The Dutch province of Limburg is home to several marl caves which have been dug out over the centuries by the local population and now attract over 300,000 visitors a year.  Work has now started in two of the caves, the Gemeentegroeve and the Sibbergroeve, to fit a ‘state-of-the art’ monitoring solution to measure and monitor the risk of subsidence.

Working together with local marl experts, Fugro will install fibre optic sensors and cables which are resistant to the extremely high humidity in the caves and are guaranteed to provide highly accurate measurements for the full 10-year monitoring period.  Special care will be taken to make sure cables and sensors are well hidden, thereby preserving the historic character of the caves.

The measurement data will be stored and presented in Gaia Insight, Fugro’s cloud-based data platform, providing all stakeholders, including the Municipality of Valkenburg a/d Geul which is responsible for the caves, with real-time access to the data.

Edo Noordermeer, Fugro’s Project Manager, commented: “The stability of the underground marl caves in Valkenburg is essential for the safety of visitors, as well as the infrastructure and buildings on the surface. With our state-of-the art monitoring solution, we will give the municipality of Valkenburg a real-time view of the safety status of the caves. With our system, the municipality will be able to take preventative actions before subsidence incidents occur”.

A leading, independent provider of geo-intelligence and asset integrity solutions for large constructions, infrastructure and natural resources, Fugro’s services are designed to support engineering design and large structure building projects.