Explosive ordnance in the ground from

Explosive ordnance from the Second World War still poses a potential risk to planned construction projects today. In order to be able to assess this risk and take it into account in further planning, M&P offers its customers pre-exploration of explosive ordnance on the basis of aerial photo analyses. In order to prepare a more meaningful aerial photo analysis, M&P has an in-house team of historians, geographers and geoinformatics specialists reconstruct the attack and the events of the war using historical sources and specialist literature. This background information provides valuable information in the search for objects relevant to ordnance in the aerial image. Conversely, aerial image analysis can also provide historical research with impetus for targeted, in-depth investigations, as the example of an explosive ordnance survey in a small community in southern Germany shows.

One eyewitness report from 1945 stood out in this project. It provided detailed descriptions of a large explosion in which several tonnes of gunpowder were supposedly destroyed. Information about the approximate location of the explosion, a wooded area, as well as extensive damage to property in the surrounding area was also found in the eyewitness report, which was deemed credible. Blasting of this kind can be expected to have an ejection radius of up to one kilometre. It was therefore necessary to investigate whether the explosion could have propelled explosive ordnance and/or unburned explosives into the area under investigation as part of the preliminary explosive ordnance survey. The first task was to localise the exact location of the explosion. It seemed unlikely that such an event would have left no aerial traces. However, despite a targeted search, no evidence of an explosion crater was found in an aerial photograph taken just a few weeks after the blast. The assumption was that the crater was located within a small forest that still exists today and was therefore invisible in the aerial image. However, even a specially procured digital terrain model (DTM), which depicts the current ground structure regardless of forest cover, did not provide any new indications of a possible blast site.

This seemed to have exhausted the possibilities of analysing the aerial photographs and it was still not clear whether the explosion could have caused explosive ordnance contamination in the area of the planned construction site. The baton was therefore once again passed to the team of experts for the historical research. They finally succeeded in locating a contemporary witness who was able to confirm and precisely localise the blast and even clarified the question of the whereabouts of the crater. According to the witness, the blast crater had been built over in the post-war period and was therefore not visible in current aerial photographs or on the DTM. With the knowledge of the blast site, the crater could now also be located in the historical aerial image. It turned out that it was almost invisible in the shadow of tall trees (see illustration).

Thanks to M&P's various specialist expertise and their close collaboration, it was possible to clarify the supposed contradictions. The distance between the now safely determined blasting site and the investigation area resulted in a reliable assessment of the explosive ordnance risk for the client's construction project.