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-- APPENDIX B WELL DESTRUCTION destruction of monitoring well MW-2 was performed by Spectfum Explar•ation, 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 device. White FVC casing scraps and a medium sand (filter pack) were brought to the surface during drilling. A split-spoon sampler was driven from 29 feet below grade and confirmed that native -material (a grey-brownmottled hard clay or silt) had heen reached. The apparent discrepancy between constructed well depth (30 feet) and the depth at which native material was confirmed (29 feet) exists because approximately one foot of material (pavement and subgrade) was removed from - the site before destruction. This means that the true well depth of 30 feet was equivalent to about 29 feet after both the pavement and subgrade had been removed. After the well was drilled out, it was sealed to a depth of 13 feet below grade by tremieiPg a cement-bentonite mixture in through a pipe inserted through the augers, from the bottom of the hole up. The hole was not sealed below 13 feet because it lay within an area to be excavated, the following day, to a depth of 14 feet. The extra foot of grout was placed to allow for grout infiltration:and settlement. This procedure was performed in the presence of San Joaquin County Public Health Services Department personnel. When this area was excavated and sampled `Febr� p � iary 8}, the excavator operator reported encountering the cement plug near the bottom of the cxcavation, f indicating that well MW-2 had been properly destroyed. Cuttings and sand produced during well destruction were placed with materials excavated from the. fuel UST excavation for subsequent sampling and disposal. B-1 H-_:ENG:4205-AppB/031291