REP28740

• Permit No: C1981047
• IBM Index Class Name: Report
• Doc Date: 2/4/1987
• Doc Name: MINE BENCH FINAL CONTOURS BLUE RIBBON COAL CO PN C-81-047
• From: MLRD
• To: SUE MOWRY
• Permit Index Doc Type: STABILITY REPORT
• Media Type: D
• Archive: No

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STATE OF COLORADO
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Roy Romer, Governor
DEPARTMENT OF NATURAL RESOURCES
MINED LAND RECLAMATION DIVISION
DAVID C. SHELTON, Director
M\\EMORANDUM
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T0: Sue Mowry
FROM: Jim Pendleton
RE: Mine Bench F' Con urs - Blue Ribbon Coal Company
(Permit C-81-047)
I have reviewe~t~letter submittal made by Blue Ribbon Coal Company in
response to our bond release inspection concerns regarding their final grading
of the "reclaimed" mine bench at the Blue ribbon Mine. Their letter included a
1"=50' topographic map of the area of concern and a cross-section profile
sketch plan depicting a proposed regrading of the drainage ditch. The ditch
profile is shown as being amended from the existing 1.3% grade to a 2.0%
grade. In addition several low spots are being removed to prevent the ponding
of water which now exists.
The regrading of the bench top drainage ditch should eliminate the immediate
• ponding problems within the ditch. However, several areas outside the ditch
will also require regrading to allow them to overland drain into the regraded
ditch, in order to eliminate ponding now occurring on the bench top. In
addition, the construction may be relatively complicated. The bench contains
gob material imported from West Elk to complete the bench stabilization. This
gob is covered with non-gob cover material. Simply deepening the ditch may
expose the gob material. The operator will have to salvage the non-gob cover
material, over-excavate the ditch profile and then replace the non-gob cover.
For purposes of properly accomplishing the regrading with a minimum of
confusion, I believe it appropriate for the Division to require the operator
to prepare a more detailed regrading plan. I recommend that we require the
preparation of a 1"=20' topographic plan map of the project area. Further,
the operator should delineate bench top areas for excavation, cover material
stockpiling and excess material disposal and regrading. Without a detailed
plan, the operator might repeat last fall's mistake. We should also require
timely certification of the final grading compliance with the amended plan, so
that a remedy could be affected prior to final seeding, if necessary.
As I mentioned in my recent memo regarding the operator's submittal of Fall
1986 stability and hydrology monitoring results for the mine bench, I am
concerned with an apparent rise in the water level in piezometer P-1. I am
concerned that this rise may be resulting from the infiltration of waters
ponded on the bench top. Therefore, I believe it is imperative to affect as
prompt a remedy as possible. Unfortunately, the operator's estimate of
• mid-summer may be realistic. However, if an early summer allowed work to
commence sooner, we should require the operator to take advantage of the
earliest construction opportunity.
cc: Bob Liddle
423 Centennial Building, 1313 Sherman Street Denver, Colorado 80203-2273 Tel. [phone]