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Ms. Margaret Lagorio Project 20805-142.008 <br /> May 18, 1998 <br /> Page 2 <br /> Well abandonment activities will be performed by a California-licensed drilling <br /> contractor under the supervision of Pinnacle personnel. The proposed abandonment <br /> methods are presented in the following paragraphs. <br /> Soil samples previously collected from the well VW-6 borehole contained residual <br /> petroleum hydrocarbons, therefore, the SJCPHS/EHD requested this well be drilled out. <br /> In order to comply with this request, well VW-6 will be drilled out using 8-inch diameter <br /> hollow-stem auger drilling equipment to remove the seal, casing, and filter pack material. <br /> Prior to drilling the well out, the total depth will be measured to confirm well <br /> construction. Upon completion of the drill out, the borehole will be sealed using neat <br /> cement grout placed through a tremie pipe from the base of the borehole to within 5 feet <br /> of ground surface. The upper 5 feet of the borehole will be backfilled with cuttings and if <br /> necessary, a concrete surface seal will be placed. <br /> Wells VW-12 and VW-13 will be pressure grouted in-place using a neat cement grout. <br /> Prior to grouting, the well depths will be measured to confirm well construction. The <br /> grout will then be pumped through tremie pipe from the base of the well to within 5 feet <br /> of ground surface. The well casing will then be fitted with a pressure cap and a pressure <br /> of approximately 35 pounds per square inch will be applied using a diaphragm pump for <br /> approximately 3 minutes to force the grout through the well screen and into the filter <br /> pack. Additional grout will be placed if necessary to within 5 feet of ground surface. The <br /> upper 5 feet of well casing and annular seal will be drilled out using 10-inch diameter <br /> hollow-stem auger drilling equipment and the resulting void will be backfilled with soil <br /> cuttings. Locations on pavement will have a surface seal installed. <br /> Cuttings generated during the drill out procedures of wells VW-6, VW-12, and VW-13 <br /> will be placed on and covered with plastic pending disposal. Groundwater samples <br /> previously collected from wells VW-12 and VW-13 did not contain detectable <br /> concentrations of petroleum hydrocarbons, thus containment of water displaced during <br /> grouting is not anticipated to be necessary and is not being proposed. <br /> SAC\A:\760DECOM.DOC-96\:1 <br />