The influence of biological and chemical clogging on the transmissivity of geonets in secondary leachate collection systems of waste containment facilities

Geosynthetics are used in a wide variety of applications, including lining and drainage of waste containment facilities. A limited amount of data were available on the clogging potential of geonets and needed to be addressed. Using leachate from a MSW landfill simulated realistic conditions. In addition, a hydraulic gradient and confining stress of 0.02 and 300 kPa respectively were used as constant test parameters. Clogging rates of 36 and 96 hours were observed with new leachate that was high in iron. Reduced rates of clogging occurred where the leachate strength was lower. All tests did, however, have rapid clogging (all test combinations would have clogged within 100 days). This clogged material pooled in the pores of the geonet and did not adhere strongly to either the geonet or the geomembrane. Differences were observed with the various combinations. Textured geomembranes had higher rates of clogging than smooth geomembranes. High density polyethylene did not reduce the cross sectional area of a geonet as much as low density polyethylene. Both the transmissivity values of the geonet as well as the geonets imprint on the geomembrane substantiated this. Geonet orientation appears to have the greatest effect on transmissivity with those geonets having their channels oriented more in the direction of flow having higher transmissivities. Further testing is, however, needed to determine if geosynthetic use in leachate collection and detection systems is adequate.Applied Science, Faculty ofCivil Engineering, Department ofGraduat