Remediation of a site contaminated by various organochlorine solvents and benzene through illegal dumping of wastes

We present an example of the ongoing remediation of soil and groundwater contaminated by illegally dumped spent solvents. The site, which was located in northern Japan, was contaminated by huge amounts of various industrial wastes. Ten organochlorine compounds, as well as benzene, were major pollutants, and dichloromethane and tri-, tetrachloroethylene were found in high concentrations (from several to several tens of milligrams per liter) in water eluted from the soil. Because the soil was deeply contaminated and the ground had very low permeability, different remediation measures were applied to the unsaturated and saturated zones. Agitation mixing of quicklime was adopted for the unsaturated zone. For the saturated zone, pumping and aeration were adopted in addition to bioremediation for long-term purification. In this study, starting with an in-depth investigation of the nature of the contamination, we demonstrate the selection of treatment measures and our observations of the environmental purification process and the current status of the site after 2 years of purification.