2008-03-03_PERMIT FILE - C2006085 ‎(2)‎

• Permit No: C2006085
• IBM Index Class Name: Permit File
• Doc Date: 3/3/2008
• Section_Exhibit Name: 2.04 Information on Environmental Resources
• Media Type: D
• Archive: No

Projections of water level changes in the coal were made utilizing
common gr~~und water equations and the hydraulic properties
determined from previous analyses and published reports. The results
of these calculations indicate that the potential impact to the one well
potentially completed in the coal seam may range from 0 to 15 feet.
For wells not completed in the coal seam there is no significant water
level declinE: anticipated from the mine operations due to the lack of
hydrologic connection between the overlying Vermejo units and the
Ocean WavE~ coal seam. Further, the magnitude of potential impact
will decrease at distance from the mine area as illustrated in
Appendices 1 and 2. Due to the low permeabilities and the interbedded
nature of the Vermejo formation, water level impacts are projected to
not propagate far from the mine operations. The low permeability acts
to isolate water level changes to areas close to the mine.
The nearby water supply wells including residential wells have low
reported yiE~lds. The Northfield monitoring wells also have low
reported yiE~lds and the construction of a residential well recently
confirms lovv yields in the area. The nearby wells are completed in
shallower st:ratigraphic intervals within the Vermejo formation and
based on the geology and the completion interval information available
pertaining to the wells are very likely hydraulically isolated from the
Ocean Wave coal seam. The permeabilities of the Vermejo sediments
including the coal seam are very low. Based on information available
pertaining to the on-site monitoring well, geologic logs .and geophysical
logs there i<.~ little vertical seepage in this unit. The results of
drawdown calculations based on the hydrologic properties of the
Vermejo including the coal seam unit, there are no significant water
level changes projected in the intervals above and below the coal.
It is recognized that subsidence of the mine will result in localized
fracturing abbove the mine cavity. The rubble zone likely to form above
the mine is projected to be less than 100 feet and is projected to be
isolated to the area within the angle of draw. In order to determine the
potential for impacts to wells in and near the rubble zone, a drawdown
analysis anti well inventory were completed for wells in and near the
rubble zone. For the purposes of the analysis, it was conservatively
estimated that the rubble zone would extend 100 feet above the mine.
Projected water level drawdowns, as detailed in Appendices 1 and 2,
indicated that water level impacts are not expected to extend more
than 1000 feet beyond the angle of draw within the interval 100 feet
above the coal. There are no wells completed in either the rubble zone
or within th~~ 1000-foot drawdown radius within the stratigraphic
interval of the rubble zone. Accordingly, impacts to wells as a result of
fracturing from subsidence are not expected.
2.04-20 Revised 11/05/07