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Postmining Topography <br />Since mining operations will be performed with shovel/truck and dozers at New Horizon 2 instead of <br />adragline, the postminingtopographywas estimated based upon a 15 percent swell factor. Experience <br />from 1995 to 1999 has shown that the initial swellis reduced over time with settling which results in <br />a net change of 8% increase in volume. The need for the slot cut along BB Road and 2700 Road will <br />cause the overburden behind this area to be slightly raised, however, the extra height is still within the <br />limits of approximate original contour. <br />The revised post-mining topography map was developed by first mapping all final contours in the <br />existing reclaimed area. As of July 1999, the mine was operating in cuts 39-46. Next a grid file as <br />made of the bottom of coal in the remaining area to be mined using Survcadd software. A final surface <br />was also developed based onpost-mining land uses and minor modifications to the terrain requested <br />by the landowners in order to facilitatethe irrigation of the reclaimed land. Volumes were calculated <br />for all existing topsoil and overburden stockpiles on site. The following equation was then made to <br />balance for the amendment area: <br />(Existing Volume OB/Soil) x swell factor +Topsoil and OB stockpilevolumes -Previous Slot Cut to Fill <br />• =Final Volume of Material <br />The parameters of the equation are given below: <br />F~cisting Volume OB/Soil <br />Existing volume OB/Soil is derived by subtracting the grid of the existing surface from the grid of the <br />bottom of coal and Then subtracting the coal volume. <br />The Survcadd report for this volume is given below: <br />Volume Report 04/01/1999 <br />Comparing GRiD file: C:/wfuels/botomelev.grd <br />and GRiD file: C:/wfuels/exist.grd <br />Grid corner locations: 1111982.96,599043.84 to 1119647.36,602981.92 <br />Grid resolution X: 200, Y: 200 Grid cell size X: 38.32, Y: 19.69 <br />Area in Cut : 6782.34 sq ft, 0.156 acres <br />(REVISED 9P9'J) 2.05.4(2)(c) - 4 <br />