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it Site Background Information Former Stefano's Gas Station Page 3 of 6 to 50 feet bsg. All soil and ground water samples analyzed from the September 2001 investigation were below detectable limits for the constituents of concern. On 20 and 21 February 2002, CPT IA and CPT2 were advanced at the site and surrounding area to determine the hydrocarbon impact to ground water.Grab ground water samples-were collected at 60 1 and 105 feet bsg in borings CPT1A and CPT2; an additional sample was collected at 130,feet bsg ` in boring CPT2.Petroleum hydrocarbons were detected in ground water samples collected at 60 and 105 feet bsg at maximum concentrations of 59,000 µg/l TPH-g, 210 µg/l benzene, 1,000 µg/1 I toluene, 840 µg/1 ethylbenzene and.5,300 µg/1 total xylenes from boring CPT1A at 60 feet bsg. i On 23 through 25 September 2003,CPT3 through CPT5 were advanced in areas surrounding the site to determine the lateral and vertical extent of the petroleum hydrocarbon impact. The borings were j advanced to a total depth of 124 feet bsg. Discrete ground water samples were collected at approximately 55-60, 72-75 and 115-120 feet bsg. TPH-g was detected in ground water samples CPT3@73-77', CPT3@115-119' and CPT4@71-75' at concentrations of 90 µg/1, 130 µg/1 and 100 µg/1,respectively. i Five soil vapor extraction wells (SVEI through SVE5)and three ozone sparge wells (OZ1 through OZ3)were installed in December 2003. In January 2004,two soil vapor extraction pilot tests were conducted to evaluate SVE as a remedial alternative. The SVE unit and associated piping were installed in August 2004. A total of four soil samples were analyzed for the constituents listed in Section 3.1.2.. No analytes of concern were detected in any of the analyzed samples. On 27 April 2006, three soil probe borings (P-1, P-2, and P-3) were advanced to total depths of 25 feet to 40 feet below surface grade (bsg) utilizing a van-mounted Geoprobe 5400 direct-push probing unit equipped-with 1.25-inch diameter probing rods; the probing unit advances soil probe borings using a hydraulic hammer to drive soil and ground water sampling tools to specified depths. The three borings were advanced in the area of the former underground storage tank(UST)to assess the extent of petroleum hydrocarbon contamination remaining .after termination of soil vapor extraction (SVE) pilot testing period.conducted onsite, and to determine whether additional soil remediation is necessary. During field activities conducted on 27 April 2006, borings P-2 and P-3 were successfully advanced to the proposed depth of 40 feet bsg; due to the soft conditions of the backfill in the tank pit area and the GeoProbe rig capabilities,boring P-1 could only be advanced to a depth of 25 feet bsg. TPH-g was detected in borings P-1 and P-3, at depths between 20 feet and 40 feetbsg,at concentrations between 7.5 milligrams per kilogram(mg/kg)(sample P-3-40')and 34 mg/kg(sample P-1-25').Trace levels of various BTEX compounds were detected in the soil samples from P-2 at 40 feet bsg,and from P-3 at 35 feet and 40 feet bsg.Toluene was detected-at a maximum concentration of 0.034 mg/kg; ethylbenzene was detected at a concentration of 0.17 mg/kg; total xylene were detected at a maximum concentration of 1.95 mg/kg. No other target analytes were detected in the samples-analyzed. Advanced GeoEnvironmental,Inc. p N ij