Laserfiche WebLink
CWDA No. 2 <br />#01349-0001 1"ruddicaon-Berry <br />01/11/16 `�. <br />VWP-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. Slight pore pressure increases were recorded in <br />VWP-08 from April 2014 through January 2015. However, a slight decrease occurred between <br />January and March 2015. Since March 2015, pore pressures have increased slightly. As <br />indicated in the referenced Stability Evaluation report, the stability of CWDA No. 2 is sensitive <br />to increases in pore pressures in VWP-08. An increase in the pore pressure of 7 psi in VWP-08 <br />would result in a reduction of the Factor of Safety to below 1.5. <br />The current pore pressure reflects a piezometric surface elevation of approximately 6098 feet <br />which is much less than the critical elevation of 6113 feet. As a result, HBET does not believe <br />that the measured pore pressures in VWP-08 are any indication of instability in CWDA No. 2. <br />VWP-()9 <br />VWP-09 was installed on May 18, 2012 near the toe of CWDA No. 2. The pore pressures <br />recorded at VWP-09 have been fairly steady since installation. This suggests that dewatering of <br />the gob in this area is likely nearly complete. It is anticipated that the pore pressures at VWP-09 <br />will remain fairly steady over time. <br />VWP-10 <br />VWP-10 was installed on May 18, 2014 near the toe of CWDA No. 2. The pore pressures <br />recorded at VWP-10 have been fairly steady since installation. This suggests that dewatering of <br />the gob in this area is likely nearly complete. It is anticipated that the pore pressures at VWP-10 <br />will remain fairly steady over time. <br />Site Visit Observations <br />HBET visited the site on December 22nd, 2015. At the time of our visit, the site was snow <br />covered. No coal mine waste was being moved or placed at CWDA No. 2. <br />General <br />Due to the site conditions, HBET was unable to visually inspect CWDA No. 2. However, based <br />upon the results of the most recent VWP and inclinometer monitoring data, HBET does not <br />believe that there is any reduction in the stability of CWDA No. 2. Continued quarterly <br />monitoring of piezometers and inclinometers is recommended. <br />We are pleased to be of service to your project. Please contact us if you have any questions or <br />comments regarding the contents of this report. <br />Respectfully Submitted: <br />Huddleston -Berry Engineering and Testing, LLC <br />Michael A. Berry, P.E. <br />Vice President of Engineering <br />X:A2008 ALL PROJECTS'01349 -Bowie Resources, LLCA01349-0001 Bowie ManeA200 - GeoAGob 2'Instrumentation Monitoring'201S-01349-0001 GP2 4thQ 2015 011116.doc 3 <br />