POTENTIAL GROUNDWATER
CONTAMINATION

Groundwater is the most likely way for radiation to be
carried from a repository to the human environment.
DOE admits that groundwater might surround waste can-
isters 20 years after the repository is closed, but maintains
that by the time this groundwater reaches the human en-
vironment, any radiation it carries will have decayed to
safe levels. Some hydrogeologists in Wisconsin and else-
WATER CYCLE
SOLAR ENERGY
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Groundwater is part of the water (hydrologic) cycle, which
is powered by gravity and solar energy. When rain falls to
earth, most of it evaporates or is taken up by plants; some water
flows downhill to a stream, lake or river and eventually reaches
the ocean. Water that doesn't run off, evaporate or enter plants,
seeps into the earth through pores and fractures in soil and
rocks of a recharge area. Eventually it reaches the top of the
saturated layer, or water table. Water below the water table is
groundwater.
Groundwater seeps from upland to lowland areas, eventu-
ally discharging in low places, where the water table intersects
the land surface - in lakes, streams and wetlands. Solar energy
causes evaporation from these surface waters; clouds form and
the cycle begins anew.
All groundwater moves continually from recharge to dis-
charge areas, but the rate of movement varies greatly. Rate of
groundwater travel depends on geological factors, such as the
size of rock fractures, the size of pores between soil and rock
particles and how extensively the pores are connected.
Water moves more quickly through material with large in-
terconnected pores like sand, than material with small pores
like clay. It can move as much as several feet per day through
sand, but only a few inches per year through clay.
Because granite has few pores, groundwater movement in
crystalline rock depends on the size, frequency and distribution
of fractures. Though these characteristics are largely unknown
in deep granite, hydrogeologists can speculate on whether
groundwater would move from a repository to the surface.
Wells in the Wolf River Batholith extend down to about 500
feet, where the granite is fractured enough to yield usable
amounts of water. The occurrence and movement of ground-
water at repository depth is not known. A program of deep drill-
ing and testing would be required to confirm which of the three
cases below is closest to the actual situation.
In any case, some groundwater in the western part of the
Wolf River Batholith flows toward the Wisconsin River.

where question DOE's conclusion.
Contaminated groundwater would have grim conse-
quences for Wisconsin. Wisconsin's entire rural popula-
tion depends on groundwater for home use and crop irri-
gation. If it were contaminated, it would also threaten
surface water. This is a vital concern.

GROUiND WAiER
Groundwater is water that occurs in and moves through
pores (tiny holes) and fractures (larger cracks) in soil and bed-
rock. The ground is like a sponge absorbing and transmitting
water, which fills available porous space. The soil or rock that
holds and transmits water is called an aquifer. Wisconsin has
many good aquifers. Contrary to common myth, groundwater
does not flow in large underground streams or rivers - except
in some caves in soluble limestone or dolomite bedrock.

Case 1..........
IF: Granite is not frac-
tured below 500 feet
THEN: Groundwater
would flow from the recharge
area to the Wolf River and/or
the Fox River and Lake Michi-
gan without contacting the
repository.
Case 2 ..........
IF: Crystalline rocks are
fractured or become frac-
tured at repository depth and
groundwater travels to the
Wolf River
THEN: Groundwater
would flow from the recharge
area, through the repository,
to the Wolf River and adja-
cent wells, in tens to hun-
dreds of years. The flow rate
would depend on number,
size and distribution of frac-
tures, and other conditions.

Case 3..........
IF: Crystalline rocks are
fractured or become frac-
tured at repository depth and
groundwater travels to the
Fox River and Lake Michigan
THEN: Groundwater
would flow from the recharge
area, through the repository,
to the Fox River and adjacent
wells, then to Lake Michigan,
in hundreds to thousands of
years. The actual flow rate
would again depend on
number, size and distribution
of fractures, and other
conditions.

High-Level Nuclear Waste