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3.1.3. Piezometers <br />It is proposed to install six (6) vibrating wire piezometers attached to the inclinometer casings (three <br />each) which will be installed along the north edge of haul road HR -1 as shown in Figure 22. These <br />devices are adept at measuring porewater pressures within the slope. High porewater pressures lead <br />to lower shear strengths within the soil and rock, which results in a higher likelihood of slope <br />movement. <br />Three devices should be attached to the inclinometer casing at each inclinometer. The depth of the <br />three piezometers should be (1) within the colluvium a few feet above the top of the granular <br />drainage blanket material, (2) in the siltstone /mudstone bedrock below the granular drainage blanket <br />material (preferably associated with a coal seam, if present), and (3) within the sandstone or <br />competent bedrock at the bottom of the inclinometer casing. The piezometers should be finished <br />using the fully grouted method. <br />3.1.4 Monitoring Schedule <br />Monitoring will be conducted according to the schedule as follows: <br />A. Survey Mirrors: It is proposed to measure these instruments monthly throughout the year. <br />B. Inclinometers: It is proposed to measure these instruments monthly throughout the year, but bi- <br />weekly readings may be warranted during the spring months when slope movement typically exhibits <br />the highest likelihood. <br />C. Piezometers: It is proposed to measure these instruments monthly throughout the year, but bi- <br />weekly readings may be warranted during the spring months when slope movement typically exhibits <br />the highest likelihood. Piezometer measurements may be taken at the same time the associated <br />inclinometers are being read. Thus, it is recommended to read the piezometers on the same schedule <br />as the inclinometers. <br />Monitoring results will be analyzed for potential movement and elevated porewater pressures. <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 />P Mpls 06 CO 26 06261003 Haul Road Slide Repair` WorkFiles Report MCC_ Slump_ Repair- Instrumentation- DrainReN_2012 -05 -25 doex <br />13 <br />