Leer South is currently mining the Lower Kittanning seam and the Clarion seam.

The Lower Kittanning seam has been heavily mined to the east and south of current mining in the Kitt mine. The Leer South Lower Kittanning reserve is situated from Mansfield, West Virginia, in the south and extends north to Rosemont, West Virginia. The reserve extends from US Route 119 on the east side to Glade Run on the west side of the reserve. The reserve is approximately 9.5 miles in length (northwest to southeast) and approximately 5.9 miles wide, (northeast to southwest).

The Lower Kittanning seam consists primarily of a dual-bench horizon (tagged as 4600) with a thin boney coal or carbonaceous shale parting between the two benches, (typically less than 1 foot in thickness). An overlying Rider seam (tagged as 4650) is present primarily within the southern portion of the mine plan that can add an additional 2.7 feet of coal to the Lower Kittanning seam. Drill holes show the seam thickness within the reserve boundary ranging from 0.0 to 6.6 feet, (10.9 feet including the rider). The Lower Kittanning seam thins to less than 3.0 feet to the west of the Leer South Lower Kittanning mine plan.

The coal produced at Leer South is typically High Volatile (>31% volatile matter) bituminous coal. Due to the historical value of the Lower Kittanning and Clarion seams as high-volatile bituminous coals, both seams have been extensively mined in the region. Multiple coal bench ........

Leer South consists of the newly commenced longwall Leer South operation in the Lower Kittanning seam, existing Sentinel underground mine in the Clarion seam.

The Leer South mine is active with five continuous mining sections and one longwall section currently operating in the Lower Kittanning Seam and four continuous miner units operating in the Clarion Seam. Continuous Miner operations at Leer South by Arch and its predecessor have been ongoing for many years. Longwall Mining has been ongoing for a number of years at Arch’s nearby Leer Mining Complex which operates in the Lower Kittanning Seam, with longwall mining commencing at Leer South in 2021. The mine plan and productivity expectations reflect historical performance and efforts have been made to adjust the plan to reflect future conditions. MM&A is confident that the mine plan is reasonably representative to provide an accurate estimation of coal reserves. Mine development and operation have not been optimized within the TRS.

Longwall production is scheduled for approximately 343 to 363 days each year, which represents production on seven days per week with allowances for holidays and longwall moves. On each day, the continuous mining sections and longwall produce coal on two shifts with an idle maintenance shift. The sections are configured as regular sections with one continuous miner available for production on each section. During mains development, two production units are brought together t ........

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