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Former Discovery Chevrolet June S, 1998 Tracy,California Corrective Action Plan analyses requested. After laboratory analysis, a determination will be made as to the selection of the aerated soil for use as onsite fill materials. 6.2.2 Description of Remedial Work - Groundwater After excavation of the hydrocarbon-impacted soil in the area of the former UST pit area, groundwater will collect within the excavation at the static depth of groundwater, which has been between 9 to 11 feet bgs. The removal and disposal of a quantity of hydrocarbon- impacted groundwater from the excavation prior to backfilling would be prudent, and would assist in the minimizing the impact to groundwater outside of the former UST pit area. After backfilling of the pit with clean imported material and aerated native material, groundwater monitoring should be conducted for a short period of time to evaluate the effectiveness of the remedial work. In addition, as a part of the corrective action, groundwater monitoring well MW-1, located on the southern side of the former tank pit will likely be destroyed during the excavation operations. During installation in September 1994, gravel was encountered in the first 8 feet of the boring for MW-1, indicating that this well is located at least partially in the UST excavation backfill. The 2-inch diameter PVC well casing will be excavated and removed f by the backhoe onsite during the excavation operations. If necessary, a well destruction permit will be acquired from the SJC PHS/EHD prior to the excavation work. V `, Also as a part of the corrective action, the apparent water well discovered outside of the northwest corner of the service bay area at the site will be destroyed. The 8-inch well casing was previously measured to a depth of 1 p y p approximately 145 feet. The steel discharge pipe and pump will be removed from the 8-inch steel casing, then a 2-inch PVC casing will be lowered to the bottom of the well casing and the well will be destroyed by pressure grouting. f Cement grout will be placed inside the well casing and the well casing will be pressurized to approximately 30 pounds per square inch (psi). This process will be repeated until the grout f level stabilizes in the well at or near to the top of the casing. Overdrilling of the well casing 1 3001-21.cap 18 HORIZON ENVIRONMENTAL INC.