Leak Sealing at HEC Sveta Petka – Penstock Galleries, FYR Macedonia

Chronic Leakage in Penstock Access Galleries

HEC Sveta Petka is a strategically important hydroelectric plant supplying energy to North Macedonia’s national grid. Over time, critical penstock galleries—which serve as inspection and maintenance corridors for the main pressure conduits—began suffering from persistent water infiltration, notably at construction joints and microcracks in the concrete lining.

This infiltration caused:

• Operational disruptions due to standing water and slippery surfaces,
• Accelerated deterioration of reinforced concrete,
• Long-term risk of structural weakening in a high-pressure zone.

Several attempts using conventional sealing methods failed to provide a permanent and resilient solution, particularly given the high saturation levels and inaccessibility of deeper capillary cracks.

EURAS® Gel Type B – Adaptive Waterproofing in High-Pressure Environments

Given the ongoing challenges and environmental constraints, the technical team at EURAS proposed a targeted injection of EURAS® Gel Type B—a bentonite-based, hydroscopic, and elastic gel engineered for active leaks and wet application surfaces.

Key product attributes leveraged in this project included:

• Self-penetration into micro-fissures and capillary networks, even under dynamic water pressure,
• Excellent adhesion to moist concrete, without requiring drying of the substrate,
• Chemical resistance to aggressive groundwater often found in mountainous geology,
• Injection capacity up to 200 bar, enabling deep and uniform dispersion,

Implementation Details

The installation was performed under difficult access conditions and involved:

1. Site mapping and borehole placement to target key ingress points and crack zones within the gallery walls and slab.
2. Use of specialized high-pressure pumps to inject EURAS Gel into the targeted joints and fissures, operating at up to 180 bar.
3. Sequential monitoring of gel propagation, confirmed by water displacement and minor backflow—an indicator of saturation.
4. Post-injection visual and instrumental assessment confirming leak stoppage and stabilization.

• Immediate and total sealing of all previously leaking surfaces,
• Restoration of safe working conditions in the gallery,
• Long-term structural protection against moisture-induced degradation,
• No re-leakage observed during post-project inspections and pressure simulations,
• A strong endorsement by the client for similar future applications across their facilities.