The reservoir can contain up to 11.1 cubic kilometers of water and feeds a 1,052 megawatt hydroelectric plant. Hundreds of thousands of people who live in the surrounding regions - the theater of conflict between Iraq and ISIS - depend on the dam for the supply of water and electricity.
However, the project suffers from important structural limitations as the waters of the Tigris have opened holes in the karst foundations which have been filled with tons of liquid cement for years.
To buffer the dangerous situation and secure the area, in October 2015 the Iraqi government launched an international tender with an urgent procedure for the consolidation and restoration of the dam's functionality.
The Italian Trevi Spa of Cesena, specialized in subsoil engineering and special foundations, was awarded the contract of 273 million euros in April 2016 and the Italian government deployed the "Praesidium" task force of approximately 450 soldiers to protect the dam and staff engaged in the works that should end in March 2018.
The role of Nautilus
Trevi - which at the end of October 2016 had already completed 15 kilometers of perforations and infiltrations - contracted Nautilus Srl to carry out underwater works for the verification and restoration of the submerged structures that guarantee the correct control of the water level of the artificial basin.
For the execution of the work, Nautilus has created a Joint Venture with the Drafinsub, a company from Genoa, also specialized in on-shore and off-shore underwater processing.
To carry out the complex intervention, the two companies transported a floating platform of size 30.00 x 18.00 meters complete with diving equipment to the artificial lake of Mosul, with a convoy of 35 trucks, which guarantee the operation of the divers in the artificial lake with dives that can reach a depth of -100 meters.
The platform hosts a complex of hyperbaric chambers that can contain a team of 6 divers who live and work for 28 days in a controlled hyperbaric environment.
The intervention was planned with the supervision of the Italian military and the USACE ( U.A. Army Corps of Engineers) supervisor in order to guarantee, in the event of a terrorist attack, the immediate evacuation of the divers from the operational area within a special decompression chamber.
The objective of Italian divers is to check and repair the steel bulkheads that allow the opening and closing of the drainage tunnels of the basin when the reservoir exceeds the guard level. Each bulkhead, weighing 80 tons, is completely lifted out of the water by using a portal crane with a lifting capacity of 250 tons.
Our team performed 328 dives for a total of 285 hours of which 462 minutes of saturation dive with injury index 0.
Last February the construction site received the visit of the Minister of Defense Roberta Pinotti who, after visiting the operational area, congratulated on the precious work done by the Italian companies.
Our contribution to the project is described in various articles published on: "Repubblica", "Il sole 24 ore", "La Stampa" (February 7, 2017) and Hydro Review.