This first figure illustrates
splitting a plume of dissolved product contamination into two discrete plumes.
The splitting of the plume is possible provided that two conditions can
be achieved or met. The conditions to be achieved or met include the following:
the capture zone boundaries exceed the downgradient extent of the source-recharge
area (this includes the requirement that no separate phase contamination
extends beyond the boundary of the capture zone as a consequence of the
strict definition of the source-recharge area); and, the capture zone boundary
exceeds the transverse-lateral extent of the plume (it is larger than the
width and depth of the plume). In this second
figure, a greater time
has elapsed with the plumelet migrating a greater distance downgradient.
Note that the areal extent of the plumelet has decreased due to such ongoing
physical phenomena as contaminant breakdown and mixing of the plume with
clean ground water. These
figures illustrate the principle that the pumping of ground water can influence
clean ground water to exhaust previous locales of ground-water contamination.
We will shortly describe
those situations where hydraulic control can be used to re-direct clean
ground-water to flow into and through those soil pores, beyond and downgradient
of the capture zone, containing dissolved phase contamination.