GSE HD geomembrane after 20 years in service at Thailand's first pumped storage hydropower plant

Overview 

Lamtakong Upper Reservoir, located in Nakhon Ratchasima (Korat), Thailand, was constructed in 1994 as a critical component of the Lamtakong Jolabha Vadhana Pumped-Storage Hydropower Plant. Due to its proximity to the Lamtakong irrigation dam's reservoir, the Electricity Generating Authority of Thailand (EGAT) selected the site for the country's first-ever pumped-storage hydropower project using advanced and modern energy technology, providing a generating capacity of 1,000 MW. With a total storage capacity of 10 million cubic meters and a maximum water depth of 35 meters. 

Challenge  

Shortly after the hydropower plant became operational in 2004, water leakage was observed in the upper reservoir located on Yai Tieng Mountain. The reservoir, constructed as a rockfill dam lined with an asphalt-concrete, was designed to store over 10 million cubic meters of water for pumped-storage operations. However, the intense hydrostatic pressure from daily pump-back cycles, combined with the region’s tropical climate and surface settlement over time, began to compromise the reservoir’s waterproofing system. This posed a significant risk to the operation of pumped-storage hydropower plant. The leakage not only threatened water retention capacity but also risked system reliability and long-term structural integrity. A flexible, durable and long-term waterproofing solution was urgently required, one that could withstand cyclic loading, UV exposure, and aging in harsh outdoor conditions. 

Solution 

To resolve the issue, EGAT selected a geomembrane liner system to replace the asphaltic material as the primary water barrier. In 2004, a 2.00 mm thick High-Density Polyethylene (HDPE) geomembrane was installed over a surface area of approximately 400,000 square meters across the inner slopes and base of the upper reservoir. The selected product, GSE® HD geomembrane, was chosen for its superior mechanical strength, chemical resistance, low permeability, and proven track record in critical containment applications. 

The installation process required proper surface preparation and quality control to ensure intimate contact between the liner and subgrade, particularly on steep embankment slopes. The newly deployed GSE HD geomembrane layer acted as a robust containment barrier, significantly reducing leakage and restoring full functionality to the reservoir system. 

Geomembrane performance after 20 years of exposure to tropical weather 

After more than two decades of continuous operation, the GSE HD geomembrane installed at the Lamtakong Upper Reservoir continues to demonstrate remarkable durability and performance.  

Evaluation of the exposed geomembrane showed that physical and mechanical properties remain generally unchanged after more than 20 years in service. No substantial changes in the internal structures of the material, and no apparent degradation in the material properties of 2.0 mm thick GSE HD geomembrane, particularly as primary water barrier.   

The success of the geomembrane lining has been instrumental in ensuring the uninterrupted operation of the pumped-storage hydropower facility. The Lamtakong Upper Reservoir project has become a regional benchmark for long-term geomembrane performance, proving that GSE HD liners, when properly designed and installed, can deliver more than 20 years of service and beyond when exposed to tropical weather under demanding environmental and hydraulic conditions. 

However, as with any aging infrastructure, proactive management is essential, particularly for the exposed sections of the geomembrane liner that experience constant UV radiation and thermal stress. Regular monitoring of a geomembrane's key properties by testing on the exhumed test coupons is crucial for assessing its long-term performance and tracing changes in geomembrane properties over time. This not only helps to ensure the geomembrane continues to function as intended but also allows for timely mitigation of any potential issues.  

In addition, leak monitoring on geomembrane-lined reservoirs is crucial to ensure environmental protection and operational efficiency. Early detection of leaks allows for timely repairs, minimizing environmental damage, reducing repair costs, and preventing loss of valuable liquids.  

This forward-thinking approach will help safeguard long-term system performance, reduce the risk of unplanned failures, and protect the reservoir's role as a vital component in Thailand’s renewable energy infrastructure.