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<br />-2- <br />Rule 2.05.3(2) Operations Description <br /> <br />The application narrative (page 4-26) and maps (4.2-4, 4.2-5 and 4.2-7) depict <br />several projected escapeways and raises daylighting at the outcrop high on the <br />Grand Hogback's northeast-facing slope. The application will require <br />amendment to adequately address the projected impact of these daylighting <br />facilities. Particular concern should be focused upon the slope stability <br />implications for construction of these portals. The Division's examination of <br />existing aerial photography determined the existence of several apparently <br />unstable areas in close proximity to the projected facility locations. <br />Rule 2.05.3(6)(a) Use of Explosives <br />The application presents a brief statement of intended compliance with our <br />regulation's blasting requirements. The application must be amended to <br />conform with the specific requirements of Rule 2.05.3(6)(a)(i) through (vii). <br />Rule 2.05.3(8) Coal Processing and Non-Coal Processing Waste <br />The application proposes the construction of a 300 foot high coal processing <br />waste slurry embankment. The application contains a geotechnical <br />investigation of the proposed site and a structural design analysis. For a <br />structure of this type and magnitude, the application must contain thorough <br />and detailed reports of geotechnical site investigation, stability analysis <br />and engineered structural design, in compliance with requirements of Rule <br />2.05.3(8), 4.09, 4.10 and 4.11. Several deficiencies exist within the <br />application presentation, which will require amendment. <br />(1) The "seismic exposure" portion of the application has been referred to <br />the Colorado Geologic Survey for review. If their review identifies any <br />inadequacies, appropriate supplement comments will be forwarded to the <br />applicant. <br />(2) The application states, on page 16 of appendix 3.3-3a; "...the course <br />refuse would be made up of shales and sandstones that will vary in strength <br />and durability from hard, durable rock to softer, slaking rock, which would <br />likely break down under construction equipment. The course waste material <br />that is unsuitable for construction of the embankment should be placed within <br />the impoundment area and additional borrow material substituted for embankment <br />fill." The applicant should elaborate on the techniques to be used to test <br />and segregate the run-of-the-plant course refuse material. <br />(3) The application observes, on page 21 and 22 of appendix 3.3-3a, that <br />collapsible soils have been determined to exist within the impoundment site. <br />Further, the application observes that pre-wetting or soil removal and <br />recompaction may be necessary to remedy this construction problem. The <br />applicant should elaborate upon detection and treatment techniques to be used, <br />in order to preclude development of hydrocampactible soil problems. <br />