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PHASE II ENVIRONMENTAL SITE ASSESSMENT INVESTIGATION REPORT APN 139-250-030 206 SUTTER STREET STOCKTON, SAN JOAQUIN COUNTY, CALIFORNIA October 19, 2022 1.0 INTRODUCTION Condor Earth (Condor) conducted a Phase II Environmental Site Assessment (ESA) for the property located at 206 Sutter Street, Stockton, San Joaquin County, California (Site, Figures 1 and 2, Appendix A). The purpose of the work was to evaluate whether past use of the property had adversely affected soil and/or groundwater beneath the Site. This investigation of the subsurface soil and groundwater at the Site was to evaluate whether historical use as commercial fueling stations and The Ambassador Hotel has resulted in contamination beneath the Site. The evaluated property included one parcel designated as Assessor Parcel Number (APN) 139-250-030 (Site), totaling 0.46 acres. The Phase II ESA comprised a screening of Site soils and groundwater for the presence of volatile organic compounds (VOCs), and total petroleum hydrocarbons (TPH) as gasoline (TPH-G), TPH as diesel (TPH-D), and TPH as motor oil (TPH-MO). Condor conducted the Phase II ESA under contract with San Joaquin County Office of Education (Client). The Client intends on purchasing the Site for construction of a parking lot that will serve an adjoining education facility. 2.0 SITE BACKGROUND Based on review of historical documents, the Site appears to have had been occupied by a commercial fueling station in the southwestern portion of the Site from approximately the 1930’s until the 1960’s. The Ambassador Hotel was constructed over the gas station in the late 1960s or early 1970s and was demolished in 2016. The hotel contained a basement that was likely removed and backfilled to a depth of 12 to 15 feet below ground surface (bgs). 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 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.