PERMFILE41947

• Permit No: C1980007A
• IBM Index Class Name: Permit File
• Doc Date: 4/8/2005
• Section_Exhibit Name: 2.05 Operation and Reclamation Part 2
• Media Type: D
• Archive: Yes

. augmentation plan (Exhibit 52). Losses within the mine are minor -less than 5 percent of
~ the total inflow which could be experienced. The decreed augmentation plan for the Dry
Fork basin conservatively provides replacement water for 100 percent of the yield of the
basin. The magnitude of replacement water provided by MCC in the Dry Fork/Minnesota
Creek basin is orders of magnitude more than will be required, based upon the subsidence
evaluation conducted by W WE with Messrs. Rold and Dunrud.
There is a very small risk (WWE has calculated the risk to be less than one percent that one
or more of the stock ponds in the Apache Rocks permit revision azea could be adversely
affected via surface cracks, This risk calculation also holds for the Box Canyon permit
revision area. Pond water could be diverted into locally permeable zones within the
overburden where it could: (1) migrate down-dip towazd the North Fork or Dry Fork to
become part of the tributary alluviaUcolluvial contribution of baseflow to the stream system,
(2) reappeaz as an ephemeral seep or spring, or (3) become strapped as storage in an isolated
zone within the overburden. If any of these circumstances were to occur, they would render
the affected stock pond temporarily useless for retaining surface water. However, the lost
water would eventually return to the Dry Fork and/or North Fork. The stock pond
embankments could conceivably be effected by surface cracking; although, the probability
of this occurring is insignificant.
It is important to note that the overburden materials in the permit area contain numerous shale and
claystones layers and lenses which tend to undergo plastic deformation under compression, thereby
• sealing fractures which develop. In addition, the sediment load within surface flows (especially
during spring runoff) will tend to fill surface cracks which may develop, thus further reducing the
potential to transmit water downward.
The most severe subsurface hydrologic consequences include:
Formation of interconnected fractures in the fracture zone with local water-bearing units of
the overburden, thereby inducing either: (1) the movement of groundwater from one
formation to another or (2) loss of water to the mine workings. Should diversion to the mine
occur, this water will be collected, treated, and dischazged into the North Fork or the Dry
Fork (see discussion above regarding the implications ofi surface water dischazges to the
North Fork and Dry Fork).
As discussed extensively within this permit document, there are no regional aquifers within
the Mesauerde Formation in the vicinity of the West Elk Mine, nor is there demonstrated
formation groundwater use at the mine or in the general area. Consequently, there aze no
aquifers which could be damaged as a result of subsidence: While there has been a sizeable
amount of groundwater inflow observed from recently ericountered fault systems (B East
Mains and 14SE Headgate) there is no evidence to indicate any use of that water regionally.
In addition, the observed inflows from these fault systems have decreased over time to a
small percentage of the initial inflows, similar to other groundwater encounters in the mine.
• Interconnection of fractures filled with water and methane: (as reported in the Oliver No. 2
• Mine) with the mine workings via the B-Seam fracture zone. This subject is discussed later
in this section and in Exhibit 60.
2.05-109 March IOOSPRI! ~ 1L D!7