2014-05-12_PERMIT FILE - C2010089A ‎(3)‎

• Permit No: C2010089A
• IBM Index Class Name: PERMIT FILE
• Doc Date: 5/12/2014
• Doc Name: Protection of Hydrologic Balance
• Section_Exhibit Name: Section 2.05.6‎(3)‎
• Media Type: D
• Archive: Yes

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Conclusion DRMS concluded in its Decision and Findings of Compliance Document (1983) for
Peabody's New Horizon Mine that no alluvial valley floors exist in either the New Horizon
permit area or the potentially affected area (Tuttle Draw) associated with the New Horizon Mine.
The tributaries of Tuttle Draw and Coal Creek Canyon are developed on and have incised a dip
slope. The water in the drainages runs on top of weathered bedrock strata. The incised channels,
with perennial flow, make it infeasible to construct a gravity flow flood irrigation system. WFC
therefore concludes that no alluvial valley floors exist along the potentially affected area of
Tuttle Draw and Coal Creek Canyon and their tributaries. This conclusion is substantiated by the
results of an EPA alluvial valley floor study (EPA 1977) which addresses most coal mining areas
of the west and the fact that flood irrigation from drainages is not being practiced.
Hydrology Monitoring Plan WFC has developed a baseline hydrological monitoring program
for the NHN Permit area with the advice and consent of DRMS. This monitoring program will
continue for the foreseeable future and is proposed to be used with possible minor modifications
during the mining and reclamation operations. The monitoring program is described in
Appendix 2.05.6(3) -3 of this section 2.05.6(3).
B) PROBABLE HYDROLOGIC CONSEQUENCES
Previous mining by WFC at the New Horizon Mine and Peabody's experience while mining at
the old Nucla mine have provided the experience upon which the determinations of "Probable
Hydrologic Consequences" are founded. This experience is documented in the New Horizon 1
and New Horizon 2 permit documents and the "Annual Hydrology" reports. The knowledge
provided by the long term hydrologic monitoring in relation to the earlier baseline data allows
more accurate prediction of consequences than would otherwise occur. Peabody Coal Company
performed extensive and detailed computer modeling to determine probable hydrologic
consequences of mining for the New Horizon Mine. Details of the computer modeling are
available in Attachment 2.05.6(3) -2 of New Horizon 2 Mine permit. While some of the old
Peabody Nucla Mine monitoring was suspended in 1987, some of the monitoring holes and
surface water monitoring sites have been revisited (monitoring resumed in 1St quarter of 2007) as
part of the "2 year close out" for the New Horizon 1 permit area. Three "old" ground water
monitoring holes of particular interest that have been monitored during 2008 and 2009 include
GW -N3, GW -N8, and GW -N9.
Probable impacts and therefore probable hydrologic consequences have been identified (see
Attachment 2.05.6(3) -2 of the New Horizon 1 Mine Permit). A summary of the hydrologic
consequences is presented in Appendix 2.05.6(3) -2 of this section of the application as Table
2.05.6(3) -2a. This table incorporates new findings with the findings from both the New Horizon
#1 and #2 mine permits. These probable impacts were either determined to have no short or long
term significance, or a plan has been presented to mitigate those impacts determined to have
significance. Potential impacts to the hydrologic balance and the likelihood that these impacts
will occur are given below.
Section 2.05.6(3) Page 11 October 2013 (TR -05)
E: \New Horizon \DRMS \NHN Perm it \04 Technical Revisions TR \TR -05 \Documents from Jason \2.05.6(3) Protection of Hydrologic Balance TR- 05.doc