SOLUBLE SALTS REDUCTION AND METALS BEHAVIOR OF DREDGED SEDIMENT FOR REUSE IN HIGHWAY SLOPE APPLICATIONS

Waterways are dredged routinely to maintain navigation channels, resulting in large quantities of dredged materials (DM) that require disposal. This study examines the innovative reuse of DM as a topsoil alternative in highway slopes. The dredged material met Maryland Department of Transportation, State Highway Administration (MDOT SHA) topsoil requirements for pH, organic matter, and particle size distribution, and required 122 cm (48 inches) of rainwater to leach soluble salts to below limits. Column leach tests were performed on DM and topsoil to evaluate metal leaching behavior; extractions were performed to determine total and potentially mobile metals content. DM leached metals concentrations below drinking water maximum contaminant levels (MCLs) for >95% of the samples tested, and passed a toxicity characteristic leaching procedure (TCLP). Extraction data showed higher total concentrations of arsenic, chromium, and lead as compared to topsoil, but similar concentrations in the EDTA-extracted fractions indicating that metals are strongly bound