Completion of the Mularroya tunnel excavation

The Mularroya Tunnel, 13.3 km long and designed to transfer up to 8 m3/s of water from the River Jalon to the Mularroya reservoir, is one of the most unique hydraulic works carried out in recent decades in Spain. In November 2020, the tunnelling machine “Crete”, began excavation in the River Grio, through to its completion on March 1st, 2024, date on which it reached the exit on the right bank of the River Jalon, following a long and hard underground excavation.  

The tunnel, with an inner diameter of 2.90 m and a 20cm thick precast concrete arch stone, required an excavation of 3.55 m.  

Geological longitudinal profile along the route 

The Mularroya Dam, constructed with loose materials, has a reservoir capacity of over 103 hm3, and will enable optimal utilisation of water resources in the area to provide irrigation for over 5,000 hectares. With the completion of the tunnel, the most significant works of this project conclude; a project in which TYPSA has been carrying out, since 2008, Project Management control, monitoring, and support services. The execution of minor works and finishings, as well as the corresponding liquidation of the works, remains to be done, with the foreseeable completion of the works in the first quarter of 2025, when the dam commences commissioning phase.  

TYPSA team working in the tunnel lining (1 March 2024) 

Working diligently in such a confined space, in the knowledge that the exterior access point is located several kilometres from the excavation site, poses a challenge which only great professionals can handle.  

Perseverance, sacrifice, and unwavering commitment were essential to overcome the significant challenges posed, thus making possible this unique infrastructure, which brings great benefit to society. In light of this achievement, the people involved deserve the utmost the recognition.

Víctor Pascual
Site Manager

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