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[jeo(ogicafTecknics im. Page 2 C& B Equipment Revised Work Plan Project No.336.2 March 15, 2000 On a coordinated schedule with Ms. Margaret Lagorio of San Joaquin County, a video survey of the domestic well will be performed. The purpose of this survey is to determine the condition of the well casing. The issue is whether it is in good enough condition to perforate the walls via knife cutting or if it is in too poor a condition for that to occur. This determination will be made in conjunction with Ms. Lagorio as the video is being made. A copy of the video will be obtained for the records. 1.3 Domestic & Monitoring Well Construction & Closure The following work will be performed during the abandonment procedure for the old domestic well (DW-1) and MW-1 through 7 & MW-101. The drilling contractor for abandonment of the old domestic well has not been selected yet. The work for abandoning the monitoring wells will be performed by V&W Drilling of Rio Vista C57#720904 (707- 374-2815), owner-Robert Vickery. Prior to start of,fieldwork, the required permits will be obtained from San Joaquin County DEH. Domestic Well The existing old domestic well appears to be approximately 93 feet deep; possibly deeper if the measure point was the pump and not the bottom of the well. The well is 10 inches I.D. and was installed in the late 1940s at the time the building was constructed. The results of the video survey will clarify the procedures needed for well closure. If the casing is in good condition, the casing will be perforated prior to closure with the cement grout. However, if the casing is in poor condition and the perforation process may run the risk of collapsing the casing,then the well will be grouted closed without perforating. The decision to perforate or not to perforate will be made by Ms. Margaret Lagorio of San Joaquin County after she has seen the video. The grouting process is as follows: • A neat cement grout (containing less then 4% bentonite) will be pumped under pressure through the tremie pipe to the bottom of the well. In this manner the grout will displace the water in the borehole insuring that the borehole is completely filled with grout. • After the grout has displaced all water from the well and flowed over the top, a pressure cap will be fitted to the casing and additional grout will be pumped into the well casing under pressure. This will force the cement into the filter pack. • Estimated cement volume is 51.0 cubic feet to close the well casing (assuming depth of well is 93 feet and 10 inch diameter). Actual grout volume used in the field will be tracked. • After the grout has been pressure installed, the top five feet of casing will be drilled out and the hole will be filled with grout to ground surface. • The pad around the well top casing will be removed. Monitoring Wells Herewith follows the protocol for abandoning the following monitoring wells: • Seven, 2" diameter x 20 feet deep (MW-1 through MW-7). • One, 2" diameter x 40 feet deep (MW-101).