Soluble Salts Reduction and Metal Leaching Behavior of Dredged Sediment for Reuse in Highway Slope Applications

Abstract

Ports and waterways are routinely dredged to maintain navigation channels, resulting in large quantities of dredged materials (DM) that require disposal. This study examines the reuse of a recent DM as a topsoil alternative in highway slopes. The DM met local highway administration topsoil requirements for pH, organic matter, and particle size distribution, and required application of 1,219 mm of rainwater to leach soluble salts to below limits. Column leach tests were performed on DM and topsoil to evaluate heavy metal (arsenic, barium, cadmium, chromium, copper, lead, mercury, silver, selenium, zinc) leaching behavior; extractions were performed to determine total and potentially mobile metals content. DM leached metals concentrations below drinking water maximum contaminant levels for >95% of the samples tested. Extraction data showed higher total concentrations of arsenic, chromium, and lead as compared to topsoil, but similar concentrations in the ethylenediamine tetraacetic acid (EDTA)–extracted fractions, indicating that metals are strongly bound.