2018-05-31_REVISION - C1982056

• Permit No: C1982056
• IBM Index Class Name: Revision
• Doc Date: 5/31/2018
• Doc Name: Adequacy Review
• From: DRMS
• To: Twentymile Coal Company
• Type & Sequence: RN7
• Email Name: TNL
• Media Type: D
• Archive: No

RN07
Page 13
5/30/18

ii. OSM Height
iii. Pond Volume
iv. Primary outlet size of holes
b. Please submit an as built drawing of Pond F that includes a general plan and cross-section of the pond
that includes relevant elevations for:
i. Top of structure
ii. Top of standpipe
iii. Dewatering holes

Response: - Most of the sedimentation control structures currently used as part of the Foidel Creek Mine drainage
and sediment control system were designed, permitted, and constructed for the prior surface mining operations
(Energy Fuels Eckman Park Mines and Mines 1, 2, and 3), and were subsequently transferred into the Foidel Creek
Mine Permit along with the associated facilities and facilities areas. It is important to note that Pond F, and all of
the sedimentation structures (Ponds A through T, excluding I) associated with the Energy Fuels Eckman Par k Mines
and Mines 1, 2, and 3 were designed and permitted under the Interim Program Regulations (prior to approval of the
Colorado Program). As such, design information for these ponds may not be totally consistent with the current
regulatory requirements, however, unless the ponds have been modified they are “grandfathered-in”, so the existing
design information is considered adequate. Exhibit 13 is from the Eckman Park Mine Permit (C-1981-071), and is
provided as historical information. Subsequent work has identified some errors and discrepancies in the information
provided in this table. More recent and accurate design information for Pond F is provided by Exhibits 8I and 26.

DRMS Response May 2018
(a)There are inconsistent numbers for Pond F between Exhibit 8i and the pond schedule (Plate 1 of
Exhibit 8p). Sediment Volume in Exhibit 8i is shown as 1.03 acre ft and on pond schedule it is listed
as 13.6 acre ft. The pond schedule shows the OSM height to be 7.5 ft and there doesn’t appear to be
an OSM height in Exhibit 8i. The Total pond volume in Exhbit 8i is 2.24 acre ft and total pond
volume in the pond schedule is 39.2 acre ft. The size of the dewatering holes in Exhibit 8i is 2in and
the pond schedule shows 4 in. Please address these inconsistencies.

(b) Resolved (information is in the pond schedule Plate 1 of Exhibit 8P).

40. Please check Exhibit 8i against as built specifications and stage storage exhibits for all ponds and update all
values in Exhibit 8P where they differ from the as built design.

Response: - Please refer to the previous responses to Comments 37 and 39.

DRMS Response May 2018
Please update all values in Exhibit 8P where they differ from the as built designs.

41. Fish Creek Borehole Treatment Facility and associated fish creek settling ponds were modified in 2006 and
2007. Please address the following:
a. Please inform DRMS if the above mentioned modifications changed anything on the ground.
b. If the 2006 and 2007 modifications changed anything on the ground, please submit to DRMS updated
as-built drawings.