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TPH as diesel was detected in the April 13, 1994 sample from MW-4 (84 ppb). Although ..., no petroleum hydrocarbons were detected in MW-4 during the January 1994 sampling, both . TPH as gasoline (140 ppb) and diesel (80 ppb) were detected in MW-4 during the& September 1993 sampling. The laboratory reports for the groundwater samples are included in Appendix D. 1 4.4 Analytical Results of Drum Sampling ' No petroleum hydrocarbons were detected in the soil composite sample Y-1, Y-2 and Y-3 or the water composite sample D-1, D-2 and D-13. However, toluene, ethylbenzene and xylenes were detected in water composite sample D-8 through D-12, at concentrations of ' 1.7 ppm, 2.1 ppm and 2.7 ppm, respectively. The analytical results of the drum and stockpile soil sampling are included in Appendix E. ' 5.0 CONCLUSIONS AND RECOMMENDATIONS ' 5.1 Petroleum Hydrocarbon Impacted Soil During the last phase of investigation (reported in the PAR, October 1993) the presence of hydrocarbon impacted soil immediately north of the site was confirmed beneath Harding Way. Petroleum hydrocarbon impacted soil was also confirmed at relatively low levels in boring B18 (south of MW-4) at depths between 25 and 35 feet. However, it is possible that the source of hydrocarbons for both detection areas originates beneath Harding Way north of the site. Figure 5 is a cross section showing the suspected source of hydrocarbons ' (originally appeared as Figure 3 in the PAR). Additionally, no petroleum hydrocarbons were detected in soil samples from MW-6 or MW-7, both located in the sidewalk along the north side of Harding Way. ' At the request of the PHS/EHD, MW-8 was installed near the southern portion of the property, to determine if hydrocarbon impacted soil remained in the area of the former ' UST's. No petroleum hydrocarbons were detected in soil samples from MW-8, confirming that no hydrocarbon impacted soil remains in the area of the former UST's. ' It appears that any petroleum hydrocarbon impacted soil remaining at the site from the former UST's is minimal; most of the impacted soil was removed during the two phases of excavation. It is likely that the remaining hydrocarbon impacted soil south of MW-4 (as detected in B18) does not exceed 25 to 30 cubic yards. The remaining impacted soil which may be present along the north edge of the site at depths greater than 20 feet, is likely the ' result of the hydrocarbon source beneath Harding Way. Since any remaining impacted soil on-site is likely the result of migration from beneath ' Harding Way, we do not recommend any further investigation or remediation of the impacted soil along the north portion of the property. Furthermore, as stated in the PAR, Ch.boml A�S.M...N. 11