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MW3 at concentrations up to 940 micrograms per liter (gg/L) and 9 0 gg/L, respectively (AEGIS 1991b) Groundwater analytical results are presented in Table i Quarterly groundwater monitoring and sampling was initiated at this time ' • June 1992 Three inactive single-walled 10,000-1-allon steel USTs and associatedp roduct piping were removed Six confirmation soil samples were collected from beneath each end ' of the three USTs 2 feet into native soil at depths of 16 feet bgs TPH-g and benzene were detected at concentrations up to 5,300 and I1 0 mg/kg, respectively Six soil samples were collected at 5 feet bgs from beneath product lines Sod samples NL-1 and OL-3 contained 28 and 160 mg/kg TPH-g, respectively None of these six product line samples contained benzene at or above the reported detection limit (AEGIS 1992) The locations of these soil ' samples are presented in Figure 2, and the analytical results are presented in Table 2 • May 1993: Seven soil borings were drilled to depths ranging from 15 to 60 feet bgs and completed as 4-inch-diameter groundwater monitoring wells MW4-MW7 and vapor extraction wells VEW1 and VEW2 (AEGIS 1993a) Petroleum hydrocarbons were not detected in any of the sod samples collected from these borings at or above the reported method detection limits with the exception of soil samples collected from between 15 5 and 35 5 feet bgs in boring VEW2, which is located within the former UST backfill (Figure 2) ' • November 1995• A soil vapor extraction (SVE) system was installed and operated at the site by FUGRO West, Inc (FUGRO) from November 1995 to March 1996 (FUGRO 1996) Wells used for vapor extraction were wells VEW1, VEW2, MW2, MW3, and MW5 Data associated with the SVE system are presented in detail in Section 2 4 2 • February 1997: A new SVE system was installed and operated by EA from February 1997 to March 1998 (EA 1998) Data associated with the SVE system are presented in detail in Section 2 4 2 2 4.2 Summary of Remedial Efforts I In May 1993, AEGIS performed a pilot-scale SVE test in vapor extraction wells VEWI and ' VEW2 to assess the feasibility of soil remediation at the site (AEGIS 1993a) In November 1993, AEGIS submitted a Remedial Action Plan which summarized site characterization and feasibility assessment data, proposed SVE as the suitable remediation alternative, and described ' the implementation of the proposed remediation plan The pilot scale vapor extraction test results indicated a radius of influence for wells VEW1 and VEW2 at 50 and 100 feet, respectively (AEGIS 1993b) In November 1995, an SVE system was installed at the site by ' FUGRO and operated from November 1995 to March 1996 (FUGRO 1996) Vapor extraction was performed at wells VEW1, VEW2, MW2, MW3, and MW5 ' A new SVE system was installed by EA and was operated from February 1997 to March 1998 (EA 1998) During the period from February 1997 to March 1998, soil vapor was extracted primarily from wells VEW1 and VEW2, as the screened intervals for the other three wells used in the past for vapor extraction (MW2, MW3, and MW5) were nearly completely submerged This is demonstrated in the hydrographs generated for each well presented in Appendix B, which F VFio,r,tsg01771Nlmter\Wp\Closuie 1 100101 37ate+u doc 5