Air
Sparging
http://en.wikipedia.org/wiki/Groundwater_remediation
Air sparging involves drilling one or more injection
wells into the groundwater-soaked soil below the water table. An air compressor
at the surface pumps air underground through the wells. As air bubbles through
the groundwater, it carries contaminant vapors upward into the soil above the
water table. The mixture of air and vapors is then pulled out of the ground for
treatment