Summary:
The coal deposits in the eastern USA are the oldest and most extensively developed coal deposits in the country. The coal-bearing formations on the properties are Carboniferous in age, being in the Pennsylvanian system, which includes the Monongahela, Conemaugh, Alleghany, and Upper Pottsville groups. These coal-bearing formations contain two-fifths of the nation’s bituminous coal deposits, extend over 900 miles from northern Alabama to Pennsylvania, and are part of what is known as the Appalachian Basin. The Appalachian Basin is more than 250 miles wide and, in some portions, contains over 60 coal seams of varying economic significance. Seams are typically between 1 foot and 6 feet in thickness, with relatively little structural deformation. Coal in the region is classified as high- to lowvolatile bituminous with rank increasing to the east. Coals are typically characterized as low to medium sulfur and high heat content.
Seams in which reserves and/or resources are reported by Corsa include the following (in descending stratigraphic order). Within each seam, there may be multiple benches consisting of riders (overlying the main seam), leaders (underlying the main seam), and splits (where main seam separates into two or more benches).
Corsa reserves and resources are found primarily within four Pennsylvanian-age coal-bearing formations: Pittsburgh, Glenshaw, Allegheny, and Pottsville.
Monongahela Group.
The Monongahela Group is named after the Monongahela River in West Virginia and southwestern Pennsylvania. The formations in this group are the Pittsburgh and Uniontown, of which the majority of coal-bearing unit strata are located in the Pittsburgh formation. The formations are comprised of sequences of limestone, calcareous mudstone, shale, siltstone, and coal. The only significant sandstone occurrences lie directly above the Pittsburgh coal seam. The formations extend from the top of the Conemaugh Group, or base of the Pittsburgh coal seam, upward to the top of the Waynesburg coal seam and include the Sewickley, Redstone, and Pittsburgh coal seams, which are of economic importance on the properties.
Conemaugh Group.
The Conemaugh Group is named after Conemaugh River in western Pennsylvania and includes the Glenshaw and Casselman formations. These formations are comprised of sequences of limestone, mudstone, shale, siltstone, sandstone, and coal. The formations extend form the Mahoning Limestone near the base of the Glenshaw Formation to the Pittsburgh Limestone, occurring at the top of the Casselman Formation and base of the Monongahela Group. The Bakerstown coal seam, which is of economic importance on portions of the properties, lies within the Glenshaw Formation.
Allegheny Group.
The Allegheny Group is named after the Allegheny River in Pennsylvania and contains the majority of economically mineable coal in Pennsylvania. The formations in this group are comprised of sequences of sandstone, siltstone, shale, thin limestone, clay, and coal. The Allegheny Formation includes the following coal seams of economic importance in stratigraphically descending order: Upper Freeport, Lower Freeport, Upper Kittanning, Middle Kittanning, Lower Kittanning, and Brookville.
Pottsville Group.
The Pottsville Group is named after the locality of which it was first described near Pottsville, Pennsylvania and contains major coal-bearing formations from Pennsylvania to Alabama. The Pottsville Group contains the majority of economically mineable coal within the Appalachian Basin outside of Pennsylvania and includes more than 10 formations, depending on the state in which it occurs. The formations are comprised of sequences of sandstone, siltstone, clay, and coal.
Structure.
The counties in which the properties are located are situated along the eastern edge of the Alleghany Plateau, bordering the Alleghany Front, the major southeast facing escarpment of the Alleghany Mountains. Regional structure is typically characterized as gently dipping with a series of northnortheast trending folds (anticlinal and synclinal) including the Youghiogheny, New Lexington/Johnstown, Somerset, Berlin, and Wellersburg synclines and Laurel Hill, Centerville Dome, Boswell Dome, and Negro Mountain anticlines. Within the major structural trends, there are typically minor undulations and local flexures. No major structural faulting or tectonic features are known to occur on the properties.
Geology of the Properties.
The geology of the properties is consistent with regional structural trends. In Maryland, the local Casselman synclinal fold is evident in the Casselman mine. Coal seams of economic importance on the properties typically range from 1 foot to 6 feet in thickness and are primarily low-volatile in rank. There are 11 coal seams on the properties that demonstrate reserve or resource potential including: Sewickley, Redstone, Pittsburgh, Bakerstown, Upper Freeport, Lower Freeport, Upper Kittanning, Middle Kittanning, Lower Kittanning, Brookville, and Mercer.
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.
Coal Seams of Interest.
Surface-mineable Seams.
There are seven primary coal seams (and associated splits) identified on the properties exhibiting surface-mineable potential. Surface-mineable coal seams are contained within the upper and middle portions of the stratigraphic section and include coal seams from the Sewickley through the Lower Kittanning coal seam. There are 11 areas within the properties where coal seams exhibit surfacemineable potential including: Bassett, Berwind Lohr, Bluelick 4, Byers, GAZ, Downey, Hart, Rhoads II, Schrock Run/Schrock Run Extension, Hamer and Shaffer. Hamer and Byers are directly adjacent to each other and are therefore reported together herein as Hamer-Byers.
Underground-mineable Seams.
There are six coal seams identified on the properties exhibiting underground-mineable potential. These coal seams are contained within the middle to lower portions of the stratigraphic section and include the Upper Freeport (E), Lower Freeport (D), Upper Kittanning (C'), Middle Kittanning (C), Lower Kittanning (B), and Brookville (A) coal seams.
