1993-06-08_GENERAL DOCUMENTS - C1981041

• Permit No: C1981041
• IBM Index Class Name: General Documents
• Doc Date: 6/8/1993
• Doc Name: Proposed Decision & Findings of Compliance For RN2
• Permit Index Doc Type: FINDINGS
• Media Type: D
• Archive: No

The Roadside and Cameo operation centers on the mining of the Cameo coal seams
found in the Mount Garfield Formation of the Mesaverde Formation of
sandstones , coal and shales . The Mount Garfield Formation is an example of
the transitory nature of many oceanic transgressions and regressions from the
Cretaceous geologic period.
Geology
The Mount Garfield Formation ranges in thickness from 472 to 536 feet in the
permit area and consists of three coal zones intertonguing three prominent
sandstone members . Moving from the top to the base , the formational sequence
is as follows : the Carbonera coal seam, (stratigraphic marker of the start of
the Mount Garfield sequence) , a 64-foot sandstone/shale sequence, the Cameo
coal seam, 9 to 12 feet thick, Rollins sandstone member, about 114 feet thick,
another shale/sandstone sequence, followed by the cliff-forming Palisade
sandstone which is 139 feet thick. Beneath the Palisade sandstone member,
named for the town nearby, is the Palisade coal seam and then the Sego
sandstone which forms the base of the Mount Garfield Formation . The
stratigraphic column can be found in Exhibits 14, 24 and 40 of the permit
application.
The Cameo coal seam is the zone of interest at the Roadside and Cameo Mines.
Of the three coal seams present in the Bookcliffs Mount Garfield Formation,
only the "B" and "C" Cameo seams are recognized as economically recoverable .
The Cameo "B" seam is presently being mined at the Roadside Mine on the east
side of the Colorado River. The Cameo Mine , located on the west side of the
river , has been inactive since 1982 . The Cameo "B" seam in the permit area
varies in thickness from a minimum of four feet to a maximum of eleven feet,
with an average minable thickness of six feet. The coal has been classified
as bituminous , with a low sulfur and high ash content.
Further information on the geology of the permit area can be found in Sections
2 .04. 5 and 2 .04.6 of Volumes I and V and Exhibits 13, 14, 15, 16, 24, 39 and
40.
Ground Water Hydrology
The water table in the Roadside southern permit area (where mining is proposed
during the next five-year permit term) is controlled by a combination of local
precipitation, topography, stratigraphy and geologic structure. The water
table is discontinuous due to the nature of the rock strata in the upper
portion of the Mesaverde Formation . Localized perched aquifers are found in
the overburden which measures between 0 to 1900 feet. Ground water moves
slowly through and between these perched aquifers via the network of
interconnected sandstone lenses .
The strata in the Roadside Mine area east of the Colorado River Valley dip NE
above the river, while the strata on the western side adjacent to the Cameo
operation dip NE below the river. This causes the strata on the east side to
discharge water into the Colorado River, while strata on the west are
recharged . Furthermore, the entire sequence of Mesaverde that overlies the
Cameo coal zone, behaves as a single hydraulic unit.
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