2023 – Reliability of Geomembranes for Optimised Dams in New Pumped Storage Schemes

Gabriella Vaschetti, Marco Scarella, Eric Guilleminot, John Cowland

Pumped storage schemes are increasing in number worldwide to facilitate the transition to clean energy. The repeated loading and unloading conditions created by the water in motion place demanding loads on the storage containment structures Geomembranes have been demonstrated to be capable of coping with the challenges of pumped storage schemes, due to their tensile and endurance properties, and due to the ingenious design alternatives that have been developed in the last three decades. This paper focuses on issues related to design and construction of the upper and lower reservoirs, which are often formed by excavating natural slopes and by earthen or rock fill embankments, and which must avoid uncontrolled water leakage due to the settlements and differential displacements that can occur during operation. An exposed geomembrane liner of adequate properties, with an underdrainage system, together with a compartmented leak detection system, allows requirements to be relaxed on internal drainage of the embankment, decreases the likelihood of piping, and allows for a more economical subgrade preparation. The geomembrane liner system can be constructed in much shorter times than an asphalt concrete or a concrete liner, with resulting earlier commissioning. Overall, a geomembrane system provides an efficient durable water barrier, improves safety, optimises design and construction, is cost- effective, and represents an additional step forward in terms of sustainability, because its carbon footprint is lower than that of traditional liners such as concrete or asphalt concrete. The paper discusses the value engineering involved in the study and design of geomembrane liners for new pumped storage schemes, the technical and financial benefits that can be obtained, and presents two case studies of new pumped storage schemes recently completed, one in Israel and one in Morocco, where the upper and lower reservoirs have been lined with an exposed geomembrane anchored with different anchorage systems against wind uplift and water level variations.

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