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38
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.
References
Avci, C.B. 1992. Flow occurrence
between confined aquifers through
improperly plugged boreholes.
Journal of Hydrology, 139(1–4):
97–114.
Chapuis, R.P. 1998. Ultrasonic method
for evaluation of annular seals
for wells and instrumented holes:
Discussion. Geotechnical Testing
Journal, 21(4): 370–371.
Chapuis, R.P., and Chenaf, D. 1998.
Detecting a hydraulic short–circuit
along a monitoring well with the
recovery curve of a pumping test
in a confined aquifer: method and
example. Canadian Geotechnical
Journal, 35(5): 790–800.
Chapuis, R.P., and Sabourin, L. 1989.
Effects of installation of piezom-
eters and wells on ground water
characteristics and measurements.
Canadian Geotechnical Journal,
26(4): 604–613.
Chesnaux, R., and Chapuis, R.P. 2007.
Detecting and quantifying leakage
through defective borehole seals: A
new methodology and laboratory
verification. Geotechnical Testing
Journal, 30(1): 17–24.
Chesnaux, R., Chapuis, R.P., and
Molson, J.W. 2006. A new method
to characterize hydraulic short–cir-
cuits in defective borehole seals.
Ground Water, 44(5): 676–681.
Church, P.E., and Granato, G.E. 1996.
Bias in ground–water data caused
by well–bore flow in long–screen
wells. Ground Water 34(2):
262–273.
Johnson, R.L., and Pankow, J.F. 1992.
Dissolution of dense chlorinated
solvents into groundwater. 2.
Source functions for pools of sol-
vent. Environmental Science and
Technology, 26(5): 896–901
Kueper, B.H., and McWhorter, D.B.
1991. The behaviour of dense
non–aqueous phase liquids in frac-
tured clay and rock. Ground Water,
29(5): 716–728.
Lacombe, S., Sudicky, E.A., Frape,
S.K., and Unger, A.J.A. 1995.
Influence of leaky boreholes on
cross–formational groundwater
flow and contaminant transport.
Water Resources Research, 31(8):
1871–1882.
Lapham, W.W., F.D. Wilde and M.T.
Koterba, 1995. Ground-Water
Data-Collection Protocols and
Procedures for the National Water-
Quality Assessment Program:
Selection, Installation, and Docu-
mentation of Wells, and Collection
of Related Data, U.S. Geological
Survey Open-File Report 95-398.
Mayo, A.L. 2010. Ambient well–bore
mixing, aquifer cross–contamina-
tion, pumping stress, and water
quality for long–screened wells:
What is sampled and what is not?
Hydrogeology Journal, 18(4):
823–837.
Meiri, D. 1989. A tracer test for detect-
ing cross–contamination along a
monitoring well column. Ground
Water Monitoring Review, 9(2):
78–81.
Morin, R.H., Leblanc, D.R., and
Teasdale,W.E. 1988. A statistical
evaluation of formation distur-
bance produced by well–casing
installation methods. Ground
Water, 26(2): 207–217.
Santi, P.M., McCray, J.E., and
Martens, J.L. 2006. Investigating
cross–contamination of aquifers.
Hydrogeology Journal, 14(1–2):
51–68.
U.S. EPA, 1992. Dense nonaque-
ous phase liquids – A work-
shop summary, Dallas, Texas,
April 16-18, 1991. Publication
EPA/600/R-92/030, Washington,
DC.
U.S. EPA, 1994. DNAPL site
characterization. Publication
9355A-16FS, EPA/540/F-94/049,
Ada, OK.
Warner, D.L. 1996. Monitoring of
class I injection wells. In Deep
injection disposal of hazardous
and industrial waste, scientific and
engineering aspects. J.A. Apps and
C.F. Tang Editors, Academic Press,
New York.
Yesiller, N., Edil, T.B., and Benson,
C.H. 1997. Ultrasonic method
for evaluation of annular seals
for wells and instrumented holes.
Geotechnical Testing Journal,
20(1): 17–28.