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of the March and September 1994 measurements indicates that groundwater at the site has dropped an average of 2.60 feet since the March monitoring. The drop in groundwater corresponds to normal seasonal fluctuations in the area. The groundwater gradient and flow - direction were calculated to be 0.0043 ft/ft directed N 700 E (Figure 3). This is consistent with previous calculations. 4.2 Groundwater Sample Results TPH as gasoline, benzene, toluene and xylenes were detected in samples this quarter from monitoring well MW-3 at concentrations of 72 parts per billion (ppb), 9.3 ppb, 0.89 ppb and 1.4 ppb, respectively. Xylenes were detected in MW-1 at a concentration of 1.3 ppb. No other petroleum hydrocarbons were detected in any of the samples. The analytical results ` of the groundwater samples are summarized in Table 2. The laboratory report and chain of custody are included in Appendix B. 5.0 CONCLUSIONS AND RECOMMENDATIONS 5.1 Hydrocarbon Impacted Soil Petroleum hydrocarbons were detected in soil samples from three of the four borings drilled in October 1992 at concentrations to 2,181 ppm. Low concentrations of hydrocarbons were detected in soil samples from the drilling of the three monitoring wells. Petroleum ,A. hydrocarbons were most recently detected in soil samples collected at the time of the removal of the USTs at concentrations up to 3,000 ppm. �- A vapor extraction pilot test was conducted on vadose well VW-1 in December 1993. Analytical results of air samples collected during the pilot test indicated that high concentrations of TPH could be removed through vapor extraction. A Remedial Action Plan (RAP) should be prepared for the site. Vapor extraction was shown to be a viable remediation alternative during the pilot test. The number and locations of additional extraction wells and a design for a vapor extraction system should be included in the RAP. 5.2 Hydrocarbon Impacted Groundwater Low concentrations of petroleum hydrocarbons were detected in MW-3 during the most ` recent monitoring. However, remediation of such low concentrations is unlikely to be effective. Remediation of impacted soil will prevent future migration of hydrocarbons from the soil to the groundwater and allow time for natural degradation to occur. Based upon the ` most recent sampling,we do not recommend any active groundwater remediation at the site at this time. However, quarterly groundwater monitoring should be continued during soil remediation. We recommend scheduling the next quarterly monitoring for December 1994. 0-ba-1 Hdit Scrvicta.lac.