Abstract In-situ surfactant flushing is an attractive alternative used for decontamination of subsurface soil. The primary objective of this research is to investigate and examine an innovative technique of in-situ flushing using colloidal gas aphron suspensions (CGA) generated from surfactant solutions. The efficiency of CGA suspensions in the removal of oily waste is compared with conventional surfactant solutions and waterfloods under different flow regimes. Results show that CGA suspensions produced using sodium dodecylsulfate had a higher recovery of waste material (56%) than conventional surfactant solutions (47%) or waterflood (43%) in the downflow (gravity-stable) mode. The efficiency of CGA suspensions was greater in the downflow mode than in upflow (gravity-unstable) or horizontal (gravity-neutral) modes, and increasing the surfactant concen- tration from 8 to 30 mM did not enhance the removal efficiency for either CGA suspensions or conventional surfactant solutions. CGA suspensions appeared to have better removal for the major chlorinated hydrocarbons present in the oily waste.