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C-1981-019 PR-03 <br />Eng/Geotech PAR <br />24-Feb-2011 <br />Page 2 of 2 <br />One access road is proposed to provide access to the Little Collum Pond. The road will be <br />constructed along the alignment of an existing two-track road. Details are illustrated on Exhibit <br />25, Item 1, Figure 1 and described on Rule 2, Page 94 and Rule 4, Page 2. 1 have no comments <br />regarding the design and construction of this road. <br />Rule 4.09 Disposal of Excess Spoil <br />A large (250,000,000 cy) temporary (-20-year) excess spoil pile is proposed. A Geotechnical <br />Study for the Collom Temporary Spoil Fill, conducted by Shannon & Wilson (S&W), is <br />provided in Exhibit 23, Item 1. The fill qualified as a "Valley Fill". Map 29C shows plan and <br />cross-sectional views of the proposed pile. General information regarding the pile is provided in <br />Rule 2, pp. 98-99; Rule 4, pp. 22-23 describes the proposed construction and inspection plans. <br />The S&W Study is thorough in its analysis of site conditions, material properties, and <br />analysis of stability. The study is dated July 2009, and was developed using the obsolete <br />plan for mining of Little Colluin X Pit. Please update the S&W Study to address any <br />revised ground or spoil pile configurations that may arise as a result of the anticipated <br />changes in mine plan for X Pit. <br />2. Exhibit 7 Item 26, Fig. 2 illustrates a proposed "Collum Sump". It appears that this sump <br />pond may be located near the toe of the proposed excess spoil pile. Please ensure that <br />S&W are informed of the presence of the sump, and its position in the mining sequence, <br />so that any potential effects it may have on the pile itself or the foundation materials may <br />be considered in the stability evaluation. <br />3. The 2nd paragraph on S&W Page 11 states that, "Prior to publication of our report, <br />Colowyo informed us the spoil slope will be decreased from the 3H: IV slop used in our <br />models to a slope of 3.5H: IV..." On Map 29C, Section A-A' does show a slope of <br />3AH: 1 V on the southern slope of the pile, but the northern (and most critical, for <br />stability) slope continues to be labeled as 311:1 V. <br />a. Please provide clarification of the actual slope proposed for construction of the <br />northern face of the temporary excess spoil pile. <br />b. The paragraph quoted in part, above, ends with an incomplete sentence. Please <br />review and revise, as appropriate. <br />4. The S&W Study (Section 8.0, page 12) provides specific conclusions and <br />recommendations regarding construction of the excess spoil pile. Section 9.0 addresses <br />S&W's Monitoring recommendations. Language found in Rule 4 (pp. 22-23) does not <br />clearly commit Colowyo to following the S&W conclusions and recommendations. <br />Please revise Rule 4 Section 4.09 to clearly communicate Colowyo's intent. <br />This concludes my review of the Collorn applications. Please do not hesitate to contact me if <br />you have any additional questions. <br />cc: Sandy Brown, DRMS <br />