2014-04-03_REVISION - C1981008

• Permit No: C1981008
• IBM Index Class Name: Revision
• Doc Date: 4/3/2014
• Doc Name: Adequacy Letter
• From: DRMS
• To: TRI-State Generation & Transmission Association Inc
• Type & Sequence: TR63
• Email Name: RDZ
• Email Name: DIH
• Media Type: D
• Archive: No

DIVISION OF RECLAMATION, MINING AND SAFETY
Department of Natural Resources
1313 Sherman St., Room 215
Denver, Colorado 80203
Phone: [phone]
FAX: [phone]
STATE OF COLORADO
COLORADO
IDIVIS10N OF
RECLAMATION
MINING
SAFETY
April 3, 2014 John W. Hickenlooper
Governor
Chris Gilbreath Mike King
Executive Director
Tri -State Generation and Transmission Association, Inc.
P.O. Box 33695 Loretta E. Pineda
Director
Denver, CO 80233 -0695
Re: New Horizon Mine (Permit No. C- 1981 -008), TR- 63 adequacy
Dear Mr. Gilbreath:
We received your technical revision application (TR -63) regarding the trench drain to route spoil water around
prime farmland. Your application was deemed complete on March 31, 2014. The following issues have been
identified with the submittal, including proposed Permit Application Package (PAP) text, the proposed map, and
the SEDCAD documentation. Please provide an updated submittal and/or explanations for each item.
1. In the cover letter of the submittal there is a list of revised PAP materials, but it does not include the
proposed attachment. Is this an oversight?
2. In the updated Table of Contents for Section 2.05.3(3), the list of maps needs to be updated to include all
maps, including the proposed Map 2.05.3(3) -21.
3. The text should include a discussion on the amount of cover on the trench drain segments and how this
will prevent damage to the drains by reclamation equipment.
4. Regarding the text and Map 2.05.3(3) -21 in your submittal, please edit the confusing nomenclature (or
provide explanation) regarding the drains. Different terms are used: trench drain, rock drain, rock draw.
Are these terms interchangeable?
5. Please explain the basis for selecting rock sizes shown on Details A and B on Map 2.05.3(3) -21.
6. More detail is needed regarding the pipe connection at the lower ends of Segments A and B. Will a "T"
connection be used? Neither the text nor Detail C on Map 2.05.3(3) -21 provides this information. Also,
in Detail C why are there two colors of rock that appear to be the same size? Please elaborate on this
nexus.
7. On Map 2.053(3) -21 a text box pointing to the nexus of segments states that "Rock draw drains into
perforated pipe." Is this incorrect?
8. On Map 2.053(3) -21, Segments A and Bare shown approximately 15 feet from the highwall. However,
Detail A indicates that these features are located much closer. Please explain this discrepancy.
9. The spoil spring is not shown on Map 2.05.3(3) -21, although the proposed text indicates that this location
is shown on the map.
10. In the approved PAP, the surface water hydrology map showing post mine drainage areas (Map 2.053(3)-
1-2) indicates that the area that reports to Pond 013 is 82.9 acres. However, in the SEDCAD model
documentation in the TR -63 submittal, the drainage area is 38.11 acres. Please explain this discrepancy.
In general, more detail is needed regarding any changes (from the approved model) to the hydrology
inputs.
11. The approved design of Pond 013 indicates a capacity of approximately 14 acre -feet (at the bottom of
emergency spillway). The submittal, however, indicates a capacity of 29 acre -feet. Please explain this
discrepancy.
12. Please include an analysis of Pond 013 capacity that includes pumping from the NH2 Pit. This could be
done in SEDCAD, or it can be a separate analysis that includes inputs from the SEDCAD model as well
as information on the volume of water in the pond and estimated pumping rates.
Office of Office of
Mined Land Reclamation Denver • Grand Junction • Durango Active and Inactive Mines