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GEOMATRIX • Petroleum hydrocarbon-affected soil has been identified in two areas along the northeast perimeter of the site: (1)within an area adjacent to the existing building and(2)within an area further west that is currently used for automobile parking (Figure 3). The maximum vertical extent of petroleum hydrocarbon-affected soil within the site is estimated to be from approximately 5 to 80 feet bgs based on pre- vious field observations and analytical results. • The lateral extent of petroleum(i.e., crude) affected soil is estimated to extend from the site to the southwest shoulder of Highway 33 (Figure 4), including boring loca- tions GMX-11 and GMX-12. No significant evidence of affected soil was observed in boring GMX-10, which is located on the northeast shoulder of Highway 33. The vertical extent of affected soil off-site was observed to be from about 32 to 44 feet bgs at boring locations GMX-11 and GMX-12. • Slight petroleum sheen(less than 0.01 inches)has been observed in on-site monitor- ing wells MW-1 and MW-2 in previous investigations. • TPHd has been detected in the groundwater samples collected from MW-1, MW-2, MW-3, GMX-6, GMX-10, GMX-11, and GMX-12 (Table 2). After a silica-gel preparation procedure, TPHd was not detected in the grab groundwater samples collected from GMX-10 and GMX-12 and was detected at lower concentrations in MW-3, GMX-6, and GMX-11. These analytical results suggest that portions of the TPHd concentrations in groundwater at the site are due to polar byproducts resulting from intrinsic biodegradation of petroleum hydrocarbons. • The lateral extent of TPHd concentrations in groundwater exceeding the WQO of 100 µg/1 is estimated to extend from the affected soil to the vicinity of GMX-10, as shown on Figure 5. The vertical extend of TPHd concentrations in groundwater exceeding the WQO is estimated to be similar to the vertical extent of affected soil. • Low concentrations (0.1 to 2.3 µg/1) of one or more PAHS have been detected in the groundwater samples collected from MW-2, GMX-6, GMX-10, and GMX-11 (Table 2). • A high concentration of TPHg (61,000 gg/1) was reported for the water sample col- lected from MW-1 in 1996. High concentrations of volatile petroleum hydrocarbon constituents are not a typical characteristic of weathered residual crude oil that might be associated with the OVP. This detection might be a result of source(s) other than the OVP. This result may also be from a separate phase petroleum sheen, as was noted in 1999 and 2002 (Table 3). Low concentrations of TPHg (110 to 140 gg/1) and BTEX (from none detected to 5.9 µg/1) have been reported for the ground- water samples collected from MW-2, GMX-6, and the vicinity of MW-1 (Table 2). TPHg and BTEX were not detected in the groundwater samples collected from MW-3, GMX-10, GMX-11, and GMX-12 in August 2003. I:\Doc_Safe\6000s\6447.001\OffSite Rpt\US Can SoiIGW Rpt 2003.doc 10