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October 4, 1994 Page 3 i' Existing hydrocarbon concentrations in the soli appear to be limited to the area around the former product islands Soils in the vicinity of the northern product island at location VW-2,within the depth interval of 20 to 30 feet, were found to have TPH-g concentrations ranging from 1,400 to 17,300-ppm with benzene concentrations ranging from 0 27 to 28 ppm Within 15 feet of VW-2, at locations MW-2 and KB-2, soil concentrations decreased to below 28 ppm TPH-g and less than 1 ppm benzene between depths of 25 and 30 feet Soils within the 20- to 30-foot depth interval are within the capillary fringe of the highest anticipated groundwater level (approximate depth of 30 feet) Soils within the area of the northern product islands appear to be defined In the area around the southern product island, Boring K133 contained 239 ppm TPH-g and 112 ppm benzene. Soils within this area were defined to the north by the tank excavation and to the south by Boring K134. An additional discussion of soils delineation at the site is presented in Applied's report dated December 12, 1990 Groundwater Conditions Groundwater occurs beneath the site within the fine-grained deposits, currently between approximate depths of 44 to 48 feet. Groundwater flow at the site has • consistently been observed (since 1988) to the northeast at an average gradient of 0.002 The maximum groundwater fluctuation was noted in Well MW-1 at 17 5 feet between 1988 and 1993. Because of the fluctuations in groundwater, Wells MW-1 and MW-2 were dry between 1990 and 1992. Well MW-3 continued to be dry through the first quarter 1993. Separate-phase hydrocarbons have never been observed in site wells Historically, the highest hydrocarbon concentrations have been observed in on-site monitoring Wells MW-2 and MW-6 PACIFIC previously analyzed five sets of groundwater analytical data between 1989 and 1993. The results of the analysis,presented in PACIFIC's Work Plan dated August 6, 1993, indicate that the configuration of the hydrocarbon plume has remained relatively stable over a 4-year period PACIFIC attributes this finding to the combination of the fine-grained sediments underlying the site, the relatively shallow gradient, and the effects of natural attenuation and degradation processes SCOPE OF WORK The investigation was conducted on July 14, 1994, to determine the extent of hydrocarbons in soil and groundwater in crossgradient and upgradient directions from the site, relative to the northeasterly direction of groundwater flow The scope of work for the investigation included drilling and constructing two off-site groundwater monitoring wells (Wells MW-8 and MW-9), field screening of 31004002/MWINSTAL