Nonlinear Nonequilibrium One-Dimensional Large-Strain Consolidation-Coupled Contaminant Transport Model of Capped Sediments

Abstract

This paper describes the development and multistep validation of a one-dimensional, large strain consolidation coupled contaminant transport model with nonlinear and nonequilibrium sorption kinetics. The RCM-XPORT2K model uses the CS2 large strain consolidation approach for modeling the deforming saturated porous medium consolidating under a surcharge stress, coupled with reactive advective/dispersive solute transport through the medium, capped with a thin-layered reactive sequestering geocomposite known as a reactive core mat (RCM). In addition to assumptions made in previously developed, one-dimensional consolidation coupled contaminant transport model RCM-XPORT2, the RCM-XPORT2K model accounts for sediment- and sorbent-specific sorption kinetics to model nonlinear, and nonequilibrium sorption behavior. Validation of the model is presented by simulating: (1) sorption kinetics tests performed on sediment sampled from Neponset River, Milton, Massachusetts, USA and a commercial product, CETCO Organoclay PM-199; (2) solute transport from the large strain consolidation coupled contaminant transport tests with Br− and Cl− using a high water content inert silt sample (New York Silt); and (3) the naphthalene transport and breakthrough times observed in upflow column tests with Neponset River sediment with various overlying cap layers.