MoSE: valves don’t hold water – a thousand parts to check and replace

New trouble for the massive project. After the encrustations and the holes in the tubes, an emergency for parts of the system.

By Alberto Vitucci

8 May 2019

VENEZIA. A thousand valves to verify, perhaps to replace. They’re leaking water and showing “fissures”, as it’s called by the engineers. MoSE’s troubles never end. The most recent, discovered by technicians from Comar a few days ago, are now confirmed by the Consorzio (Consorzio Nuova Venezia) after a site inspection. After the corrosion of the hinges and the holes in the underwater tubes, now there is the difficulty with the functioning of the valves. The problem emerged during testing of the array of dams at Lido San Nicolò. There are two types of valves; regulation valves and sealing valves. The technicians fear that the problem is with the second kind, which are supposed to seal off the water during the maneuvers to raise the dams.

The damage is confirmed, even though not through official channels. Therefore, now each of the 936 valves already mounted in the underwater dams will need to be checked one by one, which will require even more time and money; a minimum cost of several million Euro is projected to replace them.

Technical tests continue to reveal critical issues and problems. “The most recent tests raising the dams went well,” according to technicians from the Consorzio. The tests moved five dams. But it was done slowly, one at a time, and in calm seas without wind. Now, starting tomorrow, it’s time for the others to move and then return to their casing.

This concerns, moreover, the most recently installed array, finished no more than three months ago. Thus encrustations and sediment had not had enough time yet to corrode the materials sitting underwater.

That’s what happened to the dams in the array at Treporti. Work there was begun a few months before the scandal, in 2013, and the dams were raised from the bed of the lagoon only several years later. When the dams tried to lower they were blocked by the accumulation of sand, detritus and sediment.

Now the Consorzio has opened the first bid for the maintenance of these dams (won by Fincantieri but already blocked by an appeal to the TAR by the first company excluded, Brodosplit). This will involve detaching all 21 dams from their bases at Treporti and taking them to Arsenale – or to Marghera, in the ex-Pagnan area, as decided by the Superintendent of Public Works – to paint them and replace the broken pieces.

But now the trouble with the valves has appeared, along with problems of humidity in the underwater corridors of the caissons that support the dams. The emergency is signaled as well in the Environment Commission’s final report, sent in recent days to the president of ANAC, Raffaele Cantone. “It is urgent to build units for underwater heating and cooling”, we read in the report, “to eliminate encrustation and mold”.

The activation phase may, therefore, extend the length of time predicted for completion. This will make it difficult to deliver the project, as has been announced, on 12 December 2021.

Source: La Nuova Venezia

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