2012-05-11_PERMIT FILE - C1981033 ‎(3)‎

• Permit No: C1981033
• IBM Index Class Name: Permit File
• Doc Date: 5/11/2012
• Section_Exhibit Name: Rule 2.05 Operation and Reclamation Plans
• Media Type: D
• Archive: No

• 2.05.6(3) Protection of the Hydrologic Balance
Water could eventually accumulate in the mine workings and result in mine water flow through the
coal seams into the North Fork of the Gunnison River. Although the operator does not believe either
the B -Seam or the C -Seam will become totally inundated with water, a worst case analysis was
prepared to estimate the seepage from the coal seams. Darcy's Law was utilized to estimate the
seepage from the coal seams as follows:
Area =hxL
K is from MCC's TR -080 documents and provides a range of seepage rates.
Bear's existing discharge permit provides for the discharge of mine water directly to the North Fork
of the Gunnison River through outfall 001. The mine water discharge initially flowed at
approximately 20 gpm. As of April 1998, the flow increased to about 35 gpm. In order to account
• for additional flow from the mine, it will be assumed that the mine water flow equals 50 gpm. The
maximum measured TDS value for the mine water is 4090 mg/l. This TDS value will be utilized for
the mine discharge and the mine seepage. The total worst case mine seepage is calcualted above and
totals 17.0 gpm. The range in estimated outcrop seepage from the B -Seam and C -Seam is 1.4 to 17
gpm.
According to data supplied by the USGS, the annual seven day minimum flow for the North Fork of
the Gunnison River is 25 cfs. This low flow value occurred February 17, 1978, is for the period of
record from 1934 through 1995 and is measured upstream of the Town of Somerset, CO.
As shown above, the total flow through the alluvium is 136 gpm. Of that total flow, approximately
41 gpm is subject to contamination from the coal stockpile area. The quality of the contaminated
water should be similar to the water quality in well AA -1. For the period of 1987 though 1996, the
maximum TDS measured in AA -1 was 2890 in 1995.
The maximum TDS measurement at the upstream North Fork of the Gunnison River monitoring
station during 1997 was 120 mg/I. The following table presents the estimated affect the mine
discharge, mine outcrop seepage and alluvial flow will have on the quality of water in the North Fork
of the Gunnison River:
• 2.0i -5 ici Rev. 7/98
Darc 's Law Q =Kia
Flooded
Working
K -cm /sec
H - Head
w - width
h -
Seam
L -
Oulcrop
I-
H/w
Q - GPM
of coal
illar
Hei ht
Len th
B Seam
4 X 108
30
309
20
4223
0.1
0.5
B Seam
5X10'
30
309
20
4223
0.1
6.0
C -Seam
4 X 10-0
75
159
8
3964
0.47
0.9
C Seam
5 X 10'5
1 75
159
8
3964
0.47
11.0
Area =hxL
K is from MCC's TR -080 documents and provides a range of seepage rates.
Bear's existing discharge permit provides for the discharge of mine water directly to the North Fork
of the Gunnison River through outfall 001. The mine water discharge initially flowed at
approximately 20 gpm. As of April 1998, the flow increased to about 35 gpm. In order to account
• for additional flow from the mine, it will be assumed that the mine water flow equals 50 gpm. The
maximum measured TDS value for the mine water is 4090 mg/l. This TDS value will be utilized for
the mine discharge and the mine seepage. The total worst case mine seepage is calcualted above and
totals 17.0 gpm. The range in estimated outcrop seepage from the B -Seam and C -Seam is 1.4 to 17
gpm.
According to data supplied by the USGS, the annual seven day minimum flow for the North Fork of
the Gunnison River is 25 cfs. This low flow value occurred February 17, 1978, is for the period of
record from 1934 through 1995 and is measured upstream of the Town of Somerset, CO.
As shown above, the total flow through the alluvium is 136 gpm. Of that total flow, approximately
41 gpm is subject to contamination from the coal stockpile area. The quality of the contaminated
water should be similar to the water quality in well AA -1. For the period of 1987 though 1996, the
maximum TDS measured in AA -1 was 2890 in 1995.
The maximum TDS measurement at the upstream North Fork of the Gunnison River monitoring
station during 1997 was 120 mg/I. The following table presents the estimated affect the mine
discharge, mine outcrop seepage and alluvial flow will have on the quality of water in the North Fork
of the Gunnison River:
• 2.0i -5 ici Rev. 7/98