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' R <br /> A CADIS GERAGHTY&MILLER <br /> BTEX were found in NP-1 between 20 ft bgs and 80 ft bgs Low detectable concentrations of 1} <br /> BTEX were found in NP-1 at 110 ft bgs Soil samples taken at four consecutive depthsV z <br /> (spaced on 10-foot intervals)in NP-1 below the 80 ft depth of impact were nondetect for both <br />' TPHg and benzene,, 1s <br />' Maximum groundwater concentrations in NP-1 and NP-2 occurred at the 60 and 70 ft " <br /> bgs depth (Figure 5-4 and Table 5-1) Detectable concentrations of TPHg and BTEX in <br /> groundwater grab samples in NP-1 spaced on 10-foot depth intervals were found from 32 ft <br /> bgs to 110 ft bgs. <br /> The historic record of groundwater levels in the Site vicinity, the removal of the USTs <br /> during the 1967 station remodel, the pre-1992 station demolition and fuel dispensing <br /> equipment removal, and the vertical distribution of constituent concentrations as indicated by <br /> the NP-1 data, indicate that the Site release occurred during a previous time when <br /> groundwater levels were lower and that groundwater has subsequently risen into the zone of <br /> soil impact <br /> The Site release has resulted in a dissolved petroleum hydrocarbon groundwater plume <br />' of hmtted extent Out of the approximately 5-year momtonng record, free-phase petroleum <br /> hydrocarbon has been detected at the Site on only one occasion in one well (well W-1 on <br />' November 3, 1997) The detection of free-phase petroleum hydrocarbon has not been <br /> replicated <br /> MTBE has not been detected at the Site <br />' 34 <br />