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RULE 2 PERMITS <br />Groundwater in the vicinity of the Collom mining areas occurs in perched (unconfined) and confined <br />aquifers of limited areal extent within bedrock of the Williams Fork Formation, the Trout Creek <br />Sandstone (a bedrock aquifer of regional extent), and valley -fill aquifers as described in Section 2.04.7. <br />The Williams Fork Formation aquifers have no beneficial use owing to their limited extent and minimal <br />water production. Based on studies in the Collom Lite area, the saturated water table /piezometric surface <br />is at approximately 7150 feet. This level means that the area in and around the Collom Lite pit outline is <br />under static hydrologic conditions with the water level at approximately 7150 feet. Due to this static <br />condition, Colowyo may dewater this zone to allow mining of the coals below this elevation in the <br />northern cut(s) of the pit. <br />The Trout Creek Sandstone is a sandstone unit underlying most of the permit area and extending across <br />much of northwestern Colorado. It contains water of useable quantity and quality as demonstrated by <br />beneficial -use wells near the permit area. The Trout Creek Sandstone is stratigraphically several hundred <br />feet below the rock units proposed to be mined and is separated from those strata by low - permeability <br />layers within the Williams Fork Formation, particularly the KM bed, a regionally- continuous clay layer <br />(see Section 2.04.5 and 2.04.6). Additionally, the Trout Creek Sandstone was removed by erosion and <br />structural uplifts north and south of the mining area and so is isolated from the regional perspective. <br />Based on this information, mining is anticipated to have no impact on the Trout Creek Sandstone aquifer. <br />Groundwater in the shallow valley -fill aquifers of the drainages crossing the proposed permit <br />modification area is calculated to be marginally impacted by surface mining activities, as described in the <br />Probable Hydrologic Consequences section. <br />There are no registered beneficial -use wells other than monitoring wells in the Colorado Division <br />of Water Resources well database within at least one mile downgradient of the mining area (Map <br />1 I Q. In Section 2.03.4, Identification of Interests, the legal or equitable owners of record of the <br />property to be mined or affected by surface operations and facilities incidental thereto within the <br />Collom permit expansion area are: <br />Colowyo Coal Company L.P. <br />State of Colorado <br />U.S. Bureau of Land Management <br />No other private individual or group owns or controls any land in the Collom permit expansion <br />area. Thus, any well within the limits of the Collom permit expansion is controlled by Colowyo. <br />This includes the Dudek and Sweeney wells. Table 2.04.7 -44 and Map I I C reflect the location <br />and ownership and control status of these wells. <br />2.05.6 (3)(b)(i & ii) Hydrologic Controls <br />Surface water and groundwater drainage from the mining area will be controlled as described in Section <br />2.05.3(4), Section 4.05 and Exhibit 7, Item 23 of this application. Surface water flow will be diverted <br />around the mining operations where practical. Stormwater that enters the mining operations and water <br />that occurs on the mining operations will be allowed to evaporate or infiltrate. <br />2.05.6 (3)(b)(iii) Probable Hydrologic Consequences <br />Collom — Rule 2, Page 132 Revision Date: 9/28/11 <br />Revision No.: PR -03 <br />