REP49060

• Permit No: C1981038
• IBM Index Class Name: Report
• Doc Date: 10/12/1984
• Doc Name: COLO WESTMORELANDS SEMI-ANNUAL SUBSIDENCE MONITORING REPORT
• From: MLRD
• To: BOB LIDDLE
• Permit Index Doc Type: SUBSIDENCE REPORT
• Media Type: D
• Archive: No

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999
DEPARTMENT OF NATURAL RESOURCES
David H. 6atchsq Executive DlreCtor
MINED LAND RECLAMATION DIVISION
DAVID C. SMELTON, Dlnotor
Richard D. Lamm
Governor
DATE: 12 October 1984
T0: Bob Liddle
FROM: Jim Pendleton
RE: Colorado Westmq
-Annual Subsidence Monitoring Report
Pursuant to your request, I have reviewed CWI's semi-annual subsidence
monitoring report, submitted on August 22, 1984, for the Orchard Valley
underground coal mine. This report fulfills the requirements placed upon
Permit No. C-038-81.
In summary, the report contains the following observations:
(1) High-resolution gird subsidence monuments 28 through 51 were apparently
originally surveyed incorrectly. The operator requests that the
corrected location data contained in the current report be considered
as pre-mining baseline for these monuments. This is acceptable to the
Division.
(2) Development mining beneath high-resolution grid subsidence monuments 42
through 51 has been tentatively scheduled to begin in July of 1985. To
date the operator has been unable to obtain any high-resolution grid
data, which may be troublesome when requesting permission to mine
beneath any critical areas or structures. The Division is currently
reviewing such a request, in the form of a permit revision application
for the Orchard Valley mine lease extension.
(3) The high-resolution grid monument line 38 through 41, the east-west
line above Panel 4N-8N-8E, will be extended to the east for an
additional 1,200 feet, in order to better observe subsidence above that
panel. Information from this panel should begin accumulating in Juiy
of 1985. The Division welcomes the installation of additional
monuments.
(4) The operator be]ieves that some additional subsidence surface tension
cracks may be developing above Panel 25-SE. However, the operator is
concerned that these cracks may caused by unrelated landslide activity,
due to this year's abnormally wet spring. Subsequent observations may
be allow resolution of this problem.
(5) Mine ground water inflows continue to be very small. This observation
should be documented in next January's annual hydrology report.
The report is acceptable as submitted. I Continue to be concerned that the
lack of high-resolution grid subsidence data will create problems during the
review of future requests to undermine critical areas or structures:
cc: Mike long
423 Centennial Building, 1313 Sherman Street Denver, Colorado 80203 Tel. [phone]