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1 <br /> 30 September 1997 <br /> AGE-NC Project No 95-0144 <br /> i ' Page 2 of 3 <br /> F <br /> UST No 8 was reported to contain solvents, therefore samples collected from probing GPI through <br /> GP4 were analyzed for halogenated volatile organics in accordance with EPA method 8010 AGE <br /> ' has since learned that polyaromatic hydrocarbons (PAHs) were detected in samples collected <br /> ' following the UST removal Future samples collected from the vicinity of UST No 8 should be <br /> analyzed for TPH-g, TPH-d and PAHs <br /> ' As stated in the revised CAP, petroleum hydrocarbons were not detected in stockpile samples <br /> collected following the removal of UST No 2 Hydrocarbons were also not detected in samples <br /> collected from probe borings GP9 to GP12 Therefore no furthei investigation is warranted in this <br /> ' area <br /> ' GROUND WATER MONITORING <br /> At the request of the PHS-EHD, concentrations of TPH-g and ground water elevations versus dine <br /> ' were graphed for samples collected from monitoring wells MW-1, MW-2, MW-4 and MW-5 > <br /> (attached) The highest hydrocarbon concentrations have been detected in MW-1 A general decrease <br /> over time of hydrocarbon concentrations is evident in samples collected at the site The same trend <br /> is reflected in samples collected from MW-2 and MW-4 The decline in concentrations for these <br /> three wells was accelerated «hen rising ground water levels rose above the screened intervals of the <br /> ' wells,at an elevation of approximately A I feet, as shown on the plots Another factor causing the <br /> decreased hydrocarbon concentrations may be natural attenuation, but the data collected cannot <br /> confirm that this process is occurring <br /> Hydrocaiban concentrations had nearly the opposite trend in "ell MW-5 This correlation is a bit <br /> more difficult to interpret, but it can be noted that rising ground water can be expected to encounter <br /> ' more hydrocarbon-Impacted soil and MW-5 had the lowest initial hydrocarbon concentrations <br /> compared to the other three graphed wells <br /> ' Hydrocarbons are not present in samples collected from down-gradient wells, indicating that the <br /> plume is not migrating <br /> 1 i <br /> REMEDIAL ACTION OPTIONS <br /> ' Three areas of hydrocarbon-impacted soil potentially requiring remediation are present on the site <br /> The best remediation method for one area may not be the best suited for another Due to the <br /> ' distances between these areas, it is feasible to use different methods for remediation in the different <br /> areas <br /> Adtiamed GCOEM Lronnzental,Inc ` <br /> 1 <br />