2008-06-09_PERMIT FILE - C1980007 ‎(6)‎

• Permit No: C1980007
• IBM Index Class Name: Permit File
• Doc Date: 6/9/2008
• Doc Name: Exhibit 79 Part 2
• Section_Exhibit Name: Exhibit 80 Drilling Activities - TR111
• Media Type: D
• Archive: No

Response to Commenfs
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C:
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Table 5-1
DEIS Comments and Responses
Commenter Comment Comment/Response

and monitoring on disturbance areas within the MCC's permit area. The
GMUG experience with noxious weed management in this particular area
indicates that consistent application of approved herbicides is effective at
controlling the noxious weed infestations.
Western Slope 4 WSERC has had several conversations with mine managers about alternate
Environmental methods of venting methane that would not require road construction, and we
Resource Council are aware that the mine has tried interior vent systems, which failed,
considered directional drilling, which is not feasible because of the shallow
overburden, and considered helicopter delivery ofwell-drilling equipment so
as to avoid road construction.
RESPONSE: The FEIS has been changed to reflect in snore detail the various
methods of methane management employed by the mine. See Chapter 2
Alternatives Considered but Eliminated from Detailed Study.
Western Slope 5 For due diligence, we believe that the EIS should explicitly analyze these and
Environmental other options that avoid road construction.
Resource Council RESPONSE: See WSERC Comment #4.
Western Slope 6 In places, the draft EIS makes assertions that are not backed up by data or
Enviromnental explanation. For example, there is a section on page 31 that states "in places
Resource Council the overburden is not thick enough that directional drilling either from outside
the IRA is practical or possible" (sic). We would like to see more analysis
presented, including numerical descriptions of the depth of overburden and an
analysis of tecluiical limitations on directional drilling that preclude its use
given the depth of overburden.
RESPONSE: According to MCC's experience drilling directionally in the B
seam (project file); directional holes must be drilled such that the producing
part of the well above the seam is vertical. This distance was approximately
250 feet in the B seam methane drainage wells and is projected to be 150 feet
minimum in the E seam methane drainage wells. If such holes fail to achieve
vertical in this portion of the well, they are subject to collapse and ineffective
as degas holes.
The maximum safe angle of drilling (above this minimum vertical section)
that can be achieved by the drilling equipment available is 45 degrees. The
drill mast is set at 45 degrees to begin the holes. This angle must be gradually
corrected to vertical during the drilling process.
The maximum allowable dog-leg in directional drilling is 4 percent, in order
to be able to successfully install casing in the hole.
Given the parameters of overburden depth (1,000 feet for the E Seam), as it
relates to physical constraints of directional drilling, MCC is unable to reach
the required methane drainage targets from outside the roadless boundary.
Chapter 2, Alternatives Considered but Eliminated from Detailed Study of the
FEIS includes this information.
Western Slope ~ In places the draft EIS makes assertions that are not backed up by data or
Enviromnental explanation.... Another example is the statement on page 31 [DEIS] with
res ect to horizontal boreholes that "these es of boreholes alone are
Deer Creek Ventilation Shaft and E Seam Methane Drainage Wells FEIS
161