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RULE 2 PERMITS <br />Exploration test borings have been conducted within the permit area and have been utilized for the <br />following purposes: <br />Location of Subsurface Water -_Since the holes were generally dry, the primary circulation medium for <br />most exploration bore holes drilled within the mine plan area was either compressed air or drilling mud <br />when fractures were encountered. Several drill holes throughout the area encountered minor amounts of <br />ground water; however, all of the data obtained to date by Colowyo and the USGS have indicated that <br />groundwater occurrences in the are not continuous but rather are a series of perched systems. Information <br />on groundwater occurrence is set forth under Section 2.04.7. <br />Drill Hole Logs - Exhibit 6, Geological Information, contains numerous lithologic logs which show and <br />describe the lithologic characteristics and thickness of each strata and each coal seam. The location of <br />each drill hole presented in Exhibit 6, Geological Information, is shown on the Geology Map (Map 7). <br />Physical Properties Overburden - The overburden material which is removed as a part of the mining <br />operation, consists mainly of shales, claystones, siltstones, and sandstones. Generally, the shales and <br />claystones will have a relatively high erodibility and compaction factor, while sandstones and siltstones <br />will have low erodibility factors and low to moderate compaction. Because of the extremely lenticular <br />nature of the strata in the permit area and the variations in the mining techniques (dragline, truck/shovel), <br />it was difficult to determine an actual value for the swell of the overburden; therefore, the overall swell of <br />the overburden material was estimated to be approximately twenty (20) percent. Data collected during the <br />previous five years of operation has shown that the swell factor has continued to increase for the mine to <br />date as the total amount of overburden moved by dragline increases. Calculations for verification of swell <br />factors have been presented in the Colowyo Annual Report each year since 1983. <br />Chemical Analyses Overburden - Chemical analyses of overburden stratum in the area to be mined are set <br />forth in Exhibit 6, Geological Information. Examination of the data indicates that sampling did not show <br />any of the stratum to contain any potential acid-forming, toxic-forming, or alkalinity-producing material. <br />The ongoing overburden sampling program at Colowyo has indicated those earlier results are correct. <br />With the exception of Sodium Absorption Ratio, there is little evidence of any chemical constituents <br />reaching suspect levels for toxicity. Analyses of Overburden Chemistry is also present in Annual Reports <br />since 1983. <br />Rule 2 Permits 2.04.6-3 Revision Date: 6/23/08 <br />Revision No.: MR-91