USE OF ALVATECH 2.00 MM GEOMEMBRANE IN THE HIGHEST STORAGE RESERVOIR IN THE IBERIAN PENINSULA

• Location: Sierra Nevada – Monachil (Granada), Spain
• Installed Geomembrane: 36.106 m²
• Products Used:
• Upper Layer: ALVATECH COLOR 2.00 mm marrón – Geotextil PP 1.000 g/m²
• Lower Layer: ALVATECH 5002 2.00 mm negra – Geotextil PP 1.000 g/m²

Context

The Zahareña Reservoir is part of the strategic water storage system for artificial snow production at the Sierra Nevada ski resort.

Located at over 2,600 meters above sea level, it is the highest-altitude water storage reservoir in the entire Iberian Peninsula.

Operating conditions are extremely demanding:

• Continuous freeze–thaw cycles

• Ice thicknesses of up to 1 meter

• Rapid water level drawdowns (1–2 m/day)

• Temperature variations exceeding 25°C

• High UV radiation

Following repeated loss of watertightness in the original system, a complete rehabilitation of the waterproofing system was undertaken, prioritizing structural reliability and long-term durability.

Challenge

The repair of this reservoir presented several technical challenges:

High-Mountain Conditions

The geomembrane had to withstand friction from ice sheets, stresses caused by thermal contraction, and extreme UV exposure.

Aggressive Subgrade

Presence of outcropping rock (mica schists and quartzites) and sharp-edged gravels, increasing puncture risk.

Hydraulic Safety

Freeboard had to be improved and the spillway adapted to guarantee structural safety.

Critical Infrastructure

The reservoir is essential for the operation of the ski resort, requiring maximum reliability of the waterproofing system.

Landscape Integration

As the site is located within a protected natural environment, minimizing visual impact was a priority.

  

Solution

To address these challenges, a double-barrier waterproofing system was designed and installed using ALVATECH 5002 and ALVATECH COLOR BROWN 2.00 mm geomembranes.

The installed system consists of:

• PP Geotextile 1,000 g/m² as base protection layer

• ALVATECH 5002 2.00 mm black geomembrane (primary barrier)

• PP Geotextile 1,000 g/m² interlayer

• ALVATECH COLOR 2.00 mm brown geomembrane (secondary barrier and landscape integration)

The double-liner configuration allows:

• Significant increase in the safety factor

• Integration of an interlayer leak detection system connected to drainage

• Reduced puncture risk under structural ice conditions

• Extended service life of the system

The upper brown geomembrane enhances visual integration with the high-mountain environment, reducing landscape impact compared to conventional solutions.