2014-07-16_REVISION - C1981010

• Permit No: C1981010
• IBM Index Class Name: Revision
• Doc Date: 7/16/2014
• Doc Name: 3rd Adequacy Review Meno ‎(emailed)‎
• From: Susan Burgmaier
• To: Jared Ebert
• Type & Sequence: PR7
• Email Name: JLE
• Email Name: SLB
• Media Type: D
• Archive: No

1313 Sherman Street, Room 215
Denver, CO 80203
July 16, 2014
To: Jared Ebert
From: Susan Burgmaier

Re: Trapper Mine (Permit No. C-1981-010)
Permit Revision No. 7 (PR-7)
Third Adequacy Review

Per your request, I have reviewed Trapper's response to Item 23 of our adequacy concern letters
for PR-7 at the Trapper Mine (C1981010). My concern has not been adequately addressed with
Trapper's response. Below is a summary of the information we will need from Trapper to address
the concern:
23. Trapper did not submit detailed designs for post-mining drainage channels, as required by Rules
2.05.3(4), 4.05.3(1), 4.05.3(1)(e), 4.05.3(7).

Trapper provided a description and general design for a generic channel,
and dozer basin diagrams, representing proposed post-mining drainage channels. Trapper
indicates (on proposed page 4-183d) that supporting documentation for its proposed check
dam configuration is available for review at the Trapper mine of
2.05.3(4)(a), this information must be submitted to the Division
application package. Rule 2.05.3(4)(a) requires that A general plan and detailed design plan
shall be submitted for each sediment pond, impoundment, other treatment facility and
diversion proposed to be constructed within the permit area. Please provide additional
details for each postmining drainage channel, to include the estimated discharge resulting
from the design event, and a calculation of whether the proposed
configuration will safely convey the design discharge with the r
(Rule 4.05.3(7)(b)). If Trapper elects to continue with the generic channel design, the typical
cross section provided on proposed page 4-183b must indicate that the depth will vary, and
the minimum depth for each drainage must be provided. Rules 4.05.3(1)(e) and 4.05.3(7)
address the requirements for stable channels, and require that channel linings shall be
using standard engineering practices. Please provide design information for the proposed
1313 Sherman Street, Room 215, Denver, CO 80203P 303.866.3567 F 303.832.8106http://mining.state.co.us
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