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1 <br /> Site Background Information Larry's Auto <br />' Page 2 of 3 <br /> tSITE ASSESSMENT ACTIVITIES <br /> An initial subsurface assessment was performed by WaterWork Corporation One soil boring was <br />' advanced to a depth of approximately 35 feet below surface grade(bsg)near Tank A Ground water <br /> was encountered at 32 feet bsg Details of the initial investigation were summarized in a Preliminary <br /> Assessment Report dated 12 January 1990, prepared by WaterWork <br />' Five soil borings(BI through 135)were drilled at the site by Geological Audit Services,Inc between <br /> I 1 and 14 February 1994 Borings B 1 through B4 were completed as ground water monitoring wells <br />' MW-1 through MW-4,respectively Free product was encountered In MW-4 and removed between <br /> September and November 1994 Total petroleum hydrocarbons quantified as gasoline (TPH-g)and <br /> volatile aromatics benzene,toluene,ethylbenzene and xylenes(BTEX)were detected in each well <br />' TPH as diesel (TPH-d) was detected in MW-4 <br /> From 19 to 26 February 1996, six borings were advanced at the site by Advanced <br />' GeoEnvironmental, Inc Boring MW-7 was advanced to a depth of 60 feet and was completed as a <br /> ground water monitoring well Boring VW-1, drilled at an angle of 30' from vertical directed N <br /> 34'E, was advanced to a vertical depth of 55 feet bsg with a horizontal run of 31 8 feet and was <br />' <br /> backfilled to surface grade Borings VW-2,VW-3, and VW-4 were advanced vertically to a depth <br /> of 55 feet and completed as vapor extraction remediation wells (VW-2 was double-completed) <br /> Boring VW-5, drilled at an angle of 10' from vertical directed N 80° W, was advanced to a depth <br /> of 55 vertical feet bsg with a horizontal run of 9 7 feet and was triple-completed as a vapor <br /> extraction remediation well Petroleum hydrocarbons were detected In each boring at concentrations <br /> as high as 23,000 mg/kg(milligrams per kilogram,equivalent to parts per million,ppm,VW5 at 15 <br />' feet) <br /> Sample VW3-40 and VW5-30 were analyzed for bioenumeration and physicochemical properties <br />' Very low populations of both general and selective microbial populations were observed Nitrogen <br /> concentrations, however, were below optimal for biodegradation of hydrocarbons Additional <br /> background information Is summarized in the AGE-prepared Quarterly Report-August 1997 <br />' On 13 and 14 November 2001,two off-site,paired soil borings(CPT-2 and CPT-3)were advanced <br /> immediately south of the site (Figure 2) utilizing CPT technology CPT-2 was advanced to a <br /> maximum depth of 157 feet bsg and CPT-3 was advanced to 180 feet bsg Laboratory analytical <br /> results detected the highest petroleum hydrocarbon-impacted CPT water samples from fine-grained <br /> soil intervals between approximately 50 and 85 feet bsg and between 135 and 160 feet bsg at the <br /> southern tanks' location (CPT-2), the impacted ground water plume extends laterally at all depths <br /> to the CPT-3 location BTEX compounds were detected at all depths in the CPT bormgs BTEX in <br /> water samples collected from CPT-2 exceeded the DHS's Maximum Contaminant Levels (MCLS) <br /> for BTEX In ground water,however,benzene was the only BTEX compounds exceeding the MCL <br /> in water samples collected from CPT-3 VOCs were detected at all depths In the CPT borings <br /> • 1,2-DCA was present at concentrations exceeding the MCL In addition, naphthalene, n-propyl <br /> Advanced GeoEnvironmental,Inc <br />