2010-09-17_INSPECTION - C1981019

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August 24, 2010 C-1981-019/Colowyo Coal Mine JRSS -? Section 16 Pit Post-Mining Topography X-Section E Northing Easting GPS Adj Adj Elev Map 19 Diff Date Station 14 4457175.899 259404.952 7,960.4 56 8,016.4 8010 6.4 22-Jul-10 0 16 4457044.060 259318.064 7,983.7 56 8,039.7 8035 4.7 22-Jul-10 518 8 4456878.219 259263.873 7,970.7 56 8,026.7 8020 6.7 22-Jul-10 1089 12 4456750.819 259137.597 7,985.7 56 8,041.7 8035 6.7 22-Jul-10 1678 10 4456649.086 259099.114 7,963.3 56 8,019.3 8015 4.3 22-Jul-10 2034 X-Section F Northing Easting GPS Adj Adj Elev Map 19 Diff Date Station 17 4457275.928 260044.362 7,753.3 56 7,809.3 7810 -0.7 22-Jul-10 0 20 4457242.911 260150.966 7,736.0 56 7,792.0 7785 7.0 22-Jul-10 366 19 4457228.910 260282.028 7,698.7 56 7,754.7 7750 4.7 22-Jul-10 798 GPS = Elevation measured by Trimble GeoXT Adj = Elevation adjustment based on true elevation at GT-10 Adj Elev = Adjusted elevation Map 19 = Post-mining topography elevation as shown on Map 19 Diff = Adj Elev-Map 19 Date = Date data was collected Station = Station for attached cross-sections The total area requested for Phase I Bond Release for the Section 16 Pit was 78.87 acres. Based on the data points taken and the cross-sections (attached) created by the Division from that data, it appears as though Colowyo has achieved their approved post-mining topography for the Phase I areas of the Section 16 Pit. There were no signs of settling or cracking in the backfill in any of the Phase I Bond Release portions of the East Pit, West Pit or Section 16 Pit. All of the areas were stable and no erosional problems were noted. - Based on the above elevation charts it can be seen that there are several points that are measured at 7-15 feet higher than the approved post-mining topography, as shown on Map 19. The Division has evaluated the post- mining topography in these areas specifically and as a whole as it relates to the drainage pattern and the permanent, post-mining drainage channels. The Division believes that, given the overall topographic relief of the Phase I Bond Release areas of the East Pit, West Pit and Section 16 Pit and given the fact that the post-mining drainage channels have been located and constructed as designed and are functioning properly (see "Hydrologic Balance" below), these variations are acceptable. - During the inspection the Division noted a small slump on the northeast edge of reclamation block EP024, right along the border with reclamation block EP021 (See Inspection Map 13 for the slump's location). Based on the vegetation on and around this slump, it appears to be older. The slump area is small, being approximately 160' long x 60 feet wide x five feet deep (with an area of approximately 0.20 acres). The Division is not going to exclude this area from the Phase III Bond Release but Colowyo will need to continue monitoring the location. If the slump moves or continues to move it could cause problems for the Gulch A Ditch, the East Side Collector Ditch and/or the Gulch A Pond. There were also two low spots in the reclamation in reclamation block EP017. These low spots resembled small stock tanks but they are not. There is vegetation growing in them but it is Number of Partial Inspection this Fiscal Year: 3 Number of Complete Inspections this Fiscal Year: 0 Page 5 of 39