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Limited Site Investigation � Terracon Vacant Property I Tracy, California May 26, 2023 1 Terracon Project No. NA197074B In November 2019 Terracon performed a subsequent limited site investigation in the area of the former release, which included soil sampling at 16 discrete locations from soil borings completed to various depths and from stockpiled soils and native materials. Terracon advanced soil borings to total depths between 20 and 30 feet bgs for SB1 through SB8, and to 10 feet bgs for SB9 through SB16. Groundwater was not encountered during the investigation. As a result of the findings from the November 2019 (Terracon) limited site investigation, additional step-out borings were recommended to further delineate subsurface impacts near the former release, and in shallow soil beneath the area of the former soil stockpiles, which were removed in February and March 2020. A Site Detail is presented as Exhibit 3 and depicts the composite locations of soil and groundwater borings performed by Kleinfelder and Terracon at the site. Between February 25 and March 11, 2020, Ponder Environmental Services of Benicia, California coordinated the loading, transportation, and disposal of 8,623.45 tons of stockpiled soil from the site to the Waste Management Facility in Livermore, California. Additionally, during the same period (February 25 and March 11, 2020), a total of 15,962.03 tons of stockpiled soil was transported to the Recology Facility in Vacaville, California for disposal. Additionally, eight 55-gallon drums of drill cuttings and two 55-gallon drums of decontamination rinse water generated by Terracon as Investigation Derived Waste (IDW) were also transported and disposed of with the stockpile soil. The stockpile soil was transported and disposed under waste manifests. The scope of this Limited Site Investigation (LSI), which was performed on June 3, 7, and 8, 2021 was to collect supplemental data to meet the requirements of the California Regional Water Quality Control Board — Central Valley Region (CRWQCB-CVR) in support of a Low Threat Closure Policy (LTCP) petition for this project. The LTCP will support the San Joaquin County Environmental Health Department (SJCEHD) requirements to satisfy land development. The details of the investigation are presented below in Section 3.0 through 7.0. A Site Diagram and Site Detail are presented as Exhibit 2 and 3 in Appendix A. Analytical summary tables are included as Appendix B; soil boring logs are included as Appendix C; and laboratory analytical reports and chain of custody forms are included as Appendix D. 1.3 Standard of Care Terracon's services were performed in a manner consistent with generally accepted practices of the profession undertaken in similar studies in the same geographical area during the same time. Terracon makes no warranties, either express or implied, Facilities I Environmental I Geotechnical I Materials 3