Laserfiche WebLink
Further, the applicant projected a bulking factor (swollen backfilled volume divided by <br />excavated pit volume) of 0.91. Considering the average mined depth and extracted seam <br />thickness, this suggests an average post -mining topographic deflation of 4.6 feet. <br />Adjusted for the possible 4.5 percent discrepancy in observed versus original projected <br />bulking discussed above, the post -mining topography might rise by an additional 1.8 feet, <br />resulting in an average post -mining topographic deflation of 2.8 feet. In either case, the <br />projected post -mining topographic configuration is considered by the Division to <br />constitute an acceptable approximate original contour configuration. <br />In the first permit term, the Division approved a reclamation plan allowing a delay in <br />contemporaneous reclamation under Rule 4.14.1(1)(c). The approval was granted due to <br />the nature of the operation plan, which involved concurrent mining of two separate mining <br />areas (north and south) with a single dragline, in the original permit area. Pit development <br />in both the north and south blocks began with an initial box cut. Development progressed <br />from each box cut in opposite directions at different times during the operations plan. The <br />sequence of pit development did not allow for backfilling and grading to be completed <br />within 180 days of coal removal. At the point of maximum disturbance, there were <br />projected to be two open pits within each mining block. <br />Pursuant to Rule 4.14.1(1)(c), the Division approved a variance from the requirement that <br />rough backfilling and grading be conducted within 180 days following coal removal. This <br />variance applied to the entire original permit area. In addition, a variance from the <br />requirement that there be no more than 4 spoil ridges behind the pit currently being work <br />was approved for a 25.5 -acre area of the north block and a 41.8 -acre area of the south <br />block, within the original permit area. Rough backfilling and grading had been completed <br />throughout the original permit area as of October 2004, with the exception of a 300 -foot <br />segment of the Wadge "ridgeline pit" along the eastern ridgeline, at the extreme southern <br />end of the original permit area. Most of this pit is within the south extension area, and it <br />was subject to a separate variance approval and backfilling deadline, addressed below. <br />SP amended and clarified requests for a variance in contemporaneous reclamation under <br />4.14.1(1)(c), applicable to specified areas of the A Pit within the original permit area, and <br />portions of the Wadge South Pits and Wolf Creek/Sage Creek Pits within the South <br />Extension Area. As previously noted, rough backfilling and grading had been completed <br />as of October 2004 throughout the original permit area, with the exception of a 300 -foot <br />segment of the Wadge "ridgeline pit" at the extreme south end of the original permit area. <br />In accordance with variance approvals granted under PR -3 and subsequent TR -46, the <br />backfilling deadline for the "ridgeline pit" was set at December 31, 2004. <br />In the PR -4 application, the applicant proposed extensive modification of backfilling and <br />grading schedules. The modified schedule included an amended request for a variance <br />from the 180 -day backfilling and grading requirement of 4.14.1(1)(c). The variance <br />request applied to the 1600' Wadge "ridgeline pit" within the extreme southern portion <br />of the original permit area and northern portion of the south extension area. In addition, <br />the variance request applied to extensive segments of the Wadge final pits and associated <br />spoils extending through much of the length of the south extension area. The highwall <br />29 <br />