Rapidly pulsed pumping accelerates remediation in a vertical circulationwell model

Abstract

One factor that slows groundwater remediation is the sequestration of contaminant in dead-end pores, that is, pores that are not flushed through by flow through the aquifer. Furthermore, rebound of apparently remediated aquifers can occur as a result of the eventual release of the contaminant trapped in these dead-end pores. Since the operational costs generally outweigh the capital costs of a remediation project, reduction of the duration of treatment should reduce the overall cost of the average remediation. It has been shown that a rapidly pulsed flow can increase the mixing between dead-end and well-connected pores through computational fluid dynamics models with idealized pore geometry and column tests. A rapidly pulsed flow induces a deep sweep upon a sudden increase in velocity and a vortex ejection upon a sudden decrease in velocity that substantially accelerates the remediation of contaminant from these dead-end pores. To examine rapidly pulsed pumping in a more realistic configuration, a model vertical circulation well was constructed. The porous medium was well-sorted crushed glass to minimize sorption. Removal of a fluorescent dye, which represents a dissolved contaminant, under a rapidly pulsed flow was compared to a steady flow. The modeled well revealed accelerated removal of dissolved contaminants under a rapidly pulsed flow.