The Challenge

Persistent Leakage in Alpine Hydropower Galleries

Melchsee-Frutt is a high-altitude hydropower facility embedded in the Swiss Alps, supplying renewable energy across the region. Over years of operation, chronic water ingress developed in:

Construction joints of the surge chamber
Interfaces between tunnels and galleries
Micro-cracking due to freeze-thaw cycling and movement of the rock mass

These leaks were causing:

Continuous water pooling in maintenance galleries
Increased corrosion risks for steel reinforcements
Progressive weakening of aging concrete structures
Difficulty accessing infiltration zones due to confined spaces and elevation

Traditional cement grouts were ineffective in saturated, moving cracks exposed to seasonal temperature variations.

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The Solution

EURAS® Gel Type B – Elastic Sealing for Dynamic Alpine Conditions

After a technical review, EURAS® Gel Type B was chosen for its unique combination of:

Hydroscopic expansion, displacing active water even under pressure
Compatibility with wet, aging concrete and prior sealing attempts
Elasticity and adhesion, accommodating movement from thermal shifts and settlement
Non-toxic, non-shrinking formulation safe for sensitive Alpine environments

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Execution Methodology

Implementation Details

Given the confined galleries and high-altitude logistics, the work required:

Detailed mapping of infiltration pathways using endoscopy and moisture sensors
Drilling of injection ports along identified joints and cracks
High-pressure injection up to 160 bar for deep cavity saturation
Continuous monitoring of flow reduction and gel return to confirm coverage
Post-injection inspection and verification of watertightness

Despite weather constraints and elevation, the work was completed without disrupting plant operations.

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Outcome & Performance

Outcome

Complete elimination of active leaks in all treated areas
Reinforced protection of critical structural elements
Restoration of dry, safe maintenance galleries
Long-term durability against freeze-thaw cycles and mountain runoff

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Why It Matters

Engineering Takeaway

The Melchsee-Frutt project demonstrates EURAS® Gel Type B as a high-performance sealing solution in:

Alpine hydropower infrastructure
Freeze-thaw conditions with structural movement
Saturated, difficult-to-access galleries

EURAS Gel enabled a permanent, non-invasive repair in an extremely challenging environment.

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Sealing Water Ingress at Melchsee-Frutt – Switzerland

The Challenge

Persistent Leakage in Alpine Hydropower Galleries

The Solution

EURAS® Gel Type B – Elastic Sealing for Dynamic Alpine Conditions