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I Monitoring-Well Construction I Monitoring wells were constructed in the borings with thread-pointed, 4-inch-inner-diameter, Schedule 40 PVC casing No chemical cements, glues, or solvents were used in well construction The screened portion of each well consisted of factory-perforated casing with 0 020-inch-wide slots The well screen extends from the total depth of the well to approximately 5 or 10 feet above the ground-water surface This screened interval allows sampling at the air-water interface during seasonal fluctuations of the ground-water level The annular space in the well was packed with number 3 sand to approximately 1 to 2 feet above the slotted interval A 3-foot thick bentonite plug was added above the sand pack to prevent the cement from entering the well pack The remaining annulus was backfilled to grade with a bentonite cement slurry Monitoring wells were protected with a traffic-rated, cast-aluminum utility box equipped with a PVC skirt The box has a watertight seal to protect against surface-water infiltration and must be opened with a special wrench The design of this box discourages vandalism and reduces the possibility of accidental disturbance of the well -Yell Development We waited a minimum of 24 hours after well installation before developing the ground- water monitoring wells to allow the grout to seal Before developing the monitoring wells, a water sample was collected for subjective analysis from near the water surface in the well with a Teflon bailer cleaned with a laboratory-grade detergent and deionized water Floating product was not encountered The wells were developed with a surge block and pump Well development continued until the discharge water was clear of silt and sand Clay-size sediments derived from the screened portion of the formation cannot be entirely eliminated by well development After the wells stabilized for a minimum of 24 hours, the wells were purged of stagnant water and a sample was collected for laboratory analysis The well was purged of approximately 3 to 5 well volumes of water with a submersible pump, or until pH, conductivity, and temperature of the purged water have stabilized Water purged from the wells was stored in labeled, 55-gallon, steel drums approved for this use by the Department of Transportation until suitable disposal options were selected based on laboratory analysis Ground-Water Sampling The static water level in each well was measured to the nearest 0 01 foot with a Solinst electric water-level sounder cleaned with a laboratory-grade detergent and deionized water before use in each well A clean bailer was used to obtain a sample from the surface of the water in the well for subjective analysis of hydrocarbons The sample was retrieved and . examined for floating product, sheen, color, and clarity 3 W8-s