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STATE OF COLORADO <br />DIVISION OF MINERALS AND GEOLOGY <br />Department of Nalu ral Resources <br />1313 Sherman St., Room 215 <br />Dem~er, Colorado 80203 <br />Phone: (3071 866-3567 <br />FAX: (703) 832-8106 <br />Date: January 31, 1995 <br />To: Christine Johnston <br />From: Harry Ranney <br />Re: West Elk Gob Pile Analysis <br />~~ <br />DEPARTMENT OF <br />NATURAL <br />RESOURCES <br />Roy Romer <br />Governor <br />lames S. Lochhead <br />E>,ecotive Director <br />Michael B. long <br />Division Direc~or <br />I Have reviewed the relative compaction test results from the lower <br />gob pile of the West Elk Mine dated 12/27/94. The column labeled <br />Proctor Density PCF is the maximum dry density (MDD), in pounds per <br />cubic foot, determined from a series of tests (Proctor] run on a <br />typical sample of material from the gob pile. According to this <br />report, the MDD is 68 pcf when the sample was compacted at the <br />optimum moisture content of 17$. Generally speaking, any <br />Compaction done on material that deviates ±5~ from the optimum <br />moisture content will not be able to pass the standards set by our <br />rules. However, the results from this report indicate that <br />material that is 15$ drier than the optimum moisture content has <br />not only passed the required standards, but exceeds the maximum dry <br />density by 21$. This report leads one to believe that the <br />composition of the original gob sample that was tested to determine <br />the maximum dry density standard is no longer a representative <br />sample. I recommend that Mountain Coal Company perform new Proctor <br />tests in accordance with ASHTO 99-74 standards on all their gob <br />piles to determine what the MDD is for the material now being <br />placed on the piles. Please have them send us the results of these <br />tests with the associated compaction curves. <br />