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i� <br /> • CAMBRIA <br /> CONCLUSIONS <br /> The goal of this investigation was to delineate the vertical and lateral extent of petroleum <br /> hydrocarbons previously detected in soil and groundwater in the vicinity of the northeastern <br /> dispenser island (the suspected source area) and to determine if any offsite sources of petroleum <br /> hydrocarbons exist Boring CPT-5 was drilled near the northeastern dispenser island to further <br /> delineate the vertical extent (below 100 fbg) of petroleum hydrocarbons previously detected in <br /> soil and groundwater Boring CPT-6 was drilled east (downgradient) and CPT-7 was drilled <br /> west (upgradient) of the dispenser island area to delineate the lateral extent of petroleum <br /> hydrocarbons detected in soil and groundwater <br /> x <br /> Low concentrations of petroleum hydrocarbons were detected in soil samples from CPT-5 at 105 <br /> and 116 fbg and no petroleum hydrocarbons were detected at 125 These data suggest the <br /> vertical extent of petroleum hydrocarbons in soil beneath the suspected source area does not <br /> extend deeper than 125 fbg <br /> The soil sample collected from CPT-6 at 10 fbg was intended assess the possibility of an offsite <br /> . release in the vicinity of MW-17 As no petroleum hydrocarbons, fuel oxygenates, or lead <br /> scavengers were detected in this soil sample it is likely there is not an offsite source in this <br /> vicinity <br /> No gasoline constituents were detected in the 10 fbg soil sample from CPT-7 suggesting there is <br /> not an upgradient onsite source at the subject site Low concentrations of petroleum <br /> hydrocarbons detected in soil samples from CPT-7 at depths up to 125 fbg are likely due to the <br /> presence of petroleum hydrocarbons in groundwater <br /> Boring CPT-5 was drilled near CPT-1 to further assess the vertical extent of petroleum <br /> hydrocarbons in the vicinity of the suspected source area Groundwater samples collected from <br /> CPT-5 shows that the petroleum hydrocarbon concentration attenuates with depth TPHg and <br /> benzene concentrations at 60 fbg in CPT-1 of 109,000 and 29,900 ppb, respectively, attenuate to <br /> 110 and 3 0 ppb at 130 fbg in CPT-5 1' '�����ZCea t-2-6'�' <br /> Boring CPT-6 was drilled to the east of the subject site to assess the downgradient extent of <br /> petroleum hydrocarbons in groundwater previously detected in borings CPT-3 and CPT-4 <br /> Unfortunately CPT-6 could not be drilled as deep as we had intended Drilling refusal was <br /> encountered at 82 fbg However, groundwater samples collected from boring CPT-6 contained <br /> • no petroleum hydrocarbons or low concentrations of petroleum hydrocarbons Comparing the <br /> 1399 5 <br />