Hydrogeochemical and hydrogeological surveys of soil and groundwater in the site of an oil refinery found high concentrations of TPH, BTEX and PAH in the vadose zone as well as in the saturated zone of the area. The presence of these components is attributed to existing petroleum products, which leak from tank and underground pipes' cracks. A special program was developed and applied in order to not only monitor and evaluate the prevailing pollution status, but also determine and implement the most effective remediation technique for the specific occasion. Innovative methods such as fingerprinting and bioslurping were applied to fulfill the objective of the monitoring and remediation program.
Oil refineries often cause soil and groundwater pollution, due to potential leakages of petroleum products from tanks and pipes at several stages of the petroleum treatment. In the area of the refinery of this study, extended pollution of groundwater has been observed during the past 15 years. PAH, BTEX and other Non-Aqueous Phase Liquids (LNAPL) are the prime source of soil and groundwater contamination, which has been identified and remains on the surface of the local aquifer, as a free phase. Studies in the area have shown that important quantities of fugitive petroleum products have leaked into the soil and consequently into the groundwater, causing a serious pollution problem in the area. According to older investigations three hydrocarbon plumes have been observed in the porous aquifer of the area of the refinery. The existence and the type of the pollution caused the necessity of the formation of an appropriate program, which would be capable of providing a realistic and credible reflection of the existing pollution in the area. Only an accurate and integral knowledge of the prevailing conditions, would allow the assessment of an effective remediation technique.
The program that was finally created consisted of two main stages:
Stage 1: Monitoring, which comprises a thorough study and description of the existing pollution (including the extend and the mobility of the plume, the type and chemical properties of the pollutants, the determination of potential leakage points and pollutant concentrations in the soil, groundwater and soil gas).
Stage 2: Remediation, which includes the determination and the implementation of an appropriate and effective remediation method that would be competent in eliminating or at least limiting the pollution in the area (bioslurping)
Pinpointing the future remediation activities an inventory of the site conditions has to be conducted during a site assessment, combined with a data evaluation risk assessment. To ensure comparability with existing data pool and findings appropriate samples have to be collected and parameters have to be analyzed chemically in the laboratory. In the area of the refinery there are about 100 wells, which can be used either as monitoring wells or as means of remediating the site. At this stage, most of the wells were used for monitoring purposes, in the hope of providing a sober depiction of the pollution.
