Screening-Level Approach for Estimating Contaminant Export from Tributaries

Abstract

The in-place pollutant export model (IPX) is a screening-level model for estimating contaminant export from tributaries with contaminated sediments to receiving waterbodies. IPX is a modified version of the USEPA's WASP4 modeling framework. IPX synthesizes sediment transport processes for sediment aging, decreased sediment resuspendability with increasing age, and resuspension of freshly deposited sediments as a function of water velocity, into an expanded WASP4 contaminant transport and fate chassis while retaining the computational flexibility of the original framework. These process descriptions are needed to accurately simulate contaminant transport and substantially improve the framework for application to tributary systems subject to significant deposition and resuspension events. The potential for applying IPX is broad; water quality impairments attributable to contaminated sediments are widespread due to discharges from industry, agriculture, and mining and ore processing. IPX has been successfully applied to the upper and lower Fox River in Wisconsin, and the Buffalo and Oswego Rivers in New York, all impaired by contaminated sediments.