this area of San Diego are arcuate-shaped rotational failures and translational block failures. Landslides are not to be confused with minor slope failures (slumps), which are usually limited to the upper topsoil zone (usually less than 10 feet thick) and can occur on slopes composed of almost any geologic material.

Landslides can damage structures both above and below the slide mass. Structures above the slide area are typically damaged by undermining of foundations; areas below a slide mass can be damaged by being overridden and crushed by the failed slope material.

According to the hazard maps of the city’s Seismic Safety Study, only one landslide hazard is near the project alignment. The map shows a landslide occurred on the east side of the alignment just south of the Rose Creek LRT Overhead Bridge. It is likely that this landslide was identified prior to development of the property. The site is currently occupied by commercial buildings on a level, graded pad and shows no indication of landslide morphology. A site reconnaissance confirmed its level configuration and absence of signs of landsliding. It appears that the landslide (if it was ever present) was mitigated during grading. In this case, the landslide hazard is low based on the level site configuration.

Two additional ancient landslides were identified during the aerial photography review.

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Figure 4-14. Maximum Tsunami Inundation (La Jolla and Del Mar Quadrangles)

Source: CEMA, Tsunami Inundation Map for Emergency Planning La Jolla Quadrangle, 2009

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The first landslide is across from De Anza Cove. The landslide translated from east to west across the area occupied by Morena Boulevard and the project alignment, coming to rest in the area of the current location of Mission Bay Drive. Portions of this landslide are still preserved between the west shoulder of Morena Boulevard and the east side of the railroad tracks. Most of the debris flow material has been removed by grading of Morena Boulevard, the rail line, and I-5. The hazard potential from this feature is considered to be low.

The second landslide is located 0.6 mile north of Balboa Avenue. It consists of a large translational failure that slid from the hillside to the east of Morena Boulevard toward the southwest, crossing the area currently occupied by the project alignment and stopping in the Rose Creek drainage. The project alignment is located in the toe area of the slide. This feature is clearly seen on both the 1928 and 1953 aerial photographs, which were taken prior to development of this area. The slide area is up to 1,300 feet long and 700 feet wide. Since the time of the 1953 aerial photography, there has been substantial grading in this area. A comparison of the aerial photography with modern imagery and field observations indicates that much of the slide has been removed. The head of the slide was cut by grading for a large residential subdivision. Cut-type grading (more than 100 feet deep) for Morena Boulevard removed the central portion of the slide mass. In the toe area, just west of Morena Boulevard, grading (likely fill-type grading) was performed for development of several commercial building pads. A large portion of the upper and central sections of the slide has been removed, and fill was likely placed across the toe of the slide. Therefore, this area is considered to be in more stable configuration now than prior to the grading, and the hazard to the alignment is considered low.

4.2.8.2 Mudslides and Debris Flows A mudslide is a type of slope failure that typically consists of a relatively rapid fluid flow of mud-sized grains. A debris flow is similar to a mudslide, except that it contains a mixture of saturated soil consisting of an assortment of different-sized particles (mud, sand, gravel, and boulders). Each often results from failure of saturated soils on slopes during periods of heavy rainfall, but each can result from saturation that is due to over-irrigation or infiltration from ruptured water lines, sewer lines, or storm drains. Mudslides in the San Diego region can range from several feet to tens of feet deep, can travel great distances, and can be quite destructive. Based on review of the project, the hazard with respect to mudslides over most of the alignment is considered low due to low surface topography between Old Town and La Jolla Colony Drive, the stretch along the Nobel Viaduct between the I-5 crossing to La Jolla Village Drive, and from UCSD to the UTC Transit Center. The hazard is considered low to moderate for the stretches between La Jolla Colony Drive to the south abutment of the Nobel Viaduct and across La Jolla Village Drive to the UCSD West Station. These two areas are adjacent to slopes that could have small to moderate-sized mudslides.

4.2.8.3 Slope Stability Slope stability is a measure of the proneness of an inclined ground surface to failure, such as a landslide. It often is measured as a ratio known as the “factor of safety,” which is a comparison of forces driving and resisting failure. A slope with a factor of safety of 1 is understood to have a balance between the driving and resisting forces, and

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is therefore extremely close to failure. Areas most prone to landsliding are steep slopes composed of materials with high clay content. Other factors, such as inclined bedding projecting downward out of a slope face, also can facilitate instability. Within San Diego, several geologic formations are particularly prone to landsliding. One of these is the Ardath Shale, which occurs on several slopes adjacent to the project alignment. The geologic hazard maps on Figure 4-4, from the city’s Seismic Safety Study, depicts areas of low to high risk for potential slope instability (landsliding).

The project alignment between Downtown San Diego and Clairemont Drive is relatively flat, and slope stability is not an issue along this stretch, except for slopes at bridge abutments and some minor slopes and retaining walls.

North of Clairemont Drive, the alignment rises up along a low, west-facing hillside and continues across this feature to Balboa Avenue. This area is along the edge of a moderate risk zone and there are both cut and fill slopes here that range from 10 to 15 feet high. The fill slopes extend downward from the west side of the existing rail line and are constructed at gradients of up to 1.5:1 (horizontal to vertical units). They do not exhibit notable degradation or past failure, and appear to have performed well. Cut slopes up to 15 feet high are present along the east side of the project alignment and have gradients in excess of 1:1. They are rilled from erosion, but lack signs of gross instability. To address this risk, retaining walls are proposed to support cuts along the east side of the alignment.

North of Balboa Avenue, the alignment enters the Rose Creek drainage and extends along a west-facing hillside (similar to that south of Balboa Avenue) all the way to the Rose Creek South Bridge. The configuration and conditions of slopes also are similar to that previously described, and retaining walls are proposed to support cuts along the east side of the project alignment through several sections of this stretch.

North of the Rose Creek South Bridge and extending to Gilman Drive, the project alignment continues within the low-lying valley floor of Rose Canyon along the banks of Rose Creek. This pathway is positioned adjacent to the bank of Rose Creek. Slopes in this area range up to approximately 10 feet high and slope stability risk is considered low to moderate. (Potential liquefaction-related slope stability issues in this area are discussed in Section 4.2).

North of Gilman Drive, the alignment crosses out of the Rose Creek drainage and rises up to the Lindavista platform. Up to the proposed UCSD West Station, the alignment crosses between areas designated by the city as low to moderate risk. Ardath Shale is present along two sections of this stretch, but nearly all slopes are designated with favorable geologic structure with respect to slope stability. There is only one small area south of the UCSD West Station designated as having unfavorable geologic structure.

The alignment crosses the freeway east of the UCSD West Station. The crossing is over the I-5 cut and is designated as a low to moderate risk. The cut is composed of sandstone of the Scripps Formation with structure that dips at low angles to the south. The material and structure are favorable with respect to slope stability, and the risk here is considered low. East of the freeway crossing, to the end of the alignment at the UTC Transit Center, the alignment traverses the flat-lying Lindavista platform and is designated as nominal risk on the city maps.

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Rockslides are a slope stability concern. They are typically associated with high mountainous terrain where detached segments of bedrock move rapidly downslope, breaking up into many small independent units. Rockslides are not common in this region of San Diego, although they do occur in the steep sea cliffs in the coastal zone. As such, rockslides are not anticipated to affect the project.

4.2.9 Compressible Soils Compressible soils are materials that are prone to a reduction in volume when subjected to loading. Soils most prone to compression are unconsolidated alluvium, bay deposits, and poorly compacted fill. Areas of potential compressible soils are the alluvium areas located north of Old Town to the Morena Boulevard/West Morena Boulevard intersection, south of Old Town to Washington Street, isolated zones north of the Morena Boulevard/West Morena Boulevard intersection to Clairemont Drive, and within the Rose Creek drainage north of the Rose Creek South Bridge to Gilman Drive. Soils north of Gilman Drive are generally of low compressibility, except for isolated areas of fill.

4.2.10 Subsidence Ground subsidence can result from fluid (ground water and/or petroleum) withdrawal in weakly consolidated materials. It typically occurs in areas with deep ground-water aquifers that are subject to long-term ground-water withdrawal by wells, or in areas where petroleum resources are extracted.

The project area is serviced by a municipally supplied and conveyed water system, and no large-scale ground-water pumping occurs within this region. Additionally, this area does not have known petroleum resources. Therefore, the hazard associated with subsidence is considered low.

4.2.11 Corrosive Soils The corrosivity of soils is related to several key parameters: soil resistivity, presence of chlorides and sulfates, oxygen content, and pH level. Typically, the most corrosive soils are those with the lowest pH and the highest concentrations of chlorides and sulfates. High sulfate soils are corrosive to concrete and may prevent complete curing, reducing its strength considerably. Low pH and/or low-resistivity soils attack and corrode buried or partially buried metal components and structures.

