Construction of the storm surge barrier of St. Petersburg was one of most complex projects in Russia given that work started in 1979 but in 1990, construction was suspended when it was only 60% complete.
However, building got underway again in 2002 and in 2006, the project came to a peak when the most important parts began, including the construction of the access gate for vessels, the “S1”.
Dredging International was subcontracted by the main contractor for the Federal Agency of Infrastructure (Rosstroy) for the deepening works for the new access channel for the storm surge barrier. The Trailing Suction Hopper Dredger “MARIEKE” was deployed for almost three months on the project.
Once the S1 gate was fully operational, the new channel had to be re-routed via the gate. This meant that a 12.6 km section of the channel, with a width of 150 m, had to be dredged to -14m.
The project was a particular challenge because the survey of the dredging area and divers discovered a number of munitions on the seabed during the pre-dredging works and these had to be safely removed before the start of the marine works. However, the Dredging International crew took all the appropriate actions to make sure the work could be carried out safely.
The soil comprised silty clay and was dredged and dumped offshore at a maximum distance of 12 km. Eventually, around 7 million m3 and 4 million m3 were dredged by the company during two campaigns.