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I Ile Site Background Information Larry's Auto Page 2 of 3 ' SITE ASSESSMENT ACTIVITIES ' An initial subsurface assessment was performed by WaterWork Corporation One soil boring was advanced to a depth of approximately 3 5 feet below surface grade (bsg)near Tank A Ground water ' was encountered at 32 feet bsg Details of the initial investigation were summarized in a Preliminary Assessment Report dated 12 January 1990, prepared by WaterWork ' Five soil borings(B1 through B5)were drilled at the site by Geological Audit Services,hic between I 1 and 14 February 1994 Borings B 1 through B4 were completed as ground water monitoring wells MW-1 through MW-4, respectively Free product was encountered in MW-4 and removed between September and November 1994 Total petroleum hydrocarbons quantified as gasoline(TPH-g)and volatile aromatics benzene, toluene, ethylbenzene and xylenes(BTEX)were detected in each well TPH as diesel (TPH-d) was detected in MW-4 ' From 19 to 26 February 1996,six borings were advanced at the site by Advanced GeoEnvironmental, Inc Boring MW-7 was advanced to a depth of 60 feet and was completed as a ground water ' monitoring well Bonng VW-1, drilled at an angle of 30` from vertical directed N 34°E, was advanced to a vertical depth of 55 feet bsg with a horizontal run of 31 8 feet and was backfilled to surface grade Borings VW-2, VW-3, and VW-4 were advanced vertically to a depth of 55 feet and completed as vapor extraction remediation wells (VW-2 was double-completed) Boring VW-5, drilled at an angle of 10° from vertical directed N 80' W,was advanced to a depth of 55 vertical feet bsg with a honzontal run of 9 7 feet and was triple-completed as a vapor extraction remedi ation well ' Petroleum hydrocarbons were detected in each boring at concentrations as high as 23,000 mg/kg (milligrams per kilogram, equivalent to parts per million, ppm, VW5 at 15 feet) ' Sample VW3-40 and VW5-30 were analyzed for bioenumeration and physicochemical properties Very low populations of both general and selective microbial populations were observed Nitrogen ' concentrations, however, were below optimal for biodegradation of hydrocarbons Additional background information is summarized in the AGE-prepared Quarterly Report-August 1997 ' On 13 and 14 November 2001,two off-site,paired soil borings (CPT-2 and CPT-3)were advanced immediately south of the site (Figure 2) utilizing CPT technology CPT-2 was advanced to a maximum depth of 157 feet bsg and CPT-3 was advanced to 180 feet bsg Laboratory analytical ' results detected the highest petroleum hydrocarbon-impacted CPT water samples from fine-grained soil intervals between approximately 50 and 85 feet bsg and between 135 and 160 feet bsg at the southern tanks' location (CPT-2), the Impacted ground water plume extends laterally at all depths ' to the CPT-3 location BTEX compounds were detected at all depths in the CPT borings BTEX in water samples collected from CPT-2 exceeded the DHS's Maximum Contaminant Levels (MCLs) for BTEX in ground water, however, benzene was the only BTEX compounds exceeding the MCL ' in water samples collected from CPT-3 VOCs were detected at all depths in the CPT borings . 1,2-DCA was present at concentrations exceeding the MCL In addition, naphthalene, n-propyl ' Advanced GeoEnvironmental,Inc