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Remediation System Well Abandonment Work Plan JACOBS 3. Field Activities Field activities will consist of well abandonment, aboveground and underground piping removal, grouting, decontamination procedures, waste management and disposal, and removal and disposal of remediation equipment. The locations of wells to be decommissioned are shown on Figure 2. Existing well construction details are summarized in Table 1. 3.1 Well Abandonment Activities The wells will be abandoned under observation by or under the direct supervision of a professional geologist. The wells will be abandoned, in accordance with SJCEHD guidelines,as follows: • Prior to the start of abandonment activities, the monitoring wells will be inspected and the bottom of each well will be tagged 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 either a 4-inch-, 8- inch-, or 10-inch-diameter hollow-stem auger to the total depth of the wells, depending on the type of well to be removed. Each location will be cleared by hand auger or air-knife to 8 feet bgs prior to drilling. Drill cuttings and well debris will be containerized for characterization and disposal as described in Section 3.3. • If site conditions prevent overdrilling of any well, neat cement grout will be used to seal the borehole and will be placed with a tremie pipe under the supervision of a SJCEHD grout inspector. Conditions that could prevent overdrilling include: — The well is located within 2 feet of an active utility — The well is located within 5 feet of an active utility that can't be physically verified — The wells is in an area that is not accessible by a drill rig due to aboveground pipelines (some wells were originally installed using hand augers) The tremie pipe will be used to emplace neat cement under pressure from total depth to approximately 3 feet bgs. 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 upper portion of the hole will be backfilled with gravel to match the surrounding grade. 3.2 Equipment Decontamination Drilling equipment will be decontaminated prior to and between well locations, before and after work. Decontamination procedures will include, at a minimum, dry brushing to physically remove soil, washing the equipment with an Alconox(or similar detergent)solution, and a pressurized rinse with potable water. Decontamination fluids will be collected and contained in 55-gallon drums. 3.3 Remediation Equipment and Piping Removal Remediation equipment related to the AS/SVE system will be removed from the Site and reused elsewhere, disposed of, or recycled accordingly per PG&E requirements. Associated AS/SVE system aboveground and underground PVC piping will also be removed and disposed of per PG&E requirements. 3.4 Waste Characterization and Management The surface completions will be managed as non-hazardous waste and recycled where available. The drilling subcontractor will remove these materials from the Site and dispose of them at an appropriate offsite disposal facility. Drill cuttings generated from over-drilling will be collected and contained in B11204191849AKT