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Abandonment of Groundwater Monitoring Wells Work Plan Page 3 Lodi Central Plume Source Area,Lodi,California March 23,2024 ➢ CHT, along with the driller will obtain the Groundwater Monitoring Well Abandonment Permits from the San Joaquin Department of Environmental Health (SJDEH) WELL ABANDONMENT Prior to abandonment of the groundwater monitoring wells,the driller will obtain the requisite well abandonment permits and get approval from the SJDEH of the appropriate methodologies for well abandonment. All shallow and intermediate zone monitoring wells will be properly abandoned by over-drilling using an oversized hollow stem augur drills based on the diameter of the wells. For the 2-inch diameter wells an 8" outer diameter(OD) auger fitted with a 9" bit will be used, while for the 4-inch diameter wells, a 10" OD auger fitted with a I I" bit will be used to over drill the well casing. The deep and deeper zone monitoring wells will be abandoned by over drilling with a sonic drill rig. The over-drilled borehole will be grout sealed under the supervision of a SJDEH inspector using the tremie system to the target depth following removal of the well casing. Figure 1 provides the locations of the wells (encircled in red circles / ovals) that are slated to be abandoned and Table 1 provides the construction details of those wells. MANAGEMENTOFINVESTIGATIONDERIVED WASTE To support Investigation-derived waste(IDW)generated during well abandonment activities,soil cuttings and decontamination water will be stored in UN-rated, 55-gallon steel drums. IDW will be profiled and disposed off-site in accordance with local, State and Federal regulations REPORTING Following completion of the well abandonment activities, CHT will prepare a Well Abandonment Report that documents and summarizes all the activities performed at the site, including all laboratory analytical reports and chain-of-custody forms. The Report will be submitted to the Water Board and uploaded to GeoTracker within four weeks upon completion of the well abandonment activities. SCHEDULE The field work associated with the well abandonment activities is scheduled to commence from April 9, 2024, and will continue for a period of six (6) weeks. The Project Schedule is based on current information available; if any unforeseen circumstances such as inclement weather results in a delay of the proposed scheduled activities, a revised schedule will be submitted to the Water Board by CHT. The Report documenting the well abandonment activities will be prepared and submitted to the Water Board within four (4) weeks of completion of field activities. A copy of the report and associated borehole information will be uploaded to GeoTracker. 581 MONTEGO TERRACE,SUNNYVALE,CA 94089 TEL:415-424-3009