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decrease in available spoil will manifest itself in Colowyo's inability to meet their approved post-mining topography as shown on Map 19B. Keeping in mind that the Division has already granted Colowyo a variance in AOC for steep slope mining in the South Taylor area, please detail how Colowyo will achieve their currently approved AOC with the spoil deficiency that has been identified. Although Map 19B has not been changed, based on the additional 10 million yards of proposed permanent spoil and the possible deficiency in spoil from the decrease in swell (from 20% to 15%), there will be at least: a pit-wide decrease in elevation of at least 12 feet. Comments Regarding Shannon and Wilson Report 28. In the process of conducting the TR-81 adequacy review, the Division revisited the earlier Shannon and Wilson Study and Addenda Nos. 1 and 2. A discrepancy was noted in the transcription and utilization of data, as follows: Table B-1 in Appendix B presents a "Summary of Laboratory Test Results by Boring". Data in the Direct Shear "Cohesion" and "Friction Angle" columns, for Borings CO-3 and LW-1, appears to have been incorrectly transcribed from Figures B-4 and B-5, the original reports prepared by Knight-Piesold Consulting. Corrected friction angles for CO-3 and LW-1 would be 24 and 33 degrees, respectively. Similarly, the tabulated cohesion values for these two samples should actually have been 370 and 40 psf. The incorrect numbers shown in Table B-1 appear to have been used in the development of the Average Friction Angle and Cohesion values reported in Table C-1 for "Soil", which parameters were in turn used for input into the Slope/W program. Inclusion of these erroneous values may have resulted in Factors of Safety that were inaccurate (too high). Please review the information presented in Appendices B and C of the original Study, and revise as appropriate, including any conclusions or recommendations that may change as a result of the review. (We note that corrected friction angle and cohesion values from Boring CO-3 appear to have been used in the Shannon and Wilson study submitted with TR-81.) 29. The overall footprint of the Excess Spoil fill areas does not appear to have been revised between the July 2006 Study and the first two Addenda. Significant changes are proposed, however, with Addendum No. 3, dated October 21, 2009. The spoil configuration has been revised, and outslopes have been steepened, to allow sizable temporary spoil fills to be placed over the permanent spoil fills. Additional laboratory testing has been performed on spoil and clay soil overburden, and on the Carbonaceous Mudstone (CMS) layer exposed on the floor of the pit. New Figures 1 thru 6 are presented, along with a new Appendix: A. There is potential for future confusion with respect to the new "Addendum" (Addendum No. 3). Addendum No. 1 and Addendum No. 2 consisted of minor modifications to the original Shannon and Wilson Study and updated specific Figures or Tables, while maintaining the original order of the figures. Addendum No. 3 includes a new set of Figures (1 thru 6) that do not correlate with Figures 1 thru 9 of the July 2006 Study. A new "Appendix A" has been provided„ which does not appear to be designed to replace the current Appendix A. If Colowyo wishes to name the October 2009 study "Addendum