Simulation of the Borden Plume using the alternating direction Galerkin Technique

Abstract

The evolution of the chloride plume at the Borden landfill is simulated and a parametric analysis is performed. The plume is characterized by sharp vertical concentration gradients, indicating a weak transverse vertical dispersion mechanism. To handle the high‐resolution grid that is necessary because of the large contrast in the dispersive parameters, the alternating direction Galerkin technique is used. Various types of numerical error that can arise in simulations of such plumes are discussed. The parametric analysis reveals that an approximately three order of magnitude contrast between longitudinal and vertical transverse dispersivities exists in the Borden plume. A variable source concentration function will reproduce the concentration peaks that were observed in the field. However, a growing source concentration function can also produce longitudinal spreading resembling that obtained with a larger longitudinal dispersivity, indicating possible nonuniqueness. The vertical transverse dispersion parameter, which is unaffected by nonuniqueness, is within 1 order of magnitude of molecular diffusion.