The Project for Wasa Dredging’s part started in June 2018 as a subcontractor to the main contractor Dragados, the client for the project is Aberdeen Harbour.
Our part of the project is planned to go on until the end of 2019.
The project as a whole consists of a whole new harbor being built, the future harbor basin and fairway is being deepened and widened, two big breakwaters and a number of quays are being built.
Wasa Dredging’s part in this project is mainly the drilling & blasting of about 279 000 m3 solid rock and dredging of about 660 000 m3 blasted rock in the future harbor basin, Part of Wasa Dredging’s scope is also the filling and levelling of the bedding layer in the caisson trenches, which we partly also blast. The works also consists of an optional dredging work of 400 000 m3 softer soils.
The blasting is very careful due to the underwater noise limits due to nearby mammals (Dolphins/seals) and the vibration limits on nearby concrete and brick outfalls.
The blasting is mainly taken care of by our combined drilling platform/backhoe dredger “Boulder” while the blasted rock and soft soil dredging is handled by one of our other combined drilling platform/backhoe dredgers “Hector”. The blasted rock is dumped in the core of the two breakwaters that are being built and the softer soils are dumped a few sea miles away in open waters. All masses transported by our self-propelled split-hopper barge “Boann” and towed split-hopper barge “Miika II”.
The bedding layer works in the caisson trenches consists of two layers of differently graded material, very precise underwater filling and levelling operations with tolerances of as little as +5cm/-5cm.
The self-propelled barge “Boann” is filled with material in Aberdeen Harbour before it goes out to Nigg Bay and dumps the material in the caisson trenches according to our calculations.
The levelling of the rougher underlaying layer of filled/dumped material is handled by both the dredgers “Hector” and “Boulder”, whichever is free to do so at the time.
The more precise levelling of the finer material in the top layer is handled by our levelling pontoon “Kampela II” pushed by a tugboat.
In the end of July 2018 a joint venture consisting of Wasa Dredging and Van Oord Marine Contractors signed two separate contracts regarding a big project in Kokkola Harbour and Fairway.