Dry feet on campus

Call it climate adaptation, call it sustainability. Gerrit Hofland, Technical Area Manager at TU Delft, and responsible for the sewer system under the campus, prefers to call it “simply logical thinking”. And that is exactly what he does: at work, at home, on holiday – wherever he is. That way he can ensure that the campus does not get flooded.

Gerrit has to keep his eye on thirteen pumping stations and some 40 kilometres of pipes, plus three drainage systems for rain water, dirty water and water for fire extinguishing. His job is to ensure that the whole sewer system operates at its best, so that it can deal with even the heaviest downpours. “Anticipating all possible weather conditions; that’s a real challenge”, says Gerrit, grinning enthusiastically.

He shows us his computer monitor. There are images of the pumping stations along with information on how much water they contain, from which water level pumping is required and where this water will go. Gerrit also sees when there is rain. “Look, this is the pumping station at the Library.” He clicks on the image with his mouse. “I’ll call it now to connect with it. Just wait a bit… Look, a live connection. It’s currently got 49 centimetres of water in it. From the bottom. That’s good. The pumps turn on automatically when it hits 50 centimetres. But I can also turn it on manually now. See, there it goes.” Gerrit also has this software on his iPad. And on his mobile phone. That way, he is always in touch with the pumping stations, wherever he is. It is part of his daily routine: he checks how the pumping stations are working every morning, and again in the afternoon. And, of course, again if something is reported or if there is unexpectedly heavy rainfall, for example.

Reiniging, inspectie en reparatie

Gerrit’s first move at TU Delft was to implement cleaning work. He had the entire sewer flushed and saw what came out. “Mud, dirt, stones, lots of rubbish”, Gerrit explains. “We even recovered a complete lorry wheel from the culverts [the channels between two waterways, ed.] behind the campus.”

Gerrit Hofland then carried out inspections to ascertain where repairs were required. “You need to properly maintain your system. Just like your car. If you don’t service it for three years, it will simply stop running at some point.” He gradually gained a clear understanding of exactly what the underground system looked like. Some parts of it are in really bad shape, while other parts are still in good working order. “That’s occupied me for the last three years. I think we’ve now got a good picture of more than 90%. A proper understanding of the system will allow us to take a more preventative approach.”

Climate adaptation? A catch-all term

As he optimises the system, Gerrit anticipates increasingly heavy rainfall in the Netherlands, taking “climate-adaptive measures”. He detests the term “climate adaptation”, calling it a catch-all term. But that does not mean that he underestimates the impact of heavy downpours. There are several measures you can take. Increasing the size of the pipes, for example. “But the effect of that is minimal”, he points out. “You’re better off looking for smart solutions. Optimising your systems.” He turns back to his computer. “Just imagine, a large downpour is heading our way. You can see that here.” He indicates where. “The computer sends a signal, causing all dams and barriers to open. You actually drain the entire sewer system. Once it is all empty, I have created enough space for the rain water. Then when the downpour arrives, you return everything to the standard position, and let the system do its job.”

Creating a fictional downpour

“The most important thing is to create a kind of reservoir zone. And testing and learning, of course.” On his computer, Gerrit can have a fictional downpour fall into his sewer system and see how it deals with the rain water; whether or not the drains overflow, or whether water remains on the street. He is constantly working to improve the operation of the sewer system under the campus.

The TU Delft campus sewer system comprises:

40 km
Approximately 8 km of the system has so far been renovated.