A leak from underground storage tanks (USTs) at an operational petrol filling station resulted in a significant hydrocarbon contamination. The leaking USTs were excavated, however a significant mass of contaminant remained sorbed to the saturated soil, providing an ongoing source of groundwater contamination. After extensive operation, the existing pump and treat system ceased recover sufficient volumes of TPH. Therefore, an alternative solution was required to improve the recovery on site and address the migrating plume.
PetroCleanze® was injected across 16 fixed wells, in the saturated zone only. Following application, PetroCleanze was left for a period of seven to ten days to actively desorb the TPH into the ground- water, after which it was recovered using a vacuum extraction truck. Two identical injection and extraction campaigns have been carried out to fully remove the secondary source. This was followed by a full scale injection of ORC Advanced® as a full-scale polishing step, to enhance the aerobic bioremediation of the plume.
Standalone physical extraction systems are unable to remove contamination bound to soil. Desorption of TPH was observed and the product was successfully recovered during both vacuum extraction events – dramatically improving the recovery rate previously observed on site, speeding up the closure of the site.