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The objective of the part of the research from September 2000 to
January 2001 is to determine if more conventional well sampling
techniques (no packers, purging, low-flow sampling) yield similar
water sample quality as sampling from an isolated zone in a well
(packers in place or DMLS in place). This research will be performed
in one to three of our preliminary bedrock wells that has exhibited
groundwater contamination. The locations of the fractures in the
well will be known based on the borehole geophysics. In low-flow
sampling of the well, a 5 cm diameter submersible sampling pump
will be set at the locations of fractures, and then a series (between
four and seven) of sample will be taken at a low flowrate at that
location. When sampling is completed at one location, the submersible
pump will be removed from the well, decontaminated, and then lowered
to the next fracture.
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The sampling and decontamination process will continue until all
major fractures in a well are sampled. It is expected that this
sampling will take at least one day. On the next full day, after
the low-flow sampling, packer sampling will commence. The sample
pump will be set between two inflatable packers. As with the low-flow
sampling, the pump will be lowered to a location of a fracture.
At this point, the packers will be inflated to isolate this fracture
from the rest of the well. This zone will then be sampled a variety
of times as for the low-flow testing. When sampling of this zone
is completed, the packers will be deflated and the pump removed
and decontaminated and then positioned opposite another fracture
in the well. Then a DMLS will be lowered into the well and allowed
to equilibrate for at least one week before removal. The samples
from all three networks will be analyzed for the full suite of chemical
constituents and the resulting data then statistically analyzed
to infer differences in the measured water quality of samples result
from each sampling method.
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