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. North Fork Win Seismic Network - Third Quarter 2009 <br />SUMMARY <br />During the three-month period, 1 July to 30 September 2009, 21 mining-related seismic events <br />were relocated with approximate Richter local magnitudes NO 1.7 and larger using data <br />recorded on the North Fork Valley Seismic Network. Most of the seismic events were located in <br />two areas: the Elk Creek Mine and the Bowie Mine. Eight events occurred at the Bowie No. 2 <br />Mine during this quarter. The largest events to occur during this quarter were two ML 2.6 events, <br />one which was located within the Bowie Mine area and occurred on 19 September. The peak <br />horizontal ground acceleration (PGA) for this event was 0.003 g recorded at MFB g at a distance <br />of 2.3 km (1.43 mi). No mining-related events were located in the vicinity of Bruce Park Dam <br />and the adjacent slump area. The highest PGA recorded during the third quarter of 2009 was <br />0.06 g at station FGH in the Bowie Mine area, which resulted from a ML 1.7 event at a distance <br />of about 0.83 km (0.52 mi). <br />INTRODUCTION <br />This report has been prepared in partial fulfillment of a commitment by Bowie Resources LLC <br />(BRL) to monitor seismicity (including the microseismic activity near the longwall mining <br />activity) in the North Fork Valley just east of Paonia, Colorado. This commitment is to the <br />Colorado Department of Natural Resources, Division of Reclamation, Mining and Safety. This <br />0 report contains preliminary analyses of the data collected for the third quarter of 2009 (1 July <br />through 30 September). <br />The area included in this study encompasses the West Elk Mine, operated by Mountain Coal <br />Company, LLC (MCC) and Bowie No. 2 Mine, property of BRL (Figure 1). Seismicity from <br />Elk Creek Mine, owned by Oxbow Mining, Inc. is also recorded by the North Fork Valley <br />Seismic Network (NFVSN). <br />The 10-station NFVSN was established to monitor the mining-related seismicity occurring in the <br />vicinity of the West Elk and Bowie No. 2 mines, to provide event locations and magnitudes and <br />estimates of ground motions, and to determine focal mechanisms when feasible. Also, the <br />network will provide the fundamental data to develop a ground motion attenuation relationship <br />for the mining area and surrounding areas. The relationship will provide a means for predicting <br />ground motions from mining-related seismic events. Installation of the NFVSN was begun in <br />2006 and by October of that year, 5 stations were in operation (Swanson et al., 2007). By July <br />2006, 10 stations were operational. <br />NETWORK OPERATIONS <br />The NFVSN consists of 10 permanent stations, which were installed as a cooperative effort <br />between MCC, BRL and the Spokane Research Laboratory of the National Institute of <br />Occupational Safety and Health/Centers for Disease Control and Prevention (NIOSH/CDC). <br />The following factors were used to determine the station locations: access, permission of land <br />0 owners, network geometry, radio line-of-sight to the common recording site at Paonia Airport or <br />a repeater station, and uniform coverage of the target area (Figure 1). Each station consists of <br />M WAx_wds\PROJECTS\North Fork-BowielQuarteriy reports\2009 Q3\Q3_2009_BRL.d0c\0AK 1