Bilbao begins work on the two reservoirs to prevent flooding in Zorrozaurre
The main mission of these infrastructures is to prevent road flooding and damage to the stormwater network at high tide.
The works have a budget of 5,671,801.66 euros and are expected to be carried out within a period of 20 months
With the aim of improving the quality of the water that will be discharged into the estuary, a sand trap and a grease separator will be placed at the entrance of each tank
The Bilbao City Council begins the construction works of the two flood deposits predicted for the island of Zorrzaurre. The Infrastructures will be located on two municipally owned plots in Ribera de Deusto, close to the Artiach and Papelera buildings, respectively. They have a budget of 5,671,801.66 euros (without VAT) in a term of execution of 20 months.
To do this, both infrastructures must have a sufficient storage volume that allows them to accumulate water in episodes in which the tide does not allow relief by gravity, and its subsequent emptying, when the level in the estuary drops.
Specifically, a useful volume of 1,031.70 cubic meters for Deposit 1 and 1,190.25 cubic meters for Deposit 2. This solution will minimize relief by pumping.
In addition, with the aim of improving the quality of the water discharged into the estuary, a sand trap and a grease separator will be placed at the entrance of the rainwater collectors to each tank.
excavation
Bilbao City Council opted for deposits with a larger surface area and less depth. Which requires, for its execution, the excavation up to an approximate level of -2 meters.
“It should be noted that the land on which they are going to be carried out is made up of different layers of artificial fills, alluvial-estuarian soils (mostly silt), gravel with silt and sand, and finally rock. For this reason, a excavation with waterproof shoring, which also ensure the stability of the bottom. The foundation of the tanks will be solved with a concrete slab and the structure will be completed with a perimeter wall of 30 centimeters of reinforced concrete and pillars of the same material of 40×40 centimeters”, they explain from the consistory.
Spill pipes
For each of the two tanks, three conduits are planned that will discharge into the estuary: the gravity discharge conduit, the pumping conduit and the conduit from the storm sewer manhole. “In this sense, the discharge pipes to the Ria by gravity at relevant depths, requiring excavations below the current grade of more than 4 meters in some cases; and they will be carried out through open-air trenches with a sheet-pile shoring system to contain the land”, they explain from the town hall.
Thus, and in order to give continuity to pedestrian and vehicular traffic along Ribera de Deusto street, during the execution of these pipelines, it will be necessary to plan traffic diversions. These will be resolved above the projected deposits themselves, once the land filling has been completed up to the current urbanization level; and traffic will be regulated with temporary traffic lights –since vehicles can only circulate in one direction–.