Ground subsidence is a particular problem in the area around Rotterdam. It can be so severe that soil levels can change by as much as 1m within a few years. This causes problems for underground pipelines making up the infrastructure of the area to deliver gas, water and steam to local citizens and businesses. The problem is most acute where pipelines cross over each other and where they connect to the consumers’ premises where a fracture risks a severe accident.
How to know where the risk lies? Older connections are more at risk than modern ones due to use of rigid metal rather than flexible plastic combined with the modern practise of installing a loop to absorb movement. Clearly the risk is greater where the ground is subsiding faster. In this case, the stress created on the household gas connection or on the water mains in the street can cause a failure with consequent leaks. In the case of water, this can cause severe disruption to traffic or, as we heard in one case, the flooding of a hospital basement; in the case of gas, the impact can be much worse if gas builds up in the space under a house when it may even explode.