2011-08-29_REVISION - M1986015 (11)

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• • May 18, 2011 File No. 111057 - 000 Transit Mix of Pueblo P.O. Box 1030 Colorado Springs, CO 80901 Attention: Mr. Bud Herskind Subject: Slope Stability for Pueblo East, Phase 7 Mining Pueblo, Colorado Mr. Herskind: SECTION T APPENDIX A SLOPE STABILITY STUDY A DIVISION OF BRIERLEY ASSOCIATES, LLC Engineering Solutions from the Ground Down Lyman Henn, a division of Brierley Associates, LLC (Lyman Henn) is pleased to present Transit Mix of Pueblo (Transit Mix) with the results of a slope stability evaluation of the excavation slopes at the proposed Pueblo East, Phase 7 Mining Gravel Pit, an alluvial deposit located adjacent to the Arkansas River. Figure 1 shows the project location. The site is proposed as a construction materials aggregate mine and will be Phase 7 of the East mine pit. Lyman Henn performed this evaluation to determine a recommended setback between the proposed gravel mine excavation slopes/highwalls and adjacent structures. The slope stability analyses were performed using: 1) existing information from the site vicinity provided by Tuttle & Associates; 2) material strengths for the natural soil materials in the proposed cut slopes based on exploratory borings, laboratory testing, and DRMS typical soil strength parameters; 3) observed groundwater conditions; and 4) Lyman Henn's understanding of the proposed mining plan. SITE DESCRIPTION The proposed mining plan consists of one irregular shaped mining area. The site is located within parts of the NW 'A of Section 35 and the NE' /a Section 35, all in Township 20 South, Range 64 west, 6th meridian, Pueblo County, Colorado. The northern boundary of the Phase 7 mining area is adjacent to industrial businesses; the eastern edge abuts residential housing and trailers, and the western boundary flanks adjacent quarry areas. The Arkansas River lies to the south of the permit boundary area. * * See list of References at the end of this letter.