Problems with the underwater dams; submarines work to remove sand. And Mayor Brugnaro asks Minister De Micheli to manage the work until its completion.
By Alberto Vitucci
4 December 2019
LIDO. The test of MoSE at Malamocco went well enough. It remains to be ascertained why dam number 6 resisted being raised. The last of the series of 19, which were raised four at a time because the final installation is not yet complete. With just one compressor available the maneuvers lasted almost eight hours. The average time to raise one of the dams was 15 – 20 minutes.
The number “6” instead required 45 minutes. It was necessary to inject compressed air equal to 800 cubic meters, compared to 500 for the others. Why? Technicians are at work to discover the cause. Perhaps there is a loss of pressure in the tubes. Or rather instruments that have gone out of service. Work is also underway to clean all the tubes of sea water, which could cause damage and oxidation, as has already happened at Malamocco. These are maintenance problems that will be ongoing and challenging, and, according to the latest projections, will cost at least 100 million Euro each year.
In the meantime Cosorzio Venezia Nuova and Comare are once again at work on the barrier of Treporti, the first to be installed, in 2013. Five years underwater and there have not been many tests to raise them.
The problem now is to clean the caissons and remove the sediments of sand and other materials which are stuck in the mechanism underwater, where they are impeding the entry of the dams into their housings.
At the moment submarines from the company Nautilus are at work. Their job is to clean out the crevices to allow the descent of the four dams that have been out of place for a year. Maintenance and experimentation. The Malamocco test was the 31st test to raise the dams, and the first to include all the barriers, even though they were raised four at a time.
But Monday night there were many spectators at the “tests”, which are generally deserted. Even Mayor Luigi Brugnaro, who invited himself, was there, having communicated to the Ministry of Infrastructure that he intended to attend the event. He also reiterated his desire to be included in the body that will have to manage the conclusion of work on the major project, as well as the phase of activation and management. “We should be there”, says the Mayor now. The controversy over the lack of invitations to the test last November 4 – which were cancelled due to suspected vibrations in the tubes – made way for the request, which was sent to Premier Conte and repeated to the Ministry. It was also partly accepted by the last Comitatone, where a “technical roundtable” was established that will have to decide about the governance of MoSE.
At this point those who should be a part of this are the Commissioner of Sblocca Cantieri (Elisabetta Spitz), the Superintendent of Public Works (Cinzia Zincone), and the three special administrators of the Consorzio Venezia Nuova, Giuseppe Fiengo, Francesco Ossola, and the new administrator, who was nominated a few weeks ago, Attorney Vincenzo Nunziata.
These five must guarantee the completion of the work and testing within the established time frame. December 31, 2021, according to the timetable, with 2020 dedicated to the conclusion of the installation work, currently contracted to the Belgian company ABP, which won the bid published by the commissioners.
2021 will be dedicated to tests “in adverse sea and weather conditions”, which recur more frequently during the exceptional acqua alta events in which the dams would have to be activated.
Meanwhile tests are being done in “calm sea conditions”. The other evening at Malamocco the waves were at medium-low height, 80 cm over sea level. That is nothing compared to the 3 meters and the 120 km per hour winds from the night of the 12th. “The operation has had satisfactory results”, commented the technicians of Comar and the Consorzio at the end of the movement of the dams.
Other tests are now planned for the following weeks. The schedule is not yet final, but there should be one about every 45 days. They are done during night hours – beginning at 20:30 until early morning – and during those hours ship traffic is prohibited by an ordinance of the Capitaneria di Porto, communicated also to the shipping agents.
“Transit of watercraft with a displacement greater than 500 tons” is prohibited until the tests are complete. Fishing boats and small craft – under 500 tons – may enter through the navigation basin.
Source: La Nuova Venezia