The remediation treatment creates environmentally neutral species from hydrocarbon contaminants. A catalyst is injected into the site and is permitted to diffuse through the site. An oxidizing agent is then introduced into the site to release a free radical in a Fenton-type reaction. The compounds react to release a free radical, which acts upon the contaminants to form environmentally neutral species. Diffusion of both compounds is aided by turbulence induced in the groundwater. Reaction vapors are collected above ground, filtered, and vented to the atmosphere.