Criterion for acceptable bentonite loss from a GCL incorporated, into a liner system

The following case is considered in the present paper: a geosynthetic clay liner (GCL) used in the composite primary liner of a double-lined landfill is overlain by a geomembrane and underlain by the secondary leachate collec tion layer, which consists of a geonet. If bentonite particles migrate down ward out of the GCL, through the geotextile(s) that separate(s) the bentoni te layer from the geonet, they penetrate into the secondary leachate collec tion layer. Depending on the amount of bentonite particles migrating from t he GCL, these particles may decrease the hydraulic transmissivity of the se condary leachate collection layer. Also, the loss of bentonite particles fr om the GCL may decrease the performance of the composite liner. The present paper provides theoretical analyses of these detrimental effects of benton ite particle loss, which lead to an acceptance criterion that can be used t o evaluate the results of tests performed tc, determine if the geotextile(s ) that separate(s) the bentonite from the geonet is (are) suitable or if an other (or additional) geotextile is necessary.