Case History and Regulatory Aspects of a Final Cover Performance Evaluation Involving Conventional and Evapotranspirative Cover Designs

In May 2004, lysimeters were constructed at Great River Energy's Coal Creek Station to allow a comparative field-scale evaluation of the environmental performance of three earthen final cover designs. Two of the cover profiles use conventional compacted clay hydraulic barriers to limit percolation, while the third profile is designed to store and release water via evapotranspiration. Although a considerable amount of progress has been made in modeling and understanding both types of cover systems in recent years, less attention has been devoted to the challenges introduced when attempting to obtain regulatory acceptance of an alternative final cover system. In this paper, the authors present a case history of the project, with an emphasis on permitting challenges associated with alternative final cover equivalency demonstrations. Cover system field performance to date is also discussed.