PERMFILE109397

• Permit No: C1981022
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Doc Name: 1990 SOMERSET MINE INFLOW STUDY AND MAPS
• Section_Exhibit Name: Exhibit 2.04-E4 Part 5
• Media Type: D
• Archive: No

Mine Inflow Study, Page 2
3. A planimeter was used to calculate the area mined be-
tween the water level contours.
4. It was assumed that mains were developed with a mining
height of 8 feet and an average of 36% of the coal was extracted
from the mains. Eighty foot square pillars on 100' centers
leaves 6400 S.F. of coal in place for each 10,000 S.F. mined
which yields a 36% recovery.
5. It was assumed that panels were developed with a mining
height of 10 feet and 75% of the coal was extracted.
6. It was assumed that the recent dry weather in the area
will not effect the projected mine inflow rates.
B-6 Area
The water level in the B-6 Area rose from elevation 5958.2
to 6035 from October 1987 to August 1990. This equates to a rate
of increase in water level of 76.8 feet in 34 months or 2.3 feet
per month.
Table 2 shows the estimated water inflow in the B-6 Area.
It was calculated that this area Pilled at the rate of 185 gpm
from October 1987 to August 1990. The water level in this area
should peak at elevation 6060. Assuming an inflow rate of 175
gpm, the B-6 Area should reach its maximum water level during the
second quarter of 1991 in about 8 months. This equates to a rate
of increase in the water level of 3.0 Peet per month.
At a peak elevation of 6060' the B-6 Area will overflow to
the Area East of B-6. This area is believed to be connected to
the alluvium through old mine workings to the east which will
allow the mine water to eventually flow to the Gunnison River.
H-10 Area
The water level in H-10 rose from elevation 6017.5 to 6028.3
from July 1986 to May 1987. From May 1987 until October 1988 the
water level in H-10 was virtually constant because water from the
area was apparently filling the 4 Dip Area. In June 1989 the
water level in H-10 showed its first significant increase in 24
months. Since June 1989 the water level in H-10 has risen from
elevation 6032.2 to 6052.8, 20.6 feet, in 14 months or 1.5 feet
per month.
Table 2 shows the estimated water inflow in the H-10 Area.
It was calculated that this area filled at the rate of 52 gpm
from October 1989 to August 1990. The water level in this area
should peak at elevation 6100. Assuming an inflow rate of 50
gpm, the H-10 Area should reach its maximum water level, during
the fourth quarter of 1991, in about 14 months. This equates to
a rate of increase in the water level of 3.3 feet per month.