The literature review performed for this study did not yield adequate data to provide a site-specific characterization of corrosive soils. Soil types that are generally most prone to corrosivity are clays and silts with a high moisture content; coarse sandy and gravelly alluvium is typically less prone to corrosion. It is anticipated that soils in the southern section from Old Town to Gilman Drive have a low-to-moderate potential for corrosion. North of Gilman Drive, finer-grained soils consisting of clay and silt are present, and the potential for corrosion is considered moderate and possibly high in some areas.

4.2.12 Expansive Soils Expansive soils are soils subject to volumetric fluctuations in response to changes in moisture content (wetting and drying). Expansive soils have a substantial amount of clay particles, which can both release water (shrink) or absorb and hold water (swell).

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The resultant changes in soil volumes can deflect unrestrained ground and can exert stress on foundations. Lightly loaded structures are more susceptible to damage by expansive soils. Alluvial soils typically have a high sand content and, as such, typically have a low expansion potential. Thus, it is anticipated that those areas from Old Town up through Rose Canyon have a low expansion potential and limited areas of moderately expansive clays. North of Rose Canyon, the formational soils are composed of sands, silts, and clays; and therefore a greater concentration of expansive soils can be anticipated.

Based on published soil survey descriptions, only three soil types are identified as having expansion potential due to their association with Diablo series clay (Table 4-1) and are mapped along the alignment. These soils are both of the Altamont series (AtE2 and AtF) and the Salinas clay loam (SbC). Such expansive soils are found in an isolated area just north of Tecolote Road as well as a stretch located half-way between SR 52 and Gilman Drive and extending north along the project alignment to just short of Voigt Drive.

4.2.13 Erosion Potential Erosion potential was evaluated based on data from NCSS (2008) and NRCS (2008). Most of the soils with loam (HrE2, CsB, CfB, CfC, and GaF), the escarpment soil (TeF), and Altamont clay on steep slopes (AtF) have a severe erosion potential. There are six areas of severe erosion potential along the project alignment. The southernmost area is an approximate 500-foot stretch one-quarter mile south of Clairemont Drive. Within Rose Canyon, there are three approximately 1,500-foot-long stretches. One area straddles the Rose Creek South Bridge, another is north of the latitude of Jutland Drive, and the third is approximately 1,000 feet north of SR 52. The longest stretch of severe erosion potential is approximately 8,200 feet extending between Gilman Drive and La Jolla Village Drive. The last area is a stretch of approximately 200 feet long that is located approximately 300 feet east of the proposed UCSD East Station. The Altamont clay on moderate slopes (AtE2) has a slight erosion potential, and Salinas clay loam (SbC) has a slight-to-moderate erosion potential. There is only one area of moderate erosion potential and it is an approximately 1,500-foot-long stretch just north of Tecolote Road. The majority of the soils with erosion potential are located within the alluvium of the southern portion of the project alignment.

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Geotechnical, Geologic and Seismic Impacts Technical Report Chapter 5.0 – Environmental Impacts

5.0 ENVIRONMENTAL IMPACTS

This chapter describes the impacts of the No-Build and Build Alternatives on geotechnical, geologic, and seismic conditions in the Mid-Coast Corridor. The California Environmental Quality Act significance determinations are presented in Chapter 7.0. The analysis of impacts addresses direct and indirect impacts and cumulative impacts of the alternatives under consideration. Construction impacts are described in the Mid- Coast Corridor Transit Project Construction Impacts Technical Report (SANDAG, 2013c). 5.1 Direct and Indirect Impacts This section describes the direct and indirect long-term impacts of the No-Build and Build Alternatives (both operational and facilities impacts) in 2030. The Mid-Coast Corridor is subject to a number of geotechnical, geologic, and seismic risk hazards. Compliance with building and design codes would include design measures to minimize operation impacts so that they are less than adverse for faults, strong ground shaking, liquefaction, lateral spread, mudslides, slope stability, and compressible, corrosive, and expansive soils.

5.1.1 No-Build Alternative The No-Build Alternative would not likely result in geologic and seismic impacts typically associated with development projects, including slope stability and settlement potential. Under the No-Build Alternative, continuation and enhancement of Route 150, which operates between Downtown San Diego and the University area, would replace the project. Bus frequency, in particular, would be improved. The buses would operate on existing or planned roadways and no physical improvements would be required for the improved transit services other than the minor construction associated with new bus shelters within existing rights-of-way. No ground disturbance would result. The No-Build Alternative would not result in adverse impacts.

5.1.2 Build Alternative A thorough investigation was conducted to assess potential direct geotechnical, geologic, and/or seismic impacts of the Build Alternative. The inclusion of the Genesee Avenue Design Option and/or the Veterans Administration (VA) Medical Center Station Option under the Build Alternative would not change the geologic, geotechnical, and seismic hazard impacts for the project. Therefore, the discussion of direct and indirect impacts below is the same for the project with or without the VA Medical Center Station Option or the Genesee Avenue Design Option.

5.1.2.1 Local Faulting and Surface Fault Rupture Hazard Fault surface rupture is a substantial hazard for the southern section of the project alignment between Downtown San Diego and the State Route (SR) 52/Interstate (I-) 5 interchange because this segment is within the area of influence of the active Rose Canyon Fault Zone.

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South of SR 52, eight locations have been identified where suspected active faults may affect the project alignment. Three of these locations are at or near proposed San Diego Trolley (Trolley) stations; two cross at-grade track sections; and three are through or near proposed bridge sites. Potentially active faults have been identified at eight locations. The project alignment also is located within an active Alquist-Priolo Earthquake Fault Zone between Clairemont Drive and Jutland Drive (just south of SR 52). The location of the active faults means that surface fault rupture could expose structures along the project alignment to sudden differential displacements during a strong earthquake. This could adversely affect structures through the resulting damage or destruction, and could expose people to these hazards.

The Balboa Avenue Station is located within both an active State of California Earthquake Fault Zone and a potentially active City of San Diego Fault Zone. At this location, parking demand would exceed the planned capacity of the proposed parking facility. Because of its location within the fault zones and to account for worst-case conditions, parking at this station is assumed to be limited to surface parking only (i.e., no parking structure).

All structures associated with the project would be designed in accordance with current seismic design standards, as found in the CBC (2010), the latest version of the California Department of Transportation (Caltrans) Seismic Design Criteria (SDC) (2010b), and Caltrans Memo to Designers 20-10, “Surface Fault Rupture Displacement Hazard Investigations.” Therefore, structures are expected to remain standing (no collapse) but may suffer damage requiring closure and replacement.

Substantial fault rupture surface displacements may be anticipated at certain locations. Primary mitigation methods to prevent collapse at these locations include using a continuous superstructure over intermediate support locations, isolating the superstructure from the substructure, and increasing the width of supports. Single-column bents are preferred over multicolumn bents to prevent differential displacements. These project design measures would reduce the potential exposure of people to harm from fault rupture hazards such that there would not be an adverse impact.

While faulting is present north of SR 52, this region is not within a recognized area of active faulting, and no active faults have been observed within the vicinity of the project alignment. The seven potentially active faults in the northern section of the project alignment ceased their activity sometime before about 11,000 years ago. Because of the long period of non-activity, the potential exposure of structures and people to surface fault rupture in the northern section of the project alignment would not result in an adverse impact.

5.1.2.2 Strong Ground Shaking Strong seismic shaking from a local event on the Rose Canyon fault or another regional fault is considered a hazard for the project. The proximity of this fault and other nearby active faults that are capable of generating large magnitude earthquakes means that structures and the project alignment could be affected by strong seismic ground shaking. Structures could be damaged or destroyed and people could be harmed during a major seismic event.

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All structures associated with the project would be designed in accordance with current seismic design standards as found in the CBC (2010) and Caltrans SDC. Therefore, structures are expected to remain standing (no collapse), but may suffer damage requiring closure and replacement. These project design measures would reduce the exposure of people or structures to harm from strong ground shaking hazards such that there would not be an adverse impact.

