Abstract: A treatment protocol is provided for the in-situ remediation of Polynuclear Aromatic Hydrocarbons and other contaminants such as DNAPL compounds and PCB's present both in soil and in groundwater. The approach uses a modified Fenton's chemistry to treat the materials, the treatment reagents being introduced through a hollow stem auger into the contaminated soil or groundwater region. The process also provides for a pre-treatment of solid and semi-solid coal tar residues by using a polar solvent pretreatment step prior to the chemical and mechanical treatment.