10.10A.100 Geologic hazard reports

A. Upon a determination by the DRC of the scope of geologic or other hazard studies required by an applicant, the applicant, at its expense, shall provide the city with a site-specific report consistent with the requirements of this chapter that identifies all known or suspected geologic hazards on the site, whether originating on-site or off-site, and whether previously identified or previously unrecognized, that may affect the subject property. All reports shall include the original signature and wet stamp of the qualified professional geotechnical engineer or engineering geologist. Geologic hazards reports co-prepared by professional geologists and engineers must include the original signature and wet stamp of both professionals. B. The scope of the development and the potential for hazards to exist on a sensitive lands property, as determined by the DRC in consultation with the city engineer and city geologist, shall govern which of the following studies must be completed in connection with a development application (the specific requirements for the performance of such studies are found in the appendices to this chapter): 1. Surface fault rupture hazard report (Appendix B). Surface fault rupture hazard reports shall contain all requirements described in Appendix B of this chapter, Minimum Standards for Surface Fault Rupture Hazard Studies. Surface fault rupture studies shall be conducted by a qualified engineering geologist. 2. Slope stability and landslide hazard reports (Appendix C). Slope stability and landslide hazard reports shall contain all requirements described in Appendix C of this chapter, Minimum Standards for Slope Stability Hazard Studies. Slope stability and landslide studies shall be conducted by a qualified engineering geologist or a qualified professional engineer. 3. Liquefaction hazard reports (Appendix D). Liquefaction hazard reports shall contain all requirements described in Appendix D of this chapter, Minimum Standards for Liquefaction Hazard Studies. Liquefaction analyses shall be conducted by a qualified geotechnical engineer. 4. Debris flow hazard reports (Appendix E). Debris flow hazard reports shall contain all requirements described in Appendix E of this chapter, Minimum Standards for Debris Flow Hazard Studies. Debris flow hazard investigations shall be conducted by a qualified engineering geologist. Mitigation measures will generally require contributions from geotechnical engineers, hydrologists, or civil engineers. 5. Rockfall hazard reports (Appendix F). Rockfall hazard reports shall contain all requirements described in Appendix F of this chapter, Minimum Standards for Rock-Fall Hazard Studies. Rockfall studies shall be conducted by a qualified engineering geologist. Mitigation measures will generally require contributions from geotechnical and/or civil engineers. 6. Foundation excavation observation reports (Appendix H). Foundation excavation observation reports shall contain all requirements described in Appendix H of this chapter, Minimum Standards for Foundation Excavation Observation Reports. Foundation observation reports shall be conducted by a qualified geotechnical engineer or engineering geologist. C. In addition to the requirements of the aforementioned reports, all geologic hazards reports shall include the following: 1. A 1:24,000-scale geologic map, with references, showing the general surface geology (landslides, alluvial fans, etc), bedrock geology where exposed, bedding attitudes, faults, and other geologic structural features; 2. A detailed site map of the subject area, at a scale equal to or more detailed than one inch equals 200 feet, showing the locations of subsurface investigations and site-specific geologic mapping performed as part of the geologic investigation, including boundaries and features related to any geologic hazards, topography, and drainage. The site map must show the location and boundaries of the property, geologic hazards, delineation of any recommended setback distances from hazards, and recommended locations for structures. Buildable and non-buildable areas shall be clearly identified; 3. Trench logs, when applicable, prepared in the field and presented in the geologic hazard report at a scale equal to or more detailed than one inch equals five feet; 4. Boring logs, when applicable, prepared with standard geologic nomenclature; 5. Listing of aerial photographs used and other supporting information, as applicable; 6. Conclusions, clearly supported by adequate data included in the report, that summarize the characteristics of the geologic hazards, and that address the potential effects of the geologic conditions and geologic hazards on the proposed development and its occupants, particularly in terms of risk and potential damage; 7. Specific recommendations for additional or more detailed studies, as may be required to understand or quantify a geologic hazard; 8. An evaluation of whether or not mitigation measures are required, including an evaluation of multiple mitigation options; 9. Specific recommendations for avoidance or mitigation of the effects of the hazards, consistent with the purposes set forth in this chapter, including design or performance criteria for engineered mitigation measures and all supporting calculations, analyses, modeling or other methods, and assumptions. Final design plans and specifications for engineered mitigation must be signed and stamped by a qualified geotechnical, civil and/or structural engineer, as appropriate; 10. All data upon which recommendations and conclusions are based shall be clearly stated in the report; 11. A statement shall be provided regarding the suitability of the proposed development from a geologic hazard perspective; and 12. Identification of all utilities that serve the proposed development, including design and specifications of flexible expansion joints for utility lines that cross any fault line(s). D. When a submitted report does not contain adequate data to support its findings, additional or more detailed studies shall be required to explain or quantify a particular geologic hazard or to describe how mitigation measures recommended in the report are appropriate and adequate.