2020-06-04_PERMIT FILE - C1981008 (39)

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r1 LJ • The cross section extension and the new cross section H-H' are based on coal exploration holes drilled by Western Fuels-Colorado during 1993. Figure 2.04.6-1 was prepared using information obtained by geologists, hydrologists, and soil scientists during the baseline studies conducted during 1986 and 1987. Stratigraphic correlation of individual driller's logs in Maps 2.04.6-2 through 2.04.6-5 proved to be difficult, and at times, confusing because of the wide variation in driller's terminology. Only the principle stratigraphic units (i.e., coal seams, sandstone, shale, etc.) were correlated in these cross sections. The principal coal seam being mined is the #2 or lower Dakota coal seam. One localized area of upper Dakota coal (#1 seam), which includes Drill Hole Location 871 E, may be mined in this permit term. These seams lie within the "middle" Dakota lithologic unit described by Young (1973), and are characterized by carbonaceous shale and impure coal with lessor amounts of interbedded sandstone and siltstone. Basically, these coals are high BTU, low sulfur bituminous coals that show good lateral continuity. Each seam shows swell-defined system of vertical to near vertical joints (coal "cleats") at the outcrop. These joints are less evident in core samples indicating a lower porosity than would be expected by outcrop examination. Fractures of this sort are highly anisotropic. The upper Dakota (#1) seam generally ranges from 0.6 to 2.1 feet (partings omitted) in thickness with an average of about 1.2 feet and lies approximately 99 feet from the base of the Dakota. The lower Dakota (#2) seam generally ranges from 4.2 to 6.9 feet (partings omitted) in thickness with an average of about 5.5 feet and lies approximately 86 feet from the base of the Dakota. There is approximately 7.5 feet of interburden separating these seams within the New Horizon 2 permit area. A 0.4 foot laterally discontinuous "rider" coal seam is found about 7.2 feet above the upper Dakota coal seam in some parts of the permit area. Two additional coal seams, the Nucla (#3) seam and an unnamed seam, are present in the New Horizon 2 study area. The Nucla seam typically ranges from 1.5 to 3.6 feet (partings omitted) in thickness with an average of about 2.5 feet and lies approximately 56 feet from the base of the Dakota. The laterally discontinuous unnamed coal seam generally ranges from 0.5 to 1.6 feet in thickness with an average of about 1.0 feet and lies approximately 24 feet from the base of the Dakota. Sandstone and sandy shale are the predominant lithologies in overburden material within the New Horizon 2 study area. The sandstones are generally fine to medium grained, of low porosity, well cemented, lenticular, discordant, and crossbedded. Most sandstones on outcrop show a well-defined system of iron stained joints and fractures. Continuous horizontal gypsum lenses REVISED August 2006 2.04.6-9