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Transformer Oil Release Clean-up and Closure Report 1049 South Wilson Way, Stockton California No PCBs were detected in the analyzed Phase 1 asphalt and concrete samples. Aroclor 1260 was detected in the Phase 1 wipe sample from the storm drain, at a concentration of 320 micrograms per wipe (pg/wipe). Aroclor 1260 was also detected in the associated duplicate wipe sample, at a concentration of 300 pg/wipe. No other Aroclor compounds were detected 2.3 Phase 2 2.3.1 Phase 2 Excavation August 28, 2021 — Since Aroclor 1260 was detected in the storm drain wipe sample collected on August 11, 2021, PG&E returned to the site to conduct further clean-up on August 28, 2021. Approximately 110 feet of gutter along the west side of South Wilson Way was excavated. Excavation was also conducted in the driveway of the property at 1049 South Wilson Way, to the south of the transformer pole. The depths of the Phase 2 excavations varied, from approximately 0.67 to 2.5 ft bgs (Figure 2). 2.3.2 Phase 2 Verification Sampling and Results August 28, 2021 — Arcadis returned to the site and collected verification samples within the excavated area. Arcadis collected 21 soil samples from the base of the excavation along the gutter, designated as GV1 to GV21. In addition, duplicate soil samples were collected at GV1 and GV13. Three of the primary soil samples (GV3, GV4, and GV6) that were collected along the gutter were held at the laboratory and not analyzed. Arcadis collected two additional soil samples, designated as L1 and M1, at the base of the excavated areas near the transformer pole, to the west of the gutter. The soil samples were collected from the base of the excavations using a steel trowel and placed directly into laboratory-supplied containers. The trowel was thoroughly decontaminated after each sample was collected. Arcadis collected one concrete sample, designated as SD1, inside the storm drain at a depth of approximately 1 ft bgs. A duplicate concrete sample was also collected at this location. Arcadis collected one wipe sample, designated as W2, on a non-porous surface at a PVC lateral pipe inside the storm drain. All Phase 2 verification samples were placed in ice-chilled coolers and transported under proper chain of custody protocol to Castle for PCB analysis by USEPA Method 8082. The analytical results are summarized in Tables 1 and 2. Aroclor 1260 was detected in 13 of the 18 analyzed primary Phase 2 soil verification samples No other Aroclor compounds were detected. The Aroclor 1260 detections in the soil samples were evaluated relative to the applicable soil Screening Level (SL) developed by the California Department of Toxic Substances Control (DTSC). arcadis.com Stockton Release Closure R sport_07062022 4