AquaDom: Glass Masterpiece of Underwater World
The Aquadom was the largest cylindrical aquarium in the world at the time and even made it into the Guinness Book of Records in 2008. Up until the accident, the structure was a major tourist attraction right in the heart of the Germany's capital. The impressive acrylic glass container was 16 meters high and even 25 meters high with the base, with a diameter of 11.5 meters. It was free-standing in the lobby of the Radisson Collection Hotel in CityQuartier DomAquareé, a big shopping center. Here, you'll find offices right in the heart of the action, along with some great leisure facilities. There are lots of restaurants, shops, and places to stay.
The AquaDom was a great spot for both hotel residents and tourists alike, thanks to its close proximity to the Spree river and Berlin Cathedral. There was a glass elevator in the middle of the hollow body that takes visitors through Sea Life. The tour through the underwater world was incredible. There were about 1,500 fish from around 100 different species living in the AquaDom. For a moment, it felt like time stood still. It was almost like a scene from a movie, with all the different creatures, big and small, gathering in the tank and mingling together in a colorful, lively group. You could also find some familiar Pixar heroes, like Nemo and Dory, or rather real clownfish and palette surgeonfish. But there were also long-finned batfish, silverfish, red-toothed triggerfish, angelfish, and other species part of the coral reef.
The AquaDom elevator was a pretty amazing sight, and it was also a popular backdrop for bridal couples to say "I do."
The divers made sure the inside was kept up daily and got rid of the algae on the walls. There was about a million liters of salt water in the structure and adjusted it to 26 degrees Celsius. That's about the same as 5,000 bathtubs' worth. To keep the water quality up, we regularly cleaned it with a filter and replaced it continuously. This meant that it could be replaced completely once every two years, but it also meant using 18 tons of salt each year.
How was the AquaDome built?
To answer this question, let's go back in time and start with the history of the aquarium's creation. The AquaDom opened in December 2003 after years of planning and construction. The vision came from architect Sergei Tchoban. Union Investment Real Estate was in charge of making it happen, while the Berliner Gesellschaft für Großaquarien (BGG) took care of the biological side of things.
The 41 Plexiglas segments that made up the aquadome were produced by the plastics manufacturer Reynolds Polymer Technology in Colorado—26 for the outer cylinder and 15 for the inner one. In the summer of 2002, these components were shipped by sea to Hamburg and then brought to Berlin by heavy transport.
The segments were joined using a radical polymerization process. The liquid acrylic was cured in the joints within 24 hours to form a solid gel. Once the seam was heated to 90 degrees Celsius and polished, the joint was almost invisible. They sealed the lower edge of the cylinder with a special silicone. The lid and visitor platform of the aquarium were supported by four reinforced concrete columns, which were covered with PU foam and shotcrete and shaped to look like basalt columns. The interior design was finished off with some artificial corals.
The general contractors were a team made up of ICM and Müller-Altvatter. E. Sander was in charge of the systems engineering, while Hydrosight handled some of the project supervision and maintenance. GBH-Design installed the elevator. The whole AquaDom construction cost around 13 million euros at the time.
Morning Disaster: Bursting AquaDom
In our Dlubal blog, we've already looked at a few disasters involving well-known buildings. In the next few lines, we'll turn to the incident that happened 19 years after the AquaDom opened.
It was 5:43 a.m. on a chilly winter morning on December 16, 2022. Tired and frightened hotel residents of the Radisson Collection Hotel gathered around and could hardly believe what was happening in front of them: the outer acrylic glass cylinder of the famous AquaDom had shattered suddenly. Not slowly, not predictably, but suddenly. Like a flash. Devastating. The once bustling hotel lobby was transformed into a chaotic scene of flooded floors, shattered glass, and lots of dead fish.
In just a few seconds, a million liters of water from the huge aquarium spread throughout the hotel lobby and other rooms. Some cellars and the DDR Museum in the CityQuartier DomAquarée were also hit by the mass of water. The force of the water hurled objects out onto the street. Rescue workers rushed to the scene, searched through the debris, and took two injured people to the hospital.
As the saying goes, thankfully, no one was killed or seriously injured. At the time of the incident, there were about 400 guests in the hotel, who were safely evacuated. If the incident had happened just a few minutes later, the first guests would have already been sitting down for breakfast, which could have led to more serious consequences.
On the downside, though, this "blessing in disguise" has some implications for the animals. When the AquaDom burst, almost all of the 1,500 fish in the main pool were thrown through the air and most of them died on the spot. Only a few survived in puddles and were transported to Zoo Berlin or nearby Sea Life. In the basement of the building, there was a tank for breeding and care, from which fish could also be rescued. The power cut almost caused them to suffocate.
