2013-10-17_PERMIT FILE - C1982056A ‎(4)‎

• Permit No: C1982056A
• IBM Index Class Name: Permit File
• Doc Date: 10/17/2013
• Doc Name: Pages 2.05-65 to 2.05-197.3 part 2
• Section_Exhibit Name: 2.05 Operation and Reclamation Plans Part 2
• Media Type: D
• Archive: Yes

in this interval, the head differential across the interval, and the length over which these conditions prevail. The
total recharge rate is given by the standard steady state flow equation.
Q = IfI11 - hJ_
D
where: Q =recharge rate (ft3 /day)
T = Transmissivity of unmined interval (ft /day)
h, = potentiometric head in spoils (ft)
h2 = distance between head in workings (ft)
D = distance between spoil and workings (ft)
L = length perpendicular to flow over which above conditions prevail (ft)
The head differential between the spoils and the proposed underground workings is approximately 300 ft (h, —
h2). The distance between these two areas in the southeastern part of the permit area is about 1,000 feet (D), and
the length over which these conditions prevail is about 5,000 feet (L). Further to the west, the distance between
existing or proposed spoils and the proposed underground workings increases rapidly due to the location of
Pinnacle Peak. An average distance in this area is about 3,000 feet (D), and the length over which these
conditions prevail is about 15,000 feet (L). Using an average permeability for the intervening unmined material
of 0.1 ft/day, and an average thickness of 75 ft yields a transmissivity of 7.5 ft2 /day (T). Substituting the values
for the two areas into the above equation yields a total recharge rate from the spoil areas of about 170,000 gpd
(23,000 ft3 /day) or 190 acre -ft per year (see following calculation). An additional 200 gpm (320 acre -ft per
year) will come from the 6 -Right area. Since this area is higher than most of the mine workings, it is expected
to flow at that rate for most of the time the mine is refilling. Thus, the total average recharge rate after mining is
expected to be approximately 510 acre -ft per year.
Q = ((7.5 ft2 /day * 300 ft * 5,000 ft) /1,000 ft) + _ ((7.5 ft2 /day * 300 ft * 15,000 ft)/ 3,000 ft)
Q = 23,000 ft'/day = 170,000 gpd = 190 acre- ft/year
The overburden unit in mined areas is estimated to consist of a rubblized zone about 100 (t,) feet thick and an
overlying highly fractured zone about 200 feet thick (t2). The area of the proposed mining operation is about 24
square miles (13,100 acres) (A,). Outside of the mined area, the overburden unit will have reasonably similar
characteristics to baseline conditions. This area is approximately 6 square miles (3,840 acres) (AA For this
relatively simple calculation, the following parameters are estimated:
Average drawdown in mined areas
= 1,000 feet (d,)
Average drawdown in unmined areas
= 500 feet (d2)
Porosity of rubblized zone
= 0.1 (p,)
Porosity of highly fractured zone
= 0.01 (p2)
Confined storage coefficient (all zones)
= 0.0001 (S)
The total volume of water required to restore potentiometric levels to pre- mining conditions is given by:
V = A, {t,p, + t2p2 + S (d, - (t, + t2))} + A2 Sd2
where: V = total volume of water (acre -ft)
A, = area dewatered (acres)
A2 = area of potentiometric lowering but no dewatering (acres)
t, = thickness of rubblized zone(ft)
p, = porosity of rubblized zone
t2 = thickness of highly fractured zone (ft)
P2 = porosity of highly fractured zone
S = confined storage coefficient (all zones)
d, = average drawdown in dewatered areas (ft)
d2 = average drawdown in non - dewatered areas (ft)
PR09 -08 2.05 -140 04/27/09