APPCOR10177

• Permit No: C1994082
• IBM Index Class Name: Application Correspondence
• Doc Date: 3/14/1995
• Doc Name: YOAST MINE C-94-082 PERMIT APPLICATION
• Media Type: D
• Archive: No

not immediately appear following miming as a considerable
amount of time is necessary for the spoil to resaturate and
ground water flow directions to reestablish. Since most of
the mining to be conducted will start. at the coal crops and
progress downc~radient, there is no saturated portion of these
units upgradient of the mining to contribute ground water to
expedite the resaturati.on of the upgr•adient spoil by natural
ground water through flow. Each y<:ar's snowmelt and the
limited rainfall are the only avenues by which the spoil will
resaturate. This process will require considerably longer
than 107 days.
/1_P 55. The use of the term "regional gradient" on Page 7 of Chapter
~(~ ~JJ 17 was merely to point out that if the gradient of the
potentiometric surface were zero, there would be no ground
water throughflow into the pit and the q, term, which
represents the flux into the pit from ground water through
flow normal t.o the pit, would be zero. Thus, the pit inflow
computation would simplify to one of accounting for pit
induced inflow from ground water storage only, which only
involves the storage flux term qo. Yes, this is provided
mainly for illustrative purposes.
~~ 56. A complete demonstration of how wet pit areas were arrived at
57a. All input parameters and the calculations performed for the
Theis pit pumpage drawdowns are presented in Attachment 17-3
to Tab 17. Transmissivity, times, and pumping rates were
obtained fro:atthe pit inflow model outputs presented in Tables
17-2 through 17-5 in Tab 17.
b. The transmissivity values for each of the units (overburden
and coal) a.re taken from Tables 17-2 through 17-5 which
summarize tPie output values from the pit inflow model run.
Transmissivities in the model output vary from year to year
with saturated thickness (T=Kb). Transmissivities selected
for the Theis drawdown analyses were: those specified for the
highest pit inflow years. Hydraulic conductivity values input
into the p:it inflow model are taken from representative
aquifer test= values in the different areas of the proposed
mine (i.e., Wells YOV9, YOV28, YOV30, YW28, YW29, YW30, YWU29,
YWU30, and 1'WC31) and presented in Table 17-1.
c. See response to 57a. All Theis d:rawdown calculations are
presented in Attachment 17-3 to Tab 17. SCC discovered that
was given to CDMG by PWCC hydrologists on February 1, 1995.
~L The wet areas, are calculated by overl•sying the potentiometric
~ surface maps on the tOA- and bottom-of-coal contour maps with
yearly mining divisions. No calculations are performed;
rather, the portions of the overburden and coal pit bottoms
that are lower in elevation than thEn potentiometric surface
are measured using a digitizer coupled with a PC. The
measured wet areas are presented as p~irt of Attachment 17-2 to
Tab 17.
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