DREDGING SUMMIT & EXPO ’17 PROCEEDINGS POST-DREDGING RESIDUAL SEDIMENT STABILIZATION

The nature and characteristics of residual sediments have been discussed extensively. It has been shown that dredging leaves a post-dredging sediment surface much more susceptible to erosion than the sediment surface prior to dredging. The potential for erosion can be particularly acute for fine-grained sediments or sediments with a significant fine fraction. If the sediments are contaminated, post-dredging erosion may contribute significant constituent concentrations to the water column. One approach to reduce sediment and contaminant loss is to increase the critical shear stress of the residual sediments through amendments. Sand, bentonite, kaolin and lime and a matrix of combinations, called “admixtures”, were tested for relative effectiveness at increasing erosional strength of dilute sediments. Comparison of sediment mixtures was performed using a SedFlume apparatus. This research concludes bentonite clay provides the greatest resistance to erosion, requiring the least mass addition per mass of treated sediment. Bentonite was determined to be the most costeffective admixture. The results will be used to assess the practicality of rapid stabilization of post-dredging surfaces.