Andalusia has 80 large dams, of which 30 are managed by the Junta de Andalucía, as they belong to the intra-community basins whose powers in terms of water are transferred by the State to the community. These infrastructures, due to their potential risk, are classified as ‘category A’ in the event of a possible rupture, for that reason they require careful technical supervision and guarantee their maintenance and the safety of the areas and populations located downstream.

To this end, the Regional Ministry of the Environment and Territorial Planning of the Junta de Andalucia has entrusted Ayesa with the task of monitoring and inspecting the dams of the hydrographic demarcations of the watersheds on the Atlantic coast of Andalusia.

In total there are 16 large facilities, of which half are located in the basins of the Tinto, Odiel and Piedras rivers in the province of Huelva, and the other half in Guadalete and Barbate in the province of Cádiz. The amount of the contract amounts to 1.6 million euros and its duration is two years. Functions Ayesa has won the contract in UTE with Ofiteco, a company specializing in safety, instrumentation and auscultation of dams.

In this sense, Luis Castillo, head of the Hydraulic Works section at Ayesa, points out that it is a “very complementary” consortium of companies, since Ayesa covers all aspects of engineering, while Ofiteco is responsible for the follow-up and evaluation of the behavior of the dams “.

The work of these ‘guardians’ is to verify that the dams are technically complying with the Regulation of Dam Safety (for example, as regards hydrological safety or seasonal restraints for the laminating of floods) and as regards to design and construction (structural safety or general stability). Equally important is keeping the security documentation up to date, in what is known as a technical file. In other words, the team will carry out a series of ordinary activities, already foreseen in the bidding documents (classification proposals, XYZT document, operating rules, emergency plans, PE implementation project, etc.), but also extraordinary ones derived from possible climatological or geological events, such as intense rains or seismic movements. In these cases, it is necessary to go to the site to check the state of the infrastructure, supervising its general condition and behavior in relation to leaks, movements, landslides or relative displacements.

“In the first phases all the facilities are visited, both externally and through the galleries and internal elements, and the needs reports are made. In parallel, but in a coordinated manner, the companies in charge of the maintenance and conservation of each dam are carrying out improvement actions such as waterproofing injections or some replacement of drainage valves,” explains Castillo.

Guadalcacín II

The engineer points out that the dams on the Atlantic coast are in a good state of conservation in general. Among the 16 hydraulic works stands out the Guadalcacín II (Cádiz), in whose design Ayesa participated years ago, and more recently made the project to improve its bottom drainage. It is a dam of loose materials of great height and storage capacity, with 78 meters and 850 cubic hectometres (Hm3). On the other hand, stands out the Andévalo (Huelva), for being the most recent construction. It is still in the process of being filled and will be the third largest in the whole community, only surpassed by the previous one and by the Iznájar dam in Córdoba.

There are also two of mining origin: SotielOlivargas and Cueva de la Mora, with type of arc of gravity and vault respectively. These two must be adapted in full to the 1996 Dam and Reservoir Safety Technical Regulation. Castillo highlights the uniqueness of this contract, as it is not usual for these jobs to be outsourced. Normally, the surveillance and security tasks depend directly on competent administration (Hydrographic Confederations or the corresponding Ministry).

Finally, Castillo emphasizes that this contract “allows us to give continuity to a team of engineers very specialized in this type of work linked to the design, conservation, maintenance and management of dam safety”. Likewise, he points out that “other similar contracts will happen in other countries of Latin America, where we have already participated in the design of dams or even in India, where Ayesa has been present for years”.