Construction of the Brede Groene Dijk pilot project started

The Hunze en Aa’s water board and EcoShape have started the construction of the Brede Groene Dijk pilot project near Delfzijl in the Northeast of The Netherlands. The seawall will be widened over a length of 750 meters with clay, which is made of dried (ripened) sediment from the nearby Eems-Dollard estuary.

The seawall along the Dollard must be reinforced in order to remain safe in the future. As a trial, the dike will be widened over a length of 750 meters. Until 22 July, EcoShape will transport the clay from the clay ripener location in Delfzijl to the Brede Groene Dijk (wide green dike) for the construction of the dike. The construction of the dike will be completed on October 1, 2022.

Monitoring and research

A lot of data and information has already been collected about the quality and strength of this clay over the past three years. EcoShape will monitor the pilot project in the field for three years. If the trial proves successful, the water board wants to strengthen the rest of the dike in the same way. The plan is to build clay ripeners along the seawall for this purpose. The clay is then already at the location, so transport is not necessary.


EcoShape carries out the work on behalf of Rijkswaterstaat and the Hunze en Aa’s water board. The National Flood Protection Program and Wadden Fund are the financiers. The project is part of the Eems-Dollard 2050 program in which the municipality of Eemsdelta is also involved and which is led by the province of Groningen.

Between April and October, the Hunze en Aa’s water board will widen a first test piece of the Dollarddijk in Northeast Groningen into a Broad Green Dike. It concerns a stretch of approximately 750 meters near the Carel Coenraadpolder. The seawall must eventually be widened over the total length of 12.5 kilometers, so that it is also safe for the future. On the test piece (demonstration dike) we are investigating whether this can be done with locally extracted clay.

The Brede Groene Dijk is a project of the Hunze en Aa’s water board. EcoShape carries out the work. In the period from May to July, EcoShape transports clay with trucks from the Kleirijperij on the Valgenweg. The water board and EcoShape are currently investigating feasibility on various transport routes, in consultation with the environment.

The work on the dike will be completed by 1 October at the latest. After that, the water board and EcoShape will monitor the dike for 3 years. If the widening proves to be a success, the rest of the dike will also be reinforced in this way.

EcoShape will monitor the dike in the coming three years, focusing on:

  • The development of the clay over time
  • Crack formation and structure formation
  • Development of the grass cover on the dike
  • The functioning of the drainage in the dike
  • The necessary management and maintenance

The results will be used  to optimize the design of the total dike improvement, which is planned after 2025.

Infographic of Brede Groene Dijk