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• power centers in the mine to 950/480VAC for the electrical equipment.
<br />Water used for dust suppression and motor cooling in the mine is
<br />supplied via a 4-6 inch diameter HDPE pipe. Well(s) will supply the
<br />water. The well(s) will be installed in or near Hay Gulch at the south end
<br />of the project area.
<br />Ground water is generally absent and therefore spore water pressure
<br />does not contribute to instability of the roof, floor or pillars. In general,
<br />working conditions in the mine are good.
<br />STRUCTURAL CONSIDERATIONS OF THE MINE LAYOUT
<br />King II workings are confined to the upper Menefee (A) coal seam of the
<br />Menefee formation (Mesa Verde Group). The seam varies from about six
<br />to ten feet in thickness. The equipment used in the mine and the mining
<br />method itself is tailored to this seam's structural contours. The seam
<br />dips at a 2-3% grade to the Southwest. The strike of the seam is S70°E.
<br />For specific details of the local geology see Section 2.04.6.
<br />For practical purposes the upper Menefee seam may be considered flat or
<br />tabular with no rolling of seam. Consequently, the layout of the mine
<br />workings is not dependent upon the steepness of the seam as it is upon
<br />the boundary lines of the coal leases. The panels or mining sections are
<br />laid out as shown on Map King II-005 to maximize the recovery of the
<br />• lease coal. Most of the underground openings or entries aze driven along
<br />some given angle to the true dip to take advantage of the property
<br />boundaries. This angle cannot be correlated to the cleat of the coal. The
<br />tight cleat allows the mine workings to be oriented without rib spalling
<br />problems arising. In addition, the lack of ground water seepage allows
<br />the workings to be laid out without regazd to drainage slopes.
<br />The main structural consideration of the mine layout is the width of the
<br />panels (number of multiple entries) and the width of the entries. A panel
<br />width of 250 to 400 feet with five to seven entries has proved satisfactory
<br />for development and pillaz extraction. This width allows for room
<br />development upon retreat from the panel during pillar extraction.
<br />Stresses due to overburden thickness aze minimal compared to deeper
<br />operating coal mines. Maximum over-burden cover does not exceed 350
<br />feet at any point, and the stress field seems to act in a vertical direction.
<br />No ground forces other than vertical have been observed by inspection
<br />during mining operations. The shallow overburden cover would
<br />accommodate an increase in the panel width or the number of multiple
<br />entries without undue stress problems. No major faults or slip planes
<br />cross the mine workings allowing for an even greater degree of optional
<br />orientation of the workings. The widths of the openings are limited to
<br />twenty feet by MSHA for control of the immediate roof (the thickness of
<br />the roof to the top of the resin bolting horizon).
<br />.,~,,.~ ~,,,,,.,,,.,.~,.4„~,.,d„w,,,,, .~,,.~ ~ ,,,,,.~,,,, ~~ ~~a,~,,,,,.~,,,,,,.,,,,,,,,,,,,,,,,,,,,,,,,,,,~~~„
<br />National King Coal, LLC King II Mine
<br />Section 2.05.3
<br />Page 2 May, 2006
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