Inventive use of a DOP250

In northern Germany, a famous canal receives a major upgrade. The Kiel Canal is an almost 100 km long man-made canal, that connects the North Sea in the West to the Baltic Sea in the East. The canal thus connects western Europe with the Baltic countries, saving shortsea vessels the 450 km roundtrip around the Danish mainland.

An impressive history

The canal itself is one of the many feasts of engineering undertaken at the end of the 19th century. Built in a mere eight years’ time, the canal was opened in June 1895 by Emperor Wilhelm II himself. His yacht Hohenzollern was escorted through the festively decorated canal, and he laid commemorative stones at the locks at the canal’s extremities. These locks are required to control the water level in the canal system. In 1895 two small locks were inaugurated at the western side near Brunsbüttel, and in 1914 two large locks were added to accommodate the passage of larger vessels. The locks have been in continuous operation ever since.

The western locks

These days the Kiel Canal is one of the busiest waterways in Europe, with some 27.000 vessels passing through each year. Until recently no major maintenance works had been done on the locks as the ‘European Highway of shortsea transport’ would be severely hindered by them. To keep the traffic moving, it was decided to add another large lock to the existing complex, before renovating the century-old structures. As a result, the “fifth lock of Brunsbüttel” is under construction now.

An additional lock due to increased traffic

After extensive study it was decided to construct another large lock to add capacity. The only suitable location was at the central island, which is located in the middle of the mouth of the canal. This resulted in a restricted area for all construction activities. Further challenges were the continuous traffic in the existing locks which was not to be hindered, plus the fact that the Elbe River is tidal with continuously changing water levels. The lock itself will measure 330 metres, by 42 metres with a depth of 14m. Works will continue until the end of 2026, after which the old lock complex will be overhauled.

Resourceful use of the DOP pump

Many contractors are at work on the small island, all adding their particular skills to the intricate job. Dutch construction company Verboon Maasland was asked to remove large chucks of grout. These chunks were located at a depth of -17 metres on a bed of gravel. The gravel had to remain in situ. To add to that complication, there were ground anchor piles throughout the building pit which were not to be touched let alone damaged.

The resourceful team of Verboom Maasland redesigned the suction head of their DOP250. This head was able to remove the excessive amount of grout without disturbing the gravel bed underneath. The DOP submersible dredge pump was attached to a wire crane which was located along the building pit. The DOP250 was powered by a separate hydraulic power pack. The jet water, required for the special suction head, was delivered by a jet water pack placed on a pontoon. The grout mixture was pumped with a controlled flow into geotubes adding flocculant. The grout was thus removed from the building pit without as much as damaging a single pile, readying it for the application of a layer of underwater concrete.

Another example of the inventive ways a DOP dredge pump can be used in the hands of a resourceful contractor!