ARCHIVED REPORTS_VAPOR INTRUSION SURVEY - SOIL GAS SAMPLING REPORT

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' 1.2.1 Removal of UST System Two 4,000-gallon gasoline USTs and the fuel dispenser were removed for permanent closure in February 1994. The location of the former USTs is depicted on Figure 3. During the UST ' removal, the San Joaquin Health District (SJHD) inspector noted three 1/2-inch diameter holes on the bottom of the southern UST (SJHD, 1994). No record is available to confirm whether the associated UST system piping was removed during the closure activities. Following ' removal, four soil samples were collected from the excavation floor at approximately 13 feet below ground surface (bgs), and one soil sample was collected from the area of the former fuel dispenser at approximately three feet bgs (Secor, 1996). ' 1.2.2 Summary of Environmental Investigations,Remediation,and Monitoring ' Environmental investigations have been performed at the Site since February 1996. A summary of the environmental investigations is presented below. ' February 1996 — Secor International Incorporated (Secor) drilled four soil borings (MW-1, VE-1, SB-1, and SB-2) to total depths ranging from 38.5 to 46.5 feet bgs. Soil and groundwater samples were collected and analyzed for total petroleum hydrocarbons in the ' gasoline range (TPH-g), benzene, toluene, ethylbenzene, and total xylenes (BTEX). MW-1 was completed as a 2-inch diameter groundwater monitoring well screened from 26 to 46 feet bgs. VE-1 was completed as a 4-inch diameter vapor monitoring well screened from 15 to 35 feet bgs (Secor, 1996). ' October 1997—Secor drilled one soil boring (MW-7)through the former tank excavation to a total depth of 90 feet bgs. MW-7 was completed as dual-nested 2-inch diameter groundwater ' monitoring wells with MW-7S screened from 55 to 63 feet bgs and MW-7D screened from 80 to 85 feet bgs (Secor, 1997). ' December 1997 — Secor drilled three cone penetration test (CPT) borings (CPT-1, CPT-2, and CPT-3 to depths of approximately 125, 115, and 120 feet bgs, respectively. One soil sample was collected from CPT-1 at 125 feet bgs, and groundwater grab samples were ' collected at various depths from each boring(Secor, 1998). May 2007 — PSC and ETIC drilled 11 soil borings (Cl through C11). The borings were ' drilled to depths ranging from 44 to 48 feet bgs (ETIC, 2007c). July 2007 — Based on the findings of the April and May 2007 soil and groundwater ' investigation, PSC and ETIC installed four 2-inch diameter groundwater-monitoring wells (MW-lA through MW-4A) in July 2007. The wells were installed to total depths ranging from 45 to 55 feet bgs (ETIC, 2007c). ' April 2008 — Between April 2 and April 11, 2008, PSC drilled eight CPT borings to further delineate the vertical and lateral extent of petroleum hydrocarbon impacts and evaluate hydrogeologic conditions in the deeper water bearing zones beneath the site. Samples were ' collected and analyzed to further characterize the soil and groundwater at the site. PSC presented the data obtained from the April 2008 CPT investigation to the CVRWQCB in the Subsurface Investigation Report, dated July 31, 2008. Vapor Intrusion Survey Soil Gas Sampling Report ' Prepared For:Sate Lee Bakery Group,Inc. Prepared By:PSC Industrial Outsourcing,LP Sam Lee—Lincoln Street\2009_03_31-Soil Gas Sampling Repon,doc March 31,2009 2