2009-08-04_GENERAL DOCUMENTS - M1977004

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?? HOM?E'% STAKE ? Pitch Reclamation Project 28 July 2009 M _ ?gr,r, - ODIA Alan D. Cox Project Manager RECEIVED Colorado Department of Natural Resources Division of Reclamation, Mining and Safety 1313 Sherman Street Room 215 Denver, CO. 80203 Attn: Bob Oswald Re: Pitch Mine Reclamation Project, Saguache County Permit #77-004HR Response to Questions regarding 2008 Reclamation Report Dear Bob: AUG 0 4 7009 V" Division of Reclamation, Mining and Safety I apologize for not getting a response back to you sooner on the questions you posed in your May 25, 2009 letter regarding the 2008 Annual Reclamation Report. However, I wanted to assure that our geotechnical engineering consultant provided us an update on his perspective regarding the history, observations and present state with regard to the small South Pit slump feature prior to responding. The slump feature in the East wall of the South Pit referenced in your letter appears to be a slump that occurred during mining operations, that was reactivated by relatively high precipitation over the past five years. The slump is expected to slow to equilibrium and cease displacement. The slump first reappeared in 2004, and was inspected in 2005 when 13 survey monitoring points were installed to monitor the slump. The slump had a maximum displacement during the 2007 - 2008 monitoring period of 1.95 ft. The slump has occurred in shallow surficial, soil-like materials. This is evidenced by the rotational nature of the failure with material removed from the upper parts of the slump, a curvilinear failure surface, and heave at the toe. There is no evidence to suggest that this slump is related to bedrock geology or mining activity. Slope instability related to bedrock displacement has a strong signature at the site in that obsequent faulting is ubiquitously present at bedrock-founded slope displacements. The area between the crest of the East Wall of the North Pit and the headscarp above the East Wall of the North Pit is an example of this sort of displacement. Faulting at the slump at the East Wall of the South Pit is clearly rotational. The slump appears to be a reactivated feature that was present prior to the 1996 re-grading of the south pit. This is evident by the lack of sufficient material at the toe to account for the material removed, suggesting the toe material was removed during the 1996 pit re-grade. A bench was also constructed across the slide, at that time, which subsequently provided catchment for snow. The bench surface had dropped about 1.5 ft at the margins of the feature in 2005 due to slumping, which was impeding drainage along the bench and trapping water within the slump footprint. The bench has since been re-graded to drain. P.O. Box 98 / Highway 605, Grants, NM 87020 Tele: (505) 287-4456 FAX: (505) 287-9289