SITE INFORMATION AND CORRESPONDENCE_FILE 1

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V x Doug Westenhaver Page 2 There has been no confirmation testing of DMW-5 for solvents since the May 2, 1995 sample was taken. There has been no sampling of the remaining wells DMW 1, 2, 3 and 4 for solvents. In order to confirm the presence of solvents in the groundwater beneath this site, additional groundwater analysis is necessary. If solvent contamination of the groundwater is confirmed, additional work would be required to i confirm an offsite source. If additional investigation confirms an offsite source for the solvent groundwater contamination then AFP will no longer be considered the discharger responsible for remediation of this plume. The five year monitoring program proposed by Dames and Moore as a post remedial monitoring program for the diesel and waste oil tank overexcavation and bio treatment which was completed in June of 1990 includes measurement of groundwater levels, analysis of groundwater for total petroleum hydrocarbons as diesel (TPH-d), and confirmatory soil sampling in the last year of the program. 1 Measurement of groundwater levels is necessary because, when the project started in 1987 and groundwater was measured at 35 feet below ground surface (bgs), the residual contamination was considered as a threat to groundwater. When the. groundwater table elevation was measured during the installation of DMW-1, 2, 3 and 4 in July of 1990 groundwater was measured at 68.5 feet bgs. In May of 1994 groundwater was measured at approximately 60 feet bgs. Groundwater was measured at 56 feet bgs in May of 1995. Based on 1991 and 1992 groundwater-measurements of 70 feet bgs the residual contamination was no longer considered as a threat by AFP and closure was requested in the Dames and Moore August 1994 Draft Amended Closure Request. The report contains models of the residual contamination from 1990 with groundwater at 35 feet, 54 feet and 70 feet. The results of the naphthalene modeling are 36.5 ppb, 2.98 ppb and .172 ppb respectively. The text of the August 1994 report indicates that ground water would remain at 70 feet for 25 years. The potential for groundwater to return to 35 feet must-be.,determined using real data. If at the end of the five year period, groundwater elevations remain below 50 feet bgs and do not show a trend towards re-establishing the 1987 elevation, then the residual diesel contamination left in place will be protective bf groundwater quality. The current trend indicates a rise in groundwater levels. Sampling and analysis of groundwater for TPH-d and naphthalene will confirm the computer models. Additional analysis for solvents may be required pending the results of the solvent investigation. The results of the July 1995 investigation indicate that the level of residual diesel detected in 1995 is lower than in 1990, however the samples from the 1995 investigation were taken at deeper depths than the previous investigation. Borings i S