5.1.2.3 Liquefaction and Seismic Settlement Liquefaction and seismic settlement hazards exist within the project alignment. An area of potentially high liquefaction hazard is present through the area of deep alluvium between Washington Street and the Morena Boulevard/West Morena Boulevard intersection, particularly in and around the San Diego River channel. Low-to-moderate liquefaction hazard is present within Rose Canyon, where the project alignment follows the drainage course of Rose Creek. North of Rose Canyon, the liquefaction potential is nominal because of the presence of consolidated material that is not prone to liquefaction. The potential impacts of liquefaction to engineered structures include loss of bearing capacity, buoyancy forces on underground structures, ground oscillations, increased lateral earth pressure on retaining walls, post-liquefaction settlement, and “flow failures” in slopes that could lead to damage or destruction of structures and harm of people.

All structures associated with the project would be designed in accordance with current seismic design standards as found in the CBC (2010) and Caltrans SDC. Design measures would be implemented according to these codes that would reduce the impact of liquefaction and seismic settlement, including, but not limited to, ground improvement techniques such as in-situ densification or solidification, load transfer to underlying bearing layers (which are non-liquefiable), and over-excavation method (removal and replacement with compacted engineered fill). These project design measures, or a combination of these design measures, would reduce the potential exposure of people and structures to the hazard from seismic risk associated with liquefaction such that there would not be an adverse impact.

5.1.2.4 Lateral Spread There are no substantial hazards with respect to lateral spread in the northern section of the project alignment. In the southern section, lateral spreading associated with liquefaction is a potential impact in several areas of the Rose Canyon drainage basin where the project alignment is close to the banks of the creek. The closest area is the section between the Rose Creek South and Rose Creek North Bridges. With the presence of liquefiable soils and areas of sloping ground and/or free faces, the potential for lateral spreading is considered moderate to high in the area from Old Town to Clairemont Drive. Liquefaction lateral spreading displacements could lead to structures being damaged or destroyed and people being harmed.

All structures associated with the project would be designed in accordance with current seismic design standards as found in the CBC (2010) and Caltrans SDC. Design measures would be implemented according to these codes that would reduce the impact of lateral spreading, including, but not limited to, in-situ ground-improvement methods such as densification or solidification, designing the foundation to resist horizontal

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permanent ground displacement, or subsurface barrier walls. These project design measures, or a combination of these design measures, would reduce the potential impacts on structure and exposure of people or structures to harm such that there would not be an adverse impact.

5.1.2.5 Landslides, Mudslides, and Slope Stability Because all the landslide locations near the project alignment have been graded during previous construction in the area, their soils are now in a more stable configuration and the hazard is considered low. The potential for a landslide would therefore be low and the resulting exposure of structures and people to the consequences of a landslide would not be an adverse impact. Mudslides are considered a potential hazard because of the steep slopes north of Rose Canyon. Mudslides are not likely in the southern segment because of its low relief. The project alignment between Old Town and Clairemont Drive is relatively flat and slope stability is not an issue. East of I-5, the rock is flat-lying and slope stability is not an issue.

Slope stability is a potential hazard along several segments of the project alignment. North of Clairemont Drive to the Rose Creek South Bridge, slope stability hazard is considered a moderate risk. Segments with low-to-moderate risk include the area from the Rose Creek South Bridge to Gilman Drive; north of Gilman Drive to the University of California, San Diego (UCSD) West Station; and from the UCSD West Station to the I-5 crossing.

The loss of slope stability can damage structures both above and below the resulting slide mass. Structures above the slide area would be damaged by undermining of foundations, and areas below a slide mass would be damaged or destroyed by being overridden and crushed by the failed slope material. People in the slide path could be harmed. Because several of the segments along the project alignment present a moderate risk of slope failure, the potential for a slide would be moderate, resulting in exposure of structures and people to the consequences of a slide or mudslide.

American Association of State Highway and Transportation Officials (AASHTO) (2008) and Caltrans (2010a) design codes that have been adopted for the project require that slopes be designed for adequate stability. Between Clairemont Drive and the Rose Creek South Bridge, the cuts are proposed to be supported by retaining walls that would be designed for slope stability and would limit the risk. North of Gilman Drive, the location of all slopes is such that they have favorable geologic structure with respect to slope stability, except for one small area having unfavorable geologic structure. Methods that could be used to reduce the impacts of slope stability include, but are not limited to, retaining walls, remedial grading, soil nails, soldier pile walls, tiebacks, and rock bolts, which increase the stability of the slope. Mudslides also could be mitigated through the use of debris flow walls. These project design measures, or a combination of these design measures, would reduce the potential damage to structures and exposure of people to harm such that there would not be an adverse impact.

5.1.2.6 Compressible Soils Compressible soils likely are to exist in areas of alluvial soils, including Washington Street to the Morena area and Rose Creek South Bridge to Gilman Drive, with isolated

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Geotechnical, Geologic and Seismic Impacts Technical Report Chapter 5.0 – Environmental Impacts

zones from the Morena area to Clairemont Drive. Areas of large settlement can damage or—in extreme cases—destroy structures. The presence of compressible soils throughout the project alignment represents a hazard to structures and people.

AASHTO (2008), Caltrans (2010a), and CBC (2010) design codes that have been adopted for the project require that structures be designed to mitigate compressible soils. Methods that could be used to reduce the impact of compressible soils include in- situ densification of compressible soils, transferring the load to underlying non-compressible layers (i.e., through the use of pile or drilled shaft foundations), and surcharging or over-excavation method (removal and replacement with compacted engineered fill). These project design measures, or a combination thereof, would reduce the potential exposure of people or structures to this hazard such that there would not be an adverse impact.

5.1.2.7 Subsidence Subsidence is not considered a hazard along the project alignment since no large-scale ground-water pumping occurs within this region and this area has no known petroleum resources. The potential exposure of structures and people to the consequences of settlement would therefore be low and would not result in an adverse impact.

5.1.2.8 Corrosive Soils Corrosive soils are expected to occur at various locations within the project alignment. From Old Town to Gilman Drive the soils have a low-to-moderate potential for corrosion. North of Gilman Drive, the potential for corrosion is considered moderate and possibly high in some areas. The potential impacts of corrosive soils are corrosion of concrete, preventing complete curing, reducing concrete strength, and corroding buried or partially buried metal components and structures. The weakening of structures from corrosive soils could result in some structural damage or failure of underground utilities, which could expose people to harm. The presence of corrosive soils at various locations along the project alignment represents a hazard to structures and people.

AASHTO (2008), Caltrans (2010a), and CBC (2010) design codes that have been adopted for the project require that structures be designed to mitigate corrosive soils. Methods that could be used to reduce the impact of corrosive soil include using a low water-to-cement ratio to decrease the permeability of the concrete, using sulfate-resistant cement, and increasing the cover to reinforcing steel in concrete. Cathodic protection can be used to mitigate the impacts of corrosive soils on steel structures. These project design measures, or a combination thereof, would reduce the impact of corrosive soils such that there would not be an adverse impact.

5.1.2.9 Expansive Soils Expansive soils likely are to be encountered in an isolated area just north of the Tecolote Road Station, and there is potential to encounter expansive soils from half-way between SR 52 and Gilman Drive until the UCSD West Station in areas of soil with high clay content. Lightly loaded structures are more susceptible to damage by expansive soils, and the impacts of expansive soils are potential damage or (in extreme cases)

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destruction of structures. The presence of expansive soils at specific locations along the project alignment represents a hazard to structures and people.

AASHTO (2008), Caltrans (2010a), and CBC (2010) design codes that have been adopted for the project require that structures be designed to mitigate expansive soils. Methods that could be used to reduce the impact of expansive soils include drainage-control devices (to limit water infiltration near foundations), over-excavation method (removal and replacement with compacted engineered fill), or support of the structure on piles that are designed to resist the impacts of expansive soils. These project design measures, or a combination thereof, would reduce the impact of expansive soil such that there would not be an adverse impact.

5.1.2.10 Erosion Site specific Best Management Practices (BMPs) would be used to mitigate erosion along the entire project, including the six areas noted in Chapter 4.0 with erosion potential. BMP measures that would potentially be used include hydroseeding of slopes, planting, mulch, bonded fiber matrix, geosynthetics, and fiber rolls. With these measures implemented as part of the project, the impact of erosion on the environment would not be adverse. 5.2 Cumulative Impacts Cumulative impacts are defined as two or more individual impacts which, when considered together, could result in substantial adverse impacts. They may result from individually minor, but collectively substantial, project impacts taking place over a period of time.

