Pueblo Viejo Dam, Guatemala

In the central-northern part of Guatemala, approximately 100 km from the capital, stands the Chixoy River dam. This dam, a rockfill type with a central clay core, was designed with particular attention to stability and safety. The initial excavations involved preparing the support surface for the core and the trench for the perimeter injection and drainage gallery. The core was treated with a network of contact injections and protected with a mixture of clay, bentonite, and cement.

A monitoring system was installed to observe the dam's behaviour both during construction and the subsequent operational phase. On the left side of the valley, a stepped excavation was carried out to the planned level for the surface spillway.

In a circular economy approach, part of the extracted rock material was reused for the dam's counter-cores, totaling 2,430,000 m³, facilitating transportation and adhering to the scheduled execution times thanks to a 6-meter diameter shaft.

The challenges were numerous, particularly due to the plastic clay silts and large rock boulders. This required stabilising interventions with spritz-beton and negative anchoring in the most unstable areas. Additionally, the berm's surface was covered with a concrete slab to prevent water infiltration.
The dam's embankment was completed in about 22 months, despite the challenges posed by the rainy seasons. For diverting the Chixoy River, two tunnels were built on the left bank, one of which also functions as a bottom outlet.

During construction, karst phenomena were detected, requiring the filling of large caverns with high-pressure grout. Numerous smaller cavities necessitated intensifying injections through tunnels and galleries.