Recent Experience with Geomembranes in Earth Embankment Dams and Reservoirs

The application of geomembranes in dam construction has lagged its application for other geotechnical projects such as slope stabilization and lining of ponds and canals. However, over the last forty years its use has become more common, especially as applied to the lining of small reservoirs and as a primary or secondary water-proofing system in new Roller Compacted Concrete (RCC) dams or in rehabilitation of older concrete dams.
A geomembrane-lined reservoir or earth embankment is often the preferred option in areas with permeable subsurface conditions and/or areas located in regions with limited access to clayey soils. This paper discusses some recent experience and lessons learned during the design and construction of geomembrane liners for earth embankment dams. The topics discussed include:
- The use of cover soils that are not free-draining, and the effects on embankment slopes and stability during normal operation as well as for sudden drawdown and seismic loading conditions.
- The design and construction of a lined reservoir for high groundwater; including the need for and the methods used to minimize uplift pressures on the liner.
- The use of a geomembrane drainage liner to provide a leak detection system while maintaining relatively steep embankment slopes.
- The design considerations for penetrations through geomembranes used on earth embankment dams.
We present these topics in the context of six geomembrane-lined earth embankment dams and reservoirs designed, of which five were constructed in the last 5 years.