Laserfiche WebLink
(iv) The geology of the strata down to and including either the stratum immediateh <br />• below any coal seam to be mined or any aquifer below the lowest coal seam to be mined which may be adversely <br />affected by mining, whichever is deeper, shall be described for those areas to be affected by surface operations or <br />facilities only in those cases where the strata will be removed or is aheady exposed down to the level of the coal seam <br />to be mined, including the following data resulting from an analysis of test borings, core samples or outcrop samples <br />(A) The location of the subsurface water, if encountered, and the location of <br />where subsurface water will be exposed at the face -up area <br />(B) The logs of drill holes, test borings, or other sampling methods as approved <br />by the Division showing the lithologic characteristics of the strata to be affected; <br />(C) The physical properties of the strata immediately above and below the coal <br />seam affected, including texture, and other information sufficient to determine compatibility and clay content: <br />(D) The chemical analyses of the stratum immediately above and below the coal <br />seam to be muted, or any other stratum to be affected, to identify at a minunum, those horizons which contain acid - <br />forming, toxic - forming, or alkalinity - producing materials; <br />(v) The near surface geology of those surface operations and facilities not underlaid by <br />the coal seam to be extracted shall be described, including the following data resulting from analyses of test borings, <br />core samplings or outcrop samples: <br />(A) A description of near- surface strata beneath the disturbed area; <br />(B) The lithologic characteristics of the strata to be affected, including phvsical <br />and chemical properties identifying, at a minimum, texture; and analyses to identity those horizons which contain <br />(b) Att applicant may request the Division waive in whole or in part the requirements of <br />2.04.6(3)(a)(iii) and (iv). The waiver may be granted only if the Division makes a written determination that the <br />collection and analysis of such data is unnecessary because other equivalent information is available to the Division <br />in a satisfactory form. <br />RESPONSE <br />The coal to be mined by the planned underground operations is located at the southeasternmost tip of the Yampa <br />Coal Field of the Green River Region. The Yampa Coal Field is a synclinal extension of the Washakie -Sand Wash <br />Structural Basin situated in northwestern Colorado and south - central Wyoming. The main axis of the basin is <br />highly modified by numerous smaller anticlines, synclines, and faults. <br />The boundary of the Yampa Coal Field is defined to the southwest by the Axial Basin Anticline and is defined on <br />the east by the Park Range Uplift. This structural setting is outlined in Figure I, Geologic Structure Setting. <br />The permit area is within Twentymile Park, a structural and topographic basin located immediately north of the <br />reclaimed Colorado Yampa Coal Company's surface mine in Routt County. The basin is underlain by a large, high <br />quality coal reserve, which is mineable in many areas, by underground methods. The surface geology and <br />prominent structural features are illustrated in Map 5, Surface Geology. <br />. Strata in Twentymile Park has undergone a long history of structural deformation which formed large folds and <br />faults. Three large, north - trending asymmetrical folds are the most prominent structural features <br />NPR Z 4 2„90 <br />Permit Renewal No. 3 2.04 -13 4/1/99 <br />