A sparging system and process for in-situ removal of contaminants from soil and an associated subsurface groundwater aquifer of a site is disclosed. The sparge system is capable of extracting contaminant in the form of gas from groundwater in a gas/gas/water reaction. The system includes at least one microporous diffuser having a porosity matched to a soil porosity. The microdiffuser is in an injection well. Ozone or other oxidizing gas in the form of bubbles is injected into the site to extract volatile dissolved contaminants for in-situ decomposition. A pump and a pneumatic packer are disposed to alternate pumping and bubble injection into the well to maximize dispersal of bubbles within and outward from the well casing, and to provide uniform dispersion of the bubbles as they travel through the site formation.