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rr %W01 Larry's Auto Site Background Information 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 35 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(B I through 135)were drilled at the site by Geological Audit Services,Inc.between 11 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 byAdvanced GeoEnvironmental, Inc.. Boring MW-7 was advanced to a depth of 60 feet and was completed as a ground water monitoring well. Boring 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 were completed as vapor extraction remediation wells (VW-2 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 horizontal run of 9.7 feet and was triple-completed as a vapor extraction remediation 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; V W5 at 15 feet). Sample V W3-40 and V W5-30 were analyzed for bioenumeration and physicochemical properties. Very low populations of both general and selective microbial populations were observed.Nitrogen concentrations 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 in HU2 and HU 12/13 at concentrations exceeding the MCL. Advanced GeoEnviroomental,Inc