PVC geomembranes in pumped storage schemes

Auszug

Construction of pumped storage schemes is increasing in many European countries and around the world to implement/backup the energy production from windmills. To ensure efficient and safe operation, the storage reservoirs must be watertight and maintain watertightness over time. Traditional waterproofing solutions like concrete and bituminous concrete linings need periodical and/or accidental maintenance that may have significant impact on operation of the scheme. A viable alternative, based on well-proven systems adopted for new construction and rehabilitation of dams and reservoirs, is to use impervious flexible geomembranes, generally Polyvinylchloride (PVC) composite membranes embedding a backing geotextile for anti-puncture protection, which can be installed on fairly uneven base layers, reducing surface preparation. Several anchorage systems are available to maintain the liner taut to the surface under varying water level and against wind uplift. The advantages of a geomembrane system in pumped storage schemes are numerous: the geomembrane can be installed on very steep/vertical slopes unattainable with a bituminous concrete facing; being all components prefabricated and their assembly controlled at site by standardised methods, watertightness at completion of works can be checked, and monitored over service; installation times are much shorter and practically independent of weather conditions, cost advantage can be significant; one guarantee covers design, materials and installation; no maintenance needed, watertightness maintained for several decades; accidental damage can be repaired even underwater, no outage of scheme; with > 230 % 3-dimensional elongation a geomembrane liner can resist settlements/differential movements at concrete appurtenances that would cause failure of a bituminous concrete liner or a concrete facing. Design and installation aspects, and indications on future prospects, will be discussed through case histories in Italy, India, Germany and Iran. …