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 6 permeable materials within both the shallow and intermediate WBZs, with the well design including an upper 5- foot screen section and lower 15-foot screen section, totaling 20 feet of screen interval for the extraction well. After placement of the well screen and blank well riser, a clean filter pack of sand consisting of No. 2/16 (nominal sieve size 16/30) silica sand was placed in the annular space around the well from the bottom of the boring to approximately 5 feet above the top of the shallower screen interval. A finer (choker) sand consisting of No. 1/20 silica sand was placed up to 1.5 feet above the interval of No. 2/16 silica sand. A 5-foot-thick hydrated bentonite pellet seal was placed above the sand pack. The remainder of the annular space was filled with neat cement grout. There was no steel monument or concrete pad constructed for the extraction well , which will be later constructed when connected to the planned GWET system. Three bollards were installed surrounding the well riser stick-up. July 2024 Extraction and Monitoring Well Installation (NCYCC) Two monitoring wells (AMW-61S and AMW-61M) and one extraction well (CDCR-EW-3) were installed by ABC Drilling on July 16 through 26, 2024, under Arcadis’ direction. Well construction details are presented on the field boring logs (Appendix B) and in Table 1. The monitoring wells were completed with a 2-inch-diameter, Schedule 40 PVC casing and 0.010-inch factory-slotted PVC screen. The extraction well was completed with a 6-inch- diameter, Schedule 80 PVC casing and 0.020-inch factory-slotted stainless-steel screen. The total depth and screen interval for each well are provided below: • AMW-61S was drilled to a depth of 80 feet bgs, with the shallow screen extending from 60 to 80 feet bgs (screen elevation -20.01 to -40.01 feet amsl). • AMW-61M was drilled to a depth of 120 feet bgs, with the intermediate screen extending from 90 to 110 feet bgs (screen elevation -50.03 to -70.03 feet amsl). • CDCR-EW-3 was drilled to a depth of 127.5 feet bgs, with an upper screen section (shallow WBZ) extending from 80 to 85 feet bgs (screen elevation -40.25 to -45.25 feet amsl), a deeper screen section (intermediate WBZ) extending from 90 to 115 feet bgs (screen elevation -50.25 to -75.25 feet amsl), and a 5-foot sump from 115 to 120 feet bgs. For the monitoring wells, a clean filter pack of sand consisting of No. 1/20 (nominal sieve size 20/40) silica sand was placed in the annular space around each well from the bottom of the boring to approximately 3 feet above the top of the screen interval. A 5- to 7-foot-thick hydrated bentonite chip or pellet seal was placed above the sand pack. The remainder of the annular space was filled with neat cement grout. The surface completion consisted of a protective steel monument with three bollards and a 2- by 2-foot concrete pad sloping away from the well. In accordance with the RWQCB’s conditional approval (RWQCB 2023), the monitoring well screened within the shallow WBZ was installed with the top of the screen above the water table to allow for seasonal water table fluctuation. The design of extraction well CDCR-EW-3 was based on the lithologic interpretation of the borehole (Appendix B) sediments combined with review for grain size results from soil samples collected from potential screen zone(s), with the laboratory reports presented in Appendix C. The borehole was drilled to 127.5 feet and sampled, reamed to 120 feet. The well screen zones were designed to target the most permeable materials within both the shallow and intermediate WBZs, with the well design including an upper 5-foot screen section and lower 25-foot screen section, totaling 30 feet of screen interval for the extraction well. After placement of the well screen and blank well riser a clean filter pack of sand consisting of No. 2/16 (nominal sieve size 16/30) silica sand was placed in the annular space around each well from the bottom of the boring to