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Atlantic Richfield Company 2 ARCO 595,6100 North Highway 99 Stockton California September 13,2002 . tertiary amyl methyl ether (TAME), 1,2-dichloroethane (1,2-DCA), and ethylene dibromide (EDB) were not detected in the samples Approximately 189 tons of soil generated during the removal of the underground facilities and the trenching for new piping were disposed of at BFI Landfill in Livermore, California Results of this investigation are included in SECOR's report titled Soil Samples During Product Lane and Dispenser Upgrade Activities, dated December 10, 1999 In rune 2000, four groundwater monitoring wells (MW-1 through MW-4) and three soil borings (B-1, B-2, and B-3) were completed at the site The subsurface assessment confirmed that petroleum hydrocarbons had impacted the soil and groundwater beneath the site Results of this investigation are included in SECOR's Site Assessment Report, dated October 2, 2000 Documented in SECOR's Site Assessment Report, dated October 2, 2000, a water supply well survey was performed to identify the location of permitted water supply wells within a 1/2-mile radius of the site The water well survey consisted of a review of California Department of Water Resources (DWR) files for the area Additionally, SECOR contacted the City of Stockton and the County of San Joaquin, Department of Public Works (CSJDPW), which are the local water purveyors According to the City of Stockton and the CSJDPW, no municipal wells owned and operated by these agencies are located within the 1/2-mile search radius However, a total of five water supply wells • were identified within the search area, one of which is an active domestic well located on the southwest corner of the Atlantic Richfield Company property In July 2001, three additional groundwater monitoring wells (MW-5 through MW-7) and two deep soil borings (PSB-1 and PSB-2) were drilled to further delineate the lateral and vertical extent of petroleum hydrocarbons in soil and groundwater beneath and downgradient of the site, and in the vicinity of on-site domestic water supply well WSW With the exception of minor concentrations of benzene, toluene, and xylenes in the 15- foot, 25-foot, and 55-foot samples from the boring for MW-5, petroleum hydrocarbons and fuel oxygenates were not detected in any soil samples collected during the assessment With the exception of minor concentrations of benzene, toluene, ethylbenzene, and xylenes (BTEX)constituents in boring PSB-2 at 95 feet bgs, concentrations of TPHg and BTEX were not detected in discrete-depth groundwater samples and groundwater monitoring well samples MtBE (EPA Method 8260B) and 1,2-DCA were reported in discrete-depth groundwater samples from boring PSB-1 (75 feet and 90 feet bgs), discrete-depth groundwater samples collected from boring PSB-2 (64 feet and 90 feet bgs), and in wells MW-5 and MW-7 at concentrations up to 94 ppb (MW-7, August 2001) and 23 ppb (MW-7, August 2001), respectively Approximately 10 cubic yards of soil was generated during fieldwork activities, and disposed of at Forward Landfill in Manteca, California Results of this investigation are documented in SECOR's Site Assessment Report, dated December 11, 2001 i� Also in 2001, SECOR performed a 500-foot radius, door-to-door water supply well survey Water supply well survey forms were submitted to four adjacent businesses (El I%ARC0105951Reportslwel1 msta113 doc