Leaching Characteristics of Polluted Dredgings

This study is directed toward evaluating the pollution potential of leachates from seven different dredged materials and the effect of various additives on improving leachate quality, as well as sedimentation characteristics and shear strength. Based on the results of sequential series of sedimentation tests and sedimentation-leaching tests with and without additives, no significant changes in leachate quality were observed; increases in the specific ion concentrations and increases in the dissolved solids of the leachates were directly attributable to the additives used. In most cases there were increases in the solids due to flocculation, and lime was found to be effective in stabilizing the soil structure, increasing the permeability of the sediment and hastening the rate of leachate production. In an effort to assess the long-term pollution potential of such leachates with and without addition of lime, a series of repeated leaching tests were performed. The leachates from the dredged materials tested do not appear to cause any serious pollution problem.