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1 HydroGeo Consultants borings at the Site A 4-inch diameter PVC monitoring well was installed in each of the borings (MW-1 through MW-3) to depths of about 50-60 feet below grade Soil sample MW2 at 36 feet below grade indicated the only significant TPH and benzene, toluene, ethylbenzene, and xylene (BTEX) concentrations (2,200 mg/kg TPH and less than detectable to 235 mg/kg BTEX) ' In November 1992, Thrifty conducted an additional assessment that included installation of four groundwater monitoring wells (MW-3R, MW-4, MW-5, and MW-6) at the Site ' Because the water table had dropped about 30 feet since the initial wells were installed at the Site, these deeper wells were required to monitor the groundwater quality These wells were installed to 90 feet below grade and were constructed of 2-inch diameter PVC ' Also, as part of the investigation, two vapor wells (VW-1 and VW-2) were installed near the former tank pit Results of the investigation showed that soils near the western boundary of the Site contained significant hydrocarbon concentrations Groundwater in ' each of the deep wells had high contamination levels Results of the investigation are presented in Thrifty's "Site Assessment Report", dated January 17, 1988 ' In November 1994, Thrifty removed the former tanks and replaced them with the new tanks in the northeast comer of the Site These construction activities resulted in the loss of MW-1, VW-1, and VW-2, which were located in close proximity to the former tanks ' Also, well MW-3R was damaged during this installation of the new tanks During site reconstruction, some of the contaminated soil that was encountered during excavation was reportedly placed in the former tank pit cavity as fill material In December 1994, Thriftyinstalled two vadose zone wells TB-4 and TB-6 and three ( ), soil borings (TB-3, TB-13, and TB-14) at the Site TB-4 was installed to a depth of ' approximately 50 feet below grade, TB-6 to a depth of 25 feet below grade, and TB-3, TB-13, and TB-14 to 15 feet below grade Remediation piping was installed to many of the wells at this time Proposed well locations that could not be drilled were set with ' surface vaults to allow access for future drilling ' In June 1995 groundwater monitoring wells TB-1 and TB-10 were installed and constructed as 2-inch diameter monitoring wells Wells TB-7 and TB-8 were also installed and constructed as 4-inch diameter monitoring wells Vapor wells TB-3 was ' installed to a total depth of 50 feet below grade T13-9, TB-11, and TB-12 were completed as nested vapor extraction wells with a deep well screened from 35 feet to 60 feet and a shallow well screened from 5 feet to 30 feet below grade in each Well MW-3R, which ' was damaged during site construction, was re-drilled and replaced with a new well casing, and MW-3 was abandoned Additionally, one hand auger boring (TB-5) was drilled adjacent to the eastern pump island Soil sample analysis indicated that ' concentrations of TPH were detected in excess of 1,000 mg/kg at six well locations within three general areas including along the west side of the property near the pump islands and former western UST(maximum 4,100 mg/kg TPH), near the center and to the ' east of the former UST pit(maximum 5,300 mg/kg TPH), and an isolated area surrounding TB-3 (maximum of 5,700 mg/kg TPH at 30 feet below grade) • 1 ' Thrifty Oil TOC#171 Aquifer Test and RAP Rpt Page 3