The analysis of cumulative impacts included the following major projects in the 2030 Regional Transportation Plan that are located in the Mid-Coast Corridor, along with other projects and regional growth and demographic changes described in the 2030 RTP:

 Double tracking of the Los Angeles—San Diego—San Luis Obispo Rail Corridor Agency tracks and other rail improvements, with an increase in frequency of service of the COASTER to 20 minutes during peak periods and 60 minutes during off-peak periods in both directions  Constructing high-occupancy vehicle (HOV) lanes on I-5 from I-8 north to Oceanside, with direct-access ramps (DARs) at various locations, of which the DARs at Voigt Drive would be located within the Mid-Coast Corridor; the HOV lanes would be restricted to vehicles with two or more occupants  Adding a combination of high-occupancy vehicle and managed lanes on I-805 from I-5 to South Bay, with DARs at Carroll Canyon Road and Nobel Drive  Improving the low-floor system for the Trolley Blue and Trolley Orange Lines, including station platform, power, and signaling improvements, to allow for the extension of the Trolley Green Line to the 12th and Imperial Avenue Transit Center and use of low-floor vehicles throughout the system

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Geotechnical, Geologic and Seismic Impacts Technical Report Chapter 5.0 – Environmental Impacts

The projects assumed in the No-Build Alternative that are located in the Mid-Coast Corridor were considered in the analysis of cumulative impacts of the project.

In addition to the transportation projects, future development in the corridor may result in a cumulative impact. However, future development along the corridor would be subject to development and building standards designed to protect public safety in accordance with state law, the CBC, California Department of Transportation (Caltrans) codes, and/or American Railway Engineering and Maintenance-of-Way Association codes, which address geotechnical, geologic, and seismic considerations.

Structures associated with the future development projects would be designed in accordance with current seismic design standards as found in the California Building Code (CBC). Development projects assumed under the No-Build Alternative would undergo separate environmental review to determine adverse geotechnical, geologic, and seismic impacts. Any development would be subject to the laws and requirements related to such impacts and would be required to mitigate any potential hazards.

Geologic hazards related to future development are site-specific and relate to the type of structures proposed, as well as the soil composition and slope of the site. As such, the zone of potential impact typically would be limited to a narrow band of less than 100 feet stretching along the alignments of the various projects. None of the foreseeable projects share such close geographic proximity and are unlikely to have a cumulative impact when combined with the project. As a result, the No-Build Alternative would not have cumulative adverse geotechnical, geologic, or seismic impacts.

With implementation of design requirements such as the CBC and San Diego Association of Governments (SANDAG) design standards, which include AASHTO and Caltrans standards and the project-specific Basis of Design that have been adopted for the project, the project would not expose people or structures to substantial risk of loss or injury due to existing geotechnical, geologic, or seismic hazards. The Build Alternative, including the two options, when considered in addition to other foreseeable transportation projects, is not expected to have any substantial negative geotechnical, geologic, or seismic hazard impacts. Therefore, cumulative geotechnical, geologic, and seismic impacts of these future developments under the No-Build and Build Alternatives would not be adverse. 5.3 Construction Impacts The short-term impacts associated with construction of the Mid-Coast Corridor Transit Project are described in the Mid-Coast Transit Project Construction Impacts Technical Report (SANDAG, 2013c). That report also describes construction-related cumulative impacts.

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Geotechnical, Geologic and Seismic Impacts Technical Report Chapter 6.0 – Mitigation

6.0 MITIGATION

As discussed in Chapter 5.0, project measures will be incorporated into the project for the Build Alternative, as well as the Veterans Administration Medical Center Station Option and the Genesee Avenue Design Option. These measures would avoid or minimize adverse geotechnical, geologic, and seismic impacts to people and structures. These project measures will be reflected in applicable project plan sets and project construction specifications. Therefore, no mitigation would be required for the project, including both options of the Build Alternative, and the project would not result in any adverse geotechnical, geological, or seismic impacts.

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Geotechnical, Geologic and Seismic Impacts Technical Report Chapter 7.0 – California Environmental Quality Act Determination

7.0 CALIFORNIA ENVIRONMENTAL QUALITY ACT DETERMINATION

The California Environmental Quality Act (CEQA) requires state, local, and other agencies to evaluate the environmental implications of their decisions and to avoid or reduce, when feasible, the significant environmental impacts of their decisions (Public Resources Code §21002; the CEQA Guidelines [California Code of Regulations §15002, §15021]). 7.1 Significance Criteria and Significance Criteria Application Based on the CEQA Environmental Checklist (Appendix G of the CEQA Guidelines) and the City of San Diego CEQA Significance Determination Thresholds (City of San Diego, 2011), SANDAG has developed the following thresholds of significance for use in evaluating the impacts of the Mid-Coast Corridor Transit Project. The significance criteria also are described in Section 3.4.2.

Would the project expose people or structures to geologic hazards involving earthquakes, landslides, mudslides, ground failures or similar hazards? Local Faulting and Surface Fault Rupture Hazard Fault surface rupture is a major earthquake-related hazard for the southern section of the project alignment between Downtown San Diego and the State Route (SR) 52/Interstate (I-) 5 interchange. This is because this segment lies within the area of influence of the active Rose Canyon Fault Zone. The project alignment also is located within an active Alquist-Priolo Earthquake Fault Zone between Clairemont Drive and Jutland Drive (just south of SR 52). Implementation of the design measures noted in Section 5.1.2.1 would ensure that project-related exposure of people or structures to the hazards associated with surface fault rupture would be a less-than-significant impact.

While faulting is present north of the interchange, this region is not within a recognized area of active faulting, and no active faults have been observed within the project alignment north of SR 52. Because of this long period of non-activity, the potential exposure of structures and people to surface fault rupture hazards in the northern section of the project alignment represents a less-than-significant impact.

Strong Ground Shaking Strong seismic shaking from a local event on the Rose Canyon fault or another regional fault is considered a hazard for the project. The proximity of this fault and other nearby active faults that are capable of generating large magnitude earthquakes means that strong ground shaking could adversely affect project-related structures. The project design measures noted in Section 5.1.2.2 would reduce the hazard associated with the exposure of people and structures to a strong seismic event along the project alignment to a less-than-significant impact.

Would the project be inundated by seiche, tsunami, or mudflow?

Tsunami hazards are low for the project alignment, except at the Tecolote Creek Bridge where the tsunami hazard is considered low to moderate because it is near the edge of

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the State of California Tsunami Inundation Map (California Emergency Management Agency, 2009). As shown in Figure 4-14, a maximum tsunami event would not reach the project alignment except at the Tecolote Creek Bridge location.

The effects of tsunami inundation on the Tecolote Creek Bridge would be addressed in accordance with the California Department of Transportation Memo to Designers 20-13, Tsunami Hazard Guidelines (Caltrans, 2010c). Primary design measures include the use of deep foundations (cast-in-drilled-hole piles) to protect from scour and tie-down anchors (if warranted) to alleviate buoyancy effects. These project design measures would reduce the potential hazard associated with the exposure of structures and people to the consequences of a tsunami at Tecolote Creek to a less-than-significant impact.

The potential for the project to be impacted by a seiche is considered low. The only nearby source for a seiche is Mission Bay, which is 350 to 1,300 feet from the project alignment. Because of the distance between the project alignment and Mission Bay and existing topography, the potential exposure of structures and people to the consequences of a seiche would be a less-than-significant impact.

Would the project result in a substantial increase in wind or water erosion of soils, either on or off the site? The project would conform to standards for soil conservation during planning, design, and construction activities (National Engineering Handbook (Natural Resources Conservation Service, 1983) Sections 2.0 and 3.0) during grading and construction to limit soil erosion, including the use of Best Management Practices (BMPs). Therefore, the project would have a less-than-significant impact.

Would the project be located on a geologic unit or soil that is unstable or that would become unstable as a result of the project, and potentially result in on- or off-site landslide, lateral spreading, subsidence, liquefaction, or collapse? Liquefaction and Seismic Settlement Liquefaction and seismic settlement hazards exist within the project alignment. An area of potentially high liquefaction hazard is present through the area of deep alluvium between Washington Street and the Morena Boulevard/West Morena Boulevard intersection, particularly in and around the San Diego River channel. As such, the project would have a significant impact. However, the project design features noted in Section 5.1.2.3 would reduce the potential risk to the consequences of liquefaction and seismic settlement to a less-than-significant impact.

Lateral Spread In the southern section, lateral spreading associated with liquefaction is a potential impact in several areas of the Rose Canyon drainage basin where the project alignment is close to the banks of the creek. The closest area is the section between the Rose Creek South and Rose Creek North Bridges. Liquefaction lateral spreading displacements could damage or destroy structures and harm people. As such, the project would have a significant impact. However, the project design features noted in Section 5.1.2.4 would reduce the potential risk to the consequences of lateral spread to a less-than-significant impact.

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Landslides, Mudslides, and Slope Stability The potential for a landslide would be low, and the resulting exposure of structures and people to the consequences of a landslide would be considered a less-than-significant impact.

