2015-10-14_REVISION - C1981019 ‎(2)‎

• Permit No: C1981019
• IBM Index Class Name: Revision
• Doc Date: 10/14/2015
• Doc Name: Adequacy Item 1 to 86
• From: DRMS
• To: Tri-State Generation and Transmission Association, Inc
• Type & Sequence: PR4
• Email Name: RDZ
• Email Name: JRS
• Media Type: D
• Archive: No

Chris Gilbreath
Page 7

The deeper horizons are notably high in Arsenic, with a maximum value of 39.8 ppm (compared
to the WY DEQ criteria of <2.0 ppm).

The deeper horizons also have elevated levels of Sodium, as indicated by the high SAR values.

In summary, the data provided are not sufficient to adequately characterize the material that will be
disturbed by the proposed Collom pit. The analysis, as currently presented, underestimates the proportion
of material that fails to meet the suitability criteria.

Please revise table 2.04.6-5 to better reflect the content of the Wyoming DEQ reference cited.
a.
Please present additional data that will allow more adequate characterization of the overburden
b.
material in the Collom pit; pursuant to rule 2.04.6(2)(b)(ii) the Division suggests an initial
spacing of one hole per 80 acres.

Please revise Exhibit 6, Item 9; Tables 2.04.6-6 and -7; and the text of Volume 15, Rule 2, Pages
c.
15-18 accordingly.

In the process of addressing items b. and c., please be specific about which horizons will be
d.
handled selectively and how that will be accomplished.

ITEM 71. In volume 1, some of the footer information gives the permitting action revising those pages
Please change the footer to refer to PR-04 throughout.
as PR-06.

ITEM 72. In Volume 15, Rule 2, Page 14, it is stated that “The stratigraphic thickness of the Williams
Fork Formation in the Colowyo revised permit area is about 1,700 feet.” Later, on Page 19, it is stated
that “The overlying Williams Fork Formation consists of up to about 1,200 feet of alternating beds of
Please resolve the apparent inconsistency concerning
sandstone, sandy shale, mudstone, and coal.”
the thickness of the Williams Fork Formation, (see also Rule 2, Page 21).

ITEM 73. Two faults are described in Volume 15, Rule 2, Page 21, but are not shown on Map 7A (or
Please draw the faults on Maps 7A and 10B. Please also update the text of section 2.04.6
Map 10B).
to include a description of these faults.

ITEM 74. Under the subheading “Groundwater Occurrence”, in Volume 15, Rule 2, Page 21, the text
refers to bedrock and valley fill monitoring wells relevant to PR-4 presented in Table 2.04.7-38. This
table contains 34 wells, whose locations are mapped on Map 10B. Several questions relate to the table:
The MWC-04-05 wells are marked on the map as MWC-04-05FS and MWC-04-05FG. The
a.
table also has a MWC-04-05H, but this is not shown on the map. Please clarify and update
either the map or the table accordingly.

The map shows a well that is marked C-04-16. The table shows a well named C-04-16B. Please
b.
clarify.

The map shows a well that is marked MWC-05-33. This well is not in the table. Please clarify.
c.
The table contains 11 wells that are named “DHxxx.” None of these are shown on the map.
d.
Please clarify.