Dredged Material Sedimentation Basin Design

Procedures have been developed for designing dredged material sedimentation basins. These procedures can also be used for designing sedimentation basins for other slurries having high suspended solids concentrations. Dredged material sedimentation basins are slightly different from those used in water and wastewater treatment in that the dredged material basins must provide for sedimentation to achieve acceptable ef0uent quality while providing storage volume for several years of material dredged from local waterways. Guidance is presented for field sampling and laboratory testing required to obtain data for sediment characterization, data analysis, sedimentation basin (containment area) design, and estimating storage capacity required. Settling tests performed in a 8-in. (20 cm) diam column were found to be satisfactory for defining dredged material settling behavior. Settling behavior in the freshwater environment was best described by a flocculent settling test, while behavior in a salt-water environment was best described by a zone settling test. Procedures are presented for designing new containment areas for suspended solids retention and for evaluating the suspended solids retention potential of existing containment areas during planned disposal activities. The field verification work performed during this research indicated that conservative values could be estimated from laboratory tests for solids concentrations expected in the dredged material sedimentation basins.