Slope stability and the resulting mudslide is a potential hazard along several segments of the project alignment. North of Clairemont Drive to the Rose Creek South Bridge, slope stability hazard is considered a moderate risk. Segments with low-to-moderate risk extend from the Rose Creek South Bridge to Gilman Drive; north of Gilman Drive to the University of California, San Diego (UCSD) West Station; and from the UCSD West Station to the I-5 crossing. Several segments along the project alignment present a moderate risk of slope failure and mudslide, representing a significant impact. Design measures described in Section 5.1.2.5 would reduce the potential risks associated with the consequences of a slide to a less-than-significant impact.

Compressible Soils Compressible soils likely are to exist in areas of alluvial soils, including the area extending from Washington Street to Morena Boulevard and from the Rose Creek South Bridge to Gilman Drive, with isolated zones extending from Morena Boulevard to Clairemont Drive. There is therefore a significant impact due to compressible soils. Project design features described in Section 5.1.2.6 would reduce the hazard to structures and people associated with compressible soils to a less-than-significant impact.

Subsidence Subsidence is not considered a hazard along the project alignment since no large-scale ground-water pumping would occur within this region and this area has no known petroleum resources. The potential risks of settlement would be low, resulting in a less- than-significant impact.

Corrosive Soils Corrosive soils are expected to occur at various locations within the project alignment. From Downtown San Diego to Gilman Drive, soils have a low-to-moderate potential for corrosion. North of Gilman Drive, the potential for corrosion is considered moderate and possibly high in some areas, resulting in a significant impact. Project design features described in Section 5.1.2.8 would reduce the hazards to structures and people associated with corrosive soils at various locations along the project alignment to a less- than-significant impact.

Expansive Soils Expansive soils likely are to be encountered in an isolated area just north of the Tecolote Road Station. Expansive soils also could be encountered between SR 52 and Gilman Drive and extending to the UCSD West Station in areas of soil with high clay content, resulting in a significant impact. Project design features described in Section 5.1.2.9 would reduce the hazards to structures and people associated with expansive soils along the project alignment to a less-than-significant impact.

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7.2 Significance after Mitigation Project design measures and BMPs would result in the avoidance and/or minimization of potential direct or indirect geotechnical, geologic, or seismic impacts. Therefore, the Mid-Coast Corridor Transit Project would result in less-than-significant direct, indirect, and cumulative geotechnical, geologic, and seismic impacts under CEQA. 7.3 Cumulative Impacts Cumulatively significant impacts are not anticipated under the No-Build or Build Alternatives.

Under the No-Build Alternative, continuation and enhancement of bus Route 150 would not result in any geotechnical, geologic or seismic impacts. Therefore, it would not contribute to any cumulative impacts.

The cumulative impact of the project and other reasonably foreseeable projects in the Mid-Coast Corridor could impact could expose additional people and structures to seismic hazards such as ground-shaking, fault rupture, liquefaction, and landslides in hazard areas. In addition, structures could be at risk of impacts due to unstable soils, landslides, erosion, or loss of topsoil. However, it is reasonable to assume that all projects would adhere to design standards that reduce the effects of seismic activity and geologic hazards to people and structures in the same manner as the project. Further, geologic hazards related to future development are site-specific and relate to the type of structures proposed, as well as the soil composition and slope of the site. As such, the zone of potential impact typically would be limited to a narrow band of less than 100 feet stretching along the alignments of the various projects. Thus, no cumulatively significant impacts due to geologic hazards are anticipated.

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Geotechnical, Geologic and Seismic Impacts Technical Report Chapter 8.0 – References

8.0 REFERENCES

This chapter lists the references used in the preparation of this geotechnical, geologic, and seismic impacts technical report for the Mid-Coast Corridor Transit Project.

American Association of State Highway Transportation Officials (AASHTO). 2008. LRFD Bridge Design Specifications, 4th edition.

American Railway Engineering and Maintenance-of-Way Association (AREMA). 2007. Communications and Signals Manual of Recommended Practices. http://www.arema.org/eseries/scriptcontent/custom/e_arema/pubs/cs_manual.html.

American Railway Engineering and Maintenance-of-Way Association (AREMA). 2011. AREMA Manual for Railway Engineering, http://www.arema.org/files/pubs/mre/ AREMA_MRE_2011.

Bennett, R. A. and Others. 1996. “Global positioning system constraints on fault slip rate in Southern California and Northern Baja, Mexico,” Journal of Geophysical Research, vol. 101, no. B10, pp. 21,943-21,960.

California Department of Conservation. 2003. Probabilistic Seismic Hazards Assessment— Peak Ground Acceleration: http://www.consrv.ca.gov/cgs/rghm/psha/pga.htm.

California Department of Conservation. 2007. Seismic Hazard Zonation Program: http://www.consrv.ca.gov/CGS/shzp/Pages/SHMPrealdis.aspx.

California Department of Transportation (Caltrans). 2007. Fault Database: http://dap3.dot.ca.gov/shake_stable/references/2007_Fault_Database_120309.xls.

California Department of Transportation (Caltrans). 2009a. Geotechnical Services Design Manual, Version 1.0, August 2009.

California Department of Transportation (Caltrans). 2009b. Caltrans Acceleration Response Spectra (ARS) Online: http://dap3.dot.ca.gov/shake_stable/.

California Department of Transportation (Caltrans). 2009c. Acceleration Response Spectra (ARS) Technical References Website: http://dap3.dot.ca.gov/shake_stable/technical.php.

California Department of Transportation (Caltrans). 2009d. Fault Database Errata Report, http://dap3.dot.ca.gov/shake_stable/Errata_Report_120309.pdf.

California Department of Transportation (Caltrans). 2010a. California Amendments to the AASHTO LRFD (Load and Resistance Factor Design) Bridge Design Specifications, 4th edition.

California Department of Transportation (Caltrans). 2010b. Seismic Design Criteria, Version 1.6, November 2010.

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California Department of Transportation (Caltrans). 2010c. Memo to Designers 20-13, Tsunami Hazard Guidelines. January 2010. Accessed at: http://www.dot.ca.gov/hq/esc/techpubs/updates/page/mtd-20-13.pdf

California Department of Transportation (Caltrans). 2011a. Bridge Memo to Designers Website: http://www.dot.ca.gov/hq/esc/techpubs/manual/bridgemanuals/bridge-memo-to- designer/bmd.html.

California Department of Transportation (Caltrans). 2011b. Guidelines on Foundation Loading and Deformation Due to Liquefaction Induced Lateral Spreading, February 2011.

California Division of Mines and Geology (CDMG). 1991. State of California Special Studies Zones, La Jolla Quadrangle, 1:24,000 scale.

California Division of Mines and Geology (CDMG). 1993. “The Rose Canyon Fault Zone, Southern California,” DMG Open-File Report 93-02.

California Emergency Management Agency (Cal EMA). 2009. Tsunami Inundation Map for Emergency Planning, La Jolla Quadrangle, State of California, County of San Diego, 1:24,000 Scale.

California Geological Survey (CGS). 2003. Probabilistic Seismic Hazards Assessment— Peak Ground Acceleration: http://www.consrv.ca.gov/cgs/rghm/psha/pga.htm.

California Geological Survey (CGS). 2007. Seismic Hazard Zonation Program: http://www.consrv.ca.gov/CGS/shzp/Pages/SHMPrealdis.aspx.

California Geological Survey (CGS). 2010. Geologic Map of California, 2010. http://www.conservation.ca.gov/cgs/cgs.history/publishingimages/GMC_750k_MapRelea se_page.jpg.

California Geological Survey (CGS). 2011. Alquist-Priolo Earthquake Fault Zone Maps: La Jolla Quadrangle (1991) and Point Loma Quadrangle (2003). www.quake.ca.gov/gmaps/ap/ap_maps.htm. Visited in 2011.

California Government Code. 1986. California Government Code, §8877.1-8877.6, Chapter 12.4: http://law.justia.com/california/codes/gov/8877.1-8877.6.html.

City of San Diego, Department of Development Services. 2008a. Seismic Safety Study, Geologic Hazards and Faults. Updated 2008.

City of San Diego. 2008b. General Plan. Adopted by Council of the City of San Diego, Resolution Number: R-303473. Adopted by the Council of the City of San Diego on March 10, 2008.

City of San Diego. 2008c. University Towne Center Revitalization Project Environmental Impact Report.

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City of San Diego. 2011. Development Services Department, CEQA Significance Determination Thresholds, 84p.

