ARCHIVED REPORTS PHASE II ENVIRONMENTAL SITE ASSESSMENT REPORT

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LPhase 11 Environmental Site Assessment Report-Executive Summary 1025 East Main Street,Stockton,San Joaquin County,California Page ii Lportion of the Site) in subsurface soil. TPH-G was not detected at or above the laboratory reporting limit in any of the remaining I1 soil samples. Diesel (TPH-D) and motor oil (TPH-MO) were detected at L relatively low concentrations in the 12 soil samples analyzed for these constituents, with concentrations ranging from <1.0 to 150 mg/kg TPH-D (36 mg/kg average), and <5.0 to 470 mg/kg TPH-MO (180 mg/kg average). The areas of the Site used for rail purposes appear to contain low concentrations of Lheavier petroleum hydrocarbons in surface soil (upper two to three feet). Of the groundwater samples collected, only TPH-D and TPH-MO were detected at elevated concentrations, particularly beneath the southern portion of the Site (Borings 2 and 4). TPH-D and TPH- ` MO were detected at 420 µg/L and 2,100 µg/L in Boring 132; and at 1,400 µg/L and 1,500 µg/L in Boring B4,respectively. ` Condor concludes the following regarding the RECs identified in the Phase I ESA: 1. The historic rail use of the Site-Analysis of soil samples collected from the immediate area of the former rail spurs and former Western Pacific Railroad tracks indicate that the surface soil in these areas contains relatively low concentrations of heavier petroleum hydrocarbons in the diesel and motor oil range and low to moderate concentrations of lead. Lead concentrations are below the PRG ^� of 800 mg/kg for commercial land use types. Arsenic concentrations are within background concentrations or are within acceptable limits of background concentrations. L 2. The construction of the train depot structure prior to the 1970s - The elevated lead concentrations in soil around the depot's building perimeter are attributable to lead based paint. Only one sample exceeded the PRG for commercial land use types of 800 mg/kg lead. In addition, chlordane (used for L termite control) is less than the CHHSL of 1.7 mg/kg for commercial land use types. Condor recommends that a building materials survey be conducted by a California certified inspector. Additionally, some of the soil adjacent to the depot appears to have been removed and replaced with sandy soil. If the removed soil is currently being stored on Site (soil piles west of the depot), Condor L recommends sampling of this soil for lead and chlordane. 3. Multiple off-site properties with identified or suspected groundwater contamination - All of the 60 groundwater samples had small detectable quantities of chloroform, but were well below the California MCL of 80 µg/L. Analysis of the groundwater samples indicate that TPH-D and TPH-MO are present in elevated concentrations from Borings 2 and 4. These results suggest a petroleum `, hydrocarbon plume in groundwater beneath the southern most portion of the Site, likely from an off- site location. The potential plume source may be from one or more unidentified leaking under-ground storage tanks (USTs), possibly from the southern adjoining property. There has been no evidence of L USTs on the Site. LIMITATIONS TO EXECUTIVE SUMMARY LThis executive summary should only be read as a brief summary, and not as a complete discussion of the full report text. The scope of work and limitations should be understood prior to reading the Site-specific information,results, and discussion. L L L Li.1 CONDOR