Saturated and Unsaturated Hydraulic Properties of Ponded Coal Ash

摘要

Coal has been used for electrical power generation for decades. There are several hundred unlined coal ash ponds in the United States that require closure. Federal regulations passed in 2015 also mandate assessment of the risk of leaching of coal ash constituents to the groundwater. Groundwater modeling is often required to assess such risk and requires a proper characterization of the saturated and unsaturated hydraulic properties of fly ash. This experimental study involved carrying out unsaturated hydraulic conductivity testing using the instantaneous profile method of fly ash collected from a coal ash pond located in southeastern United States. The unsaturated hydraulic conductivity function predicted by the van Genuchten-Mualem equation underestimated K(ψ) at suctions greater than 10~4 cm. The prediction function was relatively accurate at matric suctions up to 10~4 cm. Thus, use of predicted unsaturated hydraulic function may underestimate the risk to groundwater.