Naphthalene Sorption to Organic Additives in Cement-Treated Soils

Cement-based solidification/stabilization (S/S) is a widely used source-controlled treatment method for contaminated sediments. Increasingly, the technology is being used to remediate sites that contain high molecular weight organic compounds. The low level of organic content in cement-based S/S mixtures often creates a need for organic additives in the mixtures in order to improve the level of sorption in the treatment process. Very little work has been published related to the quantification of the sorption of organic contaminants to cement-based S/S mixtures and the level of improvement afforded by additives such as fly ash and organoclays. The objective of this study is to examine the sorption levels of naphthalene to several cement-treated soil mixtures with and without organic additives (i.e., fly ash and organoclay) using batch testing. It is found that the sorption values of naphthalene vary but appear to be dependent on the amount of organic carbon present in the mixture. In order to assess the potential benefit of this improved sorption for field applications, contaminant migration modeling is performed using the results obtained. It is shown that cement-based S/S remediation systems can provide long-term protection against naphthalene contaminant migration, especially cement-based S/S mixtures with organoclay additives, for the assumptions considered in the modeling.