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1 Soil cuttings from the drilling operation and rinsate water from steam cleaning were transferred to 55-gallon drums for temporary onsite storage prior to disposal Samples of the investigation-derived waste (IDW) were collected on October 28, ' 1993, and submitted to the District's laboratory for waste characterization analysis The IDW will be disposed of at a facility consistent with the results of these analyses 2.2 Groundwater Monitoring Well Installation ' During the drilling of the monitoring well borings, groundwater was encountered at approximately 15 feet bgs at MW-8, and 12 feet bgs in MW-9 Each monitoring well boring was drilled to a total depth of 26 5 feet bgs The wells were ' constructed of 4-inch-diameter, Schedule 40 flush-threaded polyvinyl chloride (PVC) casing with 20 feet of 0 02-inch factory slotted screen The wells were screened from ' five feet to 25 feet bgs Lapis Lustre sand #3 was used as the filter material around the well screen A 2-foot bentonite seal was placed on top of the filter pack A 1- foot cement-bentonite grout was used as the annular seal to the ground surface The wells contain locking well caps, and are protected by flush-mounted protection boxes The depth to groundwater was measured in MW-8 and MW-9 as well as in the seven existing monitoring wells using an oil/water interface probe The depth to groundwater ranged from 1118 feet bgs to 12 25 feet bgs and are listed on Table 1 No free product was detected in any of the wells The two new monitoring wells, MW-8 and MW-9, were developed on ' September 17, 1993, using a combination of surging and pumping until approximately 10 well volumes had been removed, and the physical water quality parameters (conductivity, temperature, pH, and turbidity) had stabilized The parameters were ' considered to be stabilized when the range of values of three consecutive readings were within 10 percent Five of the seven existing onsite wells (MW-1, MW-2, MW-3, MW-4, and MW-6) were purged until three to five casing volumes of water had been removed and the physical water quality parameters (conductivity, temperature, pH, ' and turbidity) had stabilized After each well was developed or purged, one groundwater sample was collected A duplicate sample was collected from MW-9 and a split sample was ' collected from MW-8 One water sample from each monitoring well was submitted to the District's laboratory for chemical analysis The duplicate water sample was ' also submitted to the District's laboratory The split sample was submitted to Anlab Analytical Laboratory (Anlab) for quality control 93822 East Bay Muntctpal Utility Dtstnct 40429500asn 6 Stockton Svc Ctr -Sue Assessment/Remedial options