Zeolite Prevents Discharge of Strontium-90-Contaminated Groundwater

Abstract

In December 1998 a vertical, permeable 'barrier' of granular zeolite (clinoptilolite) was emplaced beneath the surface of the earth, in the path of groundwater that was transporting strontium-ninety (90Sr), one of the most ubiquitous groundwater contaminants at nuclear installations, toward a wetland on the property of AECL's Chalk River Laboratories. This emplacement of zeolite, known as the Wall-and-Curtain, constituted the nuclear industry's first permeable reactive barrier. Through the process of ion exchange, the zeolite was intended to prevent the movement of 90Sr into the wetland.


The Wall-and-Curtain featured 1) direct measurement of flow and contaminant concentration of the water exiting the barrier and 2) hydraulic adjustment of the groundwater capture zone. During the first 5 years of operation, this permeable reactive barrier save d $200,000 per year in operational costs as compared with a comparable 'Pump and Treat' system and on that basis has paid for itself in less than two years.