Effect of crude oil contamination on some chemical and engineering properties of soil

Abstract

The study has been carried out with two broad objectives - to observe the effect of crude oil contamination on different properties of soil and to predict the change in the properties quantitatively in the form of mathematical correlation. The properties of soil that are studied are consistency limits (liquid limit, plastic limit and plasticity index), compaction properties (maximum dry density and optimum moisture content), unconfined compressive strength, consolidation properties (compression index, coefficient of consolidation, coefficient of permeability), swelling properties (free swell index and differential free swell index) and some chemical properties (pH value and electrical conductivity). Crude oil is a naturally occurring complex mixture of hydrocarbons. During the process of exploration, transportation, refining and storage, crude oil may be spilled on soils. There have been some reports of accidents in oil wells which is also a cause of crude oil spill into the soil. On reaching the ground, these oil flow under gravity and contaminate the soil on its pathway. Of late, several researchers have diverted their work to study the effect of crude oil contamination (in broad sense, effect of contamination by industrial waste) on the engineering and chemical properties of soil. It is also reported by these investigators that crude oil contamination has serious effect on some of the engineering and chemical properties of soil. These effects of crude oil on soils are to be taken into account for proper design of structure on crude oil contaminated soils. Due to inadequate or poor knowledge of the properties of crude oil contaminated soil, there have been some reports of failure of structures constructed on crude oil contaminated soil (Yaji et al., 1995). According to Scott (1987), it is not possible to determine the detailed events leading to failure, but design and construction methods can be proposed for future structures which will lessen the chances of a similar event. Therefore, it is imperative to have...