The behaviour of lnapl in sand due to precipitation
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Date
2017-06
Authors
Mah, Chia Ling
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Abstract
The number of oil spill cases keeps increasing and turning serious. Any incidents can
cause oil spill such as pipeline leakage, transportation accident, natural disasters or
exploration of oil tanker. Once the oil spill happened, the remediation work may take
long time to clean the contaminated soil completely. The oil spill happened on the ground
and the sea. Oil has a density less than water, especially light non-aqueous phase liquid
(LNAPL) will float on the sea surface and groundwater table. This will truly bring effect
to the environment, animals and humans. Oil covered the sea surface, causing oxygen
and sunlight difficult to go into the sea which threaten the aqua life. The pollution of
groundwater will lead to health problems when human consumed the polluted
groundwater as drinking water. However, before starting the remediation work, the
movement of the oil in the ground needs to be determined. Hence, one dimensional (1-
D) column tests were carried out to study the rate of migration of the LNAPL due to
precipitation because the movement of oil may be affected by rain water percolation. The
column test started with drainage for 4 hours, infiltration of diesel for 24 hours,
precipitation for 1 hour and percolation of water for 24 hours. This test was conducted to
simulate the real case scenario. When precipitation occurred, the droplets infiltrate into
the ground and store as groundwater. The LNAPL infiltrate the ground surface and
occupied the pore between the soil particles. During precipitation, diesel will migrate
downwards together with rain water into the saturated capillary zone. The infiltrated
water may occupy the pores by pushing diesel downward and entrapped in deeper soil.
The different intensity of precipitation and volume of diesel was used to understand the
effect on the saturation of diesel in height.