Sea of flowers:
sediment-clean park
Technische Universität Berlin
Spree-Athen: The River as Urban Resource
UD STUDIO 01 - Winter semester 2016-2017
Prof. Dr. Philipp Misselwitz and WM Dipl.-Ing. Aine RyanTan
Cai Yan | Charalampos Tenis | Jonas Wolf | Zhang Zhaoxi
“What can we do for the river?” instead of “what can the river do for us?”
We asked ourselves: What happens if you put the river first, or at least give it a high priority in planning processes, which has never happened before? The Spree in Berlin has been and still is treated as an object to be neglected, i.e. it has been and still is used for various purposes, such as adding value to waterfront properties or dumping chemical waste in Rummelsburg Bay. Putting the river first means looking at how the river is affected by humans, especially through urban interventions, and then localising these impacts.
Polluted sediment hypothesis: The water that flows into this bay is constantly polluted by a large amount of highly contaminated sediment containing heavy metals and pollutants. There is so much pollution in this bay that it is often too much for wildlife to survive.
As a result of being so heavily polluted for so long, the environment, people and wildlife have adapted to the situation. One consequence of this adaptation is that people do not get involved in activities on the river and awareness of the river is decreasing.
Rummelsburger Bucht
Looking at the way the city affects the river was our main motivation for the city scale analysis. At the city scale, we found four pressing problems: wildlife-unfriendly embankments; uncontrolled sewage inflow due to mixed sewerage systems in the city centre; endangered groundwater due to polluted soils; and a massively polluted Rummelsburg Bay, which is a lifeline for both humans and the Spree ecosystem.
The labour- and cost-intensive approach of cleaning the bay through process engineering proved to have no effect on the high levels of heavy metals contained in the sludge. In 1999 and 2000, an attempt was made to clean the sediments using a process engineering method: the sludge was pumped out, chemically cleaned and returned to the bay. In the process, 70,000 cubic metres of sludge were treated, but to no avail. Even the most recent measurements of the bay, carried out in 2015, showed no change in toxicity levels, wasting around 70 million euros on a treatment that did not work. There are currently two test areas for a new approach to dealing with the toxic sludge; the water itself is not affected unless the sediment is stirred up. In these test plots, a new concrete mattress is being tested to cover the sediment and trap the heavy metals inside, while new sediment falls on top; so much for the theory.
Sediment treatment
In the last two decades, there has been a lot of research into phytoremediation, a process that uses special plants (hyperaccumulators) to extract heavy metals from contaminated soils. At the same time, the harsh mining landscapes are being transformed over time into wild landscapes. Time is the key component and the only drawback of this process. So why not try this method in the Rummelsburg Bay? It is cost effective, it has been proven to work and it can offer a new experience.
Unfortunately, the bay is filled with water, so we did some research on phytoremediation processes in water and found out that aquatic plants can easily clean the surrounding water, but unfortunately there are no plants that can create deep root networks in the soil in water that is up to 5 metres deep. And then we had this crazy idea of drying out the water and then planting hyperaccumulators there. Such a simple and drastic solution. But this approach would guarantee the process of sediment cleaning, because there are a lot of best practice examples. And an idea was born: What if you combined one feature with another?
What if you replaced the water with a sea of flowers that you could even interact with? From the idea that the sea of flowers could be interactive, new ideas emerged. Bridges could connect the two sides of the bay, improving access to public transport. Any missing features could be added along the bay to enhance the neighbourhood.
The dyke
The key element in drying out the sea is a dyke, a physical infrastructure to keep the water out of the bay. Since we were already proposing an infrastructural building that contrasted with our subtle way of cleaning the bay, we tried to give the dyke different functions. We wanted to use the dyke for another important purpose: to pump the water from the bay into the River Spree and clean it there.
Phytoremediation
The bay is polluted with high levels of heavy metals, up to six times the tolerance level. The pollution is a result of the influx of waste from surrounding factories, which has led to high levels of cadmium, chromium, copper, lead, mercury, nickel, zinc and more. We have put together a collection of plants that respond to the specific toxicity found in the bay: sunflower, oilseed rape, Indian mustard, Bermuda grass and widow’s weed.
As the plants grow, they take up the toxic particles through their root systems. What makes these plants special is that they can do both: withstand highly toxic soils and take up above-average amounts of toxic particles. Although all plants can extract more than one (toxic) element, there is no one plant that can cure everything. With a cyclical system of plantations we can address this problem.
Education & science
Educating people about the history of the site, and showing them how powerful and fragile nature is at the same time, means moving towards a future where this kind of pollution never happens again. Educating the public about the history and clean-up process is a perfect subject for a museum, which we can imagine on our site, and the campus can provide greenhouses for growing the plants used in the bay, as well as the typical classrooms, laboratories and studios.
10-year scheme
The whole project will take 30 years to completely remove the heavy metal. The very first step will be the construction of the dike, which will take two years. After that, two pumps will work for two years to remove the water while the plantation begins. From the 3rd year, the construction of footpaths from the dyke into the park area will begin. When it is possible to walk through the park, new areas such as the playground and the campus will be created and new activities will be developed.
Years later, the park will become an attraction for the whole city, renowned for its eco-tech research. Then more companies will be born here and it will slowly become a gathering place for the industries concerned. The 30-year process will leave an amazing park and people will be proud of the area and will make the appropriate decision whether to let the water back in or keep the beautiful landscape.
