BEST WAYS TO DEWATER DREDGED MATERIAL

Left to its own devices, fine-grained dredged material placed in confined disposal areas reaches an equilibrium water content near its Atterberg liquid limit. The high water content of such dredged material effectively prohibits its use in any productive manner, and storage of the liquid fraction reduces available volume for future dredged material disposal. Various literature and laboratory studies, followed by field experiments, were conducted to develop technically feasible, operationally practical, and cost-effective methods for removing excess water from confined dredged material and return it to normal soil consistency. Progressive trenching, to remove ponded surface water from the site and enhance evaporative drying, and various types of underdrainage dewatering were found to satisfy the selection criteria. Dewatering by vacuum well points, crust mixing and agitation, and electro-osmosis were not satisfactory.