Risk assessment, modeling groundwater contamination, capping and optimizing hazardous waste landfills from metal smelters

摘要

At the industrial site of Mo i Rana in northern Norway there major smelting plants are located on a hug alluvial delta. The waste was usually buried in the deep ravines, more or less uncontrolled, later the hazardous wastes were placed in controlled landfills with sealings and leachate control. The electric arc furnace dust landfill was terminated 5 years ago due to too high concentrations of heavy metals in the leachate. The ferrochromium producer requested to take over the dust pit for depositing his own scrubber sludge. However, the authorities demanded a thorough environmental assessment of the landfills with respect to possible unfavorable leaching effects and worst case scenarios such as failing bottom drainage in the ravine valley, failing leachate pipelines and ruptured sealings. Investigations for installing more monitoring and exploratory wells were performed as well as laboratory investigations for waste characterization and leaching properties. A comprehensive 3-D model was developed to simulate various effects such as failing drainage and remedial measures.