Bachelor thesis on flood protection in Rumpenheim
17.04.2023 – When flooding threatens in Offenbach, the dyke gates have to be closed quickly. How much lead time the civil engineering department of Stadtwerke Offenbach, which is responsible for this, will have when the Main dyke is raised is the subject of a recently completed and passed bachelor's thesis entitled: "Development of a concept for the construction of flood protection on the banks of the Main in Offenbach Rumpenheim."
It was written by Anna-Lena Tascidis from Offenbach. She was very close to the topic: in 2021, she completed an internship in the civil engineering department at Stadtwerke and then continued working there as a student trainee. Now she is joining the team as a new employee.
"I came up with the topic of my bachelor's thesis in conversation with department head Melanie Gessner," says Anna-Lena Tascidis, who studied at the Frankfurt University of Applied Sciences (UAS). "She supervised the thesis and ended up being my second examiner." In her scientific paper, the young engineer examines the question of how long the lead time for the construction of the dyke protection will be once the dyke raising, which is currently underway this year, has been completed. The structure should then be able to withstand a flood, which statistically occurs at least once every 200 years.
In future, more mobile system components will have to be installed
However, in order to secure a higher dyke with significantly more mobile system components, construction will have to start earlier than it does now. The responsible construction team is currently collecting the necessary aluminum beams from the warehouse from a water level of 3.20 meters, measured according to official internal instructions at the Frankfurt Osthafen reference measuring point. This closes the dyke gates on the Main and in future the dyke will also be raised in some places.
"The construction always starts in Rumpenheim at the Schmiedegasse dyke gate. This is the lowest point in Offenbach's urban area, so the water from the Main would enter here first. That's why Rumpenheim was the most interesting place for my bachelor's thesis," explains Anna-Lena Tascidis. "The Deichtor in Schmiedegasse has the additional difficulty that we have to build here from the Main side: The access from the town is too narrow to set up a vehicle and store the material. That's why we have to start very early so that the water doesn't cut off our return route."
In her bachelor's thesis, the new member of staff at Stadtwerke calculated how early, i.e. at what reference water level, the construction has to start after the dyke has been raised. To do this, she described the logistical preparations and the conceptual structure in detail. She listed everything that would be needed in an emergency, how much personnel and how many of the mobile elements would be needed to close the gates and raise the dyke and which machines would be required. Taking all factors into account, it has calculated that after the dyke has been raised, securing would have to begin at a reference level of 249 centimetres. There are 14.5 hours to alert staff and set up the mobile dyke system before the first water from the Main is expected to slosh against the closed gate on Schmiedegasse. "Of course, this still needs to be verified in real time, but we will assume this value in future when there is a risk of flooding," says Melanie Gessner. The civil engineering department currently needs 3 hours and 15 minutes to set up the Schmiedegasse dyke gate at a water level of 3.20 meters.
Internship awakens enthusiasm for civil engineering
Civil engineering was not initially a career choice for Anna-Lena Tascidis. Architecture would have appealed to her, she says, but she didn't enjoy drawing plans. That's why, after graduating from high school, she began studying engineering with a focus on statics. She then did her practical semester at Stadtservice: "I wanted to be sure that I could rule out civil engineering for my career."
But she hadn't reckoned with Melanie Gessner and her team, who involved the intern in the work from the very beginning and gradually got her enthusiastic about it. After all, the tasks involved in municipal drainage offered much more variety than she had imagined. This semester included the construction of the Main outlet with a gigantic construction site on the riverbank and a guided tour of the construction site for interested citizens, she learned about the open sewer construction method as well as underground work with a jacking drill, watched renovation work and gained an insight into the general drainage plan.
Because of this extensive responsibility, she decided to stay: "In structural engineering, you supervise the construction of a building and then usually never have anything to do with it again. In civil engineering, we as a department are responsible for an entire sewer network with all facets from renovation to the expansion and maintenance of all associated technical systems," she explains her decision to start her career at Stadtwerke.