With Hardy Services having a dedicated and focused sector within the utility industry and with this structure being voted as one of ‘The Seven Wonders Of The Civil Engineering World’ by the American Society of Civil Engineers, we decided that we couldn’t avoid writing an article about this. Although the Netherlands conjures up images of windmills and Tulips, the tourist books will not fail to direct you to the largest storm barrier in the world, The Delta Works.
The Delta Works are a sophisticated flood defence system that consists of sluices, locks, dikes, storm surge barriers and dams which protect the estuaries of the rivers Scheldt, Meuse and Rhine that have been subject to a large amount of flooding for many centuries before the flood defence system was constructed. Just twenty days after hundreds of fatalities occurred in the 1953 North Sea flood (named Watersnooddramp – ‘the flood disaster’ – in Dutch), the €5 billion Delta Plan was rapidly put into process.
In order to be able to build dams in the mouths of the rivers, some auxiliary dams firstly have to be built in the Krammer, the Zandkreek, the Volkerak, and the Grevelingen. These dams were known as compartment dams, as they were to divide the large area of water into thirteen multiple compartments. As this was such a large project The American Society of Civil Engineers declared Delta Works (along with The Zuiderzee Works) as one of the Seven Wonders of the Modern World.
Since some of the Delta Works dams (for example the dam on the Hollandse IJssel river) are located in important shipping trade routes, the waterway had to have a specially designed flood barrier rather than a dam, this would feature two movable sluice gates. The different types of sluices made it possible to separate the polluted (or excess) water from fresh water.
The flood system is a series of constructions (consisting of dams and storm surge barriers) which were built over a period of forty-seven years (between 1950 and 1997) in Rotterdam which is in the southwest of the Netherlands. With 20% of its territory lying below mean sea level, the Netherlands is one of the most low-lying countries in the world and so, when the water level along the coast rises, the land is often susceptible to flooding. Findings from a study which was conducted by Rijswaterstaat (the Dutch Department of Public Works) in 1937, revealed that the safety of many citizens who live on the coast of the Netherlands could not be guaranteed at all times. Due to these findings, the idea of The Delta Works is to shorten the Dutch coastline by 700km and, as a consequence, reducing the number of dikes that had to be raised.
The most expensive and reportedly the most difficult to build part of The Delta Works was the Oosterscheldekering which took more than a decade to construct. Four ships were custom designed and created for this project: a ship equipped with various ground working tools; a ship to transport and lay a special foil carpet on the seabed for the pillars to rest on; ship capable of lifting a concrete pillar from the dry dock and placing it accurately on a special foil on the seabed; and a ship that works closely with the Ostrea, cleaning the foil assisting in placing the pillars accurately in their final position. This part of The Delta Works was opened by the former Queen regent of the Kingdom of the Netherlands in 1987.
Each one of the thirteen dams and flood barriers is regularly checked and each sluice gate is closed once a month for testing. In 2010, some of the walls were strengthened and raised due to worries about a rising sea level of 1.3 meters by the year 2100.