Air emissions associated with mining and preparation processes can include dust, emissions from combustion of fuels including vehicle exhaust, and release of naturally occurring gases from the geologic strata during the mining process.
Potential dust sources include vehicle traffic on unpaved mine roads, dumping and loading activities, material crushing, storage, and — at certain sites — blasting.
A variety of methods are used to prevent or limit the generation of fugitive and non-fugitive dust emissions. The primary means is to limit those activities that create the potential for generating airborne dust. These may include strategically positioning equipment and routing vehicle traffic patterns for shortened haul ways as well as surfacing long-term roads with stone.
A Perfect Compliance Rate
While operations are underway, specific engineering controls are designed into the process equipment for the sole purpose of minimizing the generation of airborne particulates. Examples of these engineering controls include enclosures on coal and refuse conveyance devices, water sprays at material transfer points, the application of dust suppressants on road surfaces and coal storage piles, and the use of baghouse filter systems to capture particulates during material transfers of bulk loads of fine-grained process materials, to mention only a few. These engineering controls are designed and built into the permitted and approved designs of each of our operations.
The teams at each operation understand and maintain compliance with the requirements of air quality permits and perform regular self-inspections to monitor for visible emissions and conduct performance tests on air quality control devices in order to ensure proper operation. Our fully compliant systems operations and their controls are inspected by state regulators on a regular basis.
Interaction with communities near or adjacent to our facilities led two Arch operations to deploy new initiatives in 2019 to control fugitive emissions from coal stockpiles. During high-wind events, excess coal dust can become airborne. To prevent the release of particulates, and to preserve valuable product, these mines — the Viper mine in Illinois and the West Elk mine in Colorado — developed efficient methods to apply a surface crusting agent to coal piles, using a combination of water cannons and dozer-mounted applicators, in order to solidify the surface of the pile. These crusting agents are applied in lieu of traditional water applications, which tend to have limited utility once the water evaporates. The crusting agents remain in place for as long as the pile remains undisturbed.
Our subsidiaries held a total of nine air permits in 2019, and had a perfect compliance rate while operating around-the-clock and year-round at most of their operations.
By the nature of coal mining and handling operations, most Arch subsidiary operations are regulated and permitted on their emissions of only one of the six so-called “criteria pollutants,” as defined under the USEPA’s (EPA) Clean Air Act (CAA). The one criteria pollutant regulated at all of Arch’s subsidiary operations is referred to as particulate matter, or PM. Particulate matter is essentially coal and rock dust generated by the coal extraction, handling, loading and transportation processes. The other criteria pollutants, including sulfur dioxide (SOx), nitrogen dioxide (NOx), ozone, lead and carbon monoxide (CO), are not considered to be sufficiently material to exceed what are referred to as “major source thresholds” and, therefore, Arch’s subsidiary operations are not regulated for these pollutants by state air programs. The one exception to this is the Black Thunder mine, where the permit also contains emissions limits for SOx, NOx and CO for the hot water generators, emergency generators and the propane-fueled heaters that support the mine’s facilities. These pollutants, while included in the mine permit, are considered to be de minimis in terms of total emissions for Arch Resources overall.
Arch is targeting a reduction in particulate matter emissions at its subsidiary operations of 5 percent in 2021 versus 2019 levels, and a reduction in particulate matter emissions of 10 percent in 2025 versus 2019 levels. Even though SOx, NOx and CO emissions are generally not regulated at Arch’s subsidiary operations, Arch is targeting the same reduction levels — on the same timeline — for these pollutants.
The USEPA addresses particulate matter air pollution from coal mining and handling operation under the CAA regulation of 40 CFR Subpart Y. This regulation assesses particulate matter emissions based on emissions factors published in an EPA reference called AP-42 (Fifth Edition Compilation of Air Pollutant Emissions Factors) established through laboratory studies and modeling and over a long history of industry operations. AP-42 defines an emission factor as “a representative value that attempts to relate the quantity of a pollutant released to the atmosphere with an activity associated with the release of that pollutant.”
Arch operations are permitted to operate under state regulatory programs so long as they meet specific operating limits for air pollution controls and for coal production and throughput volumes and rates that maintain the generation of particulate matter from the operation to levels below major source thresholds.
The West Elk mine in Colorado is currently working with regulators to establish a permit to operate relative to measured emissions of volatile organic compounds, which is another regulated air pollutant. The mine is working with state regulators to establish the correct operating and monitoring parameters pursuant to a construction and operating permit.
Arch is targeting a reduction in particulate matter emissions from point sources at its subsidiary operations of 5 percent in 2022 versus 2019 levels; a reduction in particulate matter emissions of 10 percent in 2025 versus 2019 levels; and a reduction of 20 percent in 2030 versus 2019 levels. Even though SOx, NOx and CO emissions are generally not regulated under permit at Arch’s subsidiary operations, Arch is targeting the same reduction levels — on the same timeline — for these pollutants.