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5.0 CONCLUSIONS & RECOMMENDATIONS 5.1 Soil Contamination Very low concentrations of volatile hydrocarbons were detected in soil samples from MW-1, MW-2, and MW-3 in 1987 One objective of this investigation has been to further delineate the lateral extent of this contamination Boring B-7 was installed on the north side of the UST facility, and B-8 was installed near the abandoned dry well on the southeast corner of the property Neither of these borings encountered any soil contamination Either the contamination that was detected in MW-1 and MW-3 is very limited in extent, or it has naturally dissipated in the intervening years Before considering remedial action to remove the contamination detected in MW-1 and MW-3, GeoAudit recommends that one additional soil boring be drilled between these wells to determine whether soil contamination remains south of the UST facility I5.2 Groundwater Contamination Monitoring wells MW-5 and MW-6 were installed to further investigate the extent of hydrocarbons in groundwater Water samples obtained in previous monitoring events detected groundwater contamination to the north, west and south of the UST facility Samples obtained in this investigation indicate that groundwater in the vicinity the UST facility is not contaminated at present However, hydrocarbons are present in the two down- gradient wells (MW-2 and MW-6) and in the new up-gradient well (MW-5) These results do not provide a clear, consistent picture of the source or extent of contamination However, concentrations are very low, and only the concentration of benzene in MW-2 exceeds the Maximum Contaminant Level for drinking water Attempts to reduce such low levels to non-detect are unlikely to be successful Moreover, groundwater depth data, particularly from MW-5, do not provide reliable gradient information Therefore, GeoAudit recommends monthly monitoimg of the gradient for the next three months, but does not recommend fuither assessment of the extent of hydrocarbons-in groundwater at this time 6.4 LIMITATIONS ' Our professional services were performed using that degree of care and skill ordinarily exercised by environmental consultants practicing in this or similar localities The findings were based upon analytical results provided by an independent laboratory Evaluations of the geologic/hydrogeologic conditions at the site for the purpose of this investigation are made from a limited number of available data points (i a monitoring wells, soil samples) and subsurface conditions may vary away from these data points No other warranty, expressed or implied, is made as to the professional recommendations contained in this report 0-1-9-1 A.dm 5.1-1. 14 ' L-1w r.,d Bn QR/1 9ascas I