Geotechnical

The San Diego Gas & Electric Company (SDG&E) is proposing to construct a new 138-kV substation adjacent to an existing 138-kV substation and replace the existing 138-kV substation with a new 230-kV substation in San Juan Capistrano, California. Geosyntec was contacted by SDG&E to perform a geotechnical investigation as part of the as-needed geotechnical contract between Geosyntec and SDG&E. The geotechnical investigation was performed to characterize the subsurface at the site, perform engineering analyses, and provide geotechnical engineering recommendations related to earthwork, grading, retaining wall, and foundation design for the proposed substation. The project site is underlain by the landslide-prone Capistrano Formation and the potential for landslides was evaluated as part of the geotechnical and geologic hazards investigation. The proposed new graded pad for the new 138kV substation involved cuts and fills on the order of 25 feet with a new retaining wall planned along the new access road on the site and within the proposed new substations.