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had occurred in the vicinity of the former gasoline tank, and that further investigation was warranted. On August 24 and 25, 1994, Remcor installed an additional seven soil borings and three ee monitoring wells to further define the lateral extent of soil and ground water ' contamination identified in the initial phase of work. On March 8, 1996, AGS installed an additional three ground water monitoring wells to ifurther define the lateral and vertical extent of contamination. Monitoring well MW-7 was installed in the upgradient direction to the southeast of the former UST pit. Monitoring well MW-8 was installed west of the former UST pit to assess ground water quality in that direction. These two wells were installed to a depth of 27 feet and 25 feet below grade, respectively. ' Monitoring well MW-9 was installed adjacent to the previously installed well MW- P Y 6 to determine the vertical extent of contamination. This well was installed to a depth of 45 ' feet below grade and sealed with bentonite between the depths of 38 feet and 28 feet. 1.3 Geology The subsurface geology of the site was determined by logging soil samples collected at various intervals during the initial and supplemental site investigations. Dark brown silty clay dominates the stratigraphy from within one foot of the surface to the bottom of the borings. In general, fine sand was found within the silty clay unit near the bottom of the borings. The moisture content increased with depth and reached saturation between 12 and 16 feet below grade. ' 1.4 Hydrology Groundwater at the site is contained in a semi-confined or unconfined aquifer 10 to 15 feet below grade. Historically, groundwater at the site demonstrates a shallow gradient ' which slopes to the northwest. 1 CA45DE-029 American Geological Services, Inc. 4