2012-09-19_REPORT - C1981019 (2)

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West Pit Fill Inspection Certification On September 13, 2012, I inspected the area in which the West Pit Excess Spoil Fill is being constructed. The purpose of this inspection was to observe the surface rock drain that borders the 3H:1V Excess Fill Slope, inspect the areas dumped to final grade below the 7,400 dump elevation, inspect the revegetation on the fill surface, inspect the fill for areas of water seepage or surface drainage, inspect the final grade slopes below the 7,300 elevation of the Excess Fill Slope, and satisfy the requirements of CDRMS Rule 4.09.10 (la) and Rule 4.09.1 (1 b). During the inspection, the face of the regraded fill was observed to be stable and unchanged from prior inspections. All portions of the fill slope were visible. A small flow of about two gallons per minute is evident from the toe of the underdrain. No erosion problems were noted. No other seeps or springs were noted. Since December, 2011, the 102 Dragline has been performing regrading activities near the top of the West Pit Fill to begin to achieve the approved postmining topography. These activities continued during this report period, with approximately 154,000 cubic yards moved during the quarter. The top of the fill has been reduced to below elevation 7430. In addition, I reviewed the monument survey data collected September 4, 2012. These data indicate that the elevations of most of the monuments have not significantly changed (typically less than 0.05 feet of elevation change per calendar quarter). The most change was recorded at the 7050 West monument. This site registered an increase of 0.07 feet. Based on these data, the total displacement of the monument is not of concern with regard to the stability of the dump. There was also no evidence of structural weakness or other hazardous conditions associated with this dump. These monument survey data are available for review upon request at the Colowyo Mine site. I am a Licensed Professional Engineer in the State of Colorado and a representative of Environmental Solutions, Inc, P. O. Box 2996, Cheyenne, Wyoming. Being familiar with the Colowyo operation and the coal program permitting process in Colorado, the construction activities related to the West Pit Excess Spoil Fill are in conformance, to the best of my knowledge and experience, as specified in pages I a -2 through I a -4, Exhibit 19 I b and other applicable requirements of the approved permit documents, a portion of CDRMS Permit C -81 -019. xc: Mr. Kurtis Blunt cf 17.15.1 cf 24.20 (West Pit) • % t PF j F S y s i • V - 32257 s c-" , ........ , „ss, 11 THOMAS C PETERSON P.F. No. 32257 9//4 -(2n1v DAT