Leak Sealing at HE Đerdap 1 Hydroelectric Plant – Dilatation Joint S2-S3, Wet Gallery

Persistent Water Infiltration in a Critical Expansion Joint

HE Đerdap 1 is one of Serbia's most vital hydroelectric power stations, located along the Danube River. After decades of operation, the infrastructure began showing signs of water ingress through the S2–S3 dilatation joint located in a wet gallery — a tunnel-like space critical for maintenance and control access within the dam.

Water intrusion at such a location presented multiple risks:

• Structural degradation of reinforced concrete elements,
• Operational hazards for maintenance crews,
• Accelerated corrosion of embedded components,
• The potential for progressive failure if left untreated.

The site posed unique challenges:

• Constant water pressure from groundwater and upstream reservoir,
• Difficult access and visibility within the gallery,
• A need for sealing in fully saturated and pressurized conditions,
• Zero tolerance for shutdown or operational delays.

EURAS® Gel Type B – Engineered for Active Leaks and Harsh Environments

EPS required a sealing solution that could be injected under high pressure, function in wet and saturated joints, and maintain elasticity under future structural movement.

EURAS® Gel Type B, an injection-grade, mineral-based waterproofing gel, was chosen for its ability to:

• Absorb and displace water from its environment during injection,
• Form an internal impermeable barrier along the joint line,
• Remain elastic and stable across temperature fluctuations (-25°C to +100°C),
• Maintain cohesion and adhesion even in aggressive chemical or bitumen-rich environments,

The sealing works were carried out by a specialist contractor. The application process involved:

1. Preparation of the dilatation joint, including visual inspection, drainage setup, and joint cleaning.
2. High-pressure injection of EURAS Gel Type B into the expansion joint, using specialist pumps calibrated between 80 and 120 bar, depending on backpressure and flow conditions.
3. Real-time observation of gel expansion, ensuring full coverage and displacement of residual water.
4. Post-application verification and testing of leak stoppage and joint integrity.

The entire procedure was completed without needing to drain or shut down the gallery.

The application resulted in:

• Complete elimination of active water leakage from the dilatation joint,
• A reinforced waterproof seal that adapts to future structural movement,
• No impact on plant operation, with zero downtime,
• Successful post-injection testing confirming long-term watertightness.

The client reported high satisfaction with the speed, cleanliness, and effectiveness of the procedure.