Protecting the Environment with Geosynthetics: 53rd Karl Terzaghi Lecture

Abstract

Design- and construction-related factors that affect leakage through geomembranes, used either alone or in a composite liner, are examined. The development, detection, and number of holes that can develop during construction and operation of a facility are discussed. The relationship between leakage through holes in a geomembrane, and the hydraulic conductivity of the material above (including tailings) and below a geomembrane, is examined, considering both a relatively permeable subgrade and an underlying clay liner (including the unstressed zone beneath a wrinkle) in a composite liner. The leakage observed in the primary liners of 180 landfill cells is explained by holes in geomembrane wrinkles with a length consistent with those observed in the field and an appropriate choice of hydraulic conductivity for the clay liner below the geomembrane wrinkle with a hole. Leakage through geosynthetic clay liner (GCL) overlaps below wrinkles is examined. The latest research into the physical and chemical aging of high-density polyethylene (HDPE) geomembranes liners is discussed in the context of the compatibility of the antioxidant package and resin with the solution to be retained, liner temperature, nature of exposure, sustained tensile strains, and welds. The estimation of the service life of a geomembrane based on immersion tests and simulated field conditions is examined in terms of antioxidant depletion, stress cracking, and the maximum allowable strain in a geomembrane. It is projected that the service life of a geomembrane may range from just a few years to many centuries.