2010-02-22_REVISION - C1981022

• Permit No: C1981022
• IBM Index Class Name: REVISION
• Doc Date: 2/22/2010
• Doc Name: Adequacy Review
• From: DRMS
• To: Oxbow Mining, LLC
• Type & Sequence: TR66
• Email Name: MPB
• Media Type: D
• Archive: No

STATE OF COLORADO
DIVISION OF RECLAMATION, MINING AND SAFETY
Department of Natural Resources
1313 Sherman St., Room 215
Denver, Colorado 80203
Phone: [phone]
FAX: [phone]
February 22, 2010
COLORADO
D I V I S I O N OF
RECLAMATION
MINING
SAFETY
James A. Kiger
Environmental Manager Bill Ritter, Jr.
Govemor
Oxbow Mining, LLC Harris D. Sherman
P.O. Box 535 Executive Director
Somerset, CO 81434 Ronald W. Cattany
Division Director
Natural Resource Trustee
Re: Elk Creek Mine, Permit No. C-1981-022, Oxbow Mining LLC (OMLLC)
Technical Revision No. 66 (TR-66), Gob Vent Borehole Sealing
Dear Mr. Kiger:
The Division of Reclamation Mining, and Safety (Division) has reviewed the above referenced
technical revision application materials submitted for the proposed change to the procedures for
sealing gob vent boreholes. On revised page 2.05-69a OMLLC proposes to revise the permit text
with the following; "Gob vent boreholes consist of a steel casing already cemented in place and
will be sealed with a plug at least 10 feet from the surface and then sealed with cement to the
surface." No other information was provided regarding the revised procedures for gob vent
borehole abandonment. The Division has the following adequacy review comments regarding
the proposed plan.
1. At a minimum, all drill holes must be abandoned in accordance with Rule 4.07.3. If the
gob vent borehole is completed through an aquifer(s), then sealing must be completed in
accordance with Rule 4.07.3 (2) and the entire depth of the blank casing should be sealed
using cement (from the bottom to within 10 feet of the surface). Please demonstrate that
each borehole to be sealed is not completed to an aquifer(s) and add this information to
the permit application package (PAP) under the Measures for Sealing, Plugging, and
Managing Mine Openings and Boreholes section.
2. In accordance with 4.07.3(1) If no aquifer is present, the well shall be sealed by replacing
a suitable media in the hole and placing a suitable plug 10 feet below the ground surface
to support a cement plug to within three feet of the ground surface. Sealing by a surface
plug only may be approved on a case by case basis where both physical and chemical
properties of the formation allow.
OMLLC has proposed sealing all gob vent boreholes with a surface plug only, therefore
please provide the Division with suitable demonstration(s) that the subsurface conditions
and the physical and chemical properties of the formation(s) allow for plugging with a
surface plug only. The Division will evaluate the adequacy of the demonstrations before
allowing sealing of gob vent boreholes by surface plug only.
Office of
Mined Land Reclamation Denver • Grand Junction Durango Office of
Active and Inactive Mines