Environmental risk from the development of PFA fill earthwork structures and an improved code of practice to mitigate potential impacts

Leaching tests have demonstrated that metals and other inorganic contaminants are released from pulverised fuel ash (PFA) under laboratory conditions. Consequently, it is necessary to review the potential risks posed by large earthwork structures constructed of PFA. In this study, the findings of the recently completed risk assessment for unbound PFA in the Waste Protocols Project are compared to the results of equivalent risk assessments carried out using leachate data for PFA samples collected from the Barlow PFA storage mound at Drax Power Station. Current recommendations for an environmental code of practice for the construction of earthworks using PFA are considered in relation to the results of the generic risk assessments. A tiered methodology for the impact assessment, investigation and risk assessment to be adopted for the placement of PFA fill in large construction projects or within above ground storage mounds is presented. This methodology is intended to provide a framework for earthwork design engineers to use in order to ensure that a thorough assessment is made of the possible effects of PFA bulk fill earthworks or above ground storage mounds on the environment. Copyright © 2010 John Wiley & Sons, Ltd.