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LOF Glass Woodward-Clyde Consultants <br /> May 6, 1985 <br /> Page 4 <br /> Site Geology. The local geology underlying the spill are was determined <br /> through examination of drill cuttings from each of the borings and from <br /> split spoon samples taken at depths of 9 1/2 to 11 ft. in Boring 1 and 8 <br /> to 9 1/2 ft in Boring 7. In general, the geology consists of fine silty <br /> sand near the surface becoming more of a medium silty sand with depth. A <br /> silty sandy clay layer was found in all borings in the zone between 8 and <br /> 10 ft. In some borings the clay layer appeared to be thicker than <br /> others. Some cemented sands and gravels were observed in a few of the <br /> borings. The split spoon sample in Boring 1 displayed a thin lense of <br /> water saturated pea gravel directly below the clay layer at approximately <br /> 9 1/2 ft. Below the gravel, the material returned to fine to medium <br /> silty sand and become coarser with depth. Below 15 ft. it consisted <br /> primarily of a coarse sand with some fines. Overall, the geology of the <br /> area is very uniform and is typified in the boring log given in Figure 2. <br /> Groundwater. The groundwater in the local, unconfined aquifer is of poor <br /> quality and used only as process water. The water table is located 9 to <br /> 10 ft. below grade. Measurements of depth to groundwater on April 9, <br /> three days after completion of the wells and a week later on April 16 <br /> indicate that the water table is dropping somewhat. Well measurement <br /> data is given in Table 1. The local groundwater gradient appears to be <br /> sloping towards the south or southeast. Figure 4 provides a groundwater <br /> contour map of the spill area based on the April 15 measurements. <br /> Contamination. As mentioned previously, oil was reported on the water <br /> table in several trenches excavated by LOF shortly after discovery of the <br /> spill in addition to being observed in the drilling and development water <br /> for monitoring wells (MW) 9 and 10. However, subsequent measurement and <br /> bailing of all monitoring wells did not yield any visible evidence of oil <br /> contamination. It is possible that migration of the main portion of the <br /> spill was limited to the immediate area of the leak and that only a small <br /> amount had migrated away from the spill along the surface of the <br /> groundwater or that the traces of oil seen in outlying areas were from <br />