2010-12-17_REVISION - C1981019 (129)

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• Partings greater than 0.25 feet thick will be sampled as a separate interval. The maximum parting thickness that would be included in the composite is dependent upon various situations. Generally any parting over 2 feet would be considered interburden. Determination of the maximum parting thickness will be determined case by case. Rock Partin <0.25 feet Include in coal interval >0.25 feet Separate sample interval Gradational coal contacts and difficult determinations of the top and bottom of the seam may constitute the need for an additional sample. Significant boney horizons in the seam also should be selectively sampled. When in doubt it is best to sample. Logs may later help determine the need of the increment for testing. Roof and floor samples will be collected at designated sites. Consult the sampling plan to determine if roof and floor samples are to be collected Coal core will be brought back on a daily basis from the field and stored at the Lower Administration building to prevent loss and reactivity to heat. Coal core will is be dispatched to the laboratory upon the end of each drilling period and delivered to the lab that evening or early next morning to prevent heat exposure. Consistency in Data Reporting To maintain data consistency amongst the several field geologists that work on the project, a simplified lithology code system has been adopted. The code system is almost identical to that previously used at the Colowyo Mine and used previously by most geologists on the project. A single page "Core Description Key" was prepared that lists all the lithology and soil codes, lithological qualifiers, hardness codes, and geotechnical descriptions for use in the field. New geologists will have some overlap with other project geologists to promote consistency regarding lithologic descriptions. In addition, oversight by the geotechnical consultant has proven invaluable regarding consistency of the geotechnical and lithological data collected. Lithology data will also be reviewed for consistency and accuracy with the aid of geophysical logs. Coal seams, major sandstone units, and laterally persistent carbonaceous clay -rich mudstone units are currently being considered for subsequent modeling and are therefore important to clearly differentiate. • NAPROJECMACTIVE PROJECTS \I 159520037 RinTinlo Co11oinPnh\1).fi P—m Tut T;tbins MapPDFs \Exhibits \Exhibit 6 hetn 7 - G-logy P—F— ibility R,1 td\Appu diccsWppdix F- P.11— s\2004G.I.pc Pro—h cis_rwicnLdoc Page 3 of 6 1/16/2009 lk