2002-04-22_REVISION - M1982147

• Permit No: M1982147
• IBM Index Class Name: Revision
• Doc Date: 4/22/2002
• Doc Name: AdditionalSupport Information - Slope Stability
• From: Lafarge
• To: DMG
• Type & Sequence: TR1
• Media Type: D
• Archive: No

~LAFARG E
Apri122, 2002
RECEIVED
APR 2 22002
Ms. Erica Crosby Permit #: III -ga ' I~~ Confidental?:
Environmental Specialist Class: Type-Seq.:' -
From: To: i
Colorado Department of Minerals and Geology Doc. Name: i ~ -
1313 Sherman Street, Room 215 Doc. Date (if no date stamp): - S ~I~
Denver, CO 80203
Re: Mann Lake (DMG Permit M-1982-147) Technical Revision No. I -Additional Support
Information
Dear Ms. Crosby:
In preparing for the upcoming MLRB Board Meeting on April 24, 2002 and in trying to address
the corrective action recommended by the Division as a result of the Division's site inspection on
February 27, 2002, we have had discussions and met with representatives of the Brantner Ditch
Company several times. The goals of the meetings were to present information on the actual
mining limits in the Pond 3 area on the Mann Lake property with respect to the Brantner Ditch
and to reach an agreement with the ditch company on the DMG "compensation" agreement,
because the actual mining face was within 200 feet of the ditch. At this time, there is every
indication that the ditch company will accept the compensation agreement, however, the ditch
Board will not decide on this issue until its next regular meeting early in May, after the Apri124
MLRB Board meeting.
As a fallback approach to address the corrective actions, Lafarge's civil consultant, Applegate
Group, Inc., was directed to perform a stability analysis using the actual mining advance with
respect to the Brantner Ditch (the shortest separation at approximately 140 feet). As part of the
analysis, a failure surface was forced to pass through the area of the ditch. The factor of safety
for this surface was nearly 1.8. The conclusion of the analysis is that the integrity of the
Brantner Ditch was not threatened by the mining advance being within 200 feet of the ditch.
Thank you, for your review of this information. Please call me at 303.657.4425 if you have any
questions.
Best Regards,
../'~~
Duane W. Bollig
Division Land Manager
Enclosures:
Slope Stability Report, Mann Lakes Tech Revision 1, Applegate Group, Inc., Apri12002
cc: Greg Lindsay Ian Smith
Jeff Schwarz file 4I6-430
WESTERN MOBILE DENVER, a Subsidiary of Lafarge Corporation
DENVER METRO AGGREGATE DIVISION
7400 W. 64th Ave., P.O. BOX 275001, Denver, Colorado 80227-0599
Office; [phone] Fax; [phone]