2007-01-30_REVISION - M1987028

• Permit No: M1987028
• IBM Index Class Name: Revision
• Doc Date: 1/30/2007
• Doc Name: Second Geotechnical Adequacy Review
• From: DRMS-acs
• To: DRMS-esc
• Type & Sequence: CN1
• Media Type: D
• Archive: No

STATE OF COLORADO
DIVISION OF RECLAMATION, MINING AND SAFETY
Department of Natural Resources
1373 Sherman St., Room 215
Denver, Colorado 80203 C O L O R A D O
Phone: [phone] DIVISION o r
RECLAMATION
FAX: [phone] MIN [ N G
- ~-
SAFETY
DATE: January 30, 2007 /^ Bill Owens
Governor
TO: Erica Crosb
y Russell George
Executive Director
Ronald W. Cottony
FROM: Allen Sorenson Division Director
Natural Resource Trustee
RE: Second Geotechnical Adequacy Review, Colorado Marble, L.L.C., L ily Mines,
Conversion Application CN-Ol, Permit No. M-1987-028 ~/
r/
The Division of Reclamation, Mining, and Safety (DBMS) engineering staff have reviewed the following
documents:
Letter dated October 12, 2006 from the Operator's representative Azurite, Inc. to DBMS with the
subject line "Response to Geotechnical Adequacy Review June 1, 2006"
Revised permit conversion application for the Lily Mines received at DBMS on December 12,
2006.
Based on the review, DBMS has determined that the following geotechnical issues remain to be resolved
prior to approval of the application.
1. The Operator commits to maintain a ground configuration that will route any overtopping flows
from the lower pit to Taylor Gulch on bedrock (item 2.a.iv in the October 12, 20061etter). This is
an important permit condition that should be checked each time that DBMS inspects this operation.
If the Operator determines that routing these potential flows on bedrock is not feasible at any point
in the life of the quarry, they must file a technical revision with a design for a channel that will
non-erosively pass the 100-year flows from the lower pit to Taylor Gulch.
2. The Operator is proposing the option for installation of a sediment pond at the southeast corner of
the affected land. The pond will be 100 feet x 100 feet and no deeper than eight feet. What are not
clear in the Operator's application, is what the storage capacity of the pond will be, whether the
pond will be impounded by an embankment or will be incised or a combination of both, and
whether or not any overtopping flows from the lower pit would be intercepted by the sediment
pond. These issues must be clarified before the DBMS can evaluate the proposed pond option.
3. The Operator states that routing of upgradient water into the lower pit is a longstanding practice.
As a result, any Clean Water Act liability that this practice may create, as discussed in the DBMS
memo dated June 1, 2006, has already occurred, rendering this issue moot.
4. The current lower pit configuration provides storm water storage capacity of approximately I O
acre-feet. As mining progresses, the Operator will expand this capacity to 35 acre-feet. In the
interim, the Operator estimates that the 10 acre-foot capacity is about half of the volume that would
report to the lower pit after a 10-year, 24-hour storm. The Operator has observed that water
entering the lower pit rapidly infiltrates, and reasons that rapid infiltration would eliminate or
diminish spilling from the pit during a 10 year event, and also states that rapid infiltration assures
Office of Office of
Mined Land Reclamation Active and Inactive Mines