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r. . - " plasticity, consistency, blow counts, and any other characteristics noted along with evidence for the presence of hydrocarbons such as soil staining,obvious product odor,and PID readings. After terminating the borings, they were backfilled using a tremie pipe with a cement-bentonite slurry to surface grade. Ground-Water Monitoring Well Construction The wells were constructed using clean 2-inch-inner-diameter, thread-jointed, Schedule 40 `3 polyvinyl chloride(PVC) casing.No chemicals,glues, or solvents were used in well construction. The screened portion of the well consisted of factory-perforated casing with 0.020-inch-wide slots and extended from the total depth of the boring to about 10 feet abpve ground water. Solid casing was set from the top of the screen to several inches below surface grade. The annular space of each well was packed with sorted sand from the total depth of boring to approximately 1 foot above the top of the screen. A plug of bentonite pellets (approximately 2 feet thick) was placed above the sand to prevent cement from entering the sand pack. This seal reduces the possibility that hydrocarbons migrating downward through the overlying sand will infiltrate the aquifer. The remaining annulus was backfilled to the ground surface with a mixture of water, cement, and bentonite. The construction details of the individual wells are shown on the Logs of Borings. The wellheads were secured in cast-aluminum utility boxes with PVC aprons. The boxes have watertight seals and are set in concrete approximately flush with the surrounding ground surface f..ef to reduce surface-water infiltration. A special wrench is required to open the box. This design ' discourages vandalism and reduces the possibility of accidental disturbance to the well. Each wellhead -as also fitted with a locking well cage to further protect against unauthorized disturbance of the well. Ground-Water Monitoring Well Development Before developing the wells, static water levels were measured using a Solinst water-level meter. Following initial water-levels measurements, the water in the wells was examined for subjective evidence of hydrocarbons by lowering about half the length of a Teflon bailer past the air-water interface. The sample was retrieved and inspected for floating product, sheen, emulsion, color, and clarity. The thickness of floating product detected was recorded to the nearest 1/8-inch. Development was performed to remove the fine-grained sediment from the monitoring well by raising and lowering a 2-inch-diameter PVC surge block through the water column. After surging the well, an air-lift pump was used to remove the fine-grained sediment from the monitoring well until the water was cleared and to pack and sort the annular sand. The wells were purged using - -a.stainless.steel-submersible pump.-----_..- Ground-Water�amnling The static water level in each well was measured to the nearest 0.01-foot with a Solinst water-level sounder cleaned with industrial soap and water before use in each well. A clean bailer was used Aw,v/led Ge®SysteMS — -