ITEM 23 ATTACHMENT 6 - Project Plans

December 21, 2022 Job No. 4031.101 Page 4 BERLOGAR STEVENS & ASSOCIATES LABORATORY TESTING Laboratory testing consisted of performing four Atterberg Limits and one R-value test. The Atterberg Limits testing resulted in Liquid Limits (LL) between 26 and 59 and Plasticity Indices (PI) between 9 and 38. The samples collected on the western portion of the site had PIs between 9 and 13. The material on the eastern portion of the site had a PI of 38, which is indicative of very highly expansive soils. The R-value testing was performed on a sample collected from TP-4 and resulted in a value of less than 5. The results of our Atterberg Limits tests are presented in Appendix D. Corrosion Test Results are presented in Appendix E. 6. GEOLOGIC HAZARDS SURFACE FAULT GROUND RUPTURE We have reviewed the Alquist-Priolo Earthquake Fault Zone maps issued by the California Geological Survey (formerly the California Division of Mines and Geology). These maps were issued in response to the Alquist-Priolo Act. The site is located within a designated State of California Alquist-Priolo Earthquake Fault Zone for active faults on the western portion of the site as shown on Plate 4. According to the California Geological Survey (CGS), no known fault traces cross the site. The closest fault included in an Alquist-Priolo Earthquake Fault Zone is the Calaveras fault. As part of BGC’s 1998 Supplemental Investigation, they excavated 885 lineal feet of trench ranging from 8 to 12 feet deep. During the course of the exploration BGC met with Mr. Sandy Haye of Cotton Shires & Associates to discuss the findings. It was agreed that there did not appear to be evidence of faulting. Prior to BGC’s investigation, Harza performed a Fault Investigation and also concluded that there was no evidence of faulting in their trenches. SEISMICITY AND SEISMIC GROUND SHAKING The site is located at approximately 37.6682 degrees north latitude and 121.9138 degrees west longitude. Based on current practices (2019 CBC & ASCE 7-16), the peak ground acceleration – geometric mean (PGAM), obtained using an on-line tool provided by the Structural Engineers Association of California (SEAOC) and the Office of Statewide Health Planning and Development (OSHPD) (https://seismicmaps.org/ link available on the U.S. Geological Survey Earthquake Hazards Program website) is 0.91 g.