2011-05-18_PERMIT FILE - C1981012 ‎(2)‎

• Permit No: C1981012
• IBM Index Class Name: Permit File
• Doc Date: 5/18/2011
• Doc Name: PROBABLE HYDROLOGIC CONSEQUENCES OF MINING
• Section_Exhibit Name: Exhibit 08.4 Probable Hydrologic Consequences of Mining on the Allen & Apache Coal Seams
• Media Type: D
• Archive: No

Probable Hydrologic Consequences New Elk Mine 5
The historic sulfur content of the coals from the Maxwell, Apache, and Allen seams is low, with average
values ranging from 0.47 to 0.84 percent (Table 1). A sulfur form analysis for the Allen seam by
Commercial Testing and Engineering in 1981 indicated that the total sulfur content of the coal was 0.49
percent, of which 0.06 percent was pyritic and 43 percent was organic. These results are consistent with
analyses of core from the 2010 exploration drilling program and indicate average total sulfur contents
ranging from 0.52 to 0.53 percent, and pyritic sulfur contents ranging from 0.02 to 0.04 percent for the
Blue, Maxwell, Apache, and Allen coal seams (Table 2). These values are low and are typical of the upper
freshwater swamp delta environments in which the seams were deposited. Visible pyrite was uncommon in
the examined cores. Given that pyritic sulfur is the species of principal concern with regard to the
formation of acid rock drainage (ARD) and spontaneous combustion, the analyses from 1981 and 2010
indicate very little potential for the material to generate acidic seepage or auto ignite. Mines in the area
including the Allen and New Elk Mine have had a long history of production and have not had problems
with ARD or spontaneous combustion of coal stockpiles and refuse.
Table 1. Average Analyses for Coal from Commercial Testing and Engineering 1981
Seam
Volatile Matter
Fixed Carbon
Ash
Sulfur
0.08
Apache
0.14
0.25
Maxwell
Allen
32.81
42.77
24.41
0.47
Apache
35.48
51.62
34.50
0.84
Maxwell
33.38
63.19
23.43
0.51
Table 2. Average Sulfur Analyses for Coal from the 2010 Exploration Drilling Program
(1.4 float fraction, arb)
Seam
Pyritic Sulfur
Sulfate
Organic
Total
0.08
Apache
0.14
0.25
Maxwell
Allen
0.04
<0.01
0.48
0.52
Apache
0.03
<0.01
0.49
0.52
Maxwell
0.03
<0.01
0.51
0.53
Blue
0.02
<0.01
0.51
0.53
Sedimentary Rocks immediately above and below the coal seams consist of interbedded sandstone,
siltstone and mudstone. Lens - shaped, sandstone - filled, paleochannels occupy areas between coal beds and
contribute to local zones of interburden thickening. Paleochannels overlie coal seams locally and form
sandstone tops. Strata below the Allen seam, the lowest coal bed of mining interest, consist of alternating
layers of mudstone, siltstone, sandstone and thin coal. The base of the Raton Formation is a conglomerate
that may rest either conformably or unconformably on the Vermejo Formation (Watts, 2006a). The rocks
of the roofs and floors for the four coal seams of mining interest have low sulfur content which indicates
that they are not likely to generate ARD (Table 3).
Table 3. Average Sulfur Analyses for Roof and Floor Rocks from the 2010 Exploration
Drilling Program (1.4 float fraction, arb)
Coal Seam
Roof S ( %)
Floor S ( %)
Allen
0.11
0.08
Apache
0.14
0.25
Maxwell
0.20
0.10
Blue
0.08
0.20
4164A.110421 Whetstone Associates •
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