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The eastern side of the currently mined longwall panels is too thin to mine (consistently less than 8' tall) without <br />using a Coal Prep Plant (CPP), which was recently built and began operation in 2010. When mining from thin <br />areas of the seam where a higher percentage of total product contains rock, this material is redirected to the CPP <br />rather than through the full processing plant and directly to coal storage silos. The CPP (Point 020) is a separate <br />processing plant in an enclosed building and is used to separate rock from coal product. Material enters the CPP <br />and is first crushed and screened similar to the regular ROM processing plant. Water spray/fogging systems <br />control particulate emissions at these points. After the initial crushing and screening operations of the CPP, all <br />remaining processes are `wet' and thus APEN exempt. Screened material is `floated' across a magnetite solution, <br />and coal is skimmed off the surface while the heavier rock sinks. This is possible because the magnetite raises the <br />density of the water solution such that the coal will float. Following initial separation, the coal and refuse go <br />through a series of screens/separators used to wash and recover magnetite for re -use. Very little magnetite is lost <br />in the entire process. The separated coal is sent via conveyor to the appropriate stockpile near the silos (Point <br />014), to later be reclaimed into the product for railcar loadout. Refuse rock material, containing very little coal, is <br />sent via conveyor to the coal refuse pile for burial (Point 015). The coal refuse pile is sequentially reclaimed as <br />the pile is extended from the valley floor. <br />Prior to building their CPP, the facility would truck -haul marginal material to the nearby Bowie prep plant (Point <br />014). Similarly, some material was previously hauled by truck to customers from the ROM stockpile (Point <br />0016). Although still permitted for these activities, MCC has not truck -hauled any coal since September 2010. <br />Also permitted at the facility is an emergency backup generator (Point 02 1) which powers the Shaft #2 fan. This <br />generator was mandated by MSHA to be installed, and will operate the fan to provide adequate ventilation air to <br />miners if there is a loss of power. To prevent the engine from stalling, a small generator is used to power the <br />emergency backup generator fan during startup. Similar small emergency backup generators power emergency <br />elevator hoists to allow miners to exit if there is a loss of power and the main office building's servers. <br />VOC Emissions Discussion: <br />In 2012, the Division became aware that certain coal mine operations may be significant sources of uncontrolled <br />VOC emissions which had been previously unreported. Most of the hydrocarbon gas released during mining is <br />methane (>98%), with small amounts of ethane and longer -carbon chain hydrocarbons also present. Both methane <br />and ethane are exempt from classification as VOCs for APEN-reporting and permitting purposes (Ref: AQCC <br />Regulation 3, Part A, § II.D. Loo). However, due to the extremely large volume of gas released from certain <br />underground coal mining operations, even a small percentage of non-methane/ethane hydrocarbons (NMEHC or <br />VOC) present in the gas stream can result in significant VOC emissions. For example, MCC reported a total of <br />40,672 US tons of methane released during 2012. Even at extremely low concentrations compared to methane <br />(e.g. sample VOC:CH4 ratios of 0.522% - 0.791%), because of such high levels of methane released, the facility <br />has VOC emissions far above APEN and Permitting thresholds. <br />Since 2012, the Division has reviewed extended gas analyses of multiple samples from underground coal mines, <br />including two samples of gas exhausted from the MCC mine (2009 samples). All mines' samples consistently <br />show a low comparative ratio of VOCs to methane. However, all results showed a similar pattern that at high <br />levels of methane released, an underground coal mine will also have uncontrolled actual VOC emissions in excess <br />of APEN and permitting thresholds. In the case of MCC, the primary methane emissions points include the large <br />ventilation shafts. The facility also releases a small percentage of their total methane from the temporary methane <br />drainage well systems positioned at the surface directly above the active longwall panel. <br />The inspector has conducted several rounds of analyses using various extended gas analysis test results and the <br />facility -reported methane emissions (reported to EPA under GHG reporting rule). All analyses determined that the <br />MCC mine emitted VOCs in excess of 200 tons per year. Depending on the data year reviewed (i.e. reported <br />methane emission rate), and the extended gas analysis results applied, MCC's VOC emissions were estimated to <br />AW <br />2015 Inspection ANAT <br />0510015-INSP-2015 Page 4 of 37 <br />