Lagoons to Landfills: A Conversion Case Study, 1990 Environmental Conference Proceedings

Fort Howard Corporation began disposing of a wet sludge from its deinking mill in Green Bay, Wisconsin in a series of sludge disposal impoundments located on 117 hectares of semi-rural land near Green Bay, Wisconsin during the mid 1960s. Faced with adjacent urbanization, a dwindling site life, and the political and environmental difficulties associated with development of a new facility, Fort Howard sought methods of increasing its existing site life, while implementing several environmental and aesthetic improvements.

Background studies in a test cell were undertaken to determine the physical characteristics of the impounded sludge and monitor changes resulting from the removal of surface water. Encouraging results led to the construction of a surface water handling system, installation of sludge dewatering presses, and purchasing a new fleet of sludge transport and placement vehicles. Operating experience has shown that dewatered sludge placed in less than 1.0 meter lifts at shallow slopes will remain stable and compaction of these thinner lifts resulted in a 4% reduction in air space consumed. Also, overfilling of the cells is necessary to compensate for long-term settlement due to cover application if positive runoff is to be maintained. Delaying application of the final cover as long as practical reduces the settlement due to cover application, allows regrading of the surface prior to covering and allows for desiccation to provide a more trafficable sludge surface. The test data and field experience gained in the initial test cell were used to develop effective operating plans, account for long-term settlement in designing site grades, and optimize sludge placement techniques to increase landfill life.