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measures the total amount of gas consumed in all combined burners for all shafts, but does not <br />record the amount burned for each point. MCC reported in their 2011 Greenhouse Gas report <br />submitted to EPA that they burned a total of 6,882,298 scf of methane (the only tested gas in the <br />samples) in these burners. According to the May 2012 Draft Environmental Impact Statement <br />concerning the new Federal Coal Lease Modifications COC -1362 & COC -67232 for activities at <br />the West Elk Mine, although this gas had not been measured, the EPA estimated that the site <br />burned 170 mmscf of methane in their burners in 2006. Applying the AP -42 Table 1.4-1 NOx and <br />CO emission factors for natural gas burners (100 lbs/mmscf and 84 lbs/mmscf respectively), the <br />EPA listed gas use of 170 mmscf would require an APEN submission, as NOx and CO emissions <br />would equal approximately 8.5 and 7.1 tons per year respectively. As the estimation <br />methodology used by the EPA is not explained in the corresponding EPA report, this unmeasured <br />gas usage does not allow the inspector to confirm the accuracy of their estimation based on the <br />information provided. Alternately, MCC's reported gas usage of 6,882,298 scf of methane in <br />2011 allows the inspector to estimate that the combustion emissions from this activity are below <br />APEN reporting thresholds (less than 0.5 tons NOx and CO). No additional APEN submissions <br />are required for this activity at this time. <br />-Rock Dust Silo: It was observed during the inspection that the West Elk mine utilizes an <br />aboveground storage silo for rock dust. This silo is filled pneumatically by truck, and emissions of <br />the finely ground limestone are controlled by a pulse jet baghouse (See Picture #3). At the time <br />of the inspection, the silo was being loaded, and the baghouse appeared to be unable to control <br />emissions as designed. Emissions from the baghouse varied between 15-25% opacity, with <br />higher bursts of opacity during pulse jet cleaning. It was noted that the silo was being loaded at <br />15 psi, and the driver believed that there was no psi restriction on loading. The visible emissions <br />observed were either a result of a lack of maintenance being performed on the baghouse, or the <br />unit was being loaded at too high of a pressure. In either case, MCC was asked to address the <br />issue. MCC reported that the emissions observed during the inspection were the result of an <br />incorrectly installed access door gasket, which was replaced immediately following the inspection. <br />They reported that there have been no visible emissions observed from the point since the <br />replacement. Furthermore, in a letter response received by the Division on January 11, 2013, the <br />source indicated that they perform weekly inspections of the baghouse, and emissions have not <br />been observed coming from the baghouse vents. Based on the amount of rock dust located <br />around the base of the silo and spread along the wall next to the baghouse, it seems likely that <br />emissions from this point persisted without response for an extended period of time (See Picture <br />#4). <br />The source was also asked to address the issue relating to the recommended loading pressure of <br />the rock dust silo, as the unit was being loaded at 15 psi during the inspection with visible <br />emissions. Based on the information provided, it appears that the emissions were due to a <br />damaged door gasket. However, in the 1/11/2013 response, the source stated that "In summary, <br />the opacity observed from the faulty door gasket was not at all caused by the trucks `loading at <br />too high a pressure', as the system is open to the atmosphere and is not impacted by pressure <br />from the trucks." This statement is incorrect in that the loading pressure is a direct measure of <br />the amount of force being exerted through the delivery system, including in the baghouse/bags, <br />and a level of loading pressure above the recommended standard can result in damage to the <br />filter system and/or the silo. The source was requested to re-evaluate the loading procedure for <br />the unit and ensure that appropriate psi is utilized during loading. <br />Furthermore, as underground coal mines of this size typically use thousands of tons per year of <br />rock dust, MCC should have submitted an APEN requesting Division review of this point. It was <br />noted in the Division's Permit Tracking System (PTS) that MCC discussed the issue of the rock <br />dust silo requiring an APEN during a conversation on 11/30/2010 (see Picture #5). The source <br />contended in the response received 1/11/2013 that the baghouse system on the rock dust silo is <br />intended to capture product during loading, and should not be considered a control device. <br />According to Mr. Chip Hancock, Construction Permit Engineer Supervisor, this interpretation is <br />not consistent with the Division's policy for these units. As was observed during the inspection, <br />2012 Air Pollution Inspection <br />0510015-INSP-2012.docx Page 5 of 30 <br />