GENERAL40072

• Permit No: C1981041
• IBM Index Class Name: General Documents
• Doc Date: 5/23/2001
• Doc Name: POWDERHORN COAL CO HAZARD EVALUATION
• From: J E STOVER & ASSOCIATES
• To: DMG
• Permit Index Doc Type: GENERAL CORRESPONDENCE
• Media Type: D
• Archive: No

From: Jlm Stover To: David Berry
Dale: 5123N7 Time: a.!':54 PM
III IIIIIIIIIIIIIIII
999
J. E. STOVER 8~ ASSOCIATES
2788 COMPASS DRIVE, SUITE 101
GRAND JUNCTION, COLORADO 87506
PHONE: [phone], FAX [phone]
Mlf•E ENGINEERING
MINE RECLAMATION
May 23, 2001
David Berry
Division of Minerals and Geology
1313 Sherman St., Room 215
Denver. CO 80203
Re: Powderhorn Coal Company
Hazard Evaluation
Dear Mr. Berry:
CIVIL ENGNEERNG
CONST. MANAGEMENT
Pape 7 of 3
On behalf of Powderhom Coal Company (PCC), following are its responses to DMG's Site
Condition Report dated January 30, 2001.
,
Potential Northwest Intake Portal Discharoeand Backfill Failure '~°~`= •°
The Northwest Intake siphon has operated for over eight years and has proven to be an
effective and reliable mine dewatering system. The DMG contends there is a significarrt
potential for failure but the DMG's catastrophic failure scenario is based ori'the assumption
the dewatering system is abandoned. Since PCC has no intention of abandoning the .
dewatering system, the DMG's catastrophic failure scenario Is flawed and therefore Invalid.
The dewatering system takes a certain amount of monitoring to assure the Northwest
Intake Pool is maintained so the siphon does not break. If the level of the pool needs to be
adjusted, the valve controlling flow through the siphon is adjusted accordingly. The flow
adjustment may be required two or three times per year. Monitoring is performed in
conjunction with the weekly monitoring and sampling required by PCC's CDPS discharge
permit. Maintenance of this system is negligible. The siphon system has not required
maintenance for at least four years, if ever.
If flow though the siphon were to become restricted the following steps would be
implemented:
1. A gas or diesel pump (300 - 500 gpm) with appropriate hose fittings would be
mobilized.
2. Water would be pumped from the river back through the siphon to back flush the
system. This would displace foreign materials In the pipes and would also restart
the siphon if needed.
3. The pump could be hooked up to the siphon in an attempt to pump water from the
mine and withdraw foreign materials.