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Dryad

Determining reasonable response actions following a fly ash spill in the headwaters of Banff National Park, Canada

Abstract

It can be challenging for practitioners to determine reasonable response actions following an environmental spill because there are risks associated with the recovery process, acute constraints on time, and few case studies available from antecedent events. Here, we evaluate environmental risk using a screening level assessment (SLA) and describe risk management actions during the response phase of a train derailment that released 600 tonnes of fly ash into a headwater creek in Banff National Park, Canada. Trace metal concentrations, and physico-chemical parameters from downstream of the derailment site were compared to Canadian environmental quality guidelines and upstream reference values. There was a 1 to 2.2-fold exceedance of sediment quality guidelines (As, Cd and Se) as well as a 3.6 to 17.5-fold exceedance of water quality guidelines (Al, Cd, Fe and turbidity) downstream of the train derailment. Despite uncertainty about site-specific toxicity when using a SLA, we did require the removal of the settled fly ash from the creek based on the multiple exceedances of guidelines, regulatory context, wilderness setting and potential contribution to cumulative effects downstream. Case studies that evaluate risk and describe risk management actions help practitioners make consistent and efficient decisions during the response phase of a spill.