REP39303

• Permit No: M1980244
• IBM Index Class Name: Report
• Doc Name: 1985 ANNUAL REPORT MLRD PN 80-244
• Permit Index Doc Type: ANNUAL FEE / REPORT
• Media Type: D
• Archive: No

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Dames & Moore
TexasgulF Minerals and Metals, Inc.
January 31, 1986
Pale -2-
The thickened tailings discliaroe concept was unsuccessful, with the result
that in 1931 and 1982, tailings were disposed as a conventional slurry with the
"berm" acting as low tailings dam. Because the thickened tailings stacking
procedure did not work, the MLRB stipulated that nu Further deposition of
tailings occur until a new plan for tailings disposal is approved by the board.
They also stipulated that the existing tailings disposal scheme be monitored
periodically for stability and repaired as'necessary during the time period
until a ne•.+ disposal system is in place.
PREVIOUS INSPECTION
Dames b Moore inspected the Carlton Mill Tailings Disposal area as part of
the 1984 annual inspection. The results of the inspection were submitted in a
letter to the Hec1a Mining Company dated March 8, 1985. It was our opinion
that the existing tailings disposal scheme was stable. Features such as
slumps, tension cracks, etc., which could indicate incipient instability, were
not observed. We did recommend, however, that several drainage related
features be improved. Remedial actions were presented for the berm, and
continued observations of the east perimeter ditch discharge was recommended in
case erosion tended to undermine portions of the berm.
1985 CONSTRUCTION
During the summer of 1985, a heap leach operation was construction within
[he area of Permit No. 80-244. The heap leach occupied much of the space
contained within [he diversion ditches and upstream of the old tailings berm.
Construction included a heap leach pad and 4 operating ponds. ~s part of the
heap leap construction, the tailings "berm," which was part of the originally
perm[tted tailings disposal scheme, was upgraded to be an emergency storage dam
for the heap leach pad and ponds. Tha emergency dam was constructed by
extending the old tatlings "harm" upstream and by addim~ up to IO feet of
freeboard. In addition, an emergency outlet pipe was installed.