2012-02-03_REVISION - M1978315 (6)

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MIR all North West Colorado Consultants, Inc, r _ -- vestMO Geotechnical / Environmental Engineering • Materials Testing Subject: Geologic Hazard Evaluation and Slope Stability Analyses, Red Rock Pit, County Road 53, Routt County, Colorado. Gentlemen: December 21, 2011 Peabody Sage Creek Mining, LLC. Jay James P.O. Box 250 36600 County Road #27 Hayden, CO 81639 Job Number: 11 -9090 As requested, NWCC, Inc. (NWCC) has completed a Geologic Hazard Evaluation and Slope Stability Analyses for the proposed Red Rock Pit to be developed at the former pit location situated west of County Road 53 in Routt County, Colorado. Purpose and Scope of Work: The scope of this investigation included site visits, laboratory testing of samples obtained from the site, a review of available literature and the preparation of this report outlining our observations and conclusions concerning potential geologic hazards associated with the site. Proposed Construction: NWCC understands the project will consist of a development of a rock quarry along the west side of County Road 53 north and south of the existing Red Rock Pit previously developed and used by the Routt County Road and Bridge Department. Based on our review of provided site grading plans, quarry development will generally be approximately 3,000 feet in length, ranging from 100 to 400 feet in width. Proposed cut slopes will range from 50 to 200 feet in total height (as measured from top of cut to toe of slope) and constructed to a 1(Horizontal) to 1 (Vertical) slope configuration. Field Investigation /Site Conditions: Site visits were conducted on November 29, 2011 and December 12, 2011 to observe the proposed pit and identify potential geologic hazards within and adjacent to areas of disturbance. Site observations included visual observations of the existing natural slopes, as well as the cut slopes from previous mining operations and the construction of County Road #53. The natural slopes were generally observed to range from approximately 1 1/2 (H) : 1 (V) to 2 (H) :1 (V) configurations. The existing cut slopes were constructed from 1(H) : 1 (V) or steeper configurations. The existing cut slopes generally had from 1 to 3 feet of overburden soil/weathered bedrock overlying the sandstone bedrock. Weathered shale - claystone materials were observed over the sandstone bedrock materials in the northwest portion of the site. The overburden soils and weathered shale - claystone materials were approximately 6 feet in thickness in this (970) 879 -7888 • Fax (970) 879 -7891 2580 Copper Ridge Drive • Steamboat Springs, CO 80487