Author(s)

J C Evans

Abstract

Slurry trench cutoff walls have been used as vertical barriers in the rehabilitation of land disposal sites to mitigate subsurface contaminant transport and permit safe reuse of the site. This paper presents two detailed case studies where soil bentonite slurry trench cutoff walls have been used for the rehabilitation of existing land disposal sites. The first case study, a hazardous waste land disposal site, was successfully closed and subsurface migration of contaminants to offsite receptors was controlled by a subsurface vertical barrier installed using the slurry trench method of construction. Portions of the site have been converted to a golf course. This second case study, a municipal and industrial waste landfill, was originally the site of a sand and gravel quarry. Using a soil-bentonite slurry trench cutoff wall, the existing landfill was contained to prevent the spread of ground water contamination and converted into an industrial use. Specifically, the site cap cover was designed as a \“wear surface” cap designed to accommodate regular use for the storage of heavy equipment. The paper describes the site and subsurface conditions, the design, laboratory and analytical studies supporting the design, the construction, construction quality control measures and results and the performance of the completed systems. Based on the results of this study, it is concluded that the installation of vertical barriers using the soil-bentonite slurry trench method of construction can provide an economical and environmentally sound means to control subsurface contaminant migration from land disposal sites and, when combined with a properly designed and constructed cover, allows for site reuse. 1 Introduction This paper describes the use of soil-bentonite slurry trench cut off walls as vertical barriers for the rehabilitation of two land disposal sites: one a solid and

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