After the construction of the storm-surge barrier and the reclamation works at Bronka Container Terminal, Boskalis returned to St Petersburg, Russia, for the construction of the six-kilometer-long entrance channel and turning basin to the terminal, the company reported in the latest issue of its magazine ‘Creating New HORIZONS’.
In the publication, Boskalis highlighted a number of fascinating projects, including ‘The Need for Speed’ article about their dredging work in Russia.
“These projects were a race against the clock because weather conditions make it impossible to work in winter,” said business unit manager Mattijs Siebinga. “But this is another race we have won!”
“The history of St Petersburg has been dominated by the fight against the water, a fact that explains the close relationship between Boskalis and St Petersburg,” said Mattijs. “To protect the city from flooding, a new storm-surge barrier, with a ring road, has been built around St Petersburg.”
“As the main contractor on this project, we have been closely involved with the construction of the barrier, as well as the tunnel below it. We have years of experience with similar projects in the Netherlands and that was a decisive factor in winning this contract,” added Mattijs.
The barrier went operational in 2011 and it is virtually identical to the Dutch storm-surge barrier in the Nieuwe Waterweg near Rotterdam.
“In order to execute this project, we obtained a license from the government to take sand from a borrow area near St Petersburg. Later on, that license also helped us to win the contract for the construction of the Bronka Terminal,” explained Mattijs.
The need for speed
The sand deliveries for the construction of the Bronka Terminal, which covers an area of 85 hectares, were completed in 2013.
“The striking feature of the projects in St Petersburg was the need for speed,” said Mattijs. “Time is always the critical factor, because the winter here starts in about late November. We had to finish the work before then because the cold freezes the bow coupling and ice forms on the sandfill.”
“Work closes down until March. So our client, CJSC Baltstroy, asked us to deliver the maximum volume of sand in a short time – and to actually deliver even more than the planned volume of three million cubic meters. The extra weight of the additional sand accelerated settlement in the site, making it possible to start construction work on the terminal earlier,” he added.
The Boskalis trailing suction hopper dredgers sailed continuously between the borrow area and the sandfill, a distance of fifteen kilometers. The dredged sand was pumped through a 4.5-kilometer sinker pipeline towards the land reclamation.
A cutter suction dredger was used as a booster station halfway along the pipeline. To save even more time, and after consultations with the client, Boskalis used Russian gas pipelines for the sinker pipeline.
“By pulling out all the stops, we completed the job well on schedule. That customer-driven approach meant that the client has also asked us to take on the large follow-up contract, the construction of the entrance channel,” Mattijs concluded.