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• <br />June 23, 1995 <br />Twentymile Coal Company <br />29515 Routt County Road No. 27 <br />Oak Creek, Colorado 80467 <br />Attention: Mr. Karl Koehler <br />Subject: Processed Material Testing <br />Refuse Disposal Area <br />Twentymile Mine <br />Routt County, Colorado <br />Job No. 22,253 <br />Gentlemen: <br />• III IIIIIIIIIIIIIIII <br />FiECEIVF_D <br />JUL 0 5 ]995 <br />Division or minerals i<, Geology <br />CTVThompson, Inc. prepared a design of the RDA planned at the Twentymile <br />Mine and presented results in a report dated January 17, 1995 Job No. 22,253. The <br />design was based upon waste material parameters developed from preliminary <br />testing and from literature review. The processing plant is now in operation. This <br />letter presents the results of laboratory testing of processed coal mine waste <br />obtained from the plant. The purpose of this testing was to evaluate whether the <br />material being produced is consistent with the design parameters. <br />We obtained representative samples of the processed coal waste on May 18, <br />1995 to perform moisture content, gradation, standard Proctor and direct shear <br />testing. The results of the testing are shown on Figs. 1 through 3 and summarized <br />on Table I. The following paragraphs provide our comments regarding the test <br />results. <br />Gradation <br />Gradation results of the coarse and fine refuse indicate the percent fines is <br />higher than the sample tested for design (Fig. 1). The difference does not reduce <br />the shear strength to below design assumptions. <br />Proctor <br />The results of a standard Proctor test (ASTM D 698) are shown on Fig. 2. The <br />design indicated stability is not sensitive to unit weight. The Proctor value is within <br />the assumed range of values. <br />CTL/THOMPSON, INC. <br />CONSULTING ENGINEERS <br />1971 WEST 12TH AVENUE ~ DENVER. COLORADO 80204 • (303) 825-0777 <br />