2009-04-10_REVISION - M1978222UG

• Permit No: M1978222UG
• IBM Index Class Name: REVISION
• Doc Date: 4/10/2009
• Doc Name: Review of storm water controls
• From: Russ Means
• To: Allen Sorenson
• Type & Sequence: CN1
• Email Name: GRM
• Media Type: D
• Archive: No

STATE OF COLORADO
.DIVISION OF RECLAMATION, MINING AND SAFETY
Department of Natural Resources
1313 Sherman St., Room 215 COLORADO
Denver, Colorado 80203 DIVISION OF
RECLAMATION
Phone: [phone]
FAX: [phone]
RECE7 MINING
- &-
SAFETY
APR 17 2009
Bill Ritter, Jr.
Division o1 Reclamation, Governor
/ Miring and Safety Harris D. Sherman
cutive Director
E
DATE: April 10, 2009 xe
/ Ronald W. Cattany
I/
TO: Russ Means Division Director
Natural Resource Trustee
Allen Sorenson'
FROM
:

RE: Review of Storm Water Corols, Nuvemco, LLC, Monogra Mines,
Permit Conversion CN-01, ??Permit No. M-1978-222-UG
The following items remain to be addressed relative to proposed storm water controls pertaining to the above
referenced application.
The Division concurs with the selection of the design storm events as the basis for storm water controls for the
mine staging area, but has determined that the design basis for the ore storage area must be increased to the 100
year/24 hour plus the 10 year/24 hour precipitation. The discussion of containment for runoff from the ore storage
area indicates that a decision has not yet been made on whether to install a lined pond or a pre-fabricated vessel.
In either case, no designs or specifications for lining or vessel construction have been provided. The Operator may
either decide now on the type of containment to be used, and submit designs and specifications for review, may
submit designs and specifications for both options, or may defer the submittals to later. If the submittals are
deferred, then the designs and specifications must be provided as a future technical revision to the permit, and
storage of ore at the surface would not be allowed until the technical revision is approved.
The detention pond for runoff from the staging area is designed with 1:1 side slopes. The Division will require that
the pond designs be redone with side slopes no steeper than 2:1. The designs for this pond indicate that the outfall
will be fenced for wildlife protection; it must be clarified that the entire pond will be fenced, and the fencing to be
installed must be described. There is no design provided for the proposed outfall; a design and its basis must be
provided to include dimensions, rip rap sizing and bedding, and rip rap soundness criteria.
Rule 6.4.20(10) requires that certain storm water controls for this type of mining operation be described through
design specifications certified by a licensed professional engineer. The design specifications when re-submitted
considering the above listed issues, must be re-certified by an engineer licensed to practice in Colorado.
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