Colas Alterra secured the job in early 2019, requiring the company to extend the useful capacity of the current reservoir block – consisting of three pools – from 3,300 to 7,000 cubic metres. One complication hindering construction is that the existing pools cannot be decommissioned for the duration of the works, while the nearby sand trap structure and the utility lines that need to be relocated are also in continuous use. With a size of 45 x 8 metres each and a depth varying between 3.2 and 4.4 metres, the three new pools will surround their existing counterparts in a “U” shape. Structurally speaking, they are independent of each other, but all of them are linked to each other through pipes, while also being connected to the overflow drain of the existing units.
In terms of horizontal dimensions, the new reinforced concrete pools are identical with the old ones, but they exceed them in volume due to being 0.6 metres deeper.