Application of nonionic surfactant-enhanced in situ flushing to a diesel contaminated site

A total of 48 kg of TPH (about 88% of the initial TPH) was removed from the pilot site with five pore volumes of 2% sorbitan monooleate solution flushing; this total was more than 75 times the amount that was removed when flushing with water alone (less than 640 g). All of the extracted solution was treated by means of a chemical treatment process, which included the use of a dissolved air flotation system to lower the concentration of solution below 5 mg/L and the treated solution was then disposed of in a nearby sewage drain.