Protecting the Netherlands from floods by DEME – safety and sustainability

The Netherlands vulnerability to climate change and extreme weather events has led the country to embark on a National Flood Protection Programme, whereby it is investing approximately 1 billion euro a year in protecting its flood defences over the next 15 years.

DEME, through its subsidiary de Vries & van de Wiel, is involved in several major projects resulting from this nationwide plan, and one of these is the Gorinchem-Waardenburg (GoWa) dyke reinforcement plan. This is the Flood Protection Programme’s highest priority project following emergency dyke reinforcement work which had to take place in 1995 when the dyke was breached.

As well as being of national importance, the client Waterschap Rivierenland (WSRL) tendered the 23-km dyke reinforcement project in a completely new contract form in the sector, known as an Alliance. This was awarded to de Vries & Van de Wiel and its joint venture partners in the Waalensemble consortium in 2016.

The new contract type represents a different approach to risk sharing, with contractors involved right from the beginning. This allows DEME to show its value as a highly experienced contractor from an early stage.

The partners (WSRL and the Waalensemble) of the Alliance work together right from the planning study, and they are responsible for surveys, the design, permitting, expropriation, costing and the construction, and this is all combined into one contract.

The Waalensemble consortium started on site in June 2021, and it hasn’t stopped since.

There was a high-water event in that summer, but the team managed very well. Safety is an absolute priority, and it helps that the Alliance team has very short decision lines, meaning that potential problems can be solved swiftly, said DEME.

There are approximately 400 houses on the 23-km section of the dyke and the residents have been kept informed through bi-monthly meetings and by the consortium’s stakeholder managers.

Given that at peak times more than 10 cranes and 25 trucks are present, and that people are living on the dyke, safety is the top concern.

Sustainability is also high on the agenda and in line with this, de Vries & van de Wiel has constructed a dedicated pontoon to replace hundreds of truck journeys.

As the dyke is being extended out towards the river in some sections it is necessary to reduce the water level, therefore gullies and holes are dug out.

The sand, representing some 400,000 m3, from these gullies is dredged and loaded into vessels. These vessels then sail to the discharge pontoon which loads the material onto trucks for further distribution along the dyke.

According to DEME, this has the dual purpose of compensating for the water level rise and adding to the dyke reinforcement, while reducing truck movements dramatically.

Another important part of dyke reinforcement projects, which is in line with DEME’s mission to work in a sustainable way, is the move to work with as much zero-emission equipment as possible.

de Vries & van de Wiel has commissioned the conversion of its first electric crane, which is set to be introduced on the project in 2023.

The initiative was also awarded a so-called DKTI subsidy for an innovation project related to emission reductions for heavy-duty equipment.

Alongside this, the consortium has established the ‘Emission-free network infra’ (ENI) Foundation. This brings a network of infrastructure experts together with the aim of making it possible to achieve zero-emissions as swiftly as possible.

This foundation is already expecting to hit its zero target in 2026 rather than 2030.