Considerations for the Calculation of Permeation Rates for Geosynthetic Clay Liners in Constant Water Head Applications

Geosynthetic Clay Liners (GCL) are widely used in sealing applications throughout the world. In applications with constant water heads - such as artificial ponds, rivers, canals, etc. - the permeation rate through the GCL is of vital importance to the performance of the whole structure and the allocated function. A proper design must consider all potential sources of water loss in the designed application. This includes also the performance of overlaps or the combined effect of multiple sealing layers. Some factors are sometimes misinterpreted, underestimated or not considered. The presented paper will focus on two major topics, each affecting the performance of geosynthetic sealing systems with special focus on geosynthetic clay liners (GCL). The impact of these effect is to be illustrated on exemplary calculations for virtual projects. The quantification of these effects will result in recommendations that shall help to anticipate unfavorable situations for the operational phase of a project already in the design stage. This shall contribute to a better overall understanding of GCL and help to avoid preventable design errors. An outlook shall summarize the further efforts envisaged by the authors to provide a simple tool to allow calculation of permeation rates for GCL or complete barrier systems.