Redaccion
THE BILBAO CITY COUNCIL COMPLETES THE CONSTRUCTION WORK OF THE TWO FLOOD DEPOSITS IN ZORROTZAURRE
- These infrastructures are located on two municipal plots in Ribera de Deusto, and their main mission will be to prevent road flooding and impacts on the drainage network during high tide episodes in the vicinity of the pre-existing buildings on the island.
- They will come into operation once the Concertation Board completes the urbanization works in the area that will enable the connection to the collectors that will discharge their rainwater into each of the deposits.
- The recently completed works, very complex from an engineering point of view, especially in a terrain like Zorrotzaurre, have had a final budget of over eight million euros.
The Bilbao City Council takes a step forward in the works that will help alleviate the impact of major tides and floods in Zorrotzaurre – mainly in the area of the pre-existing buildings on the island – with the completion of the construction of the two flood deposits. Infrastructures that have required an investment of 8,275,000 euros and are located on two municipal plots in Ribera de Deusto, near the buildings of Artiach and Papelera, respectively.
Its main mission will be to prevent road flooding and impacts on the drainage network during high tide episodes – when the drainage network is below the level of the Ria – and they will come into service as soon as the Concertation Board completes the urbanization works in the area. Essential works to ensure the connection of the collectors that will discharge their rainwater into each of the deposits.
According to the Concertation Board’s planning, it is expected that the urbanization works on Deposit 2 will begin at the end of this year and those corresponding to Deposit 1 at the end of 2026 or the beginning of 2027.
Initiated in October 2022, the execution of the flood deposits has been a very complex engineering work, that has required very precise work processes and that is why the execution period has been extended by more than the initially planned twenty months.
It is worth noting that the terrain on which they are located is composed of different layers of artificial fill, alluvial-estuarine soils (mostly silt), gravels with silt and sands, and finally rock. Therefore, an excavation with impermeable shoring has been undertaken, to ensure the stability of the bottom.
Concrete walls embedded in rock have been chosen as containment elements.
CHARACTERISTICS AND MAINTENANCE
Both infrastructures have a sufficient storage volume that allows them to accumulate water in episodes where gravity relief is not possible, and to empty it when the Ria level decreases. Specifically, a useful volume of 1,031.70 cubic meters is estimated for Deposit 1 and 1,190.25 cubic meters for Deposit 2. This solution will minimize pumping relief.
In addition, with the aim of improving the quality of the water discharged into the Ria, at the entrance of the rainwater collectors to each deposit, a sand trap and a grease separator have been installed.
For each of the two deposits, three conduits have been executed that will discharge into the Ria: the gravity discharge conduit, the pumping conduit, and the conduit from the rainwater collectors’ chamber. Some of these, mainly the gravity conduits, have required excavations below ground level of more than four meters in some cases.
To facilitate the maintenance and operation of both deposits, several aspects have been taken into account:
- Access. Four accesses have been arranged, one per corner of each deposit, and have been solved through a chamber with an assisted cover and a protection barrier.
Also, accessible passage has been left to the grease separator, sand trap, cleaning chamber, and pumping equipment. - No lighting or forced ventilation has been planned inside the deposits. Instead, four chimneys have been installed to allow for natural ventilation.
- Special emphasis has been placed on controlling possible closure failures in the gravity discharge conduit to the Ria. In this regard, an intermediate chamber has been arranged in the conduit to be able to have two non-return elements: a check valve and a valve at the mouth of the Ria.
The arrangement of this chamber will allow for the measurement of the salinity of the water passing through it, facilitating the detection of possible problems in the non-return valve placed at the end of the conduit.
EUROPEAN PROJECT
The Bilbao City Council, in line with the European Strategy 2020 and the Operational Program of (POCS) and co-financed by the European Regional Development Fund, has developed the Implementation Plan for Sustainable and Integrated Urban Development (DUSI) in the Zorrotzaurre Area, an ambitious and multidisciplinary project in which different municipal areas have participated.
This plan aims to revitalize an area historically industrial and currently unused spaces to turn it into an attractive and leading neighborhood in Bilbao, well connected with the rest of the city through a sustainable model of infrastructure and mobility, with spaces for the establishment of non-polluting companies, affordable housing, numerous social and cultural facilities, and extensive areas for the enjoyment of the population. And, the flood deposits project is one of the projects that has been part of the plan.
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