MoSE, cracks in the caissons: underwater integrity at risk

MoSECracks

Engineers Manzone and Lovisari report the problem in their book, after the reports. The businesses (Mantovani, Condotte and Fincosit) which did the construction are under accusation.

By Alberto Vitucci

VENEZIA. MoSE’s caissons are at risk of cracking. The phenomenon has been observed repeatedly, and was first noticed during the construction phase. A new problem for the MoSE system, never before reported, a problem which could put at risk all the caissons which are now underwater. The news is written in a book which contains the most recent technical studies of MoSE. Signing on to this, in an unusual move, are two consultants to the Provisional Commissioner, the Torinese engineer Francesco Ossola, who has administered the Consorzio Venezia Nuova since 2015.

The book. The authors of the book are Fabio Manzone, engineer at Polictecnico di Torino who works with Ossola and has collaborated with him on the construction of the covering for Juventus stadium, and Sara Cristina Lovisari, who was named by Ossola as a consultant to the CVN in 2015. Now the reports commissioned in recent years by the commissioners – not even available on the CVN website – have been published in a 214 page volume. There is a brief illustrated history of MoSE, as is traditional, then several chapters by the engineers and experts.

Cracks. The first chapter addresses the issue of “the instances of cracks in the caissons”. The caissons are huge, 60 meters long and 50 meters wide, 11 meters high, weighing 20,000 tons, lined up on the sea floor to support the 78 dams which will rise in the case of high water. They were built by the MoSE businesses – Mantovani, Condotte and Fincosit at the shipyard of Santa Maria del Mare. “Reports from the building site”, we read on page 147 of the report by engineers Giuseppe Mancini, Gabriele Bertagnoli, Francesco Tonolo, Marzia Malavisi and Nadia Zoratto, “indicated that only 5 to 10% of the cracks discovered measured larger than .15 mm”. This is a worrisome situation, because these consultants for the Consorzio are reporting an issue kept hidden until today.

Critical Issues. Other chapters discuss the “critical issues” of the MoSE project, such as the metal structures, and the hinges and dams. A great deal of space is dedicated to the “monitoring system” for MoSE. One of the big problems that will arise, given the necessity to check the integrity of the materials – which are already partially deteriorated underwater – is the continuous maintenance. During the first test raising the dams last year, the dams could not return to their containment caissons due to accumulated debris. This detail is not to be found in the expert’s book. The new revelation of the existence of cracks will quickly open a new debate on the integrity of the system, and also about its “dynamic stability”, which has been questioned many times by expert engineers such as Vincenzo Di Della, who has in recent days sent a dossier and a request for a public meeting to Minister Toninelli. Another dossier has been sent by the commissioners, nominated in 2015 by the President of Anac, Raffaele Cantone.

These new revelations arrive on a scene of rather tense relations between commissioners Giuseppe Fiengo and Francesco Ossola and the Superintendent of Public Works, Roberto Linetti. After three years under a special commission, the businesses have asked that they be allowed to go back to work. After the scandal and the investigation, after the discovery of new critical problems, the progress of the work has gradually slowed. There are decisions to be made regarding the future and above all the “business” of managing MoSE, of the monitoring and the maintenance.

Source: La Nuova Venezia, 9 July 2018


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