Abstract: A system for treating contaminated sediments dredged from waterways is disclosed. Dredged sediments are divided into coarse and fine fractions. The coarse fraction is washed to remove contaminants. The fine fraction and the contaminants removed from the coarse fraction are admixed, followed by filtering to produce a dewatered fraction. The dewatered fraction is then melted in a plasma melter to form a molten mass of glass or slag. The molten mass is then cooled to form a stable, low-leachability product. During the plasma melting operation, organic contaminants are destroyed and contaminants such as heavy metals are contained within the matrix of the melted glass or slag. After cooling the melted material may be provided in the form of aggregate, granules or fibers useful for various applications such as road fill, roofing granules and rock wool.