| Summary: | 碩士 === 國立交通大學 === 土木工程學系 === 84 === Problems involving the contamination of soil and
groundwaterby leaky underground storage tranks (LUSTs) and
accidented oilspills are being identified more and more in
Taiwan. Cleanup actions are beginning to be required by the
public to restore the environment. To estimate the volume of the
contamination and the effect of cleanup actions cannot be
accomplised without having a good understanding of the retention
characteristics of water and organics in soil. No matter whether
free product pumping or soil vapor extraction is used to remove
the organic contaminants from the ground, there remain some
contaminants in ground. The amount of the remaining organics
depends on the oil/water retention characteristics of the soil.
The objective of this study is to use pressure cell technique to
determine the effect of soil characteristics on the retention
behavior of oil and water in soil. The results of the
experiments show that the amount of retained liquids at various
suctions increases with the content of fines of soil samples. In
the meantime, for the experiments with organic liquid as non-
wetting liquids, the amount of water retained in the soil shows
a similar trend. In addition, the amount of liquids retained in
the soils depends on the interfacial tention between the wetting
and the non-wetting fluids. The higher the interfacial tention
the more wetting liquids retained in the soil. When the change
of the interfacial tension is not large, the retention
characteristics in soil influenced by the distribution of pore
is more important than the interfacial tension. On the other
hand, the results aslo show that the volumetric content of the
wetting liquids after suction was released did not increase to
that of original value. The result of the study will help the
engineers to get a better understanding of the distribution and
migration of the origanic liquid in the vadose zone and near the
ground water table. Therefore, the engineers can estimate the
amount of organic liquids retained in the subsurface more
accurately from the characteristics of the soil.
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