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3.2.1 Survey Mirrors <br />It is proposed to install survey mirrors on the finished, soil- covered refuse pile benches. As of mid - <br />May 2012, refuse placement had not yet reached the first bench. Mirror layout will be provided as <br />refuse fill approaches the first bench elevation. Three mirrors are planned for each bench. Mirrors <br />are advantageous because they can provide extensive monitoring coverage along the slope and they <br />can provide data for very large displacements without being damaged. The disadvantage is that there <br />is a significant amount of - noise" in the readings due to temperature and other effects, and they can <br />be impacted by animals, equipment, and other elements. <br />3.2.2 Inclinometers <br />It is proposed that inclinometers are installed at two locations, as shown on Figure 23. One location <br />(Location 1) should be near the top of the colluvium portion of the buttress such that the compacted <br />colluvium buttress can be monitored. The other location (Location 2) should be at the lowest bench <br />within the refuse pile itself such that the refuse and the underlying colluvium can be characterized in- <br />situ. Location 2 should be located far enough south that the rock drainage blanket extending upslope <br />from the buttress is not intercepted. <br />At each of these locations, it is anticipated that one soil boring and associated rock coring will be <br />performed. Also, an inclinometer and at least one vibrating wire piezometer will be installed in each <br />borehole to monitor slope movement and porewater pressures, respectively. Furthermore, in -situ <br />testing including Cone Penetration Testing (CPT) and field vane will be performed 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 />the shear surface should movement occur. Disadvantages of inclinometers include the length of time <br />needed to monitor and they can shear off with sufficient subsurface movement, and might become <br />inoperable after several inches of displacement. <br />These inclinometers should be 85 mm (3.34 inches) in diameter. These are the largest diameter <br />inclinometers commonly manufactured and are recommended because they can remain functional <br />with the largest shear displacement compared to smaller diameter casing. <br />Inclinometer casing should be installed at least 10 feet into competent bedrock. <br />P Mpls 06 (D 26 06261003 Haul Road Slide Repair WorkFiles Report MCC_Slump Repair - Instrumentation- DrainRev_2012 -05 -25 doex <br />14 <br />