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Section 780.11 (a) Continued <br />• As a component of the operational and reclamation planning and <br />permitting process Kerr developed initial estimates for material swell <br />factor which were then utilized to calculate an overall material balance <br />in conjunction with the life-of-mine mining and reclamation plans. The <br />initial swell factor estimates and resultant material balance <br />calculations were based on extensive testing of the physical properties <br />of overburden materials and subsequent analysis by CTL Thompson, Inc. as <br />outlined in Exhibit 23, Physical Properties of Overburden. <br />Kerr subsequently compared production load counts and surveying and <br />mapping information on a periodic basis for ongoing operations in the <br />72o Pit to verify or adjust, as appropriate, swell factors and material <br />balance calculations. Generally for operations in the 720 Pit area, <br />documented swell factors were consistent with the original projected <br />swell factor of approximately 24 percent (bank to compacted cubic <br />yards). Review of backfill and backsloping volumes and calculation of <br />an operational material balance for the Pit 1 area following completion <br />of final reclamation activities in 1994 resulted in a swell factor of <br />approximately 16 percent. <br />• Attempts to develop an accurate life-of-mine material balance in <br />conjunction with resolution of outstanding AOC issues were hampered by <br />a lack of accurate production volumetrics and survey/mapping information <br />for previous operations in the Marr Pit and early development and <br />backfilling operations in the 720 Pit. Eased on partial reconstruction <br />of historical production information and the best information available <br />on more recent operations, the overall life-of-mine swell for all mined <br />areas appears to fall within the range from 16 to 20 percent, probably <br />tending toward the lower end of this range. From a practical <br />standpoint, some variation between premining and postmining elevations <br />and configuration is anticipated due to natural variations in coal and <br />overburden thickness and reasonable operational scheduling constraints. <br />r ~ <br />L~ <br />780-4 as Revised - 01/30/95 <br />/"(R (3 <br />