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5.1 Model Geometry <br />• <br /> <br />Stability of the coal waste bank was evaluated for the maximum section, located through the <br />approximate central portion of the waste bank. The approximate cross-section location is <br />presented on Drawing 1 (Appendix A). The maximum section represents the critical stability <br />condition due to the maximum height of waste. Geometry of the waste stockpile for these <br />analyses is as follows: <br />.- A slope of 2.5H:1V (horizontal:vertical) for the first 50 vertical feet of the stockpile <br />(beginning at the toe). This represents the current condition. <br />A 20-foot wide bench at a vertical height of SO feet. <br />An overall slope of 3H:1V above the first 50 vertical feet. The proposed overall 3H:1V <br />slope represents an increase over the currently permitted 5H:1V upper slope. <br />An ultimate height of 300 feet was modeled, as measured from the downgradient toe to <br />the top of the bank. This represents a greater ultimate height than the 240 feet <br />indicated on the CWDA No. 2 design drawings. The greater height was modeled to <br />allow potential for additional waste storage. <br />Geometry of the native ground surface was developed from a topographic survey conducted on <br />the pre-mining ground surface. Geometry of the waste bank used in the stability analyses is <br />presented in Figure 2. <br />Bowie Resources LLC <br />Bowte No. '. Mine <br />Coal Waste Dfsposat Area No 2 <br />rnav a.r~ 1s ..l,t. t,.~~d~ <br />I o.H Mlno W.Mo <br />tl' e~ <br />I SH:IV N~~r~e <br />~~ ,~ <br />N..tiv. <br />.. ~ Yu n.1u .~.. _.___ M .~.~ i.i •n'A <br />Figure 2. Geometry of coal mine waste bank used for stability analyses <br />13u~tlc Nt~' _'IiUS Rce~aluhuu ofCa~l ~tincs 1Vaate titabilily dtx <br />Protect n0~-1_'b-(il'O <br />Page q ot~ 1 <br />