The application of high power ultrasonics to concentrated slurries of soils and sediments is discussed and we show that very high destruction rates can be achieved for many of the more notorious chemical contaminants, including PCBs and organochloride pesticides. Results are presented which suggest that a convenient and cost-effective technology is generally applicable. Experiments have been conducted at laboratory and pilot plant scales showing that reduction of contaminant concentration by 90% or more can be achieved with low energy budgets and without the generation of dangerous breakdown products.