Fennie. 2005. “The Space Place, Space Planning: Seismic Retrofit Requirements and Their Triggers,” http://www.thespaceplace.net/articles/fennie200501b.php.

Geocon. 1978. Geologic Reconnaissance and Fault Investigation, View Terrace Subdivision, San Diego, California, consultant report on file at the City of San Diego Maps and Records Department.

Geocon. 1982. Geological Reconnaissance and Fault Investigation, Rose Canyon Business Park, San Diego, California, prepared for C.R. Lochhead, consultant report on file at the City of San Diego Maps and Records Department.

Geocon. 1991. Geotechnical Engineering Investigation and Geologic Reconnaissance Study for Elvira to Old Town Station Double-Track Improvements, Volumes I and II, dated October 21, 1991.

Grant, L.B., and P.M. Shearer. 2004. “Activity of the offshore Newport-Inglewood Rose Canyon Fault Zone, coastal Southern California, from relocated microseismicity,’’ Bulletin of Seismological Society of America, vol. 94, no. 2; pp. 747-752.

Grant, L.B., and T.K. Rockwell. 2002. “A northward-propagating earthquake sequence in coastal southern California,” Seismological Research Letters, Vol. 73, No. 4, pp. 461- 469.

International Conference of Building Officials (ICBO). 1997. Handbook to the 1997 Uniform Building Codes.

Kennedy, M.P. 1975. Geology of the San Diego Metropolitan Area, California, Point Loma Quadrangle, Scale 1:24,000, California Division of Mines and Geology, Bulletin 200, Prepared in cooperation with the City of San Diego.

Kennedy, M.P., and S.H. Clarke. 1999a. Analysis of Late Quaternary Faulting in San Diego Bay and Hazard to the Coronado Bridge, Open File Report 97-10A, California Department of Conservation, Department of Mines and Geology.

Kennedy, M.P., and S.H. Clarke. 1999b. Age of Faulting in San Diego Bay in the Vicinity of the Coronado Bridge—An Addendum to Analysis of Late Quaternary Faulting in San Diego Bay and Hazard to the Coronado Bridge, Open File Report 97-10B, California Department of Conservation, Department of Mines and Geology.

Kern, Philip. 1988. Preliminary Earthquake Shaking and Fault Rupture in San Diego County, A Report to the San Diego County Earthquake Preparedness Committee.

Kleinfelder. 1998. Final Report of Fault Hazard Study of Sites A, B, and C, Including Site Specific Recommendations for Fault Hazard Mitigation for Site B, Marina Sub Area, San Diego, California, unpublished consultant report.

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Kleinfelder. 2006. Preliminary Geotechnical Investigation, State Route 75 and 282 Transportation Corridor Project, Coronado, California, unpublished consultant report prepared for Parsons Brinckerhoff Quade & Douglas, Inc., dated March 2006.

Kleinfelder. 2011a. Structure Preliminary Geotechnical Report, Proposed La Jolla Colony Overhead, Mid-Coast Corridor Transit Project, San Diego California, dated December 30, 2011.

Kleinfelder. 2011b. Structure Preliminary Geotechnical Report, Proposed Nobel Viaduct, Mid-Coast Corridor Transit Project, San Diego California, dated December 29, 2011.

Kleinfelder. 2011c. Structure Preliminary Geotechnical Report, Proposed Genesee Viaduct, Mid-Coast Corridor Transit Project, San Diego California, dated December 28, 2011.

Kramer, S.L. 1996. Geotechnical Earthquake Engineering, Prentice Hall, New Jersey.

Legg, M.R., and D.C. Agnew. 1979. The 1862 Earthquake in San Diego, Earthquakes and Other Perils in the San Diego Region, edited by P.L. Abbott and W.J. Elliott, San Diego Association of Geologists Guidebook, pp. 139-142.

Leim, T.J. 1977. “Late Pleistocene maximum age of faulting, southeast Mission Bay area, San Diego, California,” Farrand, G.T. (editor), Geology of southwestern San Diego County, California and northwestern Baja California: San Diego Association of Geologists, pp. 61-64.

Lindvall, S.C., and T.K. Rockwell. 1995. “Holocene activity of the Rose Canyon Fault Zone in San Diego, California,” Jour. Geophysical Research, vol. 100, no. B12, pp. 24,121- 24-132.

Metropolitan Transit Development Board (MTDB). 1995a. Mid-Coast Corridor Alternatives Analysis/Draft Environmental Impact Statement/Draft Environmental Impact Report.

Metropolitan Transit Development Board (MTDB). 1995b. Final Environmental Impact Report for the Mid-Coast Corridor. December 1995.

Metropolitan Transit Development Board (MTDB). 2001. Mid-Coast Corridor Project Balboa Extension and Nobel Drive Coaster Station Final Environmental Impact Statement. June 2001.

National Cooperative Soil Survey (NCSS). 2008. National Soil Information System, http://pubs.usgs.gov/of/2008/1385/pdf/fortner.pdf.

Natural Resources Conservation Service (NRCS). 1983. National Engineering Handbook, http://www.mi.nrcs.usda.gov/technical/engineering/neh.html.

Natural Resources Conservation Service (NRCS). 2008. Web Soil Survey 2.0: http://www.websoilsurvey.nrcs.usda.gov.

Norris, R.M., and R.W. Webb. 1976. Geology of California, John Wiley and Sons, Inc.

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Geotechnical, Geologic and Seismic Impacts Technical Report Chapter 8.0 – References

Patterson, R.H., and Others. 1986. “Evidence for recent faulting in downtown San Diego, California,” Geological Society of America, Program with Abstracts, vol. 18, no. 2, p. 169.

Petersen et al. 2008. Documentation for the 2008 update to the United States National Seismic Hazard Maps, U.S. Geological Survey (USGS) Open File Report 2008-1128, 61p.

Rockwell, T.K. et al. 1991. Minimum Holocene Slip Rate for the Rose Canyon Fault in San Diego, California, San Diego Association of Geologists.

Rockwell, T.K. 2000. “Use of soil geomorphology in fault studies,” Quaternary Geochronology: Methods and Applications, J.S. Noller, J.M. Sowers, and W.R. Lettis, editors, AGU Reference Shelf 4, American Geophysical Union, Washington D.C., pp. 273-292.

Rockwell, T.K. 2010. “The Rose Canyon Fault Zone in San Diego,” Fifth International Conference on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics, Paper No. 7.06c, pp. 1-9.

San Diego Association of Governments (SANDAG). 2007. 2030 San Diego Regional Transportation Plan: Pathways for the Future (San Diego RTP), dated November.

San Diego Association of Governments (SANDAG). 2008. Series 11: 2030 Regional Growth Forecast Update: Process and Model Documentation.

San Diego Association of Governments (SANDAG). 2010. Mid-Coast Corridor Transit Project Comparative Evaluation of Alternatives Report, dated July 2010.

San Diego Association of Governments (SANDAG). 2011a. Mid-Coast Corridor Transit Project Final Definition of Alternatives Report, dated June.

San Diego Association of Governments (SANDAG). 2011b. 2050 Regional Transportation Plan: Our Region, Our Future (2050 RTP). Adopted October 28, 2011. http://www.sandag.org/uploads/2050RTP/F2050rtp_all.pdf

San Diego Association of Governments (SANDAG). 2013a. Mid-Coast Corridor Transit Project Draft SEIS/SEIR Plan Set. Prepared by Parsons Brinckerhoff.

San Diego Association of Governments (SANDAG). 2013b. Mid-Coast Corridor Transit Project Property Acquisitions Technical Report.

San Diego Association of Governments (SANDAG). 2013c. Mid-Coast Corridor Transit Project Construction Impacts Technical Report.

San Diego Association of Governments (SANDAG). 2013d. Mid-Coast Corridor Transit Project Water Impact Analysis Technical Report.

MID-COAST CORRIDOR TRANSIT PROJECT April 2013 8-5 Geotechnical, Geologic and Seismic Impacts Technical Report Chapter 8.0 – References

SanGIS. 2011. Regional Geographic Database, City of San Diego Geologic Hazards Data Layer. Joint Powers Agency of the City of San Diego and the County of San Diego. http://www.sangis.org.

San Diego Regional Water Quality Control Board (SDRWQCB). 2009. Construction General Permit. Order No. 2009-0009-DWQ as amended by 2010-0014-DWQ.

Testing Engineering, Dames and Moore, and Woodward-Clyde Consultants. 1985. Geologic and Fault Investigation, San Diego Police Administration and Technical Center, unpublished consultant report prepared for Starboard Development Company.

