2014-069 - Final Environmental Impact Report No. 2014-01

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HARBOR BLVD. MIXED USE TRANSIT CORRIDOR PLAN FINAL FIR CITY OF SANTA ANA 5. Environmental Analysis GEOLOGY AND SOILS a grading permit must be accompanied by plans, specifications, a soils engineering report, and engineering geology report. The geotechnical investigation would be required to calculate seismic design parameters for the project specific to the site and land use type, which would be implemented in the design of the proposed structures. Therefore, impacts would be less than significant. Impact 5.4 -2: Future development in accordance with the Harbor Boulevard Mixed Use Transit Corridor Plan would not expose people and structures to substantial adverse hazards from liquefaction or other seismic - related ground failure. [Threshold G- 1.iii] lmpactAnalysis: The entire project area is in a zone of required investigation for liquefaction designated by the California Geological Survey (CGS 1998a; CGS 1998b). Most of the project area is also mapped as an area of potential liquefaction in Exhibit 5, Potential Liquefaction Areas, of the City's General Plan. Therefore, future development in accordance with the Harbor Boulevard Mixed Use Transit Corridor Plan could subject people and structures to hazards from liquefaction. However, while the project area is within a liquefaction zone, individual development projects considered for approval under the Harbor Boulevard Mixed Use Transit Corridor Plan would be required to adhere to existing building and grading codes, including Chapter 8 (Buildings and Structures), Article 2 (Building Code) of the City's Municipal Code. These codes contain provisions for soil preparation to minimize hazards from liquefaction and other seismic related ground failures. Projects considered for approval under the Harbor Boulevard Mixed Use Transit Corridor Plan would be required to adhere to the provisions of all applicable building and grading codes, which are imposed on project developments by the City during the building plan check and development review process. Compliance with the requirements of the applicable building and grading codes would reduce hazards arising from liquefaction. Additionally, as standard procedure by the City of Santa Ana, grading and soil compaction requires the preparation of site - specific grading plans, soils and geotechnical reports (which must address liquefaction and other potential soil stability hazards), and hydrology studies, must be submitted to and reviewed and approved by the City before any grading activities. Each geotechnical investigation report would have recommendations for site grading and engineering of fill soils to minimize hazards from liquefaction and other geologic hazards identified in that investigation. Submittal of these technical plans and studies would ensure that hazards from liquefaction and other seismic ground failure would not arise, since they would be prepared in accordance with grading and engineering standards outlined in the most current CBC. Therefore, impacts would be less than significant. Impact 5.4 -3: Project buildout would not expose people or structures to substantial hazards from ground subsidence, collapsible soils, and expansive soils. FThresholds G -3 and G -4] Impact Analysis: Ground subsidence is the settling or sinking of the ground. Natural conditions, such as seismic ground shaking, and human activities, such as groundwater extraction, can cause subsidence. There is no indication that land surface changes caused or are likely to cause, any structural damage in the City of Santa Ana. However, most of the project area is mapped as an area of potential subsidence in Exhibit 4, Potential Subsidence Areas, of the City's General Plan. Therefore, future development in accordance with the October 2014 Page S.¢77