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1111111111111111111 Doc Date:12/1 . <br />navised March, 1992 <br />.~ WEST PIT EXCESS SPOIL FILL <br />• sr~ ~ <br />The following information is submitted to the Division in <br />order to meet the requirements regarding permanent excess spoil <br />disposal structures in Rules 2.05.3(6)(b), (c) and 4.09 Disposal of <br />Excess Spoil. <br />BACKGROUND <br />On March 1, 1991, CTL/Thompson, Inc. completed the report <br />"Geotechnical Investigation, West Pit Excess Spoil Disposal Site, <br />Colowyo Coal Mine, Moffat County, Colorado". The report provides <br />a geotechnical evaluation of the West Pit Fill area and a stability <br />analysis of Colowyo's proposed design for the fill. The proposed <br />design for the fill utilized by CTL/Thompson for their analysis was <br />a fill similar in construction to the Streeter Fill that is <br />designed and constructed under the alternative design standards set <br />forth in Rule 4.09.1(3). The results of the site investigation, <br />stability calculations and knowledge of the highly successful <br />performance of the Streeter Fill lead CTL/Thompson to a number of <br />findings and recommendations for construction of the West Pit Fill. <br />A design and construction plan for this fill which followed <br />• closely the design and construction of the Streeter Fill was <br />subsequently submitted to the Division on May 10, 1991. <br />MLRD later reviewed Colowyo's proposal during the preliminary <br />adequacy review process. <br />This review resulted in a determination that although MLRD <br />essentially believed the west Pit Fill could be constructed <br />appropriately under Rule 4.09.1(3) as designed, OSMRE would require <br />the fill be constructed under the requirements of Rule 4.09.2 <br />Valley Fill. OSMRE rational was that the specific design <br />requirements of Rule 4.09.2 Valley Fills, have precedence over Rule <br />4.09.1(3) General Requirements. <br />On November 19, 1991, Colowyo met jointly with representatives <br />of CMLRD and OSMRE to discuss the permitting of the two excess <br />spoil fills; West Pit and Section 16. The meeting (see attached <br />memo from OSMRE) led to a discussion of the ability of the excess <br />spoil fill designs to meet a number of the specific requirements of <br />Rule 4.09.2 Valley Fills. <br />Colowyo agreed that the design and stability analysis would be <br />supplemented so as to demonstrate compliance with Rule 4.09.2(3) <br />(a,b,c,d). CTL/Thompson completed a review of this Rule in their <br />correspondence dated December 16, 1991 attached herein. <br />• <br />I a-1 <br />