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y <br /> The annular space of each well was packed with sorted sand from the total depth of boring <br /> W-, to approximately 1 foot above the top of the screen. A plug of bentonite pellets <br /> (approximately 2 feet thick) was placed above the sand to prevent cement from entering the <br /> sand pack. This seal reduces the possibility that hydrocarbons migrating downward through <br /> the overlying sand will infiltrate the aquifer. The remaining annulus was backfilled to tite <br /> ground surface with a mixture of water, cement, and bentonite. The construction details of <br /> the individual wells are shown on the Logs of Borings. <br /> 'the wellheads were secured in cast-aluminum utility boxes with PVC aprons. The boxes <br /> have watertig;.t seals and are set in concrete approximately flush with the surrounding <br /> ground surface to reduce surface-water infiltration. A special wrench is required to open <br /> the box. This design discourages vandalism and reduces the possibility of accidental <br /> disturbance to the well. Each wellhead was also fitted with a locking well cage to further <br /> protect against unauthorized disturbance of the well. <br /> Ground-Water Monitoring Well Development <br /> Before developing the wells, static water levels were measured using a Solinst water-level <br /> meter. Following initial water-levels measurements, the water in the wells was examined <br /> for subjective evidence of hydrocarbons by lowering about half the length of a Teflon bailer <br /> past the air-water interface. 'The sample was retrieved and inspected for floating proJuct, <br /> sheen,emulsion,color,and clarity. The thickness of floating product detected was recorded <br /> to the nearest 1/8-inch. The monitoring wells were developed using a 2-inch diameter PVC <br /> c; surge block alternately raised and lowered through the water column in each well. <br /> Development was performed to remove the fine-grained sediment from the monitoring well. <br /> Ground-Water Sampling <br /> The static water level in each well was measured to the nearest 0.01-foot with a 5olinst <br /> water-level sounder cleaned with industrial soap and water before use in each well. A clean <br /> bailer was used to obtain a sample from the surface of the water in each well. The sample <br /> was retrieved and inspected for floating product, sheen, emulsion, color, and clarity. <br /> _. Applied OeOSYWOMs <br />