Tunnel Ridge, LLC, an indirect wholly-owned subsidiary of Alliance Resource Partners L.P., owns and operates the Tunnel Ridge mine.
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Summary:
The Tunnel Ridge resource block is located in the Appalachian Plateau province in northern West Virginia and southwestern Pennsylvania. This area is characterized by generally flat lying strata. The primary economic coal-bearing strata in northern West Virginia and southwestern Pennsylvania is comprised of the Monongahela Formation, including the Pittsburgh No. 8 seam. Structurally, the seam is gently folded with a series of synclines and anticlines crossing the eastern portion of the reserve that trends in a northeast-southwest direction.
The Pittsburgh No. 8 seam varies in thickness throughout the resource area. The Pittsburgh No. 8 seam is broken into a main bench, a variably thick parting and a rider coal of inferior quality. The main bench averages about 5.0 feet thick, the claystone parting varies from about zero to 1.6 feet thick. The upper bench, or rider, is anywhere from zero to over two feet thick and is typically high ash, high sulfur, lower quality coal. Depending on its thickness and the overall seam thickness, the rider is either left for roof coal or mined with the rest of the seam. The immediate roof within the TRM reserve block is generally a dark gray shale or claystone, overlain by a shaley limestone that has thin shale partings. Though it’s uncommon in the TRM reserve, a thin, discontinuous sandstone can be found in the main roof. The floor varies between a thin, shaley limestone to a gray-green claystone that transitions to a sandy shale.
The TRM extracts coal from the Pittsburgh No. 8 seam. The seam is mainly mined in northern West Virginia and southwestern Pennsylvania. The depth of cover depends on if the seam lies under a hill or valley. This results in a depth of cover that ranges from about 300 feet to over 950 feet. The area is bounded to the west, southwest, and south by previous mining. Coal-bearing strata dip toward the southeast at less than one percent grade.
The Pittsburgh No. 8 seam varies in thickness over the reserve area and averages about 7.2 feet thick, including the parting and upper bench. Coal thickness averages about 6.4 feet (including the rider).
On a 1.50 float, dry basis the Pittsburgh No. 8 seam quality averages about 8.16% ash, 3.35% sulfur, and 13,672 btu/lb.
The mineral deposit type mined at the TRM property is bituminous coal. The primary coal-bearing strata is of Carboniferous age, in the Pennsylvanian system. Coal thickness (including the rider) varies slightly throughout the area, ranging from about 3 feet to over 7 feet, though both of these thickness extremes are anomalous.
The geologic model developed to explore the reserve is a bedded sedimentary deposit model. This is generally described as a continuous, non-complex, typical cyclothem sequence that follows a bedded sedimentary sequence. The geology continues to be verified by an extensive drilling program.