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RULE 2 PERMITS <br />2.05.6 (3)(b)(iii) below), will be due to meteoric water being captured in and evaporated from the mine pit <br />during operations, and meteoric water contacting an increased surface area of soil in the vadose zone and <br />thereby theoretically increasing the mass of dissolved solids entering shallow groundwater. These <br />dissolved solids in shallow groundwater may eventually enter the surface water system, with a theoretical <br />increase in dissolved solids in the surface water. This increase is calculated to be small enough to have no <br />impact on the current or projected surface water uses in the Collom Gulch, Little Collom Gulch, and Jubb <br />Creek drainages. <br />Groundwater <br />Groundwater in the vicinity of the Collom mining areas occurs in perched (unconfined) and confined <br />water bearing zones of limited areal extent within bedrock of the Williams Fork Formation, the Trout <br />Creek Sandstone (a bedrock aquifer of regional extent), and valley -fill aquifers as described in Section <br />2.04.7. The Williams Fork Formation water beaering zones have no beneficial use owing to their limited <br />extent and minimal water production. Based on studies in the Collom Lite area, the saturated water <br />table/piezometric surface is at approximately 7150 feet. This level means that the area in and around the <br />Collom Pit outline is under static hydrologic conditions with the water level at approximately 7150 feet. <br />Due to this static condition, Colowyo may dewater this zone to allow mining of the coals below this <br />elevation in the 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 layer, 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 of <br />Water Resources well database within at least one mile downgradient of the mining area (Map 11 Q. In <br />Section 2.03.4, Identification of Interests, the legal or equitable owners of record of the property to be <br />mined or affected by surface operations and facilities incidental thereto within the Collom permit <br />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 area. <br />Thus, any well within the limits of the Collom permit expansion is controlled by Colowyo. This includes <br />the Dudek and Sweeney wells. Table 2.04.7-44 and Map 11 C reflect the location and ownership and <br />control status of these wells. <br />Collom — Rule 2, Page 109 Revision Date: 11/16/16 <br />Revision No.: MR -166 <br />