Diver checked sewer pipe for damage
22.09.2023 – It sounds more like a test of courage than a work assignment: Diving through a filled sewer pipe in the River Main at 65 meters doesn't sound like a dull day's work. But for the industrial divers at Diedrich Taucharbeiten, such jobs are routine. The company has now been diving on behalf of the civil engineering department of Stadtwerke Offenbach. The entrance from which the structure was inspected for possible damage is on Strahlenberger Straße below the lock. This sewer does not carry wastewater, but is used for rainwater drainage. It is always full of Main water, which is displaced by the inflowing water when it rains due to the inlet being higher than the Main level.
"According to the Drainage Control Ordinance, rainwater relief sewers must be inspected and assessed every ten years," says Dominik Arnold, wastewater foreman and project manager from the Civil Engineering department. "This requirement is imposed on us by the regional council in Darmstadt as the higher supervisory authority. As the Main or rainwater is quite clear and allows us to see potential damage, we can use a diver here."
The masonry was examined for cracks, damage or even collapses. However, no one seriously expected burglaries: This is because the section of Offenbach's sewer network that has now been inspected dates back to 1915, was still built by hand with clinker bricks and is so robust that no modern prefabricated pipe can compete with it. Decades later, the section of sewer was also encased in an additional layer of concrete to withstand the static pressure.
During the two-day operation, the solitary dive on a 65-metre-long hose for the oxygen supply was accompanied above ground by a whole team consisting of employees from the company commissioned with the job as well as staff from the drainage department of the municipal utilities. First, a diving robot controlled from ground level was sent out to eliminate potential dangers for the following diver as far as possible. The diver did not expect to encounter alligators or similar mythical creatures that are often associated with urban canals, but rather obstacles that could have injured him or caused the oxygen hose to get stuck or even rupture.
Although divers always have an oxygen cylinder on their backs for emergencies, they should not have to resort to it. In addition, divers are connected to the dewatering team by radio during every mission until they disembark at the ship's boat lock chamber. Marcus Diedrich also resurfaced unharmed. And he had good news for the Stadtservice: the old pipe has also survived the past ten years without any defects and no repairs are necessary.