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UST SYSTEM REMOVAL REPORT 7-ELEVEN STORE NO. 17334, 4501 N. PERSHING AVENUE, STOCKTON, CA 95207 Field Activities March 3, 2023 v:\1858\active\185851132\05_report_deliv\deliverable\reports\2023_rpt_17334_ust.docx 3.1 3.0 FIELD ACTIVITIES 3.1 UST REMOVAL ACTIVITIES On January 26, 2023, Stantec observed the removal of two 10,000-gallon double-walled steel USTs at the site. The USTs were triple rinsed on site and were approved for removal by the EHD. The tanks were transported to Sims Metal Management in Richmond, California for destruction and disposal. The product piping was also triple rinsed on site and transported to US Ecology in Beatty, Nevada for disposal. The rinsate manifest and disposal documentation for the USTs and piping are provided in Appendix A. The UST overburden soil was stockpiled during the UST removal activities and reused in the excavation as backfill. Clean, imported fill (sand and road base) was placed into the remainder of the excavation in six to eight-inch-thick lifts, and compacted using a roller. The site surface was completed with asphalt. The soil compaction report is included in Appendix B. 3.2 SOIL AND GROUNDWATER SAMPLING ACTIVITIES On January 26, 27, and 30, 2023, Stantec personnel collected eleven soil samples under the direction of the San Joaquin County EHD. Three additional soil samples were collected from the UST excavation sidewalls. Soil samples were obtained at depths ranging from two to six feet bgs beneath the former dispenser islands and product piping, at approximately 14 feet bgs from the bottom of the UST excavation, and at depths ranging from four to six feet from the excavation sidewalls. The soil samples were collected from the excavator bucket. The soil samples were immediately placed in clean laboratory supplied glass jars. Each jar was completely filed to minimize headspace and sealed with a Teflon lined screw cap. Each sample was labeled and placed on ice in a cooler. Groundwater was encountered within the excavation during tank replacement activities at approximately 11 feet bgs. One groundwater sample was collected from the UST excavation. The groundwater sample was collected with a disposable bailer and immediately placed in clean laboratory supplied containers. The sample was labeled and placed on ice in cooler. 3.3 ANALYTICAL METHODS The soil and groundwater samples were delivered under chain-of-custody to PACE Analytical National (PACE), a California state-certified laboratory located in Mount Juliet, Tennessee. Soil and groundwater samples were analyzed for total petroleum hydrocarbons as gasoline range organics (TPH-GRO) by Environmental Protection Agency (EPA) Test Method 8015, and for BTEX, MTBE, tert-amyl methyl ether (TAME), tert-butyl alcohol (TBA), diisopropyl ether (DIPE), ethyl-tert-butyl ether (ETBE), and full scan volatile organic compounds (VOCs) by EPA Test Method 8260B. Soil and groundwater samples were also analyzed for lead by EPA Test Method 6010B and methanol by EPA Test Method 8015M.