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13 November 2018 AGE Project No. 18-4357 Page 9 of 11 AdvancedGeo Environmental • TPH-d was detected above the laboratory reporting limit in six subsurface soil samples and the three stockpile soil samples. In two of the six samples, TPH-d was detected just above the laboratory reporting limit of 10 mg/kg in soil samples B-5 (11.6 mg/kg) and S12-2 (10.9 mg/kg). However, The ECI laboratory reports contained the following comment/lab note for every TPH-d detection: Peaks in diesel range but chromatogram does not match that of diesel standard. After discussing the results and lab comment with ECI, the detections of TPH-d are likely overlap from TPH-mo detections. Based on the historical use of the site as a used oil filter recycling business, AGE believes the TPH-d detections (C11 -C22) are overlap from the TPH-mo detections (C23 -C35) at the site. • TPH-mo was detected above the laboratory reporting limit (50 mg/kg) in four subsurface soil samples and the three stockpile soil samples. Additionally, TPH-mo was detected below the laboratory reporting limit in sample B-5 at a concentration of 43.0 mg/kg; the sample was flagged (J) by the laboratory with the following comment/note: trace concentration between the method detection limit and practical quantitation limit. • TPH-mo was detected in S5-2, S6-2, and S6SW-2 at 2.0 feet bsg at concentrations of 219 mg/kg, 4,220 mg/kg, and 191 mg/kg; TPH-mo was detected in SW -E at 4.0 feet bsg at a concentration of 58.9 mg/kg; and TPH-mo was detected in B-5 at 5.0 feet bsg, below the lab laboratory reporting limit, at a concentration of 43.0 mg/kg (J Flagged). TPH-mo was detected significantly below the established clean-up goal and below the ESLs for commercial and residential properties. • Based on soil samples collected at 5.0 feet bsg from S5-5, S6-5, S7-5, S8-5, S9-5, S11-5 and B-5 (TPH-mo detected below lab reporting limit), the vertical extent of TPH-impacted soil is defined. • Based on soil samples collected, the lateral extent of TPH-impacted soil is defined towards the west, north, and east, and partially defined towards the south. The lateral extent of TPH-impacted soil is defined towards the west by S12 at 2 feet bsg and S5 at 5 feet bsg; towards the north by S6SW-N, S-8, S-9, and S-11 at 2 feet bsg and SW -N at 4 feet bsg; and towards the east by S613-2 and S7 at 2 feet bsg. The lateral extent is partially undefined at 2 feet bsg to the south of S5 (219 mg/kg) and S6SW-S (191 mg/kg). Based on the concentrations detected at 2 feet bsg in S5 and S6SW-S, residual TPH impact may extend to the south at limited distances. The samples collected from S5 and S6SW-S were collected as far south on the site as possible. An underground communications utility extends along the entire southern property boundary of the site that prevented further excavation and the collection of soil samples to the south. To further assess and define shallow TPH impact to the south, soil samples would have to be collected on the adjacent property to the south (1622 North Broadway). However, based on the low concentrations in samples S5 and S6SW-S, it's likely the lateral extent to the south only extends to the property boundary. The estimated lateral extent of TPH impact in soil is depicted in Figure 4.