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Geotechnical News • June 2014
37
GEOSYNTHETICS
was informed by its “
impermeability,
stretchability, durability, stability with
reference to sliding, and the price of
the installed membrane
” (Lacroix,
1960), and was made after explor-
ing alternatives, including that of an
asphalt coating. In the end, as Lacroix
observed somewhat perfunctorily
“
Polyvinyl chloride membranes
appeared to be the most satisfac-
tory. Several brands were available.
Their properties were similar. The
selection was then based merely on
economical grounds.
” The rationale
for the specification criteria that were
developed for the plastic membrane
remain as instructive today as they
were at the time of construction. The
required strength was selected on the
basis of field trials to ascertain the
likelihood of puncture during handling
and placement; a strain at failure of
the order 200 % at room temperature
was considered satisfactory; explicit
recognition was given to the absence
of knowledge regarding durability of
the plastic membrane, and the effects
of time on its extensibility; and, in
anticipation of most deformations
occurring within a couple of years of
completion of construction and first
filling, it was considered sufficient
that the membrane possess 5 % of its
original extensibility after a period of
10 years. As Lacroix acknowledged
“
Terzaghi specified the tests leading to
the selection of the type of membrane,
outlined the design, and suggested
most construction procedures.
” In
2010, and some fifty years after its
original installation in 1960, I was
fortunate to receive from BC Hydro, a
sample of the PVC geomembrane that
had been retrieved during a program
of fieldwork at the Terzaghi Dam.
Comparison showed the thickness
of the exhumed sample to be a little
less than that of the specified mate-
rial, however its specific gravity was
measured and found consistent with
that of PVC, and its plasticiser content
was, likewise, determined and found
consistent with that of PVC. Indeed,
upon inspection of the sample of 50
year-old geomembrane, apart from
the presence of surficial scratches, it
looked and felt almost brand new -
Terzaghi himself would surely have
been impressed, doubtless satisfied,
but certainly not surprised!
It was in 1977 that the International
Conference on the Use of Fabrics in
Geotechnics, which is now considered
to have been the 1
st
International Con-
ference on Geotextiles, was organized
in Paris, France and it was during this
meeting that the words “
geotextile
”
and “
geomembrane
” were proposed
by J.P. Giroud. The 2
nd
International
Conference on Geotextiles was held at
Las Vegas, USA in 1982 and, subse-
quently, the International Geotextile
Society (IGS) was founded in 1983:
it was just over ten years later that
the word “Geotextile” was replaced
by “Geosynthetic” with approval of
the IGS Assembly in 1994. The initial
presidency of C. Schaerer (1983-86)
was followed by J.P. Giroud (1986-
90), K. Rowe (1990-94), C. Jones
(1994-98), R. Bathurst (1999-2002),
D. Cazzuffi (2002-06), and F. Tatsuoka
(2006-10).
These conferences were effectively
the precursor to a series in which the
upcoming 10
th
International Confer-
ence on Geosynthetics that will be
held at Berlin, 21-25 September 2014
is the latest to be organized under
the auspices of the IGS. During this
time, as the current IGS President
George Zornberg (2010-14) recently
observed, the changes in the growth
of the discipline are reflected in the
advance from a first conference on
the use of “Fabrics” to “Geotextiles”,
to “Geotextiles, Geomembranes and
Related Products” and, since 1998, to
the collective term “Geosynthetics”.
The IGS has organized international,
regional, and chapter conferences,
and has founded IGS chapters in 41
countries or groups of countries (Zorn-
berg, 2013). The first to be formed was
the Japanese chapter, in 1985, and it
was followed soon after by the North
American chapter, in 1986. A year
later, in 1987, the journal “Geotextiles
and Geomembranes” (edited by Kerry
Rowe) became the official journal of
the IGS and was joined, in 1994, by
a companion journal “Geosynthet-
ics International” (edited by Richard
Bathurst). It is this body of informa-
tion, contained in conferences and
peer-reviewed journals, which serves
the core purpose of the IGS “to pro-
vide the understanding and promote
the appropriate use of geosynthetic
technology throughout the world”.
“the value of a good
education is not the
learning of many
facts, but the
training of the mind
to think of
something that
cannot be learned
in textbooks”
A recent innovation of the North
American Geosythetics Society
(NAGS) has been a webinar series,
the first of which was given by Kerry
Rowe on “Recent insights on the
performance of GCLs in bottom liners
and covers” in March 2014. The next
is to be delivered by Bob Mackey on
“Composite Drainage Nets – Design
and Testing” in July 2014 (for more
details see the upcoming events sec-
tion at
. The
following webinar in the series is to be
given by your erstwhile Editor of this
column, Jonathan Fannin, on the sub-
ject of “Geofilters” in October 2014.
Returning now to the philosophical
observations of Karl Terzaghi on both
the meaning and value of evidence-
based claims, I am reminded of the
quote that is attributed to Albert
Einstein on the subject of a good
education and the textbook “
the value
of a good education is not the learn-
ing of many facts, but the training of