Abstract: The invention is a batch process for biotreatment of contaminated soil according to which the material is placed with microbes and water in a vessel such as a roll-off box with aerators. A slurry recirculating system is used every few days at a point of microbial domination to pump material from the water column into the solid phase at high pressure through a wand inductor, whose outlet is directed around the vessel to shear and agitate essentially the entire volume of material. The configuration of the vessel, agitation with the wand inductor and control of other conditions allows cost-effective microbial degradation of hydrocarbons to regulatory standards in soils having large amounts of clay, rocks, and debris.