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C"'DA No. 2 <br />/#01319 -10001 Huddlestau -Berry <br />(S <br />Discussion of Inclinometer Monitorin;_ <br />The latest inclinometer readings indicate no Significant movements since the last quarterly <br />reading. <br />Vibrating Wire Piezometers <br />Between 2005 and 2012, a total of ten vibrating wire piezometers were installed in CWDA No. <br />2. However, several of the piezometers have been damaged or have otherwise ceased to <br />function. Currently, five of the piezometers are functional. <br />Monitoring of the functioning piezometers was completed by BGI on June 29, 2014. The <br />attached monitoring report prepared by BGI includes the piezometer monitoring data and the <br />data is summarized in the following table. <br />VNVP ID <br />Initial Pare <br />Pressure <br />(psi) <br />5/21114 Pore <br />Pressure <br />(psi) <br />6/29114 Pore <br />Pressure <br />si <br />Difference since <br />Installation <br />si <br />Difference Since <br />Last Reading <br />(psi) <br />VWP -05 <br />6.8 <br />1.9 <br />2.0 <br />-4.8 <br />+0.1 <br />VWP -06 <br />11.3 <br />14.8 <br />16.0 <br />+43 <br />+1.2 <br />VWP -O <br />8.2 <br />8.9 <br />9.2 <br />+L0 <br />+0.3 <br />VWP -09 <br />2.8 <br />2.8 <br />2.8 <br />OA <br />0.0 <br />VWP -10 <br />-1,9 <br />-1.9 <br />-1.9 <br />0.0 <br />0.0 <br />cession of Vibratiniz Wire Piezometers <br />VFVP -05 <br />VWP -05 was installed on August 3, 2005 near the toe of CWDA No. 2 adjacent to the access <br />road /bench. The pore pressures recorded at VWP -05 have decreased fairly steadily since <br />installation from an initial value of 6.8 psi to the current value of 2.0 psi. The decrease in pore <br />pressures is consistent with dewatering of the gob in this area associated with no recent <br />placement of coal refuse in the vicinity of this instrument. <br />SO% 1T <br />VWP -06 was installed on June 5, 2009 near the existing top of CWDA No. 2. The pore <br />pressures recorded at VWP -06 have fluctuated since installation. The pore pressures increased <br />following installation until March 2013 and then fell until April 2014. However, since April <br />2014, the pore pressures recorded in VWP -06 have increased. This is consistent with the fact <br />that gob placement has occurred in the vicinity of this instrument during the spring of 2014. It is <br />likely that additional increases in pore pressures will be recorded during the summer months as <br />coal refuse is actively placed in the vicinity of VWP -06. However, the increases in pore <br />pressures are not anticipated to be sufficient to reflect instability in CWDA No. 2. <br />VIVP -08 <br />VWP -08 was installed on June 5, 2009 at a slightly lower elevation than VWP -06. The pore <br />pressures recorded at VWP -08 have fluctuated since installation. However, the fluctuations have <br />generally been within a narrow range of values. Since April 2014, the pore pressures recorded in <br />VWP -08 have increased slightly. As indicated in the referenced Stability Evaluation report, the <br />stability of CWDA No. 2 is sensitive to increases in pore pressures in VWP -08. Al] increase in <br />the pore pressure of 7 psi in VWP -08 would result in a reduction of the Factor of Safety to below <br />1.5. <br />X:52003 ALL PROJECFS1.00489 - JE Stover Associates lne'00A89 -0003 Botisae MineQ00 - Geo\Gob 2100x89 -0003 LR0709 W.doc 2 <br />