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Page 3 September 11,2023 Brusca File No. 260-004 Anderson Barngrover Ranch location provided by the laboratory was faulty).6 We prepared a Workplan for the required additional investigation dated June 27, 2023 and the CVRWQCB indicated approval of the Workplan in a letter dated June 29, 2023.' s INVESTIGTIVE ACTIVITIES General The additional site investigation was performed in general accord with the referenced approved Workplan. Our scope of work included: drilling permitting; utility clearance; exploratory drilling for the collection of subsurface soil and groundwater samples at three locations at the site; installation and sampling of a temporary soil gas probe at the SG3 location; laboratory analysis of the collected soil,groundwater, and soil gas samples; and, evaluation of the results. All fieldwork was overseen by a Professional Geologist from our office and sampling was conducted in accord with standard environmental protocol. The soil, groundwater, and soil gas testing was performed by State-certified analytical laboratories. Permitting and Utility Clearance Prior to the drilling and sampling at the site, we processed the required drilling permitting with the SJCEHD; a copy of the permit is attached. We pre-marked the drilling locations, and we retained a private utility locating contractor to clear the locations of underground utilities. We also contacted Underground Service Alert to further clear the locations of underground utilities. Exploratory Drilling/Soil and Groundwater Sampling Three exploratory borings (identified as TH8, TH9, and TH 10) were advanced at the locations prescribed in the approved Workplan; the boring locations are shown on Plate 3. As shown, the borings were situated at distances on the order of 110 feet to 150 feet to the north south, and west of the former UST location and were generally sited to evaluate the groundwater contamination plume configuration in those directions (the plume limit to the east of the former UST generally was defined during previous investigation at the site). The borings were performed by a C57- licensed drilling contractor utilizing a truck-mounted drill rig with hollow stem augers on August 16 and 17, 2023. Borings TH8 and TH10 were advanced to a depth of 70 feet and Boring TH9 was advanced to a depth of 75 feet. Groundwater was encountered in all three borings; the stabilized groundwater depth was measured at 64 feet in Boring TH8, and at 69 feet in Borings TH9 and TH10. 6 CVRWQCB; "Request for Additional Assessment Workplan and Completion of Vapor Intrusion Assessment, Anderson-Barngrover Ranch, 14290 East Comstock Road, Linden, San Joaquin County; Case #292009, Global ID #T10000020864";June 22,2023. 7 Brusca Associates, Inc.; "Workplan for Additional Plume Definition, Area of Removed Underground Fuel Tank, Anderson Barngrover Ranch Property,APN 091-030-130m 14290 East Comstock Road,Linden,San Joaquin County, California";June 27,2023. a CVRWQCB;"Concurrence with Workplan,Anderson-Barngrover Ranch, 14290 East Comstock Road,Linden,San Joaquin County;Case#292009, Global ID#T10000020864";June 29,2023.