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13 November 2018 AGE Project No. 18-4357 Page 10 of 11 AdvancedGeo Environmental n • Total lead was detected in all the soil samples analyzed at concentrations below the established clean-up goal and below the DTSC-SL and RSL for commercial properties. • Total lead was analyzed for STLC in one subsurface soil sample (S5-2) and two stockpile soil samples (SP -1 and SP -4) because the total lead concentration exceeded 10 times the California Hazardous Waste Limit of 5.0 mg/I. Lead was detected in the stockpile soil samples at a maximum concentration of 2.83 mg/I. Lead was detected in sample S5-2 at a concentration of 7.25 mg/I, above the California Hazardous Waste Limit of 5.0 mg/I. Soil from S-5 will be removed and disposed of at a Class I landfill. • Chromium was detected in all the soil samples analyzed at concentrations significantly below the DTSC-SL and RSL for commercial and residential properties. Also, chromium detections appear to be within the range or normal background concentrations in California soils (Background Concentrations of Metals, a Progress Report, DTSC Geological Services Unit, Glendale and Background Concentrations of Trace and Major Elements in California Soils: Kearney Foundation of Soil Science Division of Agriculture and Natural Resources University of California, March 1996). • For potential waste disposal characterization, 17 soil samples were analyzed for chromium by STLC. No detections exceeded the California Hazardous Waste Limit of 5.0 mg/I. • Only soil sample S5-2 at 2 feet bsg exceeded the California Hazardous Waste Limit by STLC analysis. And total lead was only detected at a concentration of 5.93 mg/kg in S5-5 at 5 feet bsg by TTLC analysis. Soil from S5 will be removed and disposed of at a Class I landfill. Additionally, AGE intends to properly dispose of soil removed from the Main Excavation Area and the S6 Excavation Area. 7.0. RECOMMENDATIONS Based upon the investigation performed at the site in August and November 2018, AGE provides the following recommendations: • Backfilling locations S7 through S11. TPH was not detected in soil samples collected at 2 and 5 feet bsg at S7, S8, S9, and S11; and no field evidence of impact was observed at S10. Additionally, metals concentrations detected at 2 and 5 feet bsg at S7, S8, S9, and S11 were all within the range of normal background concentrations in California soils. • Removal and proper disposal of soil excavated from the Main Excavation Area and the S6 Excavation Area. • Removal and proper disposal at a Class I landfill of soil excavated from S5.