The use of geotextiles in sludge dewatering applications has become a popular approach for many engineering projects. For contaminated sediments, the water quality of the resulting effluent is important to quantify, as it affects decisions on secondary treatment of effluent from dewatering. The purpose of this paper is to discuss a bench scale study performed for a large-scale remediation project in Nova Scotia, Canada in which geotextile tube dewatering is one of the options for dewatering the contaminated, fine-grained sediment prior to containment. Selected metal concentrations in the sediment are elevated relative to guidelines. The purpose of this paper is to examine metal concentrations in geotextile filtration effluent during gravity dewatering tests at the laboratory scale. The sampling program of the contaminated sediment is briefly described as well as the results of various physical and chemical characterization tests performed on the sediment. The results of rapid dewatering tests performed with the sediment conditioned with additives to induce flocculation and increase grain size is presented. Characteristics of the resulting filtrate (metals and particle concentrations) are presented in the paper with a focus on the primary elevated metals known to be present in the sediment (Cu, Pb, and Zn). The distribution of these metals in the filtrate in terms of total versus dissolved concentrations is also presented and compared with particle counts in the filtrate to better understand the mobility of these metals during geotextile dewatering.
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