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III IIIIIIIIIIIIIIII - °°Xo~t~,2""ZOO,- <br />July 27, 2001 <br />• <br />Lorencito Coal Company, LLC <br />clo Greystone <br />5231 South Quebec <br />Greenwood Village, Colorado 80111 <br />Attention: Mr. Mike Kolin <br />Mr. Jerry Koblitz <br />Subject: Response to CDMG Comments <br />Lorencito Surface Mine, Phase I <br />Las Animas County, Colorado <br />Job No. 32,611 <br />5~G r~Xl~/i3/>" /.~ <br />~~-,~B~JivKm~T <br />L~~1/ <br />We were requested via fax to respond to Items 31, 34, 35, 36 and 37 of the <br />CDMG Adequacy Letter. <br />Item 31a <br />Fills 1, 2 and 3 were not planned in our Phase I scope. Based on the work we <br />have performed to date, we do not anticipate problems at these fill areas. When <br />mining starts, we will have considerably more information on the spoil material, <br />• better access and on-site equipment. These fills generally "fit" within the heights, <br />slopes, and volumes assumed in our detailed stability analysis. Site specific <br />observations and/or minor excavation will be required to provide a "final" report. <br />Item 31 b <br />We do not consider the fills head of hollow. We understand Greystone will <br />revise to valley and/or non-valley fills. <br />Item 34 <br />We believe Greystone will response to the initial request regarding "individual <br />designs". With regard to adjacent blasting, we are working with Greystone to <br />quantify potential accelerations. Our pseudo-static analysis indicates a factor of <br />safety of 1.3 is maintained up to a horizontal acceleration of 0.1258. Our opinion at <br />this time is that blasting does not present a significant stability concern. <br />Item 35 <br />CTL volume estimates were very approximate. Our only concern was <br />regarding drain size if volume exceeded 1 mcy. Since volume did not approach this <br />value, we did not perform more accurate volume estimates. <br />• LORENCITO COAL COMPANY, LLC <br />do GREYSTONE <br />CTLR JOB NO. 32,671 <br />CTL/THOMPSON, INC. <br />CONSULTING ENGINEERS <br />1971 WEST 12TH AVENUE ~ DENVER, COLORADO 8020a ~ (303) 825-07 7 <br />D(o 9~~ <br />