Increasingly it is realized that, under economical and ecological aspects, conventional pump-and-treat systems for remediation of contaminant plumes do not lead to satisfying results. This is particularly true if remediation periods of several decades are anticipated, which means a continuous and, ultimately, high input of energy for pumping water from extraction wells and operating water treatment systems, as well as periodic maintenance and monitoring. In the early 90s the method of "Permeable Reactive Barriers" (PRBs) was suggested in Canada and USA. PRBs are a passive in-situ technique that runs without any need of permanent and cost-intensive operations. Once installed in the subsurface, geochemical or geophysical reactions between the material in the PRB and ground water contaminants take place without any further external interference. Research efforts at the Institute of Geotechnical Engineering (IGT) include the development of an adsorptive barrier material containing different reactive media to treat a wide range of contaminants and contaminant classes. The research programme will comprise both laboratory and full scale geochemical and geotechnical tests. 1 Dr. Rita Hermanns Stengele, Ass. Prof. in Environmental Geotechnics, Institute of Geotechnical Engineering, Swiss Federal Institute of Technology (ETH), CH-8093 Zurich 2 Sven Köhler, Scientific Assistant and PhD-Student, Institute of Geotechnical Engineering, Swiss Federal Institute of Technology (ETH), CH-8093 Zurich
Permeable Reactive Barriers are installed in the aquifer across the flow path of a contaminant plume. As the reactions that occur in such systems are affected by many parameters, successful application of this technology requires a sufficient characterisation of contaminants, ground water flow regime and subsurface geology. In case of instability of the subsoil or if great depths are to be reached, techniques of specialised heavy construction are essential for the implementation (i.e. sheetpiling, contiguous bored cased piles).