Deposit Types.
The coal reserves 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 be locally absent.
Mining Methods
- Highwall
- Contour Strip
- Continuous
- Room-and-pillar
Summary:
Mining Methods.
The resource base for the NAPP Division Properties consists of eight coal seams extending from the Sewickley coal seam at the top of the stratigraphic column down through the Brookville coal seam. The majority of the resource tons occurs in the coal seams from the Upper Freeport to the Lower Kittanning. The topographic location of the many coal seams and the physical characteristics of the coal seams provide abundant opportunities to apply several of the coal mining methods routinely employed in Northern Appalachia.
Coal seams that outcrop along the hillside or that are located near the surface may be considered for surface mining methods including, contour and/or area removal. The surface mining methods allow recovery of resources that lie close to the surface and are not suitable for safe underground mining. Coal seams that are too thin to be underground mined economically can often be recovered successfully with surface mining methods. Contour mines advance along the coal seam outcrops with overburden backstacked in the pit to eliminate the highwall. The proposed mine plan and financial model forecast approximately 2.4 million surface/auger tons; however, only 1.1 million surface/auger-mineable tons were determined to be economical for inclusion as reserves.
Underground reserves are mined using continuous mining room and pillar methods. Production sections are configured as single-unit sections, employing one continuous miner and one or two roof bolters per section; many are configured as continuous haulage units. The basic production design employed at the active mines was applied to projected operations where possible. The mine plan and financial model includes approximately 1.3 million underground tons in 2022, ramping up to approximately 1.9 million tons per year in 2028 and up to a maximum of 2.4 million tons in 2040.
Surface Mining Methods.
Schrock Run (including the associated Schrock Run Extension area) are currently the only active surface mining operations on the Property; however, Corsa has numerous idled and planned surface mines within its operational plan.
The proposed surface mines are planned to be operated by a mobile equipment spread built around Hitachi EX3600 or Komatsu PC 2000 shovels as the principal excavators. The surface mine operations are linked in the financial model by the progression of equipment spreads and crews from resource area to resource area. The configuration of this equipment spread, or fleet is projected to be maintained for the future mine projections. Surface-mining activities are projected to occur from 2020 through 2039 at annual production rates up to 306,000 tons. Equipment replacements are scheduled at appropriate times over the period for the equipment.
The Hitachi and Komatsu shovels are supported with a fleet of equipment including:
- Caterpillar 785 Rock Trucks;
- Caterpillar D11 Tractors;
- Caterpillar 16M Road Graders; and
- Other support equipment including backhoes and service trucks.
The mine model generally targeted overburden strip ratio limits of 16 to 20 bcy of overburden per ton.
Underground Mining Methods.
There are currently three active underground mines operated by Corsa: Acosta, Horning and Casselman. The Keyser underground mine is expected to begin production in 2023. Production in Acosta will be expanded to include up to 3 seams, with no more than 2 of the 3 seams being mined simultaneously at any given time; however, market conditions must improve to make the Lower Kittanning seam at Acosta economical to mine.
Projected annual production peaks at approximately 2.4 million clean tons. Mine plans are designed to project operating each resource area to depletion. Crews and equipment are scheduled to move to subsequent resource areas as depletion occurs.
The projected mines are assumed to operate similarly to the active mines, using the same equipment, crews, and methodology. Each mine is scheduled to operate one or two production sections, each configured as a single continuous miner section, most using continuous haulage. In all cases, mines are forecasted to produce coal two shifts each day and reserve the third shift for maintenance, as well as belt and power moves. Production is scheduled for two shifts Monday through Friday each week, and one shift every Saturday.
All of the mines can be accessed by box cut openings or highwall exposed by surface mining operations. Pillar extraction is not assumed for any of the current or future operations since no such plans have been approved by the appropriate regulatory agencies for those operations.
General Mine Plan.
Individual coal mines are projected with one or two production sections. The production sections are configured as single continuous miner sections. Mine ventilation system design includes 2 to 4 intake airways per section. Upon sweeping the production faces, the return air is carried away from the section in the 2 to 3 return entries. Each production section is equipped with one continuous miner. Two roof bolters are provided to install roof support on the section soon after the mine roof is exposed during production. Coal is transported from the face to the section feeder-breaker by means of continuous haulage systems or by as many as three electric shuttle cars. It is then conveyed to the surface through the section belt, followed by the main belt. Two battery-powered scoops are provided for support services on each section.
Mine conveyor belts range in width from 42 inches for section belts to 48 inches within mains and submains. The mine fans are located on the surface and are arranged for blowing or exhausting ventilation.
Production and mine development timing were based upon coal seam characteristics and continuous miner cutting heights of 42 to 60 inches. Mine productivity was projected based on expected geological conditions, coal seam height, and production section configuration. Coal pillar sizes were tested using the Analysis of Retreat Mining Pillar Stability (ARMPS) software program developed by the National Institute for Occupational Safety and Health (NIOSH). Because the mining heights assigned in the model are often greater than coal seam heights, roof or floor material must be mined, and the OSD affects the ultimate clean coal recovery from the coal preparation plant. Underground production is transported by trucks to a Corsa preparation plant for washing. The table below presents the in-seam wash recovery for the in-situ coal and the plant recovery reflecting the impact of OSD, along with a plant efficiency of 95%.