2015-01-16_REPORT - C1996083

• Permit No: C1996083
• IBM Index Class Name: Report
• Doc Date: 1/16/2015
• Doc Name: 4th Quarter 2014 Waste bank Inspection Report ‎(Emailed)‎
• From: J.E. Stover & Associates, Inc
• To: DRMS
• Permit Index Doc Type: Waste Pile/Fill Report
• Email Name: SLB
• Email Name: DIH
• Media Type: D
• Archive: No

CWDA No. 2
#01349 -0001 Huddlestou -Berry
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Discussion of Inclinometer Monitoring
The latest inclinometer readings indicate no significant movements since the last quarterly
reading.
Vibrating Wire Piezometers
Between 2005 and 2012, a total of ten vibrating wire piezometers were installed in CWDA No.
2. However, several of the piezometers have been damaged or have otherwise ceased to
function. Currently, five of the piezometers are functional.
Monitoring of the functioning piezometers was completed by BGI on January 6, 2015. The
attached monitoring report prepared by BGI includes the piezometer monitoring data and the
data is summarized in the following table.
VWP ID
Initial Pore
Pressure
(psi)
9/24/14 Pore
Pressure
(psi)
10/31/14 Pore
Pressure
(psi)
1/6/15 Pore
Pressure
(psi)
Difference Since
Installation
(psi)
Difference
Since Last
Reading (psi)
VWP -05
6.8
2.5
n/a
2.3
-4.5
-0.2
VWP -06
11.3
17.1
17.0
16.8
+5.5
-0.2
VWP -08
8.2
9.7
9.7
9.8
+1.6
+01
VWP -09
2.8
2.9
n/a
3.0
+02
+01
VWP -10
-1.9
-1.8
n/a
-1.7
+02
+01
Discussion of Vibrating Wire Piezometers
VWP -05
VWP -05 was installed on August 3, 2005 near the toe of CWDA No. 2 adjacent to the access
road/bench. The pore pressures recorded at VWP -05 showed a slight increase from the 2nd
Quarter to 3rd Quarter 2014. However, the pore pressures decreased slightly between the 3rd
Quarter to 4th Quarter 2014. In general, HBET does not believe that the pore pressure changes in
VWP -05 are cause for concern regarding stability of the gob pile
VWP -06
VWP -06 was installed on June 5, 2009 near the existing top of CWDA No. 2. The pore
pressures recorded at VWP -06 have fluctuated since installation. The pore pressures increased
following installation until March 2013 and then fell until April 2014. However, between April
2014 and August 2014, the pore pressures again increased. This likely reflects the fact that gob
placement was occurring in the vicinity of this instrument during the spring and summer 2014.
There was a slight decrease between August 2014 and January 2015 which likely reflects the fact
that gob placement operations slowed and finally ceased for the winter. HBET does not believe
that the measured pore pressures are an indication of any instability in CWDA No. 2.
IIr %' l:i
VWP -08 was installed on June 5, 2009 at a slightly lower elevation than VWP -06. The pore
pressures recorded at VWP -08 have fluctuated since installation. However, the fluctuations have
generally been within a narrow range of values. Since April 2014, the pore pressures recorded in
VWP -08 have increased slightly. As indicated in the referenced Stability Evaluation report, the
stability of CWDA No. 2 is sensitive to increases in pore pressures in VWP -08. An increase in
the pore pressure of 7 psi in VWP -08 would result in a reduction of the Factor of Safety to below
1.5.
X:\2008 ALL PROJECTS \01349 -Bowie Resources, LM01349 -0001 Bowie Mine\200 - Geo \Gob 2\1n tmn ntation Monitoring \01349 -0001 GP2 LR011415.doe 2