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PHASE II ENVIRONMENTAL SITE ASSESSMENT INVESTIGATION REPORT APN 139-250-030 206 SUTTER STREET STOCKTON, SAN JOAQUIN COUNTY, CALIFORNIA EXECUTIVE SUMMARY October 19, 2022 Condor Earth (Condor) conducted a Phase II Environmental Site Assessment (ESA) for the property located at 206 Sutter Street, Stockton, San Joaquin County, California. The purpose of the work was to evaluate whether past use of the property had adversely affected soil and/or groundwater beneath the Site. The evaluated property included one parcel designated as Assessor Parcel Number (APN) 139-250-030 (Site). Based on review of historical documents the Site appears to have had been occupied by a commercial fueling station in the southwestern portion of the Site from approximately the 1930’s to the 1960’s which was replaced by The Ambassador Hotel in the late 1960s or early 1970s. The hotel was demolished in 2016. In February 2017, Condor conducted a project-wide geotechnical engineering study for the Ten Space Development Project in downtown Stockton and advanced two geotechnical borings on the Site. Boring B- 3 was terminated at approximately 10 feet below ground surface (bgs) due to a concrete obstruction and B- 4 observations included stained soil and a smell of gasoline starting at approximately 30 feet down to the boring terminus at 50 feet bgs. Groundwater depths within the Stockton area historically ranged from 80 to 100 feet bgs during the time when shallow groundwater was utilized for public water supply until the early 1980s. Shallow groundwater subsequently was not used for public supply and rebounded to shallower depths of approximately 20-30 feet bgs beneath Stockton. Currently, the regional groundwater gradient is easterly due to the critically over- drafted groundwater basin from agricultural irrigation to the east, which has created a large regional cone of depression centered approximately 10 miles east of Stockton. This regional easterly gradient beneath Stockton has been present since the 1980s. As a result, many Stockton releases that occurred prior to the 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 total petroleum hydrocarbons (TPH) as gasoline (TPH-G), TPH as diesel (TPH-D), and TPH as motor oil (TPH-MO) and volatile organic compounds (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 micrograms per liter (µg/L), which is above the State Water Resources Control Board’s maximum contaminant level (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 California Notification Level (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.