Treiman, J.A. 1993. Rose Canyon Fault Zone, California Department of Mines and Geology.

URS. 2007. Fault Hazard Investigation of Hotel Del Coronado, Coronado, California, unpublished consultant report.

U.S. Department of Agriculture (USDA). 1953. Aerial Photo Survey of San Diego County California, 1:24,000 Scale.

U.S. Department of Agriculture (USDA). 1973. Soil Survey of San Diego Area California, http://soildatamart.nrcs.usda.gov/manuscripts/CA638/0/part2.pdf.

U.S. Environmental Protection Agency. 2009a. Introduction to the Clean Water Act: http://www.epa.gov/watertrain/cwa/.

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U.S. Geological Survey (USGS). 2011. Quaternary Faults and Fold Database of the United Sates, http://earthquake.usgs.gov/hazards/qfaults/

U.S. Navy (USN). 1928. Aerial Photo Survey of Western San Diego County, 1:12,000 Scale.

Wallace, Robert E. 1990. “The San Andreas Fault System,” California, U.S. Geological Survey Professional Paper 1515, 283 p. 59.

Weldon, R.J., and K.E. Sieh. 1985. “Holocene rate of slip and tentative recurrence interval for large earthquakes of the San Andreas fault, Cajon Pass, Southern California,” Geological Society of America Bulletin, vol. 96, no. 6, pp. 793-812.

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Geotechnical, Geologic and Seismic Impacts Technical Report Chapter 9.0 – Limitations and Preparer Signatures

9.0 LIMITATIONS AND PREPARER SIGNATURES

This work was performed in a manner consistent with that level of care and skill ordinarily exercised by other members of the geologic and geotechnical engineering profession practicing in the same locality, under similar conditions and at the date the services are provided. The conclusions, opinions, and recommendations are based on a limited number of observations and data. It is possible that conditions could vary between or beyond the data evaluated. No other representation, guarantee, or warranty is made, express or implied, regarding the services, communication (oral or written), report, opinion, or instrument of service provided. This report may be used only by the San Diego Association of Governments (SANDAG) and the Mid-Coast Corridor Transit Project team, only for the purpose of evaluating environmental issues for the project.

The geotechnical, geologic and seismic technical information contained in this report was prepared by Kleinfelder West, Inc., either directly by or under the supervision of the undersigned.

______Scott H. Rugg, PG, CEG James R. Gingery, PE, GE Senior Engineering Geologist Principal Geotechnical Engineer

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Appendix A Fault Interpretation from Aerial Photography

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Geotechnical, Geologic and Seismic Impacts Technical Report Appendix A - Fault Interpretation from Aerial Photography

APPENDIX A FAULT INTERPRETATION FROM AERIAL PHOTOGRAPHY

Several sets of vintage aerial photographs were assessed for possible use in interpretation of the potential presence and activity of strands of the Rose Canyon Fault Zone (RCFZ). The most useful sets were the 1928 series taken by the U.S. Navy (USN) and the 1953 series by the U.S. Department of Agriculture (USDA). These were most useful because they predate much of the development through this area and allow observation of the natural landscape. The 1928 aerial photographs are of reasonably high quality and were taken at low altitude, so that the scale is excellent for resolving subtle features in the landscape. In 1928, there was some development in the Morena area in the vicinity of the Rose Canyon fault, but Mission Bay (False Bay) and the entire Rose Canyon area were completely undeveloped except for some farm activity, the railroad itself, and a few roads. Consequently, this photographic set provided some of the best evidence for the location of the strands of the fault zone.

The 1953 aerial photographs are of excellent quality, although their 1:20,000 scale is not as well-suited for recognizing and mapping small geomorphic features that could be associated with active faulting. The photographs were scanned at high resolution (800 dots per inch), which allowed digital enlargement of portions of the photographs and analysis of them at a similar scale as the 1928 imagery. In 1953, Rose Canyon remained generally undeveloped, except for some farming activity. Development in the Morena area had been expanded northward, which obscured some evidence of fault activity, but the addition of many roads allowed for the superposition of the imagery and the 1953 topographic base map. Furthermore, US 101 had been constructed, and the railroad remained in exactly the same location, so there were sufficient features to match the 1928 and 1953 photographs in both scale and orientation even in the undeveloped Rose Canyon area.

By 1967, there had been substantial development northward into Rose Creek itself, including construction of the Interstate (I-) 5 corridor, State Route (SR) 52 and Ardath Road into La Jolla. It is interesting to note that the locations of portions of the railway itself were adjusted to accommodate the new freeway system. There also was substantial development of the Kearny Mesa area to the east of Rose Canyon, which provided many roads, houses and other features to match in the younger imagery and maps, and especially to the Google Earth imagery, as the current landscape is completely built out and few, if any, of the original landforms remain unchanged. Consequently, there is essentially no preservation of any of the tectonic landforms from the San Diego River northward to Rose Canyon and the SR 52 interchange. Furthermore, many roads have been moved or adjusted, and buildings have changed, so to map the RCFZ with confidence onto the modern landscape required the superposition of the maps and imagery of various dates.

The individual mapping bases are believed to be rectified correctly and superposed to within about a 25-foot uncertainty, so the resulting mapping also should be accurate to about a 25-foot location uncertainty. However, the railroad was used as one of the primary features that was used to collocate all maps and images as this feature is present in all images and maps (with the caveat that portions of the rail line were slightly relocated when the SR 52/I-5 interchange was built), so the accuracy is likely better along the railroad alignment than in other areas where there were fewer geographic features to provide control.

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The project alignment was divided within the RCFZ into eight interpretive areas based on the coverage of the 1928 aerial photographs. The aerial photographs for both 1928 and 1953 are shown in Plate A-1 through Plate A-14. Each area was stereoscopically analyzed and suspect fault related features were drawn on the photographs and with notation of the particular type of surface expression observed (“dd” for deflected drainage, “sc” for scarp, etc.). Descriptions of the results of this analysis along with images of the each interpretive area are detailed in the following sections. A.1 Interpretive Areas Area 1—Middletown Active fault-related features are apparent in the 1928 imagery from the vicinity of Washington Street, south to Laurel Street, designated here as the Middletown interpretive area. A set of three faults trending approximately N55oW and have been identified stepping up the west facing escarpment east of I-5, below Middletown. The westernmost of the faults is at the bottom of the slope and trends along San Diego Avenue in the northern portion of the interpretative area. This fault is expressed by a shallow scarp and deflected drainage displaced in a right-lateral relationship. Two faults have been identified on the face of the escarpment and extending southeast of the Washington Street drainage toward the downtown area. These faults are expressed by a series of aligned slope benches, deflected drainages, ridgeline saddles, beheaded drainages and offset canyon slopes. The central fault segment can be traced for up to 1.5 miles across the Washington Street drainage southeast of Laurel Street. The easternmost fault segment can be traced for approximately 0.4 miles near the crest of the escarpment.

The expression of the fault through this area has a rich complement of aligned features that are best interpreted as faulting. These faults do not cross the existing Trolley alignment; the nearest Trolley structure is located 800 feet to the northeast.

Historic 1928 and 1953 aerial photos pertinent to this discussion are shown in Plate A-1 and Page A-2, respectively.

Area 2—Old Town The Old Town interpretive area extends from Old Town south to an area at approximately Washington Street. One of the main features of this area is an apparent bifurcation of the fault into two structurally variant strands just southeast of the intersection of Old Town Avenue and San Diego Avenue. The strand through Old Town trends approximately N15oW, from the public golf course north of Juan Street toward the intersection of Hancock Street and Witherby Street on the southwest of I-5. The fault is expressed in the 1928 aerial images in a series of small scarps, lineaments, deflected drainages and troughs. A study by Leighton and Associates in 2008 (personal communication) encountered this fault in a trench near the intersection of Juan Street and Harney Street. This strand is projected to cross the existing Trolley alignment near the crossing over Witherby Street. The southeast bifurcated strand trends approximately N65oW, 50 degree different from the northern strand. This strand is aligned along San Diego Avenue and is expressed in a series of scarps and deflected drainages.

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Historic 1928 and 1953 aerial photos pertinent to this discussion are shown in Plate A-3 and Page A-4, respectively.

