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) THIS PAGE INTENTIONALLY LEFT BLANK 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 MID-COAST CORRIDOR TRANSIT PROJECT April 2013 i Geotechnical, Geologic and Seismic Impacts Technical Report Table of Contents 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 MID-COAST CORRIDOR TRANSIT PROJECT ii April 2013 Geotechnical, Geologic and Seismic Impacts Technical Report Table of Contents 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 ..................................................................