2013-10-21_REVISION - C1992080

• Permit No: C1992080
• IBM Index Class Name: Revision
• Doc Date: 10/21/2013
• Doc Name: Adequacy Review No. 2
• From: DRMS
• To: Goff Engineering & Surveying, Inc.
• Type & Sequence: TR17
• Email Name: MLT
• Email Name: SB1
• Email Name: SLB
• Media Type: D
• Archive: No

R Harries, Goff Engineering
C -1992 -080 TR -17 PAR Igo. 2
21 -Oct -2013
Page 2 of 5
Six revised maps: C1.0 (Post - Mining Topography), C1.1 (Carbon Junction Drainage
Basins), C1.3 (Permanent Diversion As- Built), CIA (Upper Carbon Junction Profile),
C 1.5 (Permanent Diversion Cross Sections), and C2.0 (Channel Improvement Plan).
The Division has reviewed the revised information for adequacy with respect to the Rules. Our
comments are provided below; the original numbering of the various items has been retained, for
consistency.
Adequacy Comments
1. DRMS 10/21: Inconsistencies remain between various sections of the permit document,
as currently approved, and the as -built and design information submitted under TR -17.
Given the limited time available to complete the repairs to the Carbon Junction Channel
(the abatement deadline is Nov. 22, 2013), the Division proposes the following course of
action:
Concurrent to the TR -17 application and review process, the Division and Oakridge have
been .moving through the Permit Renewal No. 4 (RN -04) application. In order to
expedite TR -17, all revisions to the current permit sections will be accomplished under
RN-04. For TR -17, please make the following formatting modifications, which will
allow the new materials to be incorporated cleanly into the permit:
The TR -17 materials will become a new "Appendix 5 -12 "for insertion into the permit
application package. Currently, the data provided is separated into three Appendices:
A, B, and C. In order to avoid confusion, please do not name the subparts
"Appendices': Rather, provide names that inform the reader what is provided with
each, e.g. A - Carbon Junction Permanent Diversion As- Built; B - Upper Carbon
Junction Channel; and C - Unnamed Tributary.
It would be appropriate to provide text for Appendix 5 -12 that will be inserted ahead of
the subparts A -B -C. This text (not in the form of a letter to the DRYS) will describe
what is provided in the appendix, and include references to the subparts and maps.
2. DRMS 09/20: The 14EC -RAS output data provided by Goff Engineering and Surveying,
Inc. appears to indicate that several segments of the Carbon Junction Permanent
Diversion are not adequately sized for the design event. For all of the segments except
16 +00, it appears that the required top width of the channel at the design flow water
surface elevation is wider than the rip rap lined portion of the ditch as constructed.
DRMS independently ran a SEDCAD utility to size the channel segments, verifying that
the required flow cross sectional area exceeds the constructed channel dimensions.
Please review the HEC -RAS table and verify the required top widths for the channel
segments. Where the required top width / flow area exceeds the channel capacity (rip
rapped portion) as constructed, Oakridge Energy will need to redesign and reconstruct the
channel and/or extend the channel lining to accommodate the anticipated runoff volume
and prevent scour along the sides of the channel (Rules 4.05.4(2)(a) and (b)).
DRMS 10 /21: This item is resolved. The October IS application did not provide the
information in a form which clearly demonstrated that the existing permanent
diversion would safely convey the design flow with the required freeboard, but the