DESY-Bahrenfeld: First elements of building pit constructed
First segments of the building pit walls have been cast. More than half of the soil has already been removed. Ammunition discovery on the site disrupted the work for a short time.
Two main activities currently determine the course of events on the construction site DESY-Bahrenfeld. On the eastern side, excavators started realizing the wall of the building pit inside the soil. The first segments – each of them 1.5 metres wide and 40 metres deep – have already been filled with concrete. In parallel, the 10-metre-high bank of the Lise Meitner Park on the western side is being removed in steps. While doing so, workers hit upon old war ammunition, which had been expected in this place and was removed by experts of the Hamburg fire brigade. This too is part of the daily work on a major construction site.
Like on the other two sites, the walls of the building pit are being realized first, more or less as adjacent subterranean trenches filled with concrete. When this enclosure will be completed, the soil inside the building pit can then be excavated and the bottom plate cast. Special procedures enable work to proceed inside the ground water, allowing the construction of a watertight pit for the underground building. Construction of this diaphragm wall has now started on the site DESY-Bahrenfeld, it will take around six months. In total, 250 metres of wall are required to stabilize the building pit.
Elsewhere on the site, activities are concentrating on the soil that has to be removed in the coming weeks in order to bring the construction site to the required level. Caution is advised here. As the area was used for anti-aircraft artillery during World War II, it was already earmarked as a site where old ammunition could potentially be found. “We are not talking about the dangerous bombs or artillery shells that did not detonate on impact and have to be defused before they can be removed,” says Peter Bodes, head of the explosive ordnance disposal service of the Hamburg fire brigade. “We do not expect to find such duds here. But buried ammunition also has to be checked carefully before it can be removed, and sometimes it is necessary to detonate it on the spot – this is part of our tasks,” Bodes explains. So far, the experts removed 24 flak shells of various calibres, one “Panzerfaust” anti-tank weapon and one anti-tank shell on this construction site. Further findings cannot be excluded. The building contractor and the construction management are warned, they are sending in specially trained staff to probe the ground beforehand, all works are carried out very carefully, and everybody concerned has the phone number of the explosive ordnance disposal squad saved in their mobile phone. If at all, activities on the site thus have to be interrupted only for a very short time.