ARCHIVED REPORTS_XR0005843 CASE 1

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I sample was then labeled and placed in iced storage Chain of Custody Records were initiated by the geologist and accompanied the samples to the analytical laboratory Ground-Water Monitoring Well The wells were constructed using clean 4-inch-inner-diameter, thread-jointed, Schedule 40 polyvinyl chloride (PVC) casing No chemicals, glues, or solvents were used in construction of the wells The screened portion of the monitoring well consists of factory-perforated casing with slots and extends from the total depth of the boring and extends above the depth where water was first encountered Unperforated casing is 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 2 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 were set in concrete approximately flush with the surrounding ground surface 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 was 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 were examined for subjective evidence of hydrocarbons by lowering about half the length of a Teflon bailer past the air-water interface The sample is 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 Monitoring wells that did not contain floating product were developed using a 4-inch diameter PVC surge block alternately raised and lowered through the water column in each well Development is performed to remove the fine-grained sediment from the monitoring well • 30055-5