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Page 2 September 28,2023 Brusca File No. 260-004 Workplan for Additional Site Assessment planned work will include additional drilling and sampling of three soil boings to the south of the former UST and generally situated to the west, south, and east of the main water supply well at the site. All work will be overseen by a Professional Geologist from our office and sampling will be conducted in accord with standard environmental protocol. The analytical testing will be performed by a State-certified laboratory. Permitting and Utility Clearance Prior to the planned additional borings at the site, the necessary drilling permit will be obtained from the San Joaquin County Environmental Health Department(SJCEHD). Prior to drilling, the boring locations will be marked, and Underground Service Alert will be contacted to clear the locations of underground utilities. Additional Drilling and Sampling/Testing We have selected three locations to the south of the former UST for additional borings for soil and groundwater sampling; the planned boring locations are shown on Plate 3. The borings will be performed with a truck-mounted drill rig using hollow stem augers by a C57-licensed drilling contractor. Each boring will extend to groundwater (expected to occur at a depth on the order of 70 feet). The conditions encountered in the exploratory borings will be observed and documented by a Professional Geologist from our office. Photoionization detector (PID) screening of soils will be performed generally at ten-foot depth intervals. A temporary PVC well will be installed within each borehole for groundwater sampling. Prior to groundwater sampling, an interface probe will be used to check for free product. Thereafter, a grab groundwater sample will be collected from each borehole via dedicated/disposal bailer; the collected groundwater samples will be quickly transferred to appropriate sample containers (VOAs) obtained from the analytical laboratory. Soil cuttings and decontamination water generated during the planned drilling will be containerized in 55-gallon steel drums and stored onsite pending proper offsite disposal. Following the sampling activities, all borings will be backfilled with neat-cement grout. The groundwater samples collected from the borings will be placed on ice and transported under chain-of-custody documentation a State-certified laboratory for analysis. The groundwater samples will be tested for gasoline, diesel, and motor oil-range petroleum hydrocarbons by EPA Method 8015B as well as volatile organic compounds (VOCs) by EPA Method 8260B, including MTBE. EVALUATION AND REPORTING The data obtained during the described additional investigation will be tabulated and evaluated. A technical report will be prepared which will include: descriptions of the procedures and observations; scaled site plan drawings; boring logs; the laboratory data; discussion regarding the results and conformance of site conditions to Low-Threat UST Closure policy (LTCP) criteria; and, the signature and stamp of the Professional Geologist in charge of the project.