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Mr. Jason Gaitan July 13, 2020 FIELD ACTIVITIES The following activities were conducted at the Site between November 2019 and May 2020. Initial Incident Response On November 10 and November 11, 2019, Patriot excavated approximately two cubic yards of diesel- impacted soil and ballast. Soil and ballast were excavated based on visual observations and field screening with a photoionization detector(PID) under Arcadis supervision.A SJCEHD representative was on-site to observe the initial response and approved the excavation footprint. The excavated soil and ballast were containerized and staged on-site in 11 properly labeled U.S. Department of Transportation (DOT) approved 55-gallon drums pending off-site disposal at a licensed facility. On November 11, 2019, one in-place soil sample (SS-1-16)was collected from the bottom of the excavation at approximately 16 inches below ground surface (bgs). The soil sample was collected in a laboratory-supplied container, labeled, placed in an ice-filled cooler, and submitted under standard chain of custody procedures to Pace Analytical, LLC (Pace) in Minneapolis, Minnesota. Pace analyzed the sample for total petroleum hydrocarbons quantified as diesel range organics (TPH-DRO) by United States Environmental Protection Agency(USEPA) Method 8015B. The excavation was backfilled with agreement by SJCEHD. Soil Boring Delineation On February 10 and 11, 2020, nine soil borings (SS-1 through SS-9)were advanced in the vicinity of the release to evaluate TPH-DRO concentrations in soil (Figure 3). Patriot advanced the soil borings using a hand auger under the oversight and direction of an Arcadis representative. Soil cuttings were screened with a PID and staining and/or odor was noted by the Arcadis representative to guide selection of soil samples. Soil cuttings were placed in two 55-gallon DOT drums staged on-site pending disposal. A total of 17 soil samples were collected at depths ranging from 9 inches bgs to 60 inches bgs. Soil samples were collected in laboratory-supplied sample containers, labeled, placed in an ice-chilled cooler, and submitted under standard chain of custody procedures to Pace for analysis of TPH-DRO and TPH as motor oil range organics (TPH-MO) by USEPA Method 8015B. On February 14, 2020, the soil borings were backfilled with neat cement grout by Cascade Drilling, L.P. (Cascade), a C-57 licensed contractor, with oversight by Arcadis and SJCEHD. Investigation Derived Waste Investigation-derived waste (IDW)from the two mobilizations was placed in a total of 13 drums and temporarily stored on site. The IDW was sampled, analyzed by Pace, and characterized as non- hazardous prior to being transported to Crosby & Overton, Inc., in Long Beach, California on January 24 and May 22, 2020. Waste manifests are provided in Attachment 1. DATA EVALUATION Screening Criteria San Francisco Bay Area Regional Water Quality Board (SF-RWQCB) Commercial Industrial (C/1) Shallow Soil Environmental Screening Levels (ESLs)were used to evaluate constituents detected in soil samples arcadis.com Page: 2020.07.13_Soil Sample Summary and Excavation Work Plan.docx 2/5