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t Seneca II-W Prelim. Adequacy - 11 - March 5, 1985 Backfilling and Grading - Rule 4.14 1. The applicant completed projections of overburden bulking, in order to project post-mining topography within the mined area. The projections included within the original application were completed prior to submittal of the original application in 1982. Subsequently, in connection with operations at the existing Seneca II mine, the applicant has completed observations of reclaimed land. These aerophotogrammetric observations have determined that the actual bulking factor slightly exceeded the original projection (19.8q in the operator's terminology, versus 15.3Y projection). The Division reformatted the applicant's analytical projections in a format more familiar to the Division. The applicant projects an average averburden swell factor (loose swollen overburden volume divided by bank overburden volume) of 1.32. Further, the applicant projects a bulking factor (swollen backfilled volume divided by excavated pit volime) of .91. This suggests an average post-mining topographic deflation of 4.6 feet. Adjusted for the possible discrepancy in observed versus original projected bulding discussed above, the post-mining topography might rise by an additional 1.8 feet, resulting in an average post-mining topographic deflation of 2.8 feet. In either case, the projected post-mining topographic configuration does constitute an acceptable approximate original contour configuration. On Page 12-60 of the amended application, the applicant states: "Peabody coal company has tried to take into account all of the factors that contribute to the development of the final topography in the preparation of the post-mining topography map, Exhibit 13-2. As mining progresses, Peabody will continue to monitor the estimated appearance of the topography with the aid of the computer. The post-mining topography map should be considered a 'best-estimate'. If Peabody finds in its monitoring of swell, grading, and field conditions that the post-mining topography will deviate significantly from that shown on the map, the Division will be notified." The operator has been producing annual post-mining topographic maps of areas graded within the Seneca II mine. This practice has proven sufficient to allow verification of the post-mining topography. The operator should specifically commit to such a monitoring program in this permit application.