The Use of Geomembranes in Dams

Geomembranes, and particularly Polyvinylchloride (PVC) geomembranes, used since more than half a century to control seepage in dams, are environmentally friendly rehabilitation technologies. In rehabilitation, geomembrane systems have been applied on all types of dams, to line the entire upstream face of the dam, or only the area/s causing most seepage, or only cracks/failing joints. The geomembrane is placed in exposed position, and is drained behind. In new construction, geomembrane systems have been applied to provide the water barrier in embankment dams and RCC dams, and as external waterstop for joints in CFRDs and for joints between monolith blocks in RCC dams. In RCC dams and fill dams, the geomembrane can be at the upstream face, in exposed or covered position, in fill dams also as a geomembrane core. The paper discusses the available options for rehabilitation and gives some information on new construction, addressing case histories in the dry and underwater. The paper introduces an innovative underwater waterproofing technology, already successfully installed on two canals, which permits repairing embankment dams and canals without impacting on operation: no dewatering, no reduction of water speed. This technology can be considered also for new construction of embankment dams and canals.