It was a great shock when the 16 meter high giant aquarium burst open in the early morning hours of December 16 in the middle of Berlin’s city centre. About a million liters of water poured into the area around the hotel near Alexanderplatz, in whose lobby the aquarium was located. The accident attracted a lot of international attention.
It is fortunate that apart from two people who were slightly injured, nobody was seriously injured. The largest of the more than 700 fragments weighed nine tons. However, almost all of the 1500 fish died. After the accident, there was much speculation about the cause: Was it material fatigue? Small cracks on the surface? Or maybe temperature fluctuations?
In a warehouse in Brandenburg, a team of engineers on behalf of the company that owns the hotel property is meticulously trying to find out what really happened. To do this, they put the fragments together as they were originally arranged. “We do it like a jigsaw puzzle: you start with the corners,” says engineer Robert Kirchner. But since a cylinder doesn’t have any corners, they used other features and worked their way from the edge to the center.
On a warm spring day in May, the material and component testing specialist stands in the midst of the huge fragments that look like glass ice floes. Depending on their shape, the employees have given them affectionate nicknames – such as “the tooth” or “the swinger”, a wavy fragment.
Together with another engineer and several assistants, Kirchner has been working full-time on the reconstruction of the aquarium for several months. They are supported by the engineer and plastics expert Christian Bonten, who is in regular contact with the team on site. At the end, Bonten will write the report on the cause of the accident – this also plays a role in the assumption of costs by the insurance company. Damage assessment is “the supreme discipline” of engineers, says Bonten.
You have to act like a detective. In a first step, the exact position of the fragments was determined at the scene of the accident and a map was created. This facilitates the reconstruction in the warehouse. The cylinder has been restored there bit by bit for a few weeks. However, not in a three-dimensional form, but lying on the floor, as if you were rolling it out, explains Bonten.
So far, the experts have recorded about half of the fragments. “Patience is not necessarily an adjective that describes me,” says Kirchner and laughs. A lot of it is needed for the reconstruction of the aquarium. Each part is digitally recorded down to the millimeter – the thickness and curvature of the acrylic glass or, for example, break lines provide information about where the fragment belongs. The puzzle is put together piece by piece. At the same time, the engineers are looking for abnormalities in the fragments that allow conclusions to be drawn about the cause.
Can the experts now say something about the cause of the bursting? “No, we’re doing detective work here and we can’t commit ourselves too early,” says Bonten. They cannot officially offer an explanation at this point in time. However, the cause could be four different factors: misuse, faulty design, faulty manufacturing or faulty material. One speaks of misuse, for example, if there was too much water in the aquarium, explains the engineer. But that can be ruled out in the case of the Aquadom.
According to Bonten, potential weak points are basically the joint seams. These are the places where the individual parts of the aquarium were assembled during construction. Because even before the accident, the cylinder did not consist of a single large piece of acrylic glass, but of several assembled parts. This is hardly noticeable to the naked eye. “The way in which the plastic at the joint seams, but also the acrylic glass itself, is broken can give us clues as to how the damage occurred,” explains Bonten. The investigation should be completed by mid-July. Bonten cannot promise that the cause of the sudden breakup can be clearly determined.
For the building owners of the Berlin hotel, which is not scheduled to reopen this year, it is now clear: There will be no Aquadom 2.0 in the property. “It was a magnet for visitors,” says spokesman Fabian Hellbusch in retrospect. Building a new pool is too expensive. A redesign of the hotel lobby is planned.
There is already positive news: almost all of the around 630 fish that were rescued from the underground tanks survived. They have returned to the breeding station or found accommodation with private aquarists or at Zoo Berlin. They are doing very well, said a zoo spokeswoman.
