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M ,ad iS Am I 3.0 FIELD METHODS 3.1 WELL DESTRUCTION Destruction of monitoring well MW-2 was performed by Spectrum Exploration, Inc. and IT. The well was drilled out to a depth of 30.0 feet using 12-inch outside diameter, hollow-stem augers, which contained a casing centering � a device. White PVC casing scran5 and a medium sand (well filter pack) were brought to the surface during drilling. A split--spoon sampler was driven from E 29 feet below grade and confirmed that native material (a grey-brown mottled hard clay or silt) had been reached. The apparent discrepancy between.constructed.well depth (30 feet) and the depth at which native material was confirmed (29 feet) exists because approximately eine foot of material (pavement and subgrade) was removed from the site before well destruction. This means that the true well depth of 30 feet was equivalent to about 29 feet after bath the pavement and subgrade had been removed. r After the well was drilled out, it was sealed to a depth of 13 feet below ' inserted grade by tremieing a cement-bentonite mixture in through a pipe L. of the hole up. The hole was not sealed through the augers, from the boki above 13 f 14 eet because it lay within an area to be excavated to a to allawtfoorfgraut feet.the following day. The extra foot of grout was placed infiltration and settlemti: t. This procedure was performed in the presence of ' San Joaquin County Publie, Health Services Department personnel. When this area was excavated and sampled {February 8}, the excavator operator reported encountering the cement plug near the bottom of the excavation, indicating that well MW-2 had been properly destroyed. t Cuttings and sand produced during well destruction were placed with materials Y.t excavated from the fuel UST excavation for subsequent sampling and disposal. The Well Destruction Permit is shown in Appendix A. E r, 3 I;OG;9193/041591 i