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West Elk Mine <br />reports. The monuments along the dam and reservoir basin will be resurveyed as soon as <br />possible if a seismic event occurs that exceeds the "threshold event" as described below. <br />If, during the inspections, cracks or other potentially damaging features are noted to be <br />occurring in the reservoir basin or dam structure, CDMG, the Minnesota Reservoir <br />Company, SEO, USFS and other appropriate agencies will be notified by MCC <br />immediately and, depending on the severity of the damage, mining may cease until a new <br />mine plan can be approved and mitigation performed. <br />4. The landslide feature that is located on and is part of the left (south) abutment will be <br />monitored for movement. MCC will install survey monuments within the landslide on <br />the hill to the south of the dam and within the toe of the landslide. These monuments will <br />be surveyed monthly, when accessible, during the months of February through July when <br />movement due to high soil moisture content would be expected. The monuments will be <br />surveyed once every three months in the period of August to January when soil moisture <br />content is expected to be lower. If a seismic event equal to or greater than the threshold <br />event for the Monument Dam as described below occurs, the monuments will be <br />inspected for movement. The results of the survey will be submitted to CDMG in the <br />semi-annual subsidence report. If movement along the landslide appeazs to potentially <br />damage the dam itself, CDMG, the Minnesota Reservoir Company, SEO, USFS and <br />other appropriate agencies will be notified by MCC***immediately***. <br />2)Freguencv and Renortin <br />Monument Dam will be surveyed and the monuments on the dam axis monthly when E-Seam <br />longwall mining is occurring within one mile of the dam and the information will be reported <br />semi-annually. If mining is occumng outside the one-mile radius of the dam, the dam <br />monuments will be surveyed on an annual basis. <br />B)Seismic Monitorine <br />In June of 2005, the mine installed one seismic monitoring station in the axis of the <br />Monument Dam, another in Sylvester Gulch, and two more above panel 24. The purpose <br />of installing these stations was to observe the seismic events actually related to mining <br />panels at the West Elk Mine. Monitoring of the four seismographs commenced in June of <br />2005, and information developed to characterize seismic response from mining activity in the <br />vicinity of the Monument Dam and Minnesota Reservoir. <br />Prior to the commencement of subsidence mining in either the E-seam E-10, E-11, and E12 <br />panels or E-1 and E-2 panels, an array of seismic stations to monitor microseismicity generated <br />by subsidence will be created. This array will consist of at least 4 to 5 strategically placed <br />accelerometers and seismometers that will collect seismic data. The accelerometer/seismometer <br />already in place in the area of the Monument Dam will be used as part of this new array. The <br />array will consist of equipment similaz to other arrays established in the past by NIOSH in the <br />North Fork Valley to monitor mining induced microseismicity, including those previously <br />established in Sylvester Gulch and over panel 24. This data will be transmitted to data storage <br />devices and to a central location where the data can be monitored on a real-time basis. The final <br />• number, locations and installation of the seismometers and data storage devices will be <br />determined by an expert in the field of collecting and interpreting mining induced seismicity. <br />1.05-/67 Revised June 2005 PRIO, Rev. March 2006; May 1006 PR10 <br />