Chapter 11: Dams with PVC membranes

PVC geomembranes have been used since 1960 to provide or enhance watertightness in new dams and for remedial works on existing dams. Their deformability and tensile resistance can be an added value in the construction of dams in seismic areas because they can withstand, without failing, the high stresses resulting from a seismic event. Upstream geomembranes are, thus, very suitable for embankment dams that experience significant static or seismic deformations as the membranes are very flexible, although they may be damaged by vandalism, ice, floating debris or rockfalls near the abutments.

In roller-compacted concrete (RCC) dams, rockfill dams and concrete faced rockfill dams, the use of flexible geomembranes from the design stage, to waterproof the whole upstream face or to prevent water infiltration at joints, is recognised and has proven in the field to be an efficient method to prevent uncontrolled water presence in the dam. In dams in seismic areas, the ability of a geomembrane to accept large displacements is certainly an asset for the safety of the dam.

An example of a concrete dam in which a PVC geomembrane was used as an additional safety measure is the 97 m-high Olivenhain RCC dam in California. The dam was required to retain watertightness in the case of a seismic event.