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Second Semi-Annual 2021 Groundwater Monitoring, Batch Extraction Results Report & Supplemental Site Investigation Waterloo Food and Fuel 3032 East Waterloo Road, Stockton, California Page 8 Well ID Extraction Date Duration of Event (minutes) EW-1 September 27, 2021 145 EW-2 September 27, 2021 130 EW-3 September 27, 2021 125 SUPPLEMENTAL SITE INVESTIGATION The 2019 AdvancedGeo Environmental, Inc., Additional Site Assessment Workplan (Workplan) for the Site proposed seven additional soil borings and soil vapor wells in an attempt to evaluate the Site under the Low-Threat UST Case Closure Policy. On August 4, 2021 CVRWQCB issued a letter, that in part, directed that only the soil boring portion of the workplan be completed at this time (Appendix A). Apex obtained permits from San Joaquin County Environmental Health Department to complete the soil borings outlined in the Workplan (Appendix C). Apex completed seven (7) soil borings (Si through S7) at the Site on October 11, 2021 (Figure 2). Soil sampling was completed utilizing direct push methodologies. Samples at each location were collected at depths of five and 10 feet bgs. Since the upper five feet at each location was cleared for underground utilities utilizing hand auger, the top and bottom of each driven sample was submitted for analysis. Apex utilized a photoionization detector (PID) to screen the soil at each boring and each sample horizon. Only soil from the location identified as S6 revealed PID reading ranging from 3.5 parts per million (PPM) to 4.8 ppm at depths ranging from six inches bgs to one-foot bgs. The ground cover at this location was observed to be fractured asphalt. All other PID readings throughout the exercise remained at 0.0. No odors (other than a slight odor at shallow depth at S6 consistent with the PID readings described above) or discoloration were observed from the soil at any of the borings completed. Each sample collected in accordance with the Workplan was submitted to California Laboratory Services in Rancho Cordova, California under chain-of-custody documentation and analyzed for TPHg, BTEX, naphthalene, the Five Fuel Oxygenates, ethylene dibromide (EDB), and ethylene dichloride (EDC) by EPA Method 8260 as outlined in the Workplan. A review of the Workplan found that the purpose of these samples was to confirm soil samples results near the historical piping samples PL-2 through PL-6. Five (5) of the borings were advanced adjacent to these historical samples, one soil boring was advanced in front of the onsite building, and one soil boring was advanced in the center of the Site. A review of the laboratory analytical results for the 14 soil samples submitted found that none of the constituents of concern were found of above their respective laboratory reporting limits. These results indicate that the release documented by the historical piping samples is no longer present at detectable concentrations. The boring logs describing the soils present are included in Appendix C. The soil results are presented in Table 6 and the associated laboratory report is included in Appendix D. Figure 2 presents the locations of the borings. All soil cuttings generated were sealed in a 55-gallon metal drum and labeled pending the analytical laboratory results and stored behind a locked fence at the Site. At the time of generation of this report, arrangements were pending for the transportation and disposal of the single drum. Documentation of drum disposal will be submitted during the next semi-annual reporting period.