Zennegat Lock – Deepening the lock chamber

 In Renovation

SBE was awarded the assignment to complete the design to deepen the historic Zennegat lock in Mechelen, Belgium. This blog describes the different steps of this invasive renovation.

The lock dates from the early 19th century and consisted of masonry gravity walls. The base of the lock is also masonry and nailed to the ground with wooden foundation piles. The base varies in height with the one half about 1m higher than the other. The aim of the assignment brings the entire lock down to the lower level – a real challenge.

The client (the Flemish Government), the contractor and the control office together with SBE conceived a method to realise this project in a very short period. The lock is situated on a busy canal, so the time the lock was unavailable was limited to two weeks.

The ground water level was lowered using pumping wells and thereby decreasing the forces on the wall. The retaining walls were then stabilised with various ground anchors. At this point the major challenge could commence; excavating the base to the desired level.

By using a well prepared and phased working schedule, SBE managed to maintain the necessary bracing-capacity of the base. Partially by the old remaining base, partially by the newly constructed one.


This project was a very good example of the success that can be achieved by open and efficient communication and collaboration by all parties in the construction process, or in this case the renovation process. Due to a direct, open and close working attitude between the client, the contractor, the control office and the engineering office a creative solution was conceived to an unusual challenge.

This collaboration already started in the early phases of the project resulting in a high-quality solution with buy-in from all parties involved. All the associated risks were mapped, managed and controlled.

It must also be noted that weather was extremely beneficial during the construction phase. That was, however, not down to anything within our control.