Summary:
The coal reserves reported by Corsa are bituminous coals. The primary coal-bearing formations on the properties are Carboniferous in age, being in the Pennsylvanian system, which includes the Monongahela, Conemaugh, Allegheny, and Pottsville groups. The average mineable seam thickness for coal horizons in these formations ranges from 1 foot to over 6 feet. The coal seams are generally continuous and non-complex but may vary in thickness and may also be locally absent. Seams retain normal stratigraphic sequence throughout the properties and no evidence has been observed that seams have been modified from pre-deformational thicknesses.
Mineralization
Mineable coal seams within the properties are typically low-ash, low to high-sulfur, and high-thermal content bituminous coals. Regionally, the coals are typically low-volatile in rank, with rank increasing from west to east. The maximum seam thickness may reach over 6.0 feet where multiple coal benches occur in proximity to one another; however, the average mineable thickness of the seams in this evaluation generally ranges from 1 foot to 4 feet. Seams are generally continuous but may be locally absent. Secondary discontinuity due to erosional features is present in most areas, resulting in seam outcropping, or visible exposure of the seam at the surface. Other than oxidation of the coal exposed at the surface, erosion of the seams has no significant impact on the mineralized deposits. Mineable seams associated with the properties are generally outcrop-accessible. Coal seams are characterized by both single-bench and multiple-bench coal horizons with parting (non-coal) material varying by seam and area. Seam parting is common within the coal seams on the properties with intra-seam parting material increasing drastically in some areas. Roof strata are typically shale or sandy shale with zones of sandstone roof being common. Floor strata are typically sandstone, shale, sandy shale, fireclay, or in the case of the Upper Kittanning, limestone.
Acosta - Upper Kittanning Seam Reserve
The Upper Kittanning seam at Acosta is not permitted and is classified as an inactive underground mine property. This reserve will be accessed via inter-seam slope from the active mine workings in the Middle Kittanning seam. Acosta’s Upper Kittanning seam reserve has been incorporated with the former Wells Creek property in the south (owned property). It has been projected that this coal is viable for sale on the metallurgical coal market. Underground mine workings exist in the north, west and east side of the reserve area. The average seam thickness of the reserve is 3.3 feet. First mining only is projected for the Upper Kittanning seam since it is underlain by the mineable Middle Kittanning seam at approximately 39 feet.
Acosta - Middle Kittanning Seam
Acosta’s Middle Kittanning seam reserve is a permitted, active underground mine property and encompasses the same property boundary as Acosta’s Upper Kittanning seam. The Middle Kittanning seam lies on average 39 feet below the Upper Kittanning seam, and first mining only is projected. The largest portion of the property is controlled through ownership while the extreme northern portion of the property is leased. Approximately two thirds of the northern portion of the Acosta Middle Kittanning seam is permitted. In the northwestern portion of the property, a small area of highwall mining in the Middle Kittanning seam has occurred. This is the only previous mining in the Middle Kittanning seam within the property.
A face-up area for the underground reserve was completed in the extreme northwestern portion of the property; production began in June 2017. Coal quality characteristics of this coal are sufficient for shipment into the current metallurgical coal market. Overlying underground mine workings in the Upper Kittanning exist in the north, west and east side of the reserve area; in the northern area, the Middle Kittanning permit includes reserves beneath the previously mined Upper Kittanning. Average seam thickness is 3.0 feet.
Acosta – Lower Kittanning Seam Reserve
Acosta’s Lower Kittanning seam property encompasses the same boundary as the Acosta Upper and Middle Kittanning seam. This reserve will be accessed via inter-seam slope from the active mine workings in the Middle Kittanning seam, or alternately via a new box cut. The Lower Kittanning seam lies on average 44 feet below the Middle Kittanning seam, as a result, first mining only is projected. The largest portion of the property is controlled through lease while the extreme southern portion of the property is owned. The Acosta Lower Kittanning seam is not permitted. No previous mining in the Lower Kittanning seam has occurred within the boundary of the property. It has been projected that this coal to likely to be viable for sale on the thermal coal market. Acosta’s Lower Kittanning reserve is classified as an inactive underground mine property. Overlying underground mine workings in the Upper Kittanning exist in the north, west and east side of the reserve area. Mine plans have not been projected underneath these mine works and therefore coal resources have not been included in the tonnage estimate. The average seam thickness is 3.6 feet.