_INSPECTION - C1982056 ‎(47)‎

• Permit No: C1982056
• IBM Index Class Name: INSPECTION
• Doc Name: Inspection Report
• From: DRMS
• To: Twentymile Coal, Company
• Inspection Date: 5/25/2010
• Email Name: JDM
• Email Name: DIH
• Media Type: D
• Archive: No

III. COMMENTS - COMPLIANCE
Below are comments on the inspection. The comments include discussion of observations made
during the inspection. Comments also describe any enforcement actions taken during the inspection
and the facts or evidence supporting the enforcement action.
This was a partial coal inspection conducted by Jason Musick of the Colorado Division of
Reclamation, Mining, and Safety(Division) on 25 May 2010. The weather was clear and the mine site
was dry during the on-the-ground inspection. This inspection was conducted as a result of
information received from the operator on Saturday May 22, 2010 describing a failure of the existing
Thickener Underflow Borehole on Wednesday May 19, 2010. During the Inspection the Division
received an application for MR-242.
Processing Waste
TCC is approved to place underground wash plant thickener underflow in sealed mine workings in the
Southern Mining District(SMD) and the Eastern Mining District(EMD). In terms of the SMD, the
underflow is piped from one of two washplants through a double-walled 6-inch pipeline for
approximately 1,800 feet to an 8-inch cased mine borehole located near the former Cyprus Coal
Company Mine Office (Brown Palace). The installation of the SMD pipeline included the installation of
four intermediate access moisture monitoring points. Due to a plug in the underflow borehole at the
Brown Palace, underflow was released at the two monitoring points along the pipeline to previously
disturbed areas uphill of Foidel Creek.
Signs and Markers
Stream buffer zone signage was in place as permitted in the area of Foidel Creek around the spill.
Roads
The Brown Palace light-use road is to the south of the area of the SMD thickener underflow pipeline
and south of two of the four monitoring sites. The roadside ditch on the south side of the light-use
road connects with haul road ditch HRC-1 and discharges through a 12" CMP under the haul road
and through a rock filter. There is an unnamed roadside ditch on the north side of the Brown Palace
light-use road that flows to a sediment basin, through a rock filter and to a different 12" CMP under
the rail line and out to Foidel Creek. The north side ditch displayed evidence of road runoff to the
sediment basin at the time of the inspection. This runoff appears to meet the underflow runoff from
the lower monitoring site at the small sediment basin.
Hydrologic Balance
The upper monitoring site displayed evidence of a small centralized ponding of underflow down slope
of the monitoring site. The underflow covered portions of ground approximately 6' X 35' and did not
appear to flow further down the slope.
The lower monitoring site displayed evidence of the underflow in and around the monitor piping, with
evidence of the flow extending —55 feet from the piping into a large catchment basin between the
hillside and the rail line. This basin appeared to drop down to a lower basin to the south and form a
pond with the runoff from the north side ditch of the light-use road. Though the underflow formed a
pond at the inlet of the 12" CMP under the rail line, no evidence of the underflow was observed at the
outlet of the culvert or in or around Foidel Creek.