Performance Evaluation of Highway Embankment Constructed with Waste Foundry Sand

Considerable savings are possible for the metal casting industry through the development of reuse applications for waste foundry sand (WFS). State departments of transportation face increased pressure to reuse waste materials in transportation construction. In 1996, the Indiana Department of Transportation and Purdue University constructed a demonstration embankment by using WFS from a ferrous foundry. WFS and control embankments were instrumented to monitor geotechnical and environmental performance during and after construction. Stockpile and jobsite WFS samples also were tested. The geotechnical investigation demonstrated that WFS can perform well as a structural fill, having strength and deformation characteristics comparable to natural sand. The compacted WFS has a hydraulic conductivity considerably lower than that of natural sand and generally cannot be considered as freely draining. Environmental testing consisted of Microtox and Nitrotox bioassays, ion chromatography, and inductively coupled plasma testing for metals. Bioassay results indicate the WFS has not leached contaminants at concentrations higher than those expected from natural sand and is not likely to have a negative environmental impact at the site. Ion migration from the WFS into the foundry sand lysimeter was found, supporting bioassay data, but at concentrations below drinking water standards or reuse regulatory criteria. Metal concentrations typically were below detection levels.