RemedX was commissioned to undertake an in-situ pilot test for contamination removal over a period of 12 weeks at a former gasworks in Southall, West London. The site geology comprised made ground over river terrace gravel overlain by London Clay. Typical gasworks contaminants were present in the gravel aquifer, including total petroleum hydrocarbons, ammonia, polycyclic aromatic hydrocarbons and coal tar.
The work included assessing the feasibility of using soil vapour extraction, air sparging and steam-enhanced, dual-phase extraction at the gasworks site.
The steam-enhanced, dual-phase extraction test demonstrated that steam reduced the viscosity of the dense nonaqueous phase liquids, thereby increasing their mobility. The nonaqueous phase liquids were recovered using bottom-loading borehole pumps. The addition of steam enhanced the mass recovery of contaminants in the vapour phase.