PERMFILE107555

• Permit No: C1982057
• IBM Index Class Name: Permit File
• Doc Date: 12/5/2005
• Section_Exhibit Name: Tab 17 Probable Part 2
• Media Type: D
• Archive: No

Wadge overburden aquifer. L=[2582 mg/I]x[2613 gal/daylx[4.77x10"9]=0.028 tons/day
Wadge coal aquifer: L=[815 mg/1]x[1241 gal/day]x[4.17x10-91=0.0042 tons/day
TOTAL: L = [0.028 tons/day] + [0.0042 tons/day] = 0.032 tons/day
The maximum pit inflow for mining in the Sage Creek/Wolf Creek area is predicted for year 2010. The
year 2010 Sage Creek and Wolf Creek ground water system inflow is estimated at 1,376 gal/day
(0.002 cfs). Chemistry data were collected from the Sage Creek/Wolf Creek mining area were
collected in September and November 2001. The mean TDS value reported in the Sage Creek
overburden from well WSOV24 was 710 mg/I. Well WSC24, which monitors the Sage Creek
coal, had a mean TDS value of 980 mgll. Mean TDS values in the Wolf Creek overburden (well
WWCOV24) and coal (well WWC24) were 635 mg/I and 730 mg/I, respectively. These wells are
located approximately 1,600 feet down dip from the mine area.
The loading estimate presented above only incorporated Wadge ground water contributions. With the
initiation of mining in the Sage Creek/Wolf Creek mine area, the chemical load to Dry Creek will include
pit inflows from all three ground water systems. Mining of the Wolf Creek coal will start in 2002,
while Sage Creek coal removal will start in 2003. During 2004 and 2011, the proposed mine
plan calls for only Wolf Creek coal removal. Both Sage Creek and Wolf Creek coal will be mined
between 2005 and 2010. During 2003, mining will be active in all three seams. The total pit
inflow in 2003 is predicted to be 3.097 gal/day (0.005 cfsl. The estimated 2003 Wadge ground
water system pit inflow is 2,449 gal/day, while the estimated Sage Creek/Wolf Creek ground
water system pit inflow is 648 gallday. The estimated 2003 chemical load is calculated as
follows:
Wadge Overburden Aquifer: L=[2,582 mgll]x[1,660 gal/day]x[4.17x10"9]=0.018 tons/day
Wedge Coal Aquifer: L=[815 mgll]x[789 gal/daylx[4.17x10'91=0.003 tons/day
Sage Creek Overburden Aquifer: L=[710 mg/1]x[184 galldaylx[4.17x10"9]=0.0005 tonslday
Wolf Creek Coal Aquifer: L=[980 mg/1]x[148 gallday]x[4.17x10"9]=0.0006 tonslday
Wolf Creek Overburden Aquifer: L=[635 mg/1]x[249 gal/day x[4.17 x 10"91=0.0007 tonslday
Wolf Creek Coal Aquifer: L=[730 mg/1]x[67 gallday]x[4.17 x 10'9]=0.0002 tons/day
TOTAL: L = [0.018 tons/day] + [0.003 tons/day] + [0.0005 tons/day] + [0.0006 tonslday]
+[0.0007 tons/day]+[0.0002 tons/day1=0.023 tonslday
The maximum pit inflow when only the Sage Creek and Wolf Creek seams are being mined is
predicted for 2070. The combined Sage Creek and Wolf Creek ground water system inflow is
estimated at 1,376 gal/day 10.002 cfs]. The estimated chemical load in 2010 is calculated as
follows:
Sage Creek Overburden Aquifer: L=[710 mg/1]x[363 gal/day]x[4. 17x10"9]=0 .001 tonslday
Sage Creek Coal Aquifer: L=1980 mg/1]x[290 gal/day]x[4. 17x10"91=0 .0012 tons/day
97 Revised 1/02