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Phase II Environmental Site Assessment Investigation Report 206 Sutter Street, Stockton, California Page 5 1980s infiltrated to depths of 80-100 feet bgs and the soil contaminant plumes were subsequently drowned. These historic drowned plumes have complicated remediation efforts throughout Stockton. On September 22 and 23, 2022, Condor advanced a total of five (5) borings at the Site. DP-1 soil boring was advanced to 60 feet bgs, DP-3 and DP-6 soil borings were advanced to 35 feet bgs, and DP-4 and DP- 7 soil borings were advanced to 45 feet bgs. A total of seven (7) soil samples and five (5) groundwater samples were collected and analyzed for TPH-G, TPH-D, and TPH-MO and VOCs. In the western portion of the Site, elevated concentrations of TPH-D, TPH-G, and TPH-D were detected in groundwater samples DP-1 located in the southwest corner of the Site with lighter than water immiscible sheen or product present, as well as the highest detected benzene concentration at 25 µg/L, which is above the MCL of 1.0 µg/L. Naphthalene was detected at 24 µg/L in DP-1 which is above the California Division of Water’s CNL of 17 µg/L. TPH-D and TPH-G were detected at 260 µg/L and 110 µg/L, respectively in groundwater samples collected at DP-4 and TPH-D was detected at 170 µg/L in DP-6. Benzene was detected at 1.3 µg/L in DP-4, which is slightly above the MCL of 1.0 µg/L. Analytical results from soil samples collected from DP-1 at 35 feet bgs indicate elevated concentrations of TPH-D, TPH-G, and TPH-MO at 8,000 mg/kg, which is above the EPA RSL for industrial soil of 560 mg/kg, 20,000 mg/kg, and 540 mg/kg, which is also above the US EPA RSL for industrial soil, respectively. TPH-D and TPH-MO concentrations significantly decrease at 45 feet bgs. TPH-G decreases to 330 mg/kg in the soil sample collected at 45 feet bgs and 3.3 mg/kg at 55 feet bgs. PID readings collected during soil sampling at DP-1 indicated measured concentrations of 15 ppm at 10 feet bgs; 5.0 ppm and lower from 15- 30 feet bgs; from 50 ppm to approximately 200 ppm at 30-45 feet bgs; and from 5 ppm to 13 ppm at 45-60 feet bgs with the associated dark blue color staining. Petroleum odors were observed by field personnel in the field with samples associated with elevated PID readings. In the eastern portion of the Site, no contamination was observed or documented with the exception of TPH-MO in the groundwater sample collected at DP-7, which was detected at 510 µg/L, just above the laboratory reporting limit of 500 µg/L. No staining was observed and the PID measured 0.0 ppm throughout the entire boring. 6.0 DISCUSSION AND RECOMENDATIONS Soil and groundwater contamination appears to be confined in the southwest and western portions of the Site where the historic fueling station was located prior to construction and demolition of the Ambassador Hotel with at least 20 feet of separation between the ground surface and the contamination plume in the subsurface. Shallow groundwater in Stockton is not used for public consumption or use; therefore, it is Condor’s opinion that the contamination plume does not pose a material risk to human health at the Site and does not likely pose a vapor encroachment concern for the Site. As a result, it is Condor’s opinion that the planned construction of a parking lot is the best land use for redevelopment of the Site. Condor recommends the development of a groundwater monitoring well network to obtain groundwater quality data over four (4) consecutive quarters to confirm concentrations as well as the extent of the past release in the direction of groundwater flow (northeast). 7.0 LIMITATIONS The scope of work for this report is intended to provide a limited review of certain information related to the potential presence of contamination at or beneath the Site. This report is not intended to eliminate all risk of the subject property bearing some degree of environmental liability. Condor cannot and will not warrant or certify that the Site is free of contaminants because it is impossible to know if such a condition