Sustainability of Vertical Barriers for Environmental Containment

Vertical barriers have long been used to control groundwater flow and subsurface contaminant migration from contaminated land sites. Commonly employed vertical barrier types available to owners and designers include those constructed using slurry trenching techniques such as soil-bentonite (SB), and cement-bentonite with slag (slag-CB), in situ soil mixed walls (SMW), as well as driven barriers such as sheet piles. The selection of the appropriate vertical barrier technique depended upon site geology, cost, and regulatory requirements with no consideration of the global environmental impact of the type of vertical barrier chosen in terms of sustainable engineering. In this paper, the sustainability of four commonly deployed vertical barrier techniques is discussed. Using the case study method, the paper evaluates a previously completed project where an SB slurry wall was constructed. Evaluations are described for an environmental sustainability assessment (based on the materials, fuels, and equipment used; transport distances for personnel travel and materials/equipment transport), an economic sustainability assessment (based on the direct and indirect costs), and a social sustainability assessment (based on a survey taken by stakeholders/professionals/experts). The paper closes with findings, conclusions, and recommendations regarding the sustainability of vertical barriers.