Laserfiche WebLink
tension crack located around I12-01, inclinometer and piezometer readings will be observed for <br />indications of conditions that may indicate potential for slope movement. A mirror has also been <br />placed adjacent to the inclinometer, which will provide indications of surface movement in this area. <br />Actions will be taken to stabilize the slope should instrument observations indicate that the slope is <br />beginning to move. <br />3.2 RPEE Buttress and Refuse Pile Area <br />This section summarizes instrumentation proposed to monitor the performance of the RPEE buttress <br />and refuse pile at West Elk Mine. Slope monitoring will be conducted in the refuse pile through <br />placement of survey mirrors, inclinometers, and piezometers. These instrumentation types are <br />described in more detail below. <br />3.2.1 Survey Mirrors <br />Survey mirrors will be installed on the refuse pile benches as the pile develops. Mirror layout will be <br />provided as the refuse fill rises and mirrors are installed. Three mirrors are planned for each bench. <br />Mirrors that have already been installed are shown on Figure 16. Mirrors are advantageous because <br />they can provide extensive monitoring coverage along the slope and they can provide data for very <br />large displacements without being damaged. The disadvantage is that there is a significant amount of <br />"noise" in the readings due to temperature and other effects, and they can be impacted by animals, <br />equipment, and other elements. <br />3.2.2 Inclinometers <br />Three (3) inclinometers were installed at the locations shown on Figure 16. Two locations (I12-03 <br />and I12-05) are on the colluvium portion of the buttress such that the compacted colluvium buttress <br />can be monitored. The other location (I12-04) is at the lowest bench within the refuse pile itself such <br />that the refuse and the underlying colluvium can be characterized in-situ and monitored. I12-04 was <br />located far enough south that the rock drainage blanket extending upslope from the buttress was not <br />intercepted. <br />A soil boring and associated rock coring was performed at each inclinometer location. Also, at least <br />two vibrating wire piezometers were installed in each borehole to monitor porewater pressures. <br />Furthermore, in-situ testing including Cone Penetration Testing (CPT) and field vane was performed <br />at each location. <br />Inclinometers are advantageous because they can accurately measure very small displacements and <br />they are less susceptible to disturbance at the ground surface. They also help to identify the depth of <br />P:\Mpls\06 CO\26\06261003 Haul Road Slide Repair\WorkFiles\Report\MCC_Slump_Repair-Instrumentation-Drain Rev 2012-12-12.doex 14 <br />