Filter for dredgings confinement areas

The consideration of diked containment areas as solid-liquid separation systems for the disposal of dredged materials often requires the use of filtering systems to clarify the effluents that are returned to the receiving waters. An extensive experimental investigation involving various granular filter media and feedwater with suspended solids concentrations up to 10 g/l was conducted, and based on the results obtained three new conceptual designs (previous dikes, sandfill weirs with or without backwash, and granular media cartridges) were developed as filter systems for dredged material confinement facilities. These systems are described herein, and information concerning the: (1) filter media; (2) system configurations; (3) operating conditions and performance capabilities; (4) guidelines for design and operation; and (5) design examples are given for each system. Although these filtering systems are technically suitable for use in the clarification of disposal area effluents under a broad range of conditions, their required size in dredging operations involving very high flow rates may render them economically unfeasible.