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STATE OF COLORADO <br />DIVISION OF RECLAMATION, MINING AND SAFETY <br />Department of Natural Resources <br />1313 Sherman St., Room 215 <br />Denver, Colorado 80203 D COLORADO <br />DIVI E SION OF <br />Phone: (303) 866-3567 RECLAMATION <br />FAX: (303) 832-8106 MINING <br />INTEROFFICE MEMORANDUM SAFETY <br />Bill Ritter, Jr. <br />Governor <br />Date: 10 March 2010 Harris D. Sherman <br />Executive Director <br />Ronald W. Cattany <br />To: Tom Kaldenbach, Lead Specialist Division Director <br />Natural Resource Trustee <br />From: Marcia L. Talvitie, P.E. G <br />Subject: West Elk Mine - Permit No. C-1980-007 <br />TR-120 - Refuse Pile Expansion East Area <br />Adequacy Review - Engineering and Geotechnical <br />As requested, I have reviewed the application package for TR-120, with an emphasis on the <br />engineering and geotechnical aspects. Overall, the package is very well done and has been <br />organized in a clear and thorough fashion. <br />In an Email to Kathy Welt of MCC on the 24"' of February, I listed some specific questions I <br />had, the answers to which might have had an impact on the overall slope design of the RPE East. <br />MCC provided supplemental information on 9 March 2010, which addressed those initial items. <br />My earlier questions are incorporated here (items 1 thru 3), for the sake of consistency, and <br />followed by the remainder of the adequacy issues. <br />Coal mine waste stored at the proposed RPE East will be a byproduct of MCC's newly approved <br />Coal Preparation Plant (CPP). Because the CPP has not yet been constructed, MCC conducted a <br />series of tests on materials placed previously at the Lower Refuse Pile (LRP), and used the <br />parameters thus obtained in the design of the RPE East. Geotechnical properties of refuse <br />generated by the CPP are predicted to be superior to those of refuse from the LRP. Section 7.2.1 <br />and Appendix C provide a description of geotechnical materials testing to be conducted on refuse <br />from the CPP plant in the early stages of production. These results will be used to verify and/or <br />modify the proposed design of the RPE East facility. The Division finds this approach to be <br />reasonable, given the development sequence of the CPP and RPE East. <br />1. DRMS 24-Feb: Section 2.2.2 (Model Parameters) explains that Standard Penetration <br />Tests (SPTs) were conducted on in-place materials in the LRP. Data from the SPTs were <br />analyzed to establish the range of potential friction angle and undrained shear strength <br />values to be modeled. SPT and laboratory data for the LRP holes do not appear to have <br />been provided with Volume I OC. Please provide: a) a map showing the locations of the <br />LRP borings in plan view; and b) the boring logs, SPT values and laboratory results <br />obtained for the LRP borings. <br />Office of <br />Office of <br />Mined Land Reclamation Denver • Grand Junction • Durango Active and Inactive Mines