2995
Technical Committee 215 /
Comité technique 215
Figure 8. Remediation Plan (Jones, 2013)
Flores et al.
present a simplified image analysis method to
assess the saturation distribution of water and Non-Aqueous
Phase Liquids (NAPLs) of different densities and viscosities
(0.73 ≤ ρ ≤ 1.20 g/cm
3
; 1.4 ≤ ν ≤ 1000 mPa·s) in granular soils
subject to fluctuating groundwater conditions. This study has
confirmed that the relationship between Optical Density (D
i
)
and water and LNAPL saturation values (S
w
and S
o
) is
approximate linear, as predicted by the Beer-Lambert Law of
Transmittance, for ten different NAPLs. Based on these
findings, it was concluded that the Simplified Image Analysis
Method can be safely used to assess water and NAPL saturation
distributions in porous media subject to dynamic conditions, for
a broad range of NAPLs. Furthermore, the authors applied this
method to study the behaviour of five different NAPLs in
experimental columns subject to drainage and imbibition
processes, and confirmed that light NAPLs can effectively get
trapped below the water table, despite their lower densities than
water
.
Inoue et al.
describe a new methodology based on using
spatial moment analysis linked with image processing of a dye
tracer behaviour in porous media to estimate dispersivities in
longitudinal and in transverse directions. Laboratory and field
tracer experiments using a relatively mobile dye tracer referred
to as Brilliant Blue FCF were conducted under saturated and
unsaturated flow conditions. Dispersivities were found to
exhibit an increasing and decreasing tendency associated with
water content and showed a dependency on infiltration rates.
Experimental results showed the effectiveness of the new
methodology for simultaneous assessment of transverse and
longitudinal dispersion in unsaturated soils in field as well as in
laboratory.
Inui et al.
address the issue of excavating stratums that
naturally contain heavy metals due to their geologic histories.
This paper addresses the long term leaching characteristics of
arsenic and lead in several rock materials, which were
weathered in outdoor for more than two years. Several
laboratory tests were conducted to estimate the long term
leaching characteristics of As and Pb in several rock materials,
and then comparing to the results obtained from outdoor
exposure tests.It was concluded that total contents of trace
metals can be regarded possibly as screening values to judge
whether detailed evaluation of leaching characteristics is
necessary. The leaching amount of As obtained in the
conventional batch leaching test was found to be a good index
of field leaching amount, and the accelerated oxidation tests
were shown that they could simulate the outdoor leaching
amount on the safe side.
5 BIOGEOTECHNOLOGY
Omine et al.
describe a geo-environmental approach used to
restore farmed land which was damaged by salinity, due to
tsunami water triggered by the mega earthquake that hit the
pacific coast of the Tohoku region in Japan in March 2011. As
a consequence of this event, the pH and EC of the agricultural
soil increased and exceeded the safer limits for cultivated crops.
Compost containing Halo bacteria/salt tolerance bacteria was
used to restore the farmland. Chemical analysis and potting
cultivation were performed on the saline soils. It was shown that
the compost containing salt tolerance bacteria can reduce the
excessive salts and consequently reduce the salinity problem. It
was also confirmed that the compost was effective for growth of
rice plants. The compost also provided necessary nutrients to
the soil and plant. However, it was not easy to distinguish
clearly in the field application the effect of the compost with
salt tolerance bacteria due to decrease of salt concentrations
caused by rainfall and vegetation.
Sassa et al.
describe a new Ecological Geotechnics
approach. They investigated the linkage between the waterfront
environment and the burrowing activity of six species of
invertebrates in intertidal flats through a series of controlled
laboratory experiments on the benthos-soil systems. The
experimental results show that there exist both suitable and
critical environmental conditions for the burrowing activities of
the diverse species irrespective of burrowing types, growth
stages and weights. On the basis of these results, an ecohabitat
chart was developed revealing complex interrelationships
among species between suitable and critical environmental
conditions. Validation of the chart was conducted through an
integrated field observations, surveys and analyses of the
waterfront environment and the species distributions at five
natural and artificial intertidal flats. The results demonstrate that
the way and where the diverse species lived are well consistent
with the ecohabitat chart developed in this study. It was
concluded that the results obtained succeed not only in
answering the fundamental question of why intertidal flats
foster a complex ecosystem by the diverse species, from a view
point of Ecological Geotechnics, but also established a new
rational basis which can facilitate the conservation and
restoration of habitats with rich natural ecosystems in intertidal
zones.
Stewart et al.
review techniques from molecular biology for
characterising microbial populations that are accessible to
Geotechnical or Geo-Environmental Engineers. With reference
to data from contaminated land studies, the paper discusses
which techniques might be appropriate to use in an engineering
context, how the data generated can be visualised and
interpreted, and the dangers of over interpretation. Polymerase
chain reaction (PCR), a technique for replicating a selected
section of a DNA fragment, based methodologies have been
proposed to manage populations of microorganisms available in
soils. PCR permit the detection of the microbes present and how
they change with changing conditions. It is relatively easy to
use in an engineering setting and the availability of reagents in
kit form along (with detailed protocols) means that the barriers
to adoption are reasonably low. The paper stress the fact that
this is a rapidly moving field and the advent of high throughput
deep sequencing technologies have led to the development of
‘metagenomics’ and ‘metatranscriptomics’ which investigates
the composite genetic potential of an ecological niche. The
authors indicate that instrumentation and cost of sample analysis
are still relatively high but likely to fall as capacity and
technology increase. In addition, the sheer volume of data
generated poses a significant challenge in terms of
bioinformatics and fully exploiting these technologies will
require multidisciplinary collaborations between engineers,
molecular biologists and informaticians.
