Bioremediation of chlorinated solvents in peat and natural attenuation of plume

The plume in the aquifer of an industrial cleaning company's site in Arnhem, the Netherlands, was investigated for redox conditions, and compounds which drive the anaerobic dechlorination of chlorinated aliphatic hydrocarbons (CAH). This study was conducted as the volatile CAH-contaminated site was proven to have a high potential for natural attenuation according to the Dutch research program NOBIS, which investigated groundwater at seven chemical laundries upon its potential for natural attenuation. A groundwater model with sequential dechlorination of CAH (RT3D) showed that the plume, with dichloroethylene and vinylchloride, has reached a steady state, indicating that with source removal the plume will attenuate in ~ 15-20 yr instead of > 700 yr. Further investigation of the feasibility of an in situ approach with a dense grid of injection screens in the center of the sandwich clay-peat-clay in a project preparation program with laboratory experiments and mechanical field tests showed that complete dehalogenation is possible in these sediments, and that the required substrate can be transported in situ. These promising results have led to the preparation of a full-scale remediation.