Area 3— Morena South The location of active fault-related features is quite apparent in the 1928 imagery for the Old Town and Morena areas. Rockwell (2010) mapped the fault in Old Town based on the presence of several drainage channels that had been deflected by about 800 feet (250 meters [m]). These channels are now buried and built over, but the location and activity of the Rose Canyon fault (Old Town strand) was confirmed by trenching (Leighton and Associates, personnel communication). The fault is interpreted to traverse through a small golf course in Old Town, cross the San Diego River, and step to the right to form a small graben on the north side of the river across a low terrace. Northward of the graben, a suspected fault strand is clearly evident in 1928 as a continuous east-facing scarp along the west side of Morena Boulevard. There is a closed depression observed in the 1928 aerial photography that is now occupied by Office Depot, and the parking lot remains the local low elevation spot. The main fault is interpreted to continue to the northwest and cross the Tecolote drainage, causing deflection of the channel walls. A secondary fault splay is interpreted to branch to the west and produce an area of topographic uplift (PR for pressure ridge in the interpretive maps); one of the inferred faults is known to be present and active in the late Quaternary as it was trenched and published in the 1970s (Leim, 1977).

Overall, the expression of the fault through the Old Town and Morena area is quite well preserved and there is no other obvious interpretation for the observed landforms. Along this section of fault, only one of the minor, secondary fault splays may affect the Trolley line, and none is interpreted through a station. However one secondary fault is mapped crossing below the abutment of the SeaWorld Drive/Tecolote Road overpass, which flies over the proposed Tecolote Road Station.

Historic 1928 and 1953 aerial photos pertinent to this discussion are shown in Plate A-5 and Page A-6, respectively.

Area 4—Morena Central The expression of the fault becomes less clear in the area just north of Tecolote Canyon between Gardena Avenue and Clairemont Drive. There are no clear and obvious scarps, although there does appear to be a diffuse zone of right-stepping lineaments that we interpret as the active fault zone. Based on the location of the clearly delineated fault zone from Tecolote Canyon to the south, and the known location of the fault to the north, the central Morena area appears to overlie a right step in the fault zone where active faulting is likely broadly distributed. One of the lineaments projects close to the Clairemont Drive Station below the overpass, although displacement on any one fault strand is expected to be lower than where the fault slip is concentrated on a primary strand.

Historic 1928 and 1953 aerial photos pertinent to this discussion are shown in Plate A-7 and Plate A-8, respectively.

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Area 5—Morena North North of Clairemont Drive at about the latitude of De Anza Cove, the fault activity appears to coalesce into a narrow zone that trends virtually coincident with the current alignment of the railroad tracks. It is possible that the tracks were located along a fault scarp, as the coincidence of the tracks with the fault extends from the area of De Anza Cove northwest to nearly Rose Creek.

The primary basis for inferring the fault through this area is that every major drainage expresses a large right-lateral offset at the tracks (Rockwell et al., 1991; Lindvall and Rockwell, 1995; Rockwell, 2010), and this series of deflections aligns with the major fault exposed in trenches at Rose Creek (Lindvall and Rockwell, 1995). The precise location of the fault could not be recognized on the early aerial photography because the railroad tracks were already in place, so location uncertainty along this section of fault is likely larger than for other areas.

The fault trends very close to the proposed Balboa Avenue Station and associated bridge across Balboa Avenue. As the rail line obliterated the details of fault expression in this area, it is not clear whether the proposed Trolley line, station or bridge would be impacted by the main fault, or not. However, east of the main fault between Ticonderoga and Brandywine Streets, three lineaments are interpreted as minor faults and two of these lineaments project close to the proposed station and bridge. During the field reconnaissance, at least one and probably two of these lineaments were confirmed as faults that juxtapose different rock units, although their expression in the geomorphology does not suggest significant activity.

Historic 1928 and 1953 aerial photos pertinent to this discussion are shown in Plate A-9 and Plate A-10, respectively.

Area 6—Rose Creek South The 1928 Images 59F7 and 59E7/E6 overlap substantially, so only the expression of the fault from Balboa Avenue and to the north in this section is discussed. North of Balboa Avenue, several distinctive geomorphic features delineate the location of the main fault, and include two pressure ridges, a sag pond, an offset channel wall, and a scarp crossing a low terrace to Rose Creek (Lindvall and Rockwell, 1995). Rockwell et al. (1991) and Lindvall and Rockwell (1995) used these geomorphic features to identify their trench site in the terrace to Rose Creek, and through three-dimensional trenching, established a minimum slip rate of 1.1 millimeters per year (mm/yr) for the Holocene. The actual rate is likely close to 2 mm/yr based on the geomorphic analysis of offset stream channels that are incised into last interglacial marine terrace deposits (Rockwell, 2010).

In the Rose Creek area, two additional lineaments are present to the west of the main fault. One of these aligns with the Country Club fault and is expressed across the Holocene terrace of Rose Creek as a tonal lineament. Nevertheless, it appears that most of the fault activity is associated with the main fault that was investigated by Lindvall and Rockwell (1995), as that fault strand has, by far, the best expression in the landscape. Other than the Balboa Avenue Station and associated bridge, no other Trolley structures are impacted by the identified strands of the fault in the south Rose Creek area.

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Historic 1928 and 1953 aerial photos pertinent to this discussion are shown in Plate A-11 and Plate A-12, respectively.

Area 7—Rose Creek Middle Activity on the Rose Canyon fault diverges into two primary fault strands north of Lindvall and Rockwell’s (1995) trench site: the Rose Canyon and Mt. Soledad fault strands. The Rose Canyon strand is mapped to continue farther to the southeast (Kennedy, 1975), although no evidence was found of active faulting southeast of Rose Creek along this fault strand. To the northwest, however, both strands appear to be Holocene-age as both faults produce typical fault-related landforms such as deflected streams, offset channel walls, and scarps.

The Mount Soledad strand is obscured by Rose Creek itself for about 2 miles (3 kilometers [km]) northwest from the trench site. Farther northwest, the fault is clearly delineated by an alignment of deflected channels and an uphill-facing scarp. This fault strand passes through the top of Mount Soledad just west of the Cross, and continues west-north-west into La Jolla.

The Rose Canyon fault strand also is obscured by Holocene alluvium in Rose Creek immediately to the north of Lindvall and Rockwell’s (1995) trench site, but scarps are identified crossing the Holocene terrace to Rose Creek south of Jutland Drive and east of Morena Boulevard, and from there to the northwest. The impact of the fault on the proposed bridges across Rose Creek is unclear, as individual fault strands are not well-located, and the fault zone appears to be distributed in this area. Projection of a fault strand to the southeast from a scarp and graben identified south of Jutland Drive (adjacent to the Costco building) projects near the southern Rose Creek bridge, but the precise location of the fault is obscured by Rose Creek itself. The northern Rose Creek bridge appears to lie between two fault strands, so is less likely to be impacted by an active fault strand. In any case, the broad distribution of fault-related features in this area argues that the fault zone is broad and that slip during individual earthquakes would be distributed, thereby decreasing the expected displacement on any single fault strand.

In the vicinity of Ariane Drive, the fault is expressed as possible scarps crossing the Holocene terrace to Rose Creek, and to the northwest, the channel wall of Rose Creek itself appears deflected. If the deflection is the result of fault motion, as appears likely, Los Angeles—San Diego—San Luis Obispo Rail Corridor Agency (LOSSAN) Bridge, all identified possible active fault strands are west of the Trolley alignment as the Rose Canyon strand bends to the west around Mount Soledad.

Historic 1928 and 1953 aerial photos pertinent to this discussion are shown in Plate A-13 and Plate A-14, respectively.

Area 8—Rose Creek North The Rose Creek north images overlapped to a very large degree with Rose Creek Middle, and as they covered the area near the SR 52/I-5 and to the north, were only marginally useful for this study. Consequently, although the imagery for fault location and activity was analyzed, the suite of plates for this section were not included in this report as all relevant information is included in the Rose Creek Middle section and plates.

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Plate A-1. Middletown Fault Interpretive Area (1928)

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Plate A-2. Middletown Fault Interpretive Area (1953)

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Plate A-3. Old Town Fault Interpretive Area (1928)

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Plate A-4. Old Town Fault Interpretive Area (1953)

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Plate A-5. Morena South Fault Interpretive Area (1928)

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Plate A-6. Morena South Fault Interpretive Area (1953)

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Plate A-7. Morena Central Fault Interpretive Area (1928)

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Plate A-8. Morena Central Fault Interpretive Area (1953)

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Plate A-9. Morena North Fault Interpretive Area (1928)

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Plate A-10. Morena North Fault Interpretive Area (1953)

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Plate A-11. Rose Canyon South Fault Interpretive Area (1928)

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Plate A-12. Rose Canyon South Fault Interpretive Area (1953)

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Plate A-13. Rose Canyon Middle Fault Interpretive Area (1928)

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Plate A-14. Rose Canyon Middle Fault Interpretive Area (1953)

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