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CA ARNG Field Quality Assurance Project Plan <br />geologic setting) (ASTM, 1993). The ASTM standard includes a discussion of various materials suitable <br />for decommissioning wells and examples of typical abandonment practices. <br />8.8.4 Upon completion or termination, each soil boring will be filled with a neat, non -shrinking, cement <br />grout. The cement grout will consist of a mixture of Type 11 Portland cement or equivalent with 3 pounds <br />of powdered nonbeneficiated bentonite and 7 gallons of water per 94 -pound sack of cement; grout <br />materials will be weighed or metered. Grouting procedures differ for boreholes created by different <br />drilling techniques. <br />8.8.5 Overdrilling of the wells may be performed to remove casing and well construction materials from <br />the borehole prior to grouting for abandonment. A hollow -stem auger will be used to drill out existing 2 - <br />inch and 4 -inch diameter casing. The size of the augers (ID) will be at least 2 inches larger in diameter <br />than the ID of the casing. The full depth of the wells will be drilled out. After all casing has been <br />removed, the augers will be rotated at the bottom of the borehole to remove all well construction debris <br />to create a satisfactory seal between the new grout and the borehole wall. Grout will then be placed in the <br />borehole (through the augers) using a tremie pipe. <br />field QAPP.DOC 8-7 May 2000 <br />