SITE INFORMATION AND CORRESPONDENCE

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AUG 20 197 02:54PM CLEARWATER GROUP P.3/7 CLEARWATER i s r, o IJ 1', INC 1':fi nl n++✓r++'rrl Ml.tirlir Ifrh • That,while testing showed that limited contaminant migration had occurred, this movement was mostly restricted to the subject site. A soil sample collected from boring SI-5(drilled and sampled in October, 1993),located near the eastern site boundary,was shown to contain low levels of hydrocarbon contamination. Concentrations were approximately half those measured in sample UGS,collected from soil immediately beneath the fbn-ncr unleaded UST. Grab groundwater samples were collected by Kennedy/Jenks Consultarxts in March, 1995. Results of sample analysis confirmed that a limited fraction of fuel hydrocarbons had migrated beyond the property boundary. As shown on the attached figure, concentrations attenuated significantly with distance from the former tank basin,with the extent of benzene dissolved in groundwater(above 1 ug/1) shown to be in the vicinity of SV-3/SV-4,approximately 100 feet from the former UST basin. It should be noted that the Kennedy/Jenks sampling effort confmned the presence of contamination in the vicinity of the nearby 7-14 convenience store. The pattern of contaminant distribution in sampling points confirmed that this release was associated with the activities at this convenicnce stare. • Concentrations of fuel hydrocarbons measured in groundwater samples collected from the monitoring wells installed during the earliest stage of investigation have been highest in the samples collected from NW-3 and MW-4. As you recall,these wells are located immediately adjacent to the former US'Ts. It must be noted,however,that the measured concentrations in these wells declined significantly in the pe-riod immediately following the removal of the tanks and additional soil. This decline in concentration cannot be attributed either to a significant change in water levels, as none had occurred, or to well-screen occlusion, as the water table was still intercepted by the screened interval at this time, well screens have been since submerged by rising water levels,bur coneentradons continued to decline during the period of slow water level advancement, documenting the positive effect of source removal at this site. Concentrations over the course of the last two years have been below or near detectable levels. CAonternolated Future Activity Conversations most recently have involved consideration of an additional monitoring well downgradient of the former UST basin and existing monitoring wells. It appears as if you feel closure is imminent, and the intended purpose, of this additional well .installation is to provide additional informations required for your final closure analysis. After reviewing the file, I believe