2018-04-02_REVISION - C1982056

• Permit No: C1982056
• IBM Index Class Name: Revision
• Doc Date: 4/2/2018
• Doc Name: Adequacy Review Response
• From: Twentymile Coal, LLC
• To: DRMS
• Type & Sequence: RN7
• Email Name: TNL
• Media Type: D
• Archive: No

c. Please inform DRMS if cross-section drawings exist for Area I Pit Temporary Water Storage Basin;
and if they exist where in the permit they are located.
d. If there are no cross-section drawings for Area I Pit currently in the permit please submit drawings
to DRMS.
e. Also, please make sure all design information in the permit pertaining to rule 2.05.3(4) reflects the
most recent updates and changes to all ponds, impoundments, diversions and treatment facilities and
associated spillways and culverts.
f Please submit to DRMS any updated design, as built drawings and SedCad results that pertain to
bringing Section 2.05.3 up to date to accurately reflect the infrastructure that is "on the ground" at
Foidel.
Response: - The 6MN Mine Water Storage Reservoir was approved under TR07-61. The TR submittal included
revised TOC pages, including page vi, which shows Exhibit 8CC (copies attached). Design drawings for the
6MN Reservoir are included in Exhibit 490. The Area 1 Temporary Water Storage Basin is part of the last open
cut remaining from the previous surface mining activities, and was originally used as a storage area for low -
quality coal, prior to construction of the original Foidel Creek Mine Coal Preparation Plant. With construction of
the original Coal Preparation Plant in 1995, the low -quality coal was removed and processed, and the Area 1 Pit
was converted to a temporary water storage basin to support mine and plant operations. The Area 1 Pit was
designated and approved as a mine impoundment under TR05-47. Design documentation for the Area 1 Pit is
provided in Exhibit 8v, including the drawing and stage -storage curves for this impoundment (Figure EX8V-1).
For any drainage structure that has been modified, a revision including revised design information was submitted
and approved, as summarized in the response to Comment 37.
2.05.4 — Reclamation Plan
45. Section 2.05.4(2)(C) portal area section indicates that the design details for upland diversions depicted on
Map 25 are located in Exhibit 8-R. It appears these designs are located in Exhibit 8N. Please revise this
page accordingly.
Response: - The referenced permit text sections have been reviewed and any erroneous references corrected.
Copies of any revised text pages accompany these responses for replacement in the PAP.
46. Map 31, Post -Mining Topography Map only depicts the postmine topography of the main portal facilities
area. Rule 2.05.4(2)(C) requires a postmining contour map and appropriate cross-sections that are typical
and representative of the anticipated character of the final surface configuration of the proposedpermit area.
Please provide postmining contour maps that depict the postmine configurations of all of the surface
disturbed areas.
Response: - Facilities disturbances outside of the main portal/facilities area are generally pad areas, which are
limited in size and do not vary significantly from the original terrain. At each of these locations, the pads have
been constructed using cut/fill construction methods, with no imported or exported material. Reclamation will
involve regrading the existing material to blend with the surrounding terrain and promote effective site drainage.
To date and given these considerations, the CDRMS has not required detailed postmining configuration drawings
or cross-sections for these limited disturbance activities. For reference, design drawings reflecting cut/fill
construction and by direct reference, the reverse action of regrading, are provided for the following outlying
facilities areas; 5MN Cement Borehole (MR14-283, Ex 49AA); 16LT Utility Borehole (TRI 1-78, Ex 49Z); 18LT
Ventilation Shaft Installation (TR06-66, Ex 49R); 6MN Mine Water Storage Reservoir (TR07-61, Ex 490); 6MN
Ventilation Shaft Installation (TR05-48, Ex 49A); 18RT Intake Shaft (TR04-44, Reclaimed).
47. Page 2.05-108 indicates the depth of topsoil placement is shown on Map 29. This information is not depicted
on Map 29. Please update Map 29 to depict the depth topsoil will be placed over the reclaimed areas.
Response: - As discussed in the previous response to Comment 36, soil depths can be highly variable, depending
on a number of factors. The reality of soil removal/replacement operations in the field, is that TC attempts to
recover all reasonably available and suitable soil material from new disturbance areas, and places these materials
in stockpile for later replacement during the reclamation process. Soil replacement operations and depths are,
therefore, limited to the stockpiled soil materials that are available. Table 49a, Topsoil Stockpile Summary,