2017-10-23_GENERAL DOCUMENTS - C1980007

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Page 4 of 5 ratio percentage by dividing the total percent of VOC by the total percent of methane in each sample. This ratio was then multiplied by 2012 EPA -reported yearly methane emissions from each mine to establish total VOC emissions based on each samples' analysis. This methodology yielded similar total VOC results for the MCC samples taken on the same day (even though they had very different methane concentrations), and similar results for the Oxbow samples (taken on two days separated by six (6) months). Estimated VOC emissions using 2012 CH4 data (in US short tons): Shaded boxes indicate values from samples taken at respective mines *Parenthetical values in top row represent VOC:Methane ratios calculated for each sample **These three mines are in close geographic proximity and are considered `gassy' mines (see map on next page) Below is a graphical illustration of the information included in the previous table, including reference to applicable thresholds: 450 ons VOC 400 350 300 250 200 150 100 s0 0 Oxbow -Elk MCC -West Bowie No. 2 Creek Elk ■ MCC #0851 Sample ■ MCC #0840 Sample a Oxbow 2/20/14 Sample ■ Oxbow 8/11/14 Sample PSD threshold Title V threshold Permit threshold 10 Tons VOC 9 8 7 6 5 4 3 2 1 0 O�0O S a ■ MCC #0851 Sample ■ MCC #0840 Sample Oxbow 2/20/14 Sample ■ Oxbow 8/11/14 Sample Permit threshold APEN threshold Conclusion: Even at extremely low concentrations of VOCs, because of the high volume of gas/methane released, there can be substantial VOC emissions from underground coal mines. Based on the newly acquired Oxbow exhaust gas testing results, and as originally stated in my 2012 inspection reports, it is clear that there are uncontrolled VOC emissions above reporting, construction permitting, and Title V permitting thresholds for several of Colorado's gassy underground coal mines. 4300 Cherry Creek Drive S., Denver, CO 80246-1530 P 303-692-2000 www.colorado.gov/cdphe ,t cr t John W. Hickenlooper, Governor Larry Wolk, MD, MSPH, Executive Director and Chief Medical Officer •, I � 2012 Total CH4 reported to EPA VOC by MCC #0851 Sample (0.007677)* VOC by MCC #0840 Sample (0.007913)* VOC by 2/20/14 Oxbow Sample (0.005216)- .005216 *Oxbow VOC by 8/11/14 Oxbow Sample Oxbow-Elk Creek** 51,574.5 395.9 408.1 269.0 311.9 MCC - West Elk** 40,672.4 312.2 321.8 212.1 246.0 Bowie No. 2** 14,623.5 112.3 115.7 76.3 88.4 McClane Canyon 1,080.9 8.3 8.6 5.6 6.5 Twentymile 755.7 5.8 6.0 3.9 4.6 Blue Mt Energy 341.1 2.6 2.7 1.8 2.1 Sage Creek 0 0 0 0 0 Shaded boxes indicate values from samples taken at respective mines *Parenthetical values in top row represent VOC:Methane ratios calculated for each sample **These three mines are in close geographic proximity and are considered `gassy' mines (see map on next page) Below is a graphical illustration of the information included in the previous table, including reference to applicable thresholds: 450 ons VOC 400 350 300 250 200 150 100 s0 0 Oxbow -Elk MCC -West Bowie No. 2 Creek Elk ■ MCC #0851 Sample ■ MCC #0840 Sample a Oxbow 2/20/14 Sample ■ Oxbow 8/11/14 Sample PSD threshold Title V threshold Permit threshold 10 Tons VOC 9 8 7 6 5 4 3 2 1 0 O�0O S a ■ MCC #0851 Sample ■ MCC #0840 Sample Oxbow 2/20/14 Sample ■ Oxbow 8/11/14 Sample Permit threshold APEN threshold Conclusion: Even at extremely low concentrations of VOCs, because of the high volume of gas/methane released, there can be substantial VOC emissions from underground coal mines. Based on the newly acquired Oxbow exhaust gas testing results, and as originally stated in my 2012 inspection reports, it is clear that there are uncontrolled VOC emissions above reporting, construction permitting, and Title V permitting thresholds for several of Colorado's gassy underground coal mines. 4300 Cherry Creek Drive S., Denver, CO 80246-1530 P 303-692-2000 www.colorado.gov/cdphe ,t cr t John W. Hickenlooper, Governor Larry Wolk, MD, MSPH, Executive Director and Chief Medical Officer •, I �