_ENFORCEMENT - C1981017 ‎(12)‎

• Permit No: C1981017
• IBM Index Class Name: Enforcement
• Doc Name: Bid Documents ‎(IMP)‎ Violation CV-91-02-355-002
• Media Type: D
• Archive: No

Inspection Report
Coal Basin Mine
August 27 - 30, 1991
This was a follow-up inspection to actions taken as a result of
ten-day notices written after an October 1990 RSI and erosion and
road drainage problems recognized during the last 10 months,
beginning with the October 1990 inspection. Diane Delaney and Lew
Thompson represented Midcontinent Resources, Inc. (MRI) and Dan
Matthews represented MLRD.
We began the inspection at the 016 ponds with the intent of
insuring that the decision to accept a time delay on the planned
changes in the mine drainage system was based on a stable system
to handle the current drainage. MRI had received approval of a
technical revision to change the mine water treatment from ponds
016 to a hydroclone package plant after an OSM TDN addressing high
sediment in the 016 discharge. Installation of the hydroclone has
been delayed until the mine resumes activity. MRI submitted
calculations to prove that the ponds, which had been extensively
dredged in the last 18 months, had significant long term sediment
storage for the minimal sediment load carried by the mine water
when the mine is not active.
The mine water was running clear and the three ponds in series had
good storage capacity. Some problems with pond maintenance and/or
design were noted. THese included:
Pond 1 of 3 - inflow is incised multiple channels. No trash rack
on standup culvert which elbows to discharge pipe buried in
embankment. At the time of inspection the trash collected at the
mouth of the culvertwas significantly impeding flow. Lew Thompson
cleaned away much of the trash while we were inspecting the area.
The concern is that the pipe will get plugged and the pond will
overtop. It appears that this may have already occurred because
the high water mark indicates a recent discharge through the
emergency spillway. Additionally if the pipe got permanently
blocked where it elbows it would create alot of disturbance to
repair the problem. Trash, such as plastic bottles, was floating
in the pond. The permit on site and later at AFO was checked to
see if a trash rack was required. Neither the company or I could
determine is what the actual design of this particular pond
discharge structure.
Pond 2 Of 3 - no trash rack. Sediment delta in pond from road run-
off.
Pond 3 of 3 -Sediment delta from road run-off. In times of high
flow water flows under outfall channel riprap. Mine water varies
in flow, appeared clear throughout the inspection. Discharge pH
range 8-8.5.