INSPEC16571

• Permit No: C1982056
• IBM Index Class Name: Inspection
• Doc Date: 5/5/2005
• Doc Name: OSM Oversight Inspection Issues
• From: Jerry Nettleton
• To: Delbert Lobb
• Media Type: D
• Archive: No

Walker, Byron
From: Jerry Nettleton [[e-mail][
Sent: Thursday, May 05, 2005 8:43 AM
To: [e-mail]
Cc: Delbert Lobb; [e-mail]; [e-mail]; Dave
Wallace
Subject: Twentymile Coal - OSMRE Oversight Inspection Issues
Byron
I was disappointed, as I'm sure you were, that we had the two issues
identified in the field during our inspection. As you know, we have been
working diligently to make sure that things are in good order and full
compliance. In order to both understand why the observed problems occurred
and to address them appropriately in a timely manner, Z am proceeding with
an internal inquiry, and have obtained the following additional relevant
information:
Discharge at Northwest Mains Ventilation Fan Installation
On Monday night during graveyard shift (prior to our inspection on Tuesday
morning), we had a roll seal fail on our underground mine water system.
Our mine water system supplies cooling and dust control water to both the
longwall and the continuous miners used for development work. Because of
the volume of water required, the system operates at high pressures (300 -
700 psi, compare with a typical pressure washer at 250 - 500 psi). When
the roll-seal (which is a pressure accumulator device) failed, pressure in
the system built-up and started causing pipe joints to fail and separate.
When this was discovered, valves were shut-off to minimize damage to the
water system and prevent uncontrolled flow underground.
The pipe that we observed at the Northwest Mains Vent Fan is connected to
the mine water system and is designed to function as a pressure relief and
accumulator. As I understand it, the approximately 1,000' column of air in
the pipe serves as a buffer to minimize air-hammer in the system with
pressure changes and has functioned effectively for some time. With
failure of the roll-seal and closure of valves underground, pressure in the
water system built-up to well above normal levels and was sufficiently high
to allow water to push the column of air out the relief pipe, resulting in
surface discharge. Onti1 it was discovered early Tuesday morning that
there was discharge from the pipe, flows as high as 200 gpm may have
occurred. When we visited the site, I was unaware of the underground water
problems and related surface discharge, but as I indicated to you and
Mitch, was suspicious that the localized surface flooding that we were
seeing was due to something other than normal runoff, It was during the
subsequent part of the inspection that Z was able to talk with Mike Berdine
(on the road to the 18-Right Shaft) and find out what had happened.
The discharge that resulted in the observed problem was due to
unanticipated operational (upset) conditions, and discharge volumes far
exceeded the design storm runoff for this area and for the designed
drainage and sediment control structures. Fortunately, discharge was
contained within the immediate and adjacent areas by the designed system
and natural topographic features, resulting in little or no discharge to
Fish Creek. Discharge flows were also clean mine water that is not
sediment laden like typical disturbed area runoff. Under normal surface
runoff conditions, the designed system has function effectively to control
surface runoff and sediment.
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