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• 5.3 Inclinometers <br />Historic inclinometer movements are used to establish the shear plane and rate of shear. <br />Inclinometers along the cross section in Figure 2 (I-6, I-7, and I-50) show a relatively flat shear <br />plane at about 30 to 50 feet below the surface. Figures 10A, lOB, and lOC are the inclinometer <br />movement plots for I-7 and I-50, respectively, that show the precorrection shear plane. <br />Inclinometer I-6 sheared at a depth of about 32 feet below ground surface shortly after installation <br />and no plot is available. <br />Inclinometer plots I-98-O6 and I-98-07 show post correction movement of the landslide and are <br />presented as Figures lOC and lOD. Inclinometer I-98-06 (replaced I-6 at same location) shows a <br />deeper shear plane than I-6, but is moving at a very slow rate of 0.0006 ft/day. Inclinometer 1-98- <br />07 (replaced I-7 at same location), shows a similar shear plane as I-7, but with a faster rate of <br />shear (.005 fbday). The rate of shear is similar to that currently being measured near the head of <br />the landslide. <br />5.4 Inclinometers in Pins (Micro-Piles) <br />Inclinometers installed in the pins are used to compare the actual movement of the pins with the <br />predicted movement from the FLAC model. These inclinometers are also used to determine if <br />additional shear planes are being developed either above or below the inclinometers. Figure 11A <br />shows the actual movement of selected inclinometer pin I.1C-3. Based upon the movement <br />measured so far, it appears that the pins are deforming as predicted but that a lower shear plane <br />may be developing below the pins near I-1C-23 at the east end of Phase 1. This is also verified by <br />Inclinometer I-98-06. A plot of Inclinometer I-1C-23 is shown as Figure 11B. However, the lower <br />shear plane movement may decrease after the Phase 2A pins have been installed. If not, <br />additional deeper pins on the east end of Phase 1 may have to be installed. <br />5.5 Stone Columns <br />The response of the piezometers in the stone columns is shown by the groundwater contours on <br />Figure 12 which can be wmpared to the groundwater contours shown on Figure 9 prior to <br />installation of the stone columns (Drawings from HLA). The stone columns are intended to be a <br />long-term dewatering method and the monitoring period is not sufficient to evaluate their <br />effectiveness at dewatering the body of the landslide. Based upon information collected tc-date, <br />the water levels have remained about constant or risen only slightly. <br />C 1 <br />0626024\6899LLABM 11 <br />