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Geotechnical News • June 2013
www.geotechnicalnews.com
GROUNDWATER
tion, but the risk still exists.
The installation of a single MW or of a
multilevel system in the aquitard must
proceed as soon as the borehole is
completed. This avoids having a long
period of time with cross contamina-
tion and diffusion, which starts in the
small annular space between the cas-
ing and the aquitard during drilling or
in the open–hole (waiting time prior to
MW installation) as soon as a DNAPL
enters these spaces. Otherwise,
misinterpretation of contamination
will result from misunderstanding the
reasons for cross–contamination.
This 1980s case history teaches us
that cross–contamination may happen
during drilling. Also, since the details
reported here never went public, many
professionals were kept unaware of
this problem and the simple way (time
of soil sampling) to detect it. This
negative aspect of the confidentiality
rules, which work against the order or
corporation’s mandate to protect the
public, is unfortunate for the engineer-
ing profession.
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