Cellular Confinement Systems to Prevent Resuspension in Sediment Basins

Abstract

Sediment basins provide quiescent conditions that enable settling of fine particles present in runoff, mitigating environmental effects created by excessive sediment discharges. Yet, settled particles are susceptible to undesired resuspension if, during dewatering of the basin, new flows are admitted that increase velocities, shear forces, and turbulence near the basin bottom. This study presents results from an investigation of the benefits of confinement cells as a lining strategy for the bottom of sediment basins. Characteristics of effluents in an experimental apparatus representing the bottom of sediment basins were studied for varying geometries of confinement cells and flow conditions. A significant decrease in effluent turbidity was reported with the use of cellular confinement cells, with smaller cell widths as a key parameter to reduce outflow turbidity. Computational fluid dynamics modeling was used to determine which geometries were more likely to succeed in decreasing turbulence and shear within confinement cells. A nondimensional resuspension parameter RP was proposed to correlated cell geometry and intracell flow velocity for the tested sediment.