REV11559

• Permit No: C1981041
• IBM Index Class Name: Revision
• Doc Date: 3/26/2001
• Doc Name: POWDERHORN COAL MINE REVIEW OF WATER PLAN CALCULATIONS SELLARDS AND GRIGG PROJECT 2001014-21
• From: SELLARDS & GRIGG INC
• To: DMG
• Type & Sequence: TR33
• Media Type: D
• Archive: No

III IIIIIIIIIIIIIIII
Sellards
Grigg, Inc. March 23, toot
CONSULTMG ENGMEERS /LAND SUR\'E\'ORS
Mr. David Berry
Coal Program Supervisor
Division of Mines and Geology RECEIVED
Department of Natural resources
1313 Sherman Street, Room 215 MAR 2 5 2001
Denver, Colorado 80203
RE: Powderhorn Coal Mine, review of water plan calculations Division of MineralsBGeology
Sellards and Grigg Project No. 2001014-21
Dear Mr. Berry;
BACKGROUND
Sellards and Grigg, Inc. (S&G) has been retained by the State of Colorado Division of
Minerals and Geology to review calculations by J. E. Stover & Associates (Stover) for the
discharge from the Powderhorn Mine for the discharge water plan. S&G understands that
the Mine is in the process of being abandoned. The State of Colorado will accept
responsibility for the Mine once it is abandoned. The abandonment requires leaving the
Mine in a safe condition so that it cannot be entered by amateur spelunkers who could
become lost or trapped. Ground water collects in the Mine and can build to a dangerous
level capable of compromising the integrity of the entrance plug at the Northwest Portal.
To relieve the water, the Powderhorn Coal Company (PCC) has installed a siphon system.
Since the flow of ground water varies, the amount of discharge also varies. As a result,
the siphon system can cease to operate and need repriming. To keep the siphon working,
personnel from the PCC use a throttling valve to keep the siphon primed. The State of
Colorado prefers a system that operates automatically and does not require tinkering with
the throttling valve.
Stover while working for the PCC has proposed such a system to be constructed in the
area of the North Decline. The North Decline is at both the north end and the low point of
the existing Mine. The Mine at this point is lower in elevation than the Colorado River.
The purpose of this letter is to verify the calculations in order that the State may feel more
confident that the proposed system will continue to operate properly in all conditions and
will not require constant monitoring.
390 Union Boulevard, 303.986.1444
Suite 630 FAX [phone]
Lakewood, Colorado 80228 E-MAIL [e-mail]