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� v ' A S S O C I A T E 5 I N C ' Soil ' Laboratory analytical data from previous soil investigations indicated petroleum hydrocarbon constituents were detected in soil samples collected from so4l borings advanced in the vicinity of the former UST �iarid m boring B-$ advanced southeast of the fuel dispenser location (borings BH-2, BH-4, BH-5, and BH-4 ' Island Petroleum hydrocarbons were also detected in soil samples collected from borings advanced along the western property boundary (borings B-10, B-11, B-12, B-13, and MW-5) Low concentrations of petroleum hydrocarbons were also detected in a soil sample collected from beneath the existing product line ' and from below the former location of the used oil UST The highest concentration of TPHg, 2,000 milligrams per kilogram, was reported in the soil sample collected from B-8 at a depth of 6 5 feet bgs Based on the laboratory analytical data, petroleum impacted soil extends to 6 5 feet bgs along the western boundary ' of the site, along the western side of the USTs, at the northeastern corner of the USTs, and southeast of the fuel dispenser island Petroleum impacted soil was not detected in two borings (B-20 and B-21) advanced in the sidewalk at the southwestern corner of the site Petroleum impacted soil was detected in borings (B-15, ' B-16, and B-17) advanced in the sidewalk on the western side of Holly Drive and in the sidewalk at the southwestern corner of the intersection of Holy Drive and Grant Line Road (B-18) It is not clear if the petroleum hydrocarbons detected in these off-site borings are associated with the hydrocarbon plume at the ' subject site Analytical data from soil samples collected at the site are summarized in Table 2 The estimated extent of petroleum impacted soil is shown on Figure 6 Groundwater Laboratory analytical results of groundwater samples collected at the site on November 26 2003 indicated petroleum hydrocarbons were detected in the groundwater samples collected from MW-1,"MW-4,"MW-5; MW-6, and MW-8 MTBE was detected in the groundwater samples collected from MW-1, MW-4, MW-5, MW-6, and MW-8 at concentrations of 9 0 micrograms per liter (µg/L), 190 µg/L, 260 µg/L, 100 µg/L, and 240 µg/L, respectively Benzene, ethyl benzene, and tertiary butyl alcohol were detected in the groundwater ' sample collected from MW-4 at concentrations of 15 gg/L, 7 0 pg/L, and 38 µg/L, respectively Tertiary amyhAe er%was detected in the groundwater samples collected from MW-5 and MW-8 at concentrations of 1 8 µg/L and 0 8 µg/L, respectively ' Groundwater samples collected from wells MW-2, MW-3, and MW-7 did not contain concentrations of TPHg, BTEX constituents, or fuel oxygenates at or above the laboratory reporting limits Analytical data for groundwater samples collected at the site are summarized in Table 3 The estimated extent of MTBE in groundwater is shown on Figure 7 Graphs showing benzene and MTBE concentrations in groundwater samples collected from selected monitoring wells are included as Figures 8 through 12 POTENTIAL EXPOSURE PATHWAYS ' General Pathways of exposure are the means through which an individual may come into contact with a chemical Exposure pathways are determined by environmental conditions, potential for a chemical to move from one medium to another, and the population's general lifestyles Although several potential pathways may exist Former Cheaper#37 January 29 2004 ATC Project Number 5425847 0037 Page 5