The Role of Clay as a Natural Geological Barrier in Oil Pollution Control of Abadan Refinery

Abadan Refinery is located between Arvandrud and Bahmanshir rivers. These rivers supply urban, industrial and agricultural water of Abadan city. During the warbetween Iran and Iraq, leakage of large amounts of oil and its refined products from storage tanks, pipe lines, and refinery units of Abadan refinery to surroundingenvironment occurred. Also, leakage of petroleum and its products during the operation of Abadan refinery to surrounding environment led to conduct a researchfor determination of oil pollution extension of underground layers in Abadan refinery. Utilization of clays as natural geological barriers in environmentalapplication and pollution control has been widely recognized. Abadan city was formed by recent Estuarine; these alluviums had a diverse variety in grain sizeand material. In the case of dominant presence of clay in underground layers, petroleum pollution control hypothesis of Abadan refinery is confirmed. In order toprove the above hypothesis the following items were conducted: 1) determination of material type of underground layers, 2) determination of petroleum pollutionin underground layers and defining the oil saturation of the cores, and 3) determination of petroleum pollution in underground waters by one year samplingof underground waters along with measurement of piezometric head of groundwater monitoring wells. Location of twenty groundwater monitoring wells wasinvestigated by considering petroleum leakage to surrounding area during and after war. Geological underground layers of Abadan refinery was determined fromcoring during drilling of the groundwater monitoring wells. The results of this investigation has shown that the material type of underground layers of Abadanrefinery had a significant role to encapsulate petroleum leakage, in such a manner that leaked petroleum was observed in all of the drilled boreholes. On theother hand floated leaked petroleum on groundwater was observed just in two groundwater monitoring wells. These two polluted groundwater monitoring wellswere shown to be from leakage of recent activities of Abadan refinery. Finally the results show that the majority of existing petroleum in underground layers ofAbadan refinery was absorbed by clay.