Reclamation of solid waste landfills by capping with dredged material

A cost-effective method for reclaiming solid waste landfills by capping with clayey dredged material is illustrated in this paper using a closure design developed for bauxite residue landfills in Texas. The design consisted of capping the landfills with dredged material obtained from maintenance dredging at a nearby bay and establishing a vegetative layer on the cap using salt-tolerant plant species. A research methodology comprised of laboratory cylinder tests, field revegetation tests and computer-based transport modeling was used to evaluate the effectiveness of the various capping alternatives and to select the final design parameters for the landfill. Results from this study indicated that a cap consisting of a 0.31 m (1.0 ft) sandy dredged material layer (topsoil layer for establishing vegetation) underlain by a 0.61 m (2.0 ft) clayey dredged material layer (low permeability layer) can be used as an effective barrier for closure of solid waste landfills yielding effective isolation of the waste from the environment. The design developed in this study can be applied to other similar solid waste sites with minor modifications depending upon the waste properties, site characteristics, and closure requirements of the facility.