A methodology for assessing the potential environmental impact of failure of leachate-retaining earthen dams

Abstract

We describe herein a useful model for assessing the environmental impact of the breakage of earthen dams used to retain leachate fluids. To create this model, we analyzed three parameters: (1) the characteristics of both the earthen dam and the leachate; (2) the behavior of the leachate cascade resulting from breakage of the dam; and (3) the environmental effect of the resulting pollution. To accomplish this, we first analyzed the failure of earthen dams for leachate according to the Dam Break Inundation Analysis methodology, which provides the characteristics of the leachate cascade or avalanche resulting from the dam breakage. We then used data for different earthen dams for leachates and calculated the volume of leachate that would reach each point the leachate-flow bed downstream of the dam to generate a graph identifying areas at risk from the leachate cascade. As a third step, we calculated the pollutant charge of leachate, and lastly identified and assessed the environmental factors (EFs) within the risk area. Through these steps we formulated an equation for the environmental risk index (ERI EF), which quantifies the potential environmental impact of the rupture of an earthen dam for leachate on the area surrounding such a dam, and which has a value that ranges from 0 to 1. In order to validate this methodology, we applied the ERI EF equation to nine man-made earthen dams for leachates. All nine are considered safe facilities in having had no accidents in the years since their construction. All have ERI EF values below 0.12, indicating that this value can serve as an appropriate guide to the environmental impact of the rupture of earthen dams that retain leachates