PERMFILE52847

• Permit No: C1981028
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Doc Name: GROUND-WATER RESOURCES STUDY
• Section_Exhibit Name: ASH DISPOSAL PLANS APPENDIX A
• Media Type: D
• Archive: No

25
• the elevation of the top of the Laramie are presented in the cross-section
in Figure 4.
It can be observed that the water table profile lies beneath the
top of the Laramie. This suggests that the overburden aquifer is uncon-
fined over the rest of the project area.
C. Piezometric Surface
lJater surface elevations in 23 wells were measured relative to a
common datum. The data obtained is summarized in Table 2. Contour maps
of the piezometric surface were prepared for the overburden and coal
aquifers and are presented in Figures 13 and 14 respectively.
The piezometric surface in the overburden is relatively featureless
and slopes toward the northeast at a gradient of about 0.006 as shown
• in Figure 13, indicating that the ground water in the project zrea dis-
charges into the subsurface deposits in Ennis Draw. The discharge rate,
Q, through the boundaries of the leasehold was computed on the basis of
Darcy's Law which can be expressed as:
Q = TIL
where T is the transmissivity, I the hydraulic gradient and L the width
of flow. Using an average transmissivity of 7 x 10-3 ft2/min, a hydraulic
gradient of .006 and an average flow width of 6000 feet,.the discharge
rate through the eastern boundary of the study area was estimated to be
approximately 3 acre feet per year. In a similar manner the discharge
through the northern boundary ryas computed to be about 2.4 acre feet per
year. This gives a total discharge from the project area to Ennis Draw
• of approximately 5.4 acre feet per year.
The piezometric surface map in the coal depicts a ground water divide
along wells 134 and 116 as shown in Figure 14. East of the divide the

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