REP15867

• Permit No: C1981041
• IBM Index Class Name: Report
• Doc Name: STABILITY ANALYSIS CAMEO REFUSE DISPOSAL AREA 1 POWDERHORN COAL CO CAMEO COLO FEB 1994 ADDENDUM May,
• Permit Index Doc Type: STABILITY REPORT
• Media Type: D
• Archive: No

STABILITY ANALYSIS
' CAMEO REFUSE DISPOSAL AREA No
POWDERHORN COAL, COMPANY
CAMEO, COLORADO
' FEBRUARY, 1994
SCOPE:
' The present stability analysis of Cameo Refuse Disposal Area
No.l (CRDA No.l) is requested by Western Associated Coal
Corporation in response to piezometer measurements indicating
' piezometric readings within the disposal pile which appear to
exceed original design parameters. On December 14, 1993, Western
Engineers, Inc was retained to examine the existing pile, review
' the available design and piezometer measurement data, evaluate
disposal pile stability and submit this report of findings and
recommendations.
' SITE INSPECTION:
On January 25, 1994, the existing disposal pile was examined
' by Western Engineers and Mr. Larry Reschke with Powderhorn Coal,
Co. The main objectives of the site inspection were to determine
the general configuration of the pile; examine piezometer
' installations and locations; identify surface seepage areas and
their possible (visible) sources; observe drainage paths including
the discharge from underdrains; and to examine the pile for visual
signs of instability or distress,
' The disposal site is located on the south side of Coal Canyon,
northwest of the existing Public Service Power Generating.Plant and
' approximately 1 mile west of the Colorado River. The disposal area
fills a small basin-like feature at the toe of the northeast slope
of Mount Lincoln. The present pile geometry consists of fairly
' uniform 2:1 slopes, which are stair stepped with a series of 12 to
15-foot wide horizontal benches. The first bench is located 50-
feet (vertically) from the toe of the pile, subsequent benches are
typically separated by 30-feet of elevation. A shallow
' sedimentation pond is located at the west toe of the pile
(approximately 50-feet east the Coal Canyon streambed) at elevation
4830 +/-, Mr. Reschke noted that the finished pile will extend to
' elevation 5025 and the placement of refuse material ceased in late
1986 at approximate elevation 4965 +/- (no material has been placed
since that time). Thus, the present crest or top of the pile is at
elevation 4965+/-. Heavily armored (2 to 3-foot diameter rip
' rapped) drainage ditches surround the perimeter of the pile at the
contact point with original ground. These toe or groin ditches
discharge into the sedimentation pond at the west toe of the pile.
' Mr. Reschke noted that a small, intermittently flowing drainage,
from the north, is intercepted by the northwest groin ditch. Even
though surface runoff was observed, no flow was readily apparent in
' the southeast groin ditch.
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