Sorbing Vertical Barriers

Abstract

This chapter presents an overview of vertical barrier technologies that use sorbing materials to remove contaminants from groundwater. Two classes of system are considered: 1) low-permeability earthen barriers, in which sorbing additives are used to reduce the diffusive flux of organic contaminants, and 2) high-permeability treatment walls designed to remove contaminants under advection-dominated natural groundwater conditions. The focus of the discussion is on the performance assessment of strongly sorbing barrier materials using laboratory tests. Emphasis is placed on the design and analysis of column studies to characterize the barrier sorption capacity and the appropriate formulation of mathematical models to extrapolate long-term barrier performance. Two case studies are considered: the amendment of soil-bentonite slurry walls with an organic-rich additives, and the use of natural zeolite to remove strontium-90 from groundwater.