1997-07-28_GENERAL DOCUMENTS - M1973021 ‎(9)‎

• Permit No: M1973021
• IBM Index Class Name: GENERAL DOCUMENTS
• Doc Date: 7/28/1997
• Doc Name: 1996 Annual Report- Geotechnical Addendum.
• From: CAMAS
• To: DMG
• Permit Index Doc Type: General Correspondence
• Media Type: D
• Archive: No

Terra Testing as subcontractor to Haley & Aldrich. The testing results are
presented in Appendix C and a discussion of the results is provided below in
the Geotechnical Data Analysis section.
D. Temporary Inclinometer
A temporary "inclinometer" was installed in Boring B104 which was drilled
at an angle of 40 degrees from vertical from above the northern side of the
slide head scarp, and which intercepted several clay gouge seams thought to
define, at least in part, the slide failure surface. The "inclinometer" consisted
of approximately 55 ft of ungrouted 1-1/4 in. diameter PVC casing installed
in the completed boring so that potential continued shear displacement along
the clay gouge seams could be detected. Potential movement was determined
by probing the casing with a weighted tape measure and recording tight spots,
if any. A discussion of observations made in the temporary inclinometer
before it was destroyed by repair activities is included in the data analysis
chapter below.
iA permanent inclinometer installation using manufactured inclinometer casing
grouted in place was not practical in the immediate vicinity of the slide area
' because this area was predetermined to require considerable excavation and
regrading to repair the slide and the installation could only be short term.
Haley & Aldrich has recommended, and CAMAS is planning for, installation
of at least one permanent bedrock inclinometer near the failure area to
provide for long term subsurface monitoring of the area to supplement the
ongoing optical survey monitoring for continued movement.
E. Optical Survey
CAMAS provided survey support of the investigation and repair of the
' localized failure in the East Highwall. Survey support included 1) obtaining
accurate surveyed locations for the rock core borings; 2) installing and
monitoring two arrays (pre- and post-repair) of surface survey monuments in
1 and around the slide mass; 3) surveying selected slide area features such as
scarps and tension cracks to assist in mapping the slide geometry; and 4)
providing horizontal and vertical control for existing and revised highwall cut
lines and for the Limit of Mining boundary for the East Highwall.
Data collected from the optical survey work is presented in Appendix D and
is discussed in the geotechnical data analysis chapter that follows. Included in
Appendix D is a plan map showing the locations of an array of 20 pre-repair
monitor points (1001 through 1020) and the present array of 26 post-repair
' monitor points (2001 through 2026), and displacement plots for all 46 monitor
points for the 1996 calender year. Optical surveying of surface monitor by
CAMAS points on the East Highwall is continuing in 1997 on an
' approximately quarterly basis.
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