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23 June 1998 <br /> AGE-NC Project No. 96-0229 <br /> Page 2 of 5 <br /> product piping. The samples were submitted to a state-certified analytical laboratory for <br /> analysis of total petroleum hydrocarbons quantified as gasoline (TPH-g) and volatile <br /> aromatics(benzene,toluene, ethylbenzene and xylenes: BTE&X). Results of the laboratory <br /> analysis indicated that TPH-g and BTEX were detected in soil samples at concentrations <br /> ranging up to 2,200 parts per million(ppm; reported as milligrams per kilogram). <br /> • In December 1994, five soil borings (B-1 through B-5) were advanced at the site near the <br /> former UST area. Soil borings B-1, B-3 and B-5 were advanced to depths of 35 feet; B-2 <br /> and B-4 were advanced to depths of 65 feet. Petroleum hydrocarbon impacted soil was <br /> encountered in all five soil borings at depths between 10 feet and 65 feet. <br /> • In January 1995,four additional soil borings(MW-1 through MW-3 and B-6)were advanced <br /> at the site as part of the ongoing investigation. Soil boring B-6 was advanced to a depth of, <br /> 65 feet; MW-I through MW-3 were advanced to depths of 80 feet and completed as 2-inch <br /> diameter ground water monitoring wells. Petroleum hydrocarbon impacted soil was <br /> encountered in all four soil borings at depths between 35 feet and 65 feet. Dissolved TPH-g <br /> and BTE&X was detected in initial ground water samples from all three wells at <br /> concentrations up to 11,000 parts per billion(ppb;reported as micrograms per liter or ug/1). <br /> • In December 1995,three soil borings(VW-1 through VW-3)were advanced near the former <br /> UST area and one soil boring(MW-4)was advanced downgradient of the former UST area. <br /> Soil borings VW-1 through VW-3 were advanced to depths of 63 feet and completed as soil <br /> vapor extraction (SVE) wells. Soil boring MW-4 was advanced to a depth of 75 feet and <br /> completed as a 2-inch diameter ground water monitoring well. Hydrocarbon-impacted soil <br /> was encountered in all three SVE wells at depths of 15 feet to 60 feet; no petroleum <br /> hydrocarbons were detected in soil samples collected from MW4.Dissolved TPH-g was not <br /> detected in initial ground water samples collected from MW-4. However, benzene was <br /> detected in MW-4 in later sampling events at concentrations up to 2.8 ppb. <br /> • In January 1996, one soil boring(MW-5)was advanced upgradient of the former UST area <br /> to a depth of 70 feet. Soil boring MW-5 was completed as a 2-inch diameter groundwater <br /> monitoring well. Petroleum hydrocarbon impacted soil was encountered at depths of 45 and <br /> 50 feet.Dissolved TPH-g was detected in initial ground water samples collected from MW-5 <br /> at concentrations up to 23,000 ppb. <br /> • An 8-hour soil vapor extraction(SVE)pilot test was conducted at the site in January 1996. <br /> The pilot test was performed to provide vapor extraction data for proper system design of a <br /> remediation system. <br /> • In March 1996, a Corrective Action Plan (CAP) was submitted to the PHS-EHD, and <br /> included details of the SVE pilot test.Recommendations in the CAP included installation of <br /> an SVE system to remediate hydrocarbon-impacted soil in conjunction with an in-situ air <br /> sparging (IAS) system to remediate hydrocarbon-impacted ground water. <br /> Advanced Ce FE vironmmW,Inc. <br />