2010-12-17_REVISION - C1981019 (141)

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Mr. Jim Stark September 23, 2005 Page 2 of 6 allow these valley bottoms to support more lush vegetation even where sub-irrigation is not a factor. Based on information from monitoring wells installed in the valley fill and from seeps and springs occurring in the valley fill, groundwater in the valley fill is present under a variety of conditions and interacts with the surface water and bedrock groundwater systems. In the upstream reaches, surface water infiltrates into the valley fill. Some of the valley fill groundwater may recharge the bedrock units while the balance flows in the lower part of the valley fill. In the downstream reaches, the bedrock units appear to discharge to the valley fill, particularly in the northern part of the permit area, and this discharge to the valley fill augments baseflow to the stream channels. The topography of the valley bottoms is simple, with surface water being directed to a single main channel in the valley bottoms. Due to the deep incision of gullies present in many of the valley bottoms, floodplains are generally very narrow (<20 feet) and flooding does not escape the incised feature. With the exception of the terrace that comprises the main floor of each valley bottom (now considered a terrace due to the deeply incised channel), local and regional terrace levels are not evident within or immediately adjacent to the permit area on any available topographic maps. Only one feature observed during the soil survey appears to be an old (Quaternary, but not active for several thousand years) terrace remnant. This feature is located at the Jubb Creek road entrance in the southwest quarter of Section 16, Township 4 North, Range 93 West, and is of undetermined extent. Gravels found in the subsoil offer the primary evidence that this is a terrace remnant. However, changes in the topography are too subtle to provide adequate evidence for precise delineation of the feature. Geologic mapping that includes all or parts of the Collom permit area has been conducted by numerous parties over the past 25 years. The documents listed below were referenced during the present work. While slight differences exist, there is general agreement among the previous studies and between the work conducted by Maxim and the previous studies. • Reheis, M.C., 1981. Geologic Map and Coal Resources of the Easton Gulch Quadrangle, Moffat County, Colorado: U.S. Geological Survey Coal Resources Investigations Map C-87. • Madole, R.F., 1989. Surficia) Geologic Map of the Meeker 30' x 60' Quadrangle, Garfield, Moffat, Rio Blanco, and Routt Counties, Colorado: U.S. Geological Survey Miscellaneous Investigations Series Map I-1823. • Dames and Moore, 1980. Danforth Hills Project Alluvial Valley Floor Preliminary Identification and Evaluation. • Dames and Moore, 1995. Colowyo Alluvial Valley Floor Analysis Report: Report prepared for Colowyo Coal Company, December 5, 1995. • James P. Walsh & Assoc., Inc., 1984. Reconnaissance Alluvial Valley Floor Investigation Danforth Hills Project: Report prepared for Consolidation Coal Company, September 12, 1984. • James P. Walsh & Assoc., Inc., 1984. Reconnaissance Alluvial Valley Floor Investigation - Lower Good Spring and Milk Creeks, Danforth Hills Project: Report prepared for Consolidation Coal Company, December 15, 1984. • --------------------- "Scientists and Engineers Committed to Client Satisfaction"