The experts: “salinity and inadequate materials”; “The phenomenon is widespread and could stop the entire operation”.
By Alberto Vitucci
27 June 2019
VENICE. MoSE’s hinges are corroded and “inadequate”. They need to be redesigned and replaced with materials different from those used during the original construction. In Rome they talk about autonomies and commissioners, but in the lagoon the search is for a way to patch the problems that have been discovered in the underwater dams. In this case the trouble revolves around the hinges that attach MoSE’ dams to the concrete caissons on the lagoon floor.
The request for bids by the Consorzio Venezia Nuova and the Provveditorato alle Opere Pubbliche expires on 14 July. The sum of 34 million Euro has been provisioned to find someone who can repair the damage. The duration of the contract has been set at 3650 days, which is to say 10 years.
That is a huge amount of time, which extends well beyond the period predicted for conclusion of the work and testing. It certainly raises further doubts about the possibility of finishing the work by the end of 2021. The situation is dramatic, as we read in the introductory technical report which delivers the findings of the technicians and the inspections that were carried out. “The phenomenon of damage to the group of dams, in particular to the axles,” write the experts, “is widespread with differing degrees of seriousness at all the mouths of the port”.
The causes, according to the experts at the Provveditorato, are related to “the material of the axles and the wet, salty environment of the structure”. In essence, the humidity and salinity inside the caissons are such that they have compromised not only lifespan of the axle-tensioners, but the work as a whole.
The example cited is the corrosion of the iron parts that are underwater such as handrails. If that’s not enough, from the technicians’ report we also read that the salinity is causing “red percolation in the concrete walls” and that there are spots of localized corrosion. In short, a work that was designed to live under water is showing the first signs of distress only a few months after having been placed underwater.
The situation has now been made clear by the analysis of the Consorzio, and the experts from the Provveditorato Mapelli and Ormellese. There is also the report from Rina, the Italian naval Registry, which has certified that there are widespread occurrences of corrosion, in particular in the dams at Treporti, “due to galvanic corrosion from the electrochemical reactions between the nickel coating and the steel”.
The average life of the hinges, which in the design were guaranteed for 100 years, is reduced to less than 30 years. How could this happen? The hinges were built by Fip di Selvazzano, a division of the Mantovani group. The project was inaugurated with great pomp with the ministers of the day, Regional President Giancarlo Galan, and the former president of the Magistrato alle Acque, Patrizio Cuccioletta. All of these people ended up in one way or the other part of the inquest in to the MoSE scandal.
However, troubles soon came to light. Now it will be necessary to find, as called for in the new request for bids signed by the provisional adminstrators of Anac, “a material that can be used to prevent the corrosive phenomenon that is spreading very rapidly”. Protecting the hinges by employing used fats “will not improve functioning” according to the technicians.
The decision to launch the new request for bids for new hinges was also determined by the results of evaluations and inspections, like those in January 2017, when the hinges were tested by professors Brutti and Mascia along with the experts from Cvn Ossola, Lovisari and Ardone. Numerous “non-conformities” were found, starting with the welding, corrosion in the tensioners, and corrosion in the rings, but above all in the “locking nuts”.
“The replacement of what is currently installed with other parts of the same dimensions,” write the experts, “but with materials that can resist corrosion is essential”. This means, clearly, that MoSE as it was built up to now is not even safe from short term corrosion.
Source: La Nuova Venezia