Electricity and Control January 2023

MEASUREMENT + INSTRUMENTATION

In the Dutch province of Limburg, the Grensmaas Consortium extracts about one hundred thousand tons of gravel every week – a quantity that entails a major logistical operation and requires a close watch on the fluctuating water levels of the Meuse River.With a single sensor, Hans van der Meer, Head of Production andTechnical Services at the Grensmaas gravel extraction site, can monitor the water level and the risk of interruption to the gravel extraction process. One small sensor makes a big difference

V an der Meer says, “One ton of gravel is equivalent to eleven full wheelbarrows. On an annual basis, we extract four and a half million tons of gravel at this site. And this gravel extraction is an important aspect of the Grensmaas project. It is the financial engine and one of the three pillars of the project. The process of gravel extraction for onward use means there are no costs for the taxpayer and, at the same time, we achieve a high level of water pro tection and the development of the natural environment,” van der Meer explains. Gravel extraction It’s a win-win-win solution. In 1993 and 1995, the province of Limburg witnessed two floods on the River Meuse, which caused damage amounting to some €200 million. Citi zens demanded greater flood safety, but the cost of some €700 million was a stumbling block for years. That was until an agreement was reached with Consortium Grensmaas – a partnership of contractors, gravel producers, and Natuur monumenten – the Dutch organisation for the conservation

and development of nature. Both high-water safety and the development of the natural environment would be paid for with the proceeds from sand and gravel extracted along the Meuse. At the same time, the river has been given 350 hec tares of extra space to allow excess water to drain off. That is the area of some 500 football fields. The stream bed was widened, banks were lowered, and dykes were raised. The residents noticed the benefits immediately: after long periods of rain the water level rises less quickly and stays lower. The land in the south of Limburg now stays dry at the same water level as was seen in the 1993 and 1995 floods. And along the Meuse, a thousand hectares of ‘new nature’ are being created, which in time will attract cyclists and walkers, as studies have shown. It is through the process of gravel extraction in the Grensmaas project that the consortium must recoup its in vestment of €700 million in providing flood protection and developing the natural environment. And that depends on the smooth running of the process logistics. Van der Meer notes, “All the minerals are transported by barge, and the

In the Grensmaas Project, one 26X digital level sensor provides all the information needed to monitor the fluctuating water levels.

JANUARY 2023 Electricity + Control

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