_GENERAL DOCUMENTS - C1981017 ‎(142)‎

• Permit No: C1981017
• IBM Index Class Name: GENERAL DOCUMENTS
• Doc Name: Bid Documents ‎(IMP)‎
• Permit Index Doc Type: General Correspondence
• Media Type: D
• Archive: No

Fred Banta - 3 - September 11 , 1985
was the saturation of this loose material that had been
placed the previous fall and a slump occurred. This area
has a slope of approximately 3 to 1 of flatter than any
part of the refuse pile.. . ."
This earlier episode of flow activity on slopes of less than 3(H):1(V) should
have demonstrated the potential for mudflow activity on the pile to the
operator, if proper placement specifications were not followed. These
responses were made in early 1982, as a portion of their permanent program
permit approval process. Therefore, the operator' s technical and
environmental personnel should have been aware of the potential of mudflow
activity on the coal processing waste pile.
Four additional NOV's, cited as a portion of Section A of your Pattern of
Violations Determination, relate to the construction and management of the
rock tunnel refuse pile at Coal Basin Mines. These NOV' s are C-84-052,
C-84-060, C-84-083 and C-84-154. These NOV's regard the flow of refuse
materials off the pile or non-complying placement of coal processing waste
material within the rock tunnel refuse pile.
In the case of the rock tunnel refuse pile, the investigation performed by the
operator's consultant, Geo-Hydro Consultants, Inc. , referred to above,
determined that the operator had analogously failed to comply with the
approved standard specifications for material placement.
On pages 7 and 8 of the May 8, 1984 report, Geo-Hydro Consultants observes:
". . .The original design recommended to place the waste
systematically in lifts and to eliminate end-dumping. The
thickness of individual lifts is not to exceed 12 inches
and compaction by the placing equipment were recommended
for the outer shell of the pile. .. .
Our testing showed that the waste has been deposited in
horizontal lifts, as specified, and it was compacted to an
acceptable degree. The only exceptions on locations where
high moisture content of the fill, probably prompted by
recent snowfall , results in less satisfactory compaction.
In view of the good quality of the rock fill and the
extremely conservative design of the pile, we do not
consider these local variances as critical for the
stability.
Inspection showed, however, that end-dumping or pushing of
material over the crest of the pile may have a very
negative influence on the stabiity of the wastepile's
outer s opes. Shallow sloughs, slides and mudf ows can
develop when the material is saturated. This was
apparently the case during the last month; the material
rom the upper part o t e pile was pushed across the
crest. Because of the high moisture content, loca
stability problems were encountered."