Evaluating and managing potential groundwater pollution from leaking usts at a coastal city in Saudi Arabia

Leaking underground fuel storage tanks (USTs) are the main source of petroleum hydrocarbon contamination of soil and groundwater. The distribution and flow of the leaked hydrocarbon is influenced by capillary and gravity forces. Depending on the leaked volume and the soil properties, the hydrocarbon could exist as a residual phase completely held in the soil above the water table or as both free phase product and residual. Various components of gasoline will affect the groundwater quality and each will spread according to its own characteristics. The pollution processes are studied through the development of a combination of two models: a compositional and a potential flow model. The former was developed using the mass balance principle and is capable of using the organic compound and the subsurface properties to predict the concentration of the various components of benzene, toluene and xylene (BTX) mixture in a leachate from a site contaminated by a residual mixture. Potential flow theory was utilized to model the advective transport of contaminants towards municipal wells. Capture zones were defined and travel times for different municipal wells were estimated for a sample study area at a coastal city in eastern Saudi Arabia. Modeling and field survey indicated the high potential for groundwater pollution and concluding that more effort should be directed to promote leak prevention through management strategies that include developing proper design regulations and installation requirements like monitoring wells for new and existing service stations.