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Working To Restore Nature February 12, 1993 • ' BP Oil Facility No. 11193, Stockton, California. 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. ' Well Development We waited a minimum of 24 hours after well installation before developing the groundwater * 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. Groundwater Samvling ' 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. ' Approximately 3 well volumes (approximately 50gallons) were purged from each well with a stainless-steel electrical submersible pump to allow sampling of representative formation water. The pump, cables, and hoses were cleaned with a laboratory-grade detergent and water before use in each well. The wells were purged until pH, temperature, and electrical conductivity of the water stabilized, as measured by portable meters calibrated to a standard ' buffer and conductivity standard. • 17051.01 'i'