A mining company's train fuel station and maintenance yard in northern Brazil, near the Amazon rainforest, became contaminated as a consequence of fuel spills from its underground tanks. In 2005, a series of environmental studies were performed which identified a severe groundwater contamination. Two source areas and an extensive groundwater plume were found.
Two distinct source areas were identified, each contributing to the contamination of an extensive groundwater plume. The contamination encompassed approximately 4,000 square meters of Ligh tNon-Aqueous Phase Liquid (LNAPL), along with a dissolved phase containing Polycyclic Aromatic Hydrocarbons (PAH), Total Petroleum Hydrocarbons (TPH), andBTEX. Contaminated groundwater was found at a maximum depth of approximately 20meters below ground level (m-bgl).
Several environmental consultancies were engaged in the investigation and remediation of the site without success. From 2010 until 2018, hydraulic barrier and MPE were implemented by installing 28 wells. The groundwater was then being treated with activated carbon. The technology resulted ineffective.
The remediation strategy suggested by GreenSoil Group was to implement a cyclic remediation design due to the little information known about the site. The 1st phase of the remediation project was focused on the LNAPL removal, combined with groundwater circulation. To this end, 60 new wells for extraction/infiltration and a bioreactor for the groundwater treatment were installed. Groundwater is extracted, LNAPL are separated through the oil/water separator and then treated in the aerobic bioreactor. Before reinfiltrating the water in the soil, nutrients are supplied. A 2nd phase of the project saw the installation of airsparging lances and the stimulation of in-situ bioremediation.
During the operation of the system there was a considerable reduction of the free phase thicknesses in the monitoring wells. After 17 months of operation, free phase was no longer reported in the study area demonstrating the efficiency of the implemented system. The in-situ aerobic remediation was ended in 2021 successfully achieving the remediation objectives”
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