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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 />