2991
General Report of TC 215
Environmental Geotechnics
Rapport
J
énéral du TC 215
Géotechnique de l’
H
nvironnement
Bouazza A.
Monash University, Melbourne, Australia
ABSTRACT: Twenty two (22) papers have been allocated to this session. They originated from twelve (12) countries and five (5)
continental regions (Asia, Europe, North America, South America and Oceania). They described and presented laboratory and field
studies and numerical modelling addressing numerous topics which included novel materials, chemical compatibility of barrier
materials, unsaturated behaviour of geosynthetic liners, soil-geosynthetic liner interface behaviour, waste geotechnical properties,
phytoremediation, permeable reactive barriers, soil and groundwater remediation, image analysis, natural leaching of heavy metals
and biogeotechnology. This general report offers a review of all the papers submitted to this session and highlights the major findings
reported by the authors of these papers.
RÉSUMÉ : Vingt-deux (22) communications ont été allouées à cette session. Elles proviennent de douze (12) pays et de cinq (5)
régions continentales (Asie, Europe, Amérique du Nord, Amérique du Sud et Océanie). Ces communications décrivent et présentent
des études de laboratoire et sur site ainsi que des études de modélisation numérique. Elles traitent de nombreux sujets comprenant les
nouveaux matériaux, la compatibilité chimique des matériaux d'étanchéisation, le comportement insaturé des géosynthétiques, le
comportement de l'interface sol-géosynthétique, les propriétés géotechniques des déchets, la phytoremédiation, les barrières réactives
perméables, l'assainissement des sols et des eaux souterraines, l’analyse d'images, le lessivage naturel des métaux lourds et la
biogéotechnologie. Ce rapport général présente une revue de tous les documents soumis à cette session et met en évidence les
principaux résultats rapportés par les auteurs de ces documents.
KEYWORDS: biogeotechnology, containment barriers, geotechnical properties, groundwater, soil, remediation, waste,
1 INTRODUCTION
Environmental Geotechnics has evolved dramatically from
the 1980s/1990s practice where the focus was on addressing
problems related to contaminated sites as well as waste
management. Nowadays, the discipline has expanded
dramatically to tackle new challenges brought about by a
continuous evolving world. Energy (geothermal energy, CO2
sequestration, coal seam and shale gas, methane hydrates, etc.),
oil and gas resources, mining, reservoir engineering, effect of
climate change on built structures and biogeotechnical
engineering, are examples of areas Environmental Geotechnics
has expand to. Consequently, this had the effect of bringing
other different disciplines (chemistry, biology, soil science, etc.)
even closer than before.
Significant and rapid progress in research and development
has enabled the development of Environmental Geotechnics as a
discipline to the level where it is now. This is reflected by the
contributions made to this session which includes novel
materials to deal with very aggressive solutes to biological
approaches to restore land devastated by natural events.
Twenty two (22) papers have been allocated to this session.
They originated from twelve (12) countries and five (5)
continental regions (Asia, Europe, North America, South
America and Oceania). Most papers have presented laboratory
studies. Papers including field studies and numerical modelling
were also presented. The papers have been grouped into the
following themes:
Containment barriers
Municipal solid waste and other types of waste
geotechnical properties
Soil and groundwater remediation
Biogeotechnology
This general report offers a review of all the papers submitted to
this session. It highlights the major findings reported by the
authors of these papers.
2 CONTAINMENT BARRIERS
Bohnhoff et al.
describe a study on bentonites that have been
chemically modified to achieve greater chemical compatibility
when used as containment barriers such that the desirable
engineering properties of the bentonites are not compromised.
They have considered three bentonites. These bentonites include
(1)
a natural Na-bentonite polymerized with acrylic acid to form
polyacrylate polymerized bentonite, referred to as a bentonite
polymer nanocomposite or BPN,
(2)
a propylene carbonate (PC)
modified Na-bentonite, referred to as "multiswellable bentonite"
or MSB, and
(3)
Na-bentonite amended with sodium
carboxymethyl cellulose (Na-CMC), referred to as "HYPER
clay" or HC. Two potential applications were considered: 1) soil
bentonite (SB) vertical cut off walls and 2) geosynthetic clay
liners. In both cases hydraulic conductivity to water and CaCl
2
solutions were compared with those of three natural Na-
bentonites commonly used in geoenvironmental containment
applications. Permeation with deionised water, DIW, (plotted at
0.1 mM CaCl
2
in Fig. 1) resulted in low
k
w
(i.e., 4.2 x 10
-12
to
3.4 x 10
-11
m/s) regardless of the bentonite type. However, the
BPN, HC2, and MSB exhibited superior hydraulic behaviour
(i.e., lower
k
c
) relative to the GCL bentonites. The influence of
CaCl
2
on the
k
of backfill specimens containing 5.7 % NB1 or
5.6 % MSB and specimens containing 7.1 % NB2, 2.4 % BPN,
and 5.5 % BPN is shown in Fig. 2b. All of the specimens were
susceptible to an increase in
k
, i.e.,
k
c
/
k
w
> 1, where
k
c
=
hydraulic conductivity to the CaCl
2
solution, when permeated
with ≥ 10 mM CaCl
2
solutions. The increases varied from
approximately two-fold to 15-fold depending, in part, on the
