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Geospte& consultants well boxes to eliminate field staff errors in identification of well numbers, and re-development of wells where 20% of the well screen or more is blocked by sediments. Wells that had changes made to the height of the casing will be surveyed as part of the 2024 well maintenance activities. During the 2023 well maintenance activities, some well casings were cut to accommodate new well caps or well boxes, and other well casings had new PVC couplers and risers added to replace damaged PVC in the top 4 feet of the well. These wells, as listed in Table 1, will be resurveyed so the groundwater elevation information can accurately be calculated as part of the 2024 annual reporting process. Geosyntec plans to install QR codes printed on metal tags and secured to the inside of the well boxes of the monitoring wells that will be sampled as part of the 2024 groundwater monitoring program. Geosyntec also plans to install QR codes in some of the wells that will be gauged. QR code efforts will be focused on wells that Confluence has mixed up during gauging events previously, like wells in pairs or clusters. Geosyntec staff will tag the wells for total depth to confirm the well identification before the QR code tags are installed. These QR codes will be scanned by the field sampling technician before sampling and will link to a mobile field app that will confirm the well identification and well construction information. The QR codes will be installed in an effort to reduce sampling errors and well mix-ups during sampling. Prior to the start of the 2024 groundwater monitoring event, Geosyntec staff will measure the total well depth of all wells proposed to be sampled in 2024. Wells with sediment accumulation that covers more than 20% of the well screen will be bailed to remove sediment, and the wells will be re-developed using a combination of bailing, surging and pumping. Well re-development will be performed in accordance with the standard operating procedure (SOP) included in Appendix A. The monitoring wells that are anticipated to require well re-development,based on measurements of total depth in 2023, are included on Table 1. 2.4 Well Destruction Activities Damaged wells that are obstructed, compromised at depth, or unrepairable will be destroyed. Five groundwater monitoring wells, located and assessed in 2023, are proposed to be destroyed, as listed on Table 1. Well destruction permits will be obtained from San Joaquin County Environmental Health Department(SJCEHD). The well destructions will be conducted by a C-57 licensed drilling contractor working under the supervision of a California licensed professional geologist. Each well that is destroyed will be overdrilled using the hollow stem auger(HSA) drilling method to the total well depth using an auger diameter greater than the original well borehole and the well materials removed from the subsurface. Once the well materials have been removed, the borehole will be tremie grouted with Portland cement grout under inspection by SJCEHD from the bottom of the borehole to 5 feet bgs. In accordance with the California Well Standards, the top 5 feet bgs will be backfilled with native soi15. The soil cuttings and well casing removed from the ground as part of the well destruction activities will be stored in drums or bins, the soil 4 DTSC and CVRWQCB will be notified if an alternative drilling method will be used. 5 Department of Water Resources(DWR), 1991.California Well Standards.Bulletin 74-90.June. RRI 2024 Groundwater Monitoring Work Plan 10 June 13,2024