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e <br />• • iiiiiiiiiiiiiiuiii <br />999 <br />STATE OF COLORADO <br />DIVISION OF MINERALS AND GEOLOGY <br />DepartmeN of Natural Resources <br />131 J Sherman 51., Roam 215 <br />Denver. Colorarlo 80203 <br />Phone: (303) 866-356; <br />FAk. 1303) 832-8106 <br />I~~~~ <br />DEPARTMENT OF <br />NATURAL <br />RESOURCES <br />Roy Romer <br />Governor <br />dames S Lochhead <br />Executive Direcbr <br />Michael B. Long <br />Division DveUOr <br />RE: "Review of xis ' g Compaction Data and Testing <br />Frequency for the Existing Refuse Pile, Southfield Mine - <br />Florence, Colorado" by TerraMatrix, Inc. <br />(Permit No: C-81-014) <br />DATE: February 20, 1997 <br />TO: Susan Burgmaier ~~ <br />FROM: Jim Pendleton <br />In accordance with your request I have completed a review of the above <br />referenced report prepared for the Southfield Mine by TerraMatrix, Inc., a <br />geotechnical consultant. The Division recently directed the mine to address the <br />possibly substandard compaction results submitted for the coal refuse pile at <br />the Southfield Mine. In preparing my review I have also revisited a similar <br />reanalysis of the Southfield Mine coal refuse pile prepared in 1992 by ACZ, Inc., <br />a former geotechnical consultant to the operator. <br />The Situation at the Southfield Mine Coal Refuse Pile <br />The permit, as amended in 1992, specifies that coal refuse will be placed and <br />compacted in two foot lifts. A thin lift of fine coal refuse was to be placed and <br />then covered with coarse refuse to a combined thickness of two feet. The <br />combined material was then to be compacted to 90% relative density. <br />TerraMatrix reports; "However, based on TerraMatrix's observations actual <br />placement practices have been slightly different. Fines are generally being <br />placed in one-foot lifts followed by a two to four foot lift of coarse refuse. The <br />fine lifts were not compacted. However, the coarse lifts were compacted by a <br />dozer with a pull behind sheeps-foot compactor. Additional compaction was <br />provided from truck traffic." <br />