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4.0 PERMANENT MONITORING WELL VERIFICATION SAMPLING AND WELL ABANDONMENT The well abandonment procedures for the well replacement program are designed to effectively prevent the direct vertical migration of surficial water to the screened portion of the aquifer via the monitoring well's casing and to minimize obstructions to possible future land development. The abandonment of the original monitoring wells will be completed after verification samples have been collected from both the replacement and original wells and analyzed for compounds of concern. The verification samples will be collected during the February 1997 PW sampling event which is the next scheduled event. Groundwater sample analytical results from both sets of wells will be compared. Based on this comparison, the original wells will either be resampled or abandoned. If resampling is required, the wells will be abandoned once the resampling analytical data has been obtained. A discussion of the comparison will be included in the February 1989 Semi-Annual Permanent Monitoring and Injection Well Report prepared for the Groundwater Remedial Program. The abandonment will be initiated by excavating the soils surrounding the protective casing to a depth of five feet bgs. At that depth, both the protective casing and well casing will be cut and removed. The well will then be sealed shut with a sealing material consisting of a sand-cement grout which will be pumped into the well casing via a tremmie pipe. The tremmie pipe will extend to the bottom of the well and will be removed as the grout is placed into the well. The grouting will be performed in one continuous operation for each well. To assure that the well is filled and there has been no bridging of the grout, the volume of material placed in the well will be verified to equal at least the volume of the well. If the volume of grout is less than the calculated volume, the tremmie pipe will be reinserted into the well and the 7