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RULE 2 PERMITS <br /> Physical Properties Overburden - The overburden material which is removed as a part of the <br /> mining operation, consists mainly of shales, claystones, siltstones, and sandstones. Generally,the <br /> shales and claystones will have a relatively high erodibility and compaction factor, while <br /> sandstones and siltstones will have low erodibility factors and low to moderate compaction. <br /> Because of the extremely lenticular nature of the strata in the permit area and the variations in the <br /> mining techniques (dragline, truck/shovel), it was difficult to determine an actual value for the <br /> swell of the overburden; therefore, the overall swell of the overburden material was estimated to <br /> be approximately twenty (20) percent. Data collected during the previous five years of operation <br /> has shown that the swell factor has continued to increase for the mine to date as the total amount <br /> of overburden moved by dragline increases. <br /> Chemical Analyses Overburden-Chemical analyses of overburden stratum in the area to be mined <br /> are set forth in Exhibit 6, Geological Information. Examination of the data indicates that sampling <br /> did not show any of the stratum to contain any potential acid-forming,toxic-forming,or alkalinity- <br /> producing material. The ongoing overburden sampling program at Colowyo has indicated those <br /> earlier results are correct. With the exception of Sodium Absorption Ratio, there is little evidence <br /> of any chemical constituents reaching suspect levels for toxicity. <br /> 2.04.7 Hydrology Information <br /> Groundwater <br /> Occurrence of Groundwater <br /> General Area <br /> Colowyo Coal Company's general area of operation is defined by the area bounded by Goodspring <br /> and Wilson Creeks, both of which are tributaries to the Yampa River. The mine permit area and <br /> its relationship to Goodspring and Wilson Creeks are shown on Map 32. Colowyo Coal <br /> Company's, mining operations are in an area of limited hydrology. Precipitation averages 21.5 <br /> inches for the drainages in the "general area" and runoff is limited. Flows in Wilson, Taylor and <br /> Goodspring Creeks are mostly from snowmelt or thunderstorm events. Groundwater resources on <br /> and adjacent to the mine property are also limited. Base flows observed in Goodspring and Wilson <br /> Creeks are mostly groundwater discharged from the thin and limited alluvial/colluvial aquifers that <br /> can be found in the valleys of both creeks. There are no known places of groundwater discharge <br /> from bedrock units to Goodspring, Taylor, or Wilson Creeks from the sandstones between the <br /> coals to be mined. <br /> Rocks on the property are part of the Mesa Verde Group. These rock units are almost entirely <br /> interbeds of sandstones and shales. The uppermost geologic unit in the permit area is the Williams <br /> Fork Formation. The coals to be mined on the property are part of the Fairfield Group,the principle <br /> coal-bearing zone in the area. The sandstones are predominately fine to medium-grained, poorly <br /> sorted and calcareous. In the upper part of the formation they are generally channel sandstones and <br /> exhibit unilateral and vertical continuity. In the lower part of the formation the sandstones are more <br /> continuous than in the upper part. The thickness of the Williams Fork Formation, in the general <br /> cued, is estimated to be about 1600 feet. <br /> Rule 2 Permits 2.04-11 Revision Date: 12/20/19 <br /> Revision No.: TR-135 <br />