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Remediation System Well Abandonment Work Plan JACOBS 1 . Introduction and Background Jacobs Engineering Group Inc. (Jacobs), on behalf of Pacific Gas and Electric Company (PG&E), has prepared this Remediation Well Abandonment Work Plan (Work Plan)for the PG&E Las Vinas Dehydrator Station (Site) located in San Joaquin County, California (Figure 1). This work plan proposes the abandonment of remediation wells and removal of Air Sparging/Soil Vapor Extraction (AS/SVE) system equipment. Fifty-four wells have been installed at the Site during multiple investigations dating back to 1997. The wells have been installed for multiple purposes, including groundwater monitoring, air sparging, ozone sparging, soil vapor monitoring, and soil vapor extraction. Currently, 52 wells remain, with 2 abandoned previously in 2016. Twenty-eight wells related to remediation activities are proposed to be abandoned and are described further in this report. 1.1 Objective The objective of the proposed work is to permanently abandon 28 remediation wells in accordance with the applicable State and San Joaquin County Environmental Health Department(SJCEHD) requirements. In addition, AS/SVE system equipment and associated aboveground and underground piping will be removed from the Site. 1.2 Site Description and Background PG&E currently owns and operates the Las Vinas Dehydrator Station, which was used to dehydrate and odorize natural gas for transport via the Site's natural gas transmission system. The Site is located approximately 0.5 mile west of Ray Road, 0.25 mile south of Woodbridge Road, and 4.0 miles northwest of Lodi, California (see Figure 1; figures and tables are presented at the end of this letter report). The station, built in 1942, is approximately 200 feet wide by 200 feet long and is enclosed by a chain-link fence. The Site is currently graveled and has a small production fluids tank, a control building, and aboveground piping. Equipment formerly located at the Site included two reboilers, one production fluids tank, two contactor towers, one glycol tank, and odorization tanks and equipment. Former equipment and remedial investigation well locations are depicted on Figure 2. The constituents of concern (COCs) at the Site consist of petroleum hydrocarbons including gasoline range organics (GRO); diesel range organics (DRO); motor oil range organics (ORO); and benzene, toluene, ethylbenzene, and xylenes (BTEX). The presence of these COCs in soil and groundwater is the result of release(s)of natural gas condensate from previous Site operations. Gas condensate consists of light, volatile, low carbon range organics (C6 to C12). An AS/SVE system operated at the Site from April 2015 through September 2016. A Pilot Study Completion Report was submitted in December 2017 (CH2M, 2017)with Central Valley Regional Water Quality Control Board (CV-RWQCB) concurrence in January 2018 (CV-RWQCB, 2018). CV-RWQCB concurrence followed collection of one additional round of soil gas vapor sampling that was presented in a Pilot Study Completion Report Addendum (Jacobs, 2018), the CV-RWQCB concurred with PG&E's recommendation to dismantle the AS/SVE system and destroy wells associated with the system (CV-RWQCB, 2019). 1.3 Well Details Of the 54 wells installed, 28 wells related to remediation activities are proposed to be abandoned. Two wells related to remediation activities (SV-6 and SVE-11)were previously abandoned in May 2016 due to PG&E gas operation upgrade construction activities at the Site (CH2M, 2016). Five remediation wells (SV-1, SV-2, SV-3, SVE-8, and SVE-10)are located less than 10 feet from monitoring wells sampled in the current Monitoring and Reporting Program (MRP). In order to minimize any impacts from well abandonment activities, including grouting, these five wells will not be abandoned at this time. Nineteen monitoring wells will be maintained for use in future Site monitoring activities. Biosparge well BS-1, which is voluntarily monitored on a semi-annual basis (ETIC, 2019), is included in the list of wells to be abandoned. This well, constructed for biosparging activities, has a 2-foot long screen B11204191849AKT