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iiiiiiiiiiuiiuiii 999 STATE OF COLORADO DIVISION OF MINERALS AND GEOLOGY Deparlmenl of Natural Resources 1313 Sherman 51., Room 115 Denver, Colorado 80203 Phone: 13031 866 3567 FA%~O031 A32-P106 November 18. 1996 Mr. Jim Stover J.E. Stover and Associates 2768 Compass Drive, Suite 101 Grand ]unction, CO 81506 ~~~ DEPARTMENT OF NATURAL RESOURCES Ruy Romer Governor lames S. Lochhead C.rcwive Dueaor Mii hael B. Long Dimsmn Duecmr RE: "Additional Geotechnical Study, Evaluation of the Stability of Reclaimed slopes, Bowie No. 2 Miue, Bowie, Delta County, Colorado" -Permit No. C-96-083 Dear Mr. Stover: The above-referenced additional geotechnical study has been reviewed by Jim Pendleton, and [he review comments are presented below. The study was prepared by MAXIM Technologies, Inc., a geotechnical subcontractor to Morrison Knudsen, the primary design contractor for Addington Resources. The study was prepared to address adequacy comments included in our review memorandum addressing the original Maxim Technologies Geotechtlical study, dated August 4, 1996. The study was submitted by J.E. Stover & Associates, the permit consultant for the Bowie No. 2 Mine. General Comment The Maxim Technologies additional geotechnical study evaluates one specific aspect of the previous geotechnical adequacy concerns. It addresses the stability of reclaimed bench cuts backfilled with on-site materials, and it provides the results of a one-hole boring program, including laboratory characterization of the soils and bedrock encountered in that additional boring. The study includes analyses of two of the highest cuts proposed a[ the site, those of the stockpile bench and the portal bench. It provides general recommendations for the design of reclamation fills at the Bowie No. 2 Mine, based on these general analyses. It does not, however, provide significant information regarding the reclamation of specific cuts and fill benches at the site. It may also be limited by its analytical assumptions. The Division cannot approve any mine permit until the applicant has demonstrated that the mine site disturbances can be successfully reclaimed. Unravelling, meta-stable backfilled slopes do no[ represent successful reclamation and cannot be judged by the Division as meeting the mandate to return to the mine site to a beneficial use. The initial geotechnical adequacy comments generally expressed concern that insufficient geotechnical information had been provided with the application to demonstrate that the site could be reclaimed in a stable configuration. The original Maxim Technologies study, while it presented wnsiderable viable geotechnical information, did not solve this inadequacy. The supplemental study provides additional useful information; however, it leaves many of the earlier geotechnical concerns unaddressed.