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<br />Phvsical grope-ties Overburden - The overburden material whicin ~s <br />~ - - <br />removed as a part of the mining operation, consists mainly of <br />shales, claystones, siltstones, and sandstones. Generally, the <br />shales and claystones will have a relatively high =rodibility and <br />compaction factor, while sandstones and siltstones will have low <br />erodibility factors and low to moderate compaction. Because of the <br />extremely lenticular nature of the strata in the permit area and <br />the variations in the mining techniques {dragline, truck/shovel}, <br />it was difficult to determine an actual value for.the swell of the <br />overburden; therefore, the overall swell of the ove=burden material <br />was estimated to be approximately twenty (20) percent. Data <br />collected during the previous five years- of operation has shown <br />that the swell factor has continued to increase for the mine- <br />to-date as the total amount of overburden moved by dragline <br />increases. Calculations for verification of swell factors have <br />been presented in the Colowyo Annual Report each year since 1983. <br />Chemical Analyses Overburden - Chemical analyses of overburden <br />stratum in the area to be mined are set forth in Exhibit 6, <br />Geological information. Examination of the data- indicates that <br />sampling did not show any of the stratum to contain any potential <br />acid-forming, toxic-forming, or alkalinity-producing material. The <br />- ongoing overburden sampling program at Colowyo has indicated those <br />earlier results are correct. With the exception of Sodium <br />Absorption Ratio, there is little evidence of any chemical <br />constituents reaching suspect levels for toxicity. Analyses of <br />Overburden Chemistry is also present in Annual Reports since 1983. <br />;• <br />(.' <br />2.04.6-9 <br /> <br />