COMPLIANCE INFO_EW-5 INSTALL PERMIT PACKAGE 2/14/25

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WELL INSTALLATION AND INTERIM REMEDIAL ACTION REPORT www.arcadis.com FINAL_Forward CHCF (CDCR) Well Installation Report_10182024 3 3 Regional Geology and Hydrogeology Located at the northern end of the San Joaquin Valley, San Joaquin County lies in the region of the confluence of the San Joaquin and Sacramento Rivers. The San Joaquin Valley is bordered by the Coast Ranges on the west and the foothills of the Sierra Nevada to the east. The San Joaquin Valley basin has been filled over time with up to a 6-mile-thick sequence of interbedded clay, silt, sand, and gravel deposits. The sediments range in age from more than 144 million years old (Jurassic Period) to less than 10,000 years (Holocene). The most recent sediments consist of coarse-grained (sand and gravel) alluvial deposits along river courses and fine-grained (clay and silt) deposits located in low lying areas. The most recent deposit, the Victor Formation, is typically heterogeneous and laterally and vertically discontinuous, indicative of a fluvial depositional environment. The Victor Formation is generally coarse -grained but is slightly clayey in the interfan sediment areas near Forward Landfill. In this area, the Victor Formation is approximately 100 feet thick. The sand and gravel deposits of the San Joaquin Valley basin are highly permeable and are regionally and locally used for water supply for agricultural and domestic purposes. Most of the production wells in the area are constructed to depths in the order of 500 feet and produce water from the Laguna Formation (SWT Engineering Inc. 2013); however, from record searches of well logs it is noted that some local wells were screened at shallower depths either using long single screen intervals or with multiple de pth screen intervals within single wells.