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October 14, 1993 Working To Restore Nature ARCO Station No. 548, Sacramento, California Monitoring wells are 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 Development is performed a minimum of 24 hours after well installation to allow the grout to seal. Before developing the monitoring wells, a water sample is collected for subjective analysis from near the water surface in the well with a Teflon bailer cleaned with a laboratory-grade detergent and decon►zed water The wells are developed with a surge block and pump Well development continues until the discharge water is 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 are stabilized for a minimum of 24 hours, the wells are purged of stagnant water and a sample is collected for laboratory analysis The well is 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 is stored in labeled, 55-gallon, steel drums approved for this use by the Department of Transportation until suitable disposal options are selected based on laboratory analysis Groundwater Sampl* _, The static water level in each well is measured to the nearest 0.01 foot with a Sol►nst electric water-level sounder cleaned with a laboratory-grade detergent and deionized water before use in each well A clean bailer is used to obtain a sample from the surface of the water in the well for subjective analysis of hydrocarbons. The sample is retrieved and examined for floating product, sheen, color, and clarity Approximately 3 well volumes (approximately 50 gallons) are purged from each well with a stainless-steel electrical submersible pump to allow sampling of representative formation water The pump, cables, and hoses are cleaned with a laboratory-grade detergent and water before use in each well The wells are purged until pH, temperature, and electrical conductivity of the water stabilized,as measured by portable meters calibrated to a standard buffer and conductivity standard The water level is allowed to recover to at least 80 percent of the initial water level A sample of the formation water then is collected from the surface of the water in each of the wells with the Teflon bailer and slowly transferred to laboratory-cleaned sample containers The recovered fluids from sampling in each well 0917ccar 30004-TOW