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CBI <br /> 180 Promenade Circle,Suite 320 <br /> . Sacramento,CA 95834 <br /> Telephone:916-565-4316 <br /> January 20,2015 <br /> Project 149259 <br /> Taj M.Bahadori,P.E. <br /> San Joaquin Department of Public Works <br /> Solid Waste Division <br /> 1810 E.Hazelton Avenue <br /> Stockton,CA 95205 <br /> Re:Review of the Stability Analysis at the Foothill Sanitary Landfill <br /> Dear Mr.Bahadori: <br /> This letter is CB&I's response to the Central Valley Regional Water Quality Control Board (CVRWQCB) staff <br /> request for the review of the stability analysis at the Foothill Sanitary Landfill (FSL). This is the second letter <br /> addressing seismic stability at FSL;a previous letter was submitted to CVRWQCB dated January 13,2015(Attached). <br /> The seismic analysis that was performed by Shaw in 2012 applied a constant horizontal acceleration of 0.75 x peak <br /> ground acceleration(PGA)(0.75 x 0.058=0.038g). With the horizontal acceleration value of 0.038g,the results of <br /> the analysis yielded factors of safety greater than 1.5. To respond to the concerns the CVRWQCB has regarding <br /> the PGA used in the 2012 analysis,a seismic displacement analysis was performed based on the very conservative <br /> assumption that the PGA is equal to 0.20g taken from the USGS 2014 National Seismic Hazard Map of the U.S. <br /> (see Attachment A). <br /> The seismic displacement analysis was performed for the Central Valley Coast Range (CVCR) fault and the San <br /> Andreas Fault. The results of the seismic displacement analyses yielded median displacement values of 0.022 inch <br /> for the CVCR Fault and 0.33 inch for the San Andreas Fault; and 16% probability of exceedance values of 0.65 <br /> inch for the CVCR Fault and 3.7 inches for the San Andreas Fault. All values are deemed negligible and are less <br /> than the limit of 12 inches recommended by the U.S. Environmental Protection Agency in their 1995 Seismic <br /> Design Guidance for Municipal Solid Waste Landfills. Title 27 California Code of Regulations does not specify an <br /> acceptable value for permanent displacement under seismic loading. Based on our experience in performing <br /> landfill stability analyses in California, these displacement values are acceptable and verify that the Foothill <br /> Sanitary Landfill meets Title 27 slope stability requirements. <br /> Please call if you have any questions. <br /> Sincerely, Q�pFESS/ <br /> pN <br /> CB&I Environmental and Infrastructure,Inc. o PCO 0•Y4 F <br /> as <br /> LU 33718 ohm <br /> �o a� J m <br /> AUAN C.ItNAS pires'y <br /> C. N0 {ii1 • //�� k <br /> • c>rNnr1E� sT clv1�- <br /> EN6INEENINt <br /> d�, t€etwlst �. 9TE OF C Al <br /> Julian C.Isham,PG,CEG,CHG 6f C����0� Leonard O.Yamamoto,PE <br /> Geology Manager Senior Civil Engineer <br /> Attachment A—Seismic Displacement Analysis <br /> 2015-01-20 FSL Seismic Analysis.docac <br />