On July 16, 2000 a major oil spill occurred at the side of the Araucaria refinery of Petrobras. A total of 4,000 m3 of a light crude oil (41° API) ran down along a small two kilometers creek referred to as Arroio Saldanha, crossing and contaminating a series of four wetlands. The oil discharged into the Barigüi River, a tributary of the Iguassu River. It's estimated that twenty per cent of all the oil spilled volatilized. After running along the creek and its wetlands, the oil contaminated 6 kilometers of the Barigüi River and 60 kilometers of the Iguassu River. A comprehensive oil recovery emergency response operation was immediately engaged to clean the impacted area and the rivers. Some 3000 persons worked around the clock during the peak of the operations. Helicopters, trucks, oil recovering boats, light boats, mechanical excavators, dredgers and 3,200 meters of retention booms were used. Roads and accesses were reformed or built. The overall emergency response effort proved to be successful; in nine days, all of the free oil was removed from the rivers. The cleaning of the riverbanks and inundation areas was completed in three months. The Saldanha Creek and the four wetlands areas upgradient of the Barigüi River retained approximately 70 per cent of all of the oil spilled, all superficial oil was removed until it could not move superficially, the remaining oil impregnated in the upper soil profiles. Since then, various remediation techniques were implemented to remediate both, soil surface water and groundwater. The upper portion of the soil profile is remediated with bioremediation, using natural indigenous microorganism. This technique consists in cultivating the soil with mechanical agricultural equipment or manually where accessibility does not allow the use of mechanical equipment. Nutrients and other amendments can be added when required. In some cases soil are bioaugmented with microorganisms of the “landfarming” cells of the refinery. This technique is a variant of the landfarming technique that has been studied at the Repar (Refinaria Presidente Getúlio Vargas) refinery for more than ten years. Such technique has proven to be more efficient than traditional landfarming. The soil below 40 centimeters cannot be remediated with this technique. Soils at such depth are being recovered through a series of drainage and injection trenches. Water injected in the injection trench forces the free and trapped oil to move laterally to the recovery trenches. The largest contaminated swamp was transformed in a treatment wetland and its recovery is being monitored and adjusted to quicken the recovering, thus minimizing interference with the natural ecosystem.

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