Between Renovation and Ruin: AquaDom Restoration
Before we look at what caused the accident, it's important to take a look at the extensive renovation work that was done on the AquaDom between 2019 and 2022. The costs for this amounted to around two million euros. After more than a decade without any problems, a leak developed that needed to be repaired. The water was therefore drained from the aquarium and the fish were temporarily relocated.
It was important to make sure there weren't any cracks in the acrylic glass, which could have been caused by the high humidity in recent years. To do this, the glass was first covered with foil and then polished to get rid of any scratches. The silicone seals on the floor were also replaced and an extra secondary seal was put in. The condition of the elevator was also checked and fixed through maintenance measures. However, because of the COVID-19 pandemic, there were delays in the reopening of the AquaDom.
In Search of Clues: Causes of AquaDom Disaster
The damage from the incident is estimated to be in the tens of millions of euros. No matter what caused it, one thing is for sure: nobody saw the AquaDom bursting coming.
Even the architect Michael Jessing thought it was unlikely that the acrylic glass, which was up to 20 centimeters thick, could break. In a video from 2003, he said that handguns or similar could only create a small hole from which some water might escape, but couldn't cause the entire cylinder to burst. He even called such accidents "Hollywood scenarios" (FOCUS online [2022, December 18]). The Aquadom was supposedly indestructible. The architect gave his work a thumbs-up just after construction. YouTube. https://www.youtube.com/watch?v=gi7r9Py5EMo).
It's pretty shocking that this actually happened. But what caused this disaster? Unfortunately, the report published in 2023 doesn't really shed any light on what went wrong. On the bright side, it seems that external factors like sabotage didn't play a role here. They also couldn't find any evidence that a tilted foundation was to blame. Also, it doesn't seem like cleaning or temperature changes caused the material to give way.
However, it cannot be ruled out that the water basin was damaged during the renovation work. If a tool had struck the acrylic glass and left a small gap, this could have developed into a dangerous crack over time. The expert is convinced that there must have been a specific trigger for the accident.
In the previous section, we mentioned that the huge aquarium was closed for several months due to the COVID-19 pandemic and was unable to receive visitors. This standstill could have caused the walls of the AquaDom to dry out while it was completely empty, making them more susceptible to cracking.
Professor Christian Bonten's third hypothesis was that one of the adhesive seams had failed. An engineer and plastics expert, he was appointed as an expert for the follow-up investigations, which began at the start of January 2023. Despite active support, a total of 1,100 engineering hours were invested in documenting the locations where the debris was found and analysing all the components in detail. Around 700 fragments of the acrylic glass were transported to a hall in Brandenburg and laid out in order to reconstruct the events as accurately as possible.
The remains were examined under a microscope in the test laboratory of the Institute for Plastics Technology in Stuttgart. At the same time, the Fraunhofer IAP in Potsdam analyzed the molecular chain lengths of the acrylic glass segments and glued joints. Despite these extensive efforts, the public prosecutor's office closed the investigation in the autumn of 2023. The bursting of the AquaDom was finally classified as an insurance claim.
Berlin After AquaDom Burst: What's Next?
The accident on December 16, 2022 was devastating – especially for the many fish that were swept to their deaths by the AquaDom's sudden collapse. The incident is a powerful reminder of how fragile even the most impressive structures can be. For a long time, the question arose as to what would happen to the site of the former AquaDom. A new aquarium was out of the question, in part due to pressure from a prominent animal rights organization.
At the end of 2024, the residents and visitors of Berlin's city center will have a new perspective: the opening of a 16-meter-high vertical garden, the so-called "Living Tree". From now on. it will fill the middle of the hotel lobby and offer a spectacular view. Around 2,000 plants of 22 different species will be mounted on 36 tree-like vertical slats. The design is adapted to the structure of the former AquaDom and the base is retained – an economic and sustainable advantage.
The "Living Tree" is characterized by a striking 6.5 meter wide trunk that merges into an abstract treetop. With a height of up to 24 meters, it will extend under the glass atrium roof and reach a diameter of 20 meters. The lush planting and integrated irrigation will create a pleasant indoor environment, almost like an ecosystem in its own right. The installation should also significantly reduce noise levels. Best of all, the approximately 700 pieces of acrylic glass in the AquaDom will be recycled and reused. The reopening of the Radisson Collection Hotel, which was closed for some time due to the incident, is also planned.
Hopefully, similar disasters can be avoided in the future. In any case, the "Living Tree" shows great determination to learn from the past and build a new, sustainable future. Perhaps the project will be featured in one of our next Dlubal blog posts – stay tuned.