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Well Decommissioning Work Plan JACOBS I Field Activities Field activities will consist of well decommissioning, grouting, decontamination procedures, and waste management and disposal. The locations of the wells to be decommissioned are shown on Figure 2. Well construction details are summarized in Table 1. 3.1 Well Decommissioning Activities The wells will be abandoned under observation by or under the direct supervision of a California-licensed Professional Geologist. The wells will be decommissioned in accordance with SJCEHD guidelines (SJCEHD, 2005) and California Department of Water Resources (DWR) requirements,as follows: • Prior to the start of decommissioning activities, the monitoring wells will be inspected and the bottom of each well will be gauged to verify their depths. Obstructions will be removed, if necessary. • The surface completions will be removed. • The well casings and construction material will be removed by over-drilling with an appropriately sized hollow-stem auger to the total depth of the wells, to remove sand and bentonite around the 4-inch well casing. Each location will be cleared by hand auger or air-knife to 5 feet below ground surface (bgs) prior to drilling. Drill cuttings and well debris will be containerized for characterization and disposal as described in Section 3.3. The resulting borehole will be filled and sealed with neat cement through a tremie pipe from the bottom of the boring to the top. Grout volume calculations will be logged in the field. • If site conditions prevent overdrilling of any well, a variance will be requested through SJCEHD, and neat cement grout will be used to seal the borehole. Conditions that could prevent overdrilling include, but are not limited to the following: — The well is located within 3 feet of an active utility. — The well is located within 5 feet of a potentially active utility that can't be physically verified. — Other health and safety concerns related to hazardous conditions such as working in an active electrical substation near flammable materials or overhead transmission lines. Based on direction from SJCEHD and supervision of an SJCEHD inspector, a tremie pipe will be used to emplace neat cement under pressure or by gravity from total depth of the well to the top. The well casing will be cut at approximately 2 feet bgs and a grout"mushroom cap" will be placed on top of the cut casing to approximately 6 to 12 inches bgs. The grout will be allowed to settle for a minimum of 12 hours. The upper portion of the hole will be backfilled concrete to match the surrounding grade and condition. • Historical boring logs and well construction diagrams were unavailable for review. As noted in the 2018 Monitoring Well Destruction Report(MW--5, MW-7, MW-8, MW-9R, MW-18, and MW-19R) (ETIC, 2018), two wells located in Zone B (MW-5 and MW-19R)were installed with steel conductor casings from just below the well box to approximately 65 feet bgs. Decommissioning activities to remove those conductor casings included the use of an 18-inch diameter auger to 65 feet bgs, pulling the conductor casing from the ground at ten-foot sections, and dismantling those sections using torch-cutting methods. It is possible MW-23R, which is located in Zone B, may contain a similar conductor casing and may not be visible by visual inspection of the well. MW-23R is located within 25 feet of an active propane tank in the PG&E Substation portion of the site (Appendix A- Photographs). Using torch-cutting or cutting methods to remove the conductor casing would pose a serious health and safety risk and is not feasible. Prior to submittal of the well permitting application to SJCEHD, PG&E will request a variance for MW-23R if a conductor casing is identified. If the variance is not approved and a conductor casing is identified, PG&E would not decommission the well during these activities but would restore and maintain the monitoring well until such time that the decommissioning can be performed safely. • An approved traffic control plan and subcontracted traffic control company will be used during well decommissioning activities at well MW-21 located on the sidewalk next to West Hazelton Avenue and FES0817211625BAO