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REI-P91-0202.R6 January 23 , 1992 Page 8 appear to be at least locally lenticular, similar to our previous study. Also, a relatively laterally consistent clay bed was encountered at depths ranging from 77. 5 to 80 feet below grade (and which extends to a least the maximum depths explored) . DISCUSSION AND RECOMMENDATIONS Analytical results of the soil samples collected from monitoring wells MW4 through MW9 and exploratory borings EB1 and EB2 , and the ground water samples collected from monitoring wells MW1 through MW9, indicated non-detectable levels of TPH as gasoline, BTX&E, TPH as diesel, TOG, and all EPA method 8010 constituents in virtually all of the samples analyzed. The only detectable levels of contaminants found in ground water were in the water sample collected from MW2 , where TPH as gasoline was detected at 240 ppb and benzene at 1. 4 ppb. The only detectable levels of contamina- tion found in soil were in soil sample MW6 (74) , where TPH as gasoline was detected at 5.7 ppm and benzene at 0.061 ppm, and in sample MW6 (60) , where benzene was detected at 0. 016 ppm. Furthermore, analytical results of soil samples collected from previously installed monitoring wells MW1 through MW3 indicated non-detectable levels of TPH as gasoline and BTX&E in virtually all samples analyzed. Four samples indicated levels of TPH as gasoline ranging from non-detectable to 5. 0 ppm and levels of benzene ranging from 0. 0094 ppm to 1.9 ppm. Analytical results of the final soil samples collected from the underground fuel storage tank pit and pipe trench excavations also indicated minimal levels of TPH as gasoline and BTX&E, with a maximum concentration of TPH as gasoline of 6 . 1 ppm, and a maximum concentration of benzene of 0. 57 ppm. TPH as diesel was non- detectable in all of the samples that were analyzed. It appears that the impact of hydrocarbon contamination to the soil and ground water beneath the site is minimal and restricted to a small area on site. Based on the above analytical results, KEI. recommends that no further work related to contamination delinea- tion is presently warranted at the subject site. However, KEI recommends continuation of the current monitoring and sampling , program for all nine existing wells in order to verify the current residual to non-detectable levels of ground water contamination detected. Results of the monitoring program will be documented and evaluated after each monitoring and sampling event. Recommenda- tions for altering or terminating the program will be made as needed.