Applied Hydrogeology

C. W. FETTER, JR. University of Wisconsin-Oshkosh

Charles E. Merrill Publishing Company A Bell & Howell Company

Columbus Toronto London Sydney

NRC-108 Submitted: 9/28/2015

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United States Nuclear Regulatory Commission Official Hearing Exhibit In the Matter of: CROW BUTTE RESOURCES, INC.

(License Renewal for the In Situ Leach Facility, Crawford, Nebraska)

ASLBP #: 08-867-02-OLA-BD01 Docket #: 04008943 Exhibit #: Identified: Admitted: Withdrawn: Rejected: Stricken:

Other:

NRC-108-00-BD01 9/28/201510/8/2015

8.9 EFFECT OF HYDROGEOLOGIC BOUNDARIES

Boundaries are considered to be either recharge or barrier boun­daries. A recharge boundary is a region in which the aquifer is replenished. A barrier boundary is an edge of the .. aquifer, where it terminates, either by thinning or abutting a low-permeability formation, or has been eroded away. Parts A and B of Figure 8.21 show the effect of boundaries on the cross section of the potentiometric surface of a pumped aquifer. Boundaries have the most dramatic impact on the drawdown of a pumped well for the aquifer with no source of vertical recharge. As the well withdraws water only from storage in the aquifer, drawdown proceeds as a function of the logarithm of time.

Figure 8.22 shows a theoretical straight-line plot of dr"awdown as a function of time on semilogarithmic paper. The effect of a recharge boundary is to retard the rate of drawdown. Drawdown can become zero if the well comes to be supplied entirely with recharged water. The effect of a barrier to flow in some region of the aquifer is to accelerate .the drawdown rate. The water level declines faster than the theoretical straight line.

REAL SYSTEM

Drawdown component Drawdown component of image well of real well

Discharging Q Q Discharging real well image well

=~~~~~~==~~= =-=~~]?~~~~- ~~t0~I~I~1E~= NOTE: Aqwifer thickness b should be very large compared to resultant drawdown near real well

HYDRAULIC COUNTERPART OF REAL SYSTEM

FIGURE 8.21 B. Idealized cross section of a well in an aquifer bounded on one side by an impermeable boundary. SOURCE: J. G. Ferris et al., U .S. Geological Survey Water Supply Paper 1536-E, 1962.

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