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(b) If the operator so elects, the drill hole may be sealed by the placement of a neat <br />cement grout column from a point not less than 50 feet below that contact. Following the setting of the neat <br />cement grout plug, a minimum 5 foot column of Portland cement concrete should be installed above the neat <br />cement grout plug. The remainder of the drill hole can be backfilled as described in Section 5.41(3) of the <br />regulations. <br />(5) Permanent abandonment of any drill hole which penetrates unsaturated unconsolidated <br />materials and continues deeper than 10 feet into bedrock, but does not encounter an aquifer: <br />(a) A non-slip hole plug should be placed at a point 5 feet below the upper surface of <br />the bedrock or 10 feet below the original land surface or the collar of the hole, whichever is the lower <br />elevation. A minimum 5 foot column of Portland cement concrete should be placed above the non-slip plug. <br />The top of the Portland cement concrete column should be a minimum of 2 feet below either the original <br />land surface, or the collar of the hole, whichever is the lower elevation. The remainder of the drill hole can <br />be backfilled as described in Section 5.41(3) of the regulations. <br />M:',min'shar TROSPECrDH Abandonment Suggest.doc