Given the time of year with memories of attempts to blow up parliament celebrated by letting of small explosive devices, we thought it might be timely to reflect on our experiences with ordnance – unexploded and otherwise.


We have had a few recent projects where phase 1 desktop studies have highlighted a potential risk from unexploded ordnance (UXO) from WWII. In some cases, these sites were fairly obvious – anti-aircraft gun emplacements for example where you might expect bombing to have possibly occurred or UXO from incorrectly disposed of or stores munitions. In the one case a thorough review of the history showed that this was an unlikely scenario, with the store rooms intact and pressed into use for more mundane activities.


Potential risks have been highlighted in less obvious locations. These were n areas of housing dating back to the early 20th Century or before. Reviewing historical maps can be quite telling in these locations, especially comparing pre-war and post-war maps. In a number of cases, the latter show buildings missing on or near to the site and even more tellingly the word ‘ruin’ where a building had previously stood. In these situations, we would carry out an internet search to establish records of bombing in or near to that location. It can also be fruitful to talk to the relevant contaminated land officer at the local authority to check any information. Still, you may ask, the bomb didn’t hit my site and it was years ago so there cant be any risk can there? Unfortunately that is not a given. Not all unexploded bombs were recorded, and if they entered the ground, the may travel prescribing what is know as a ‘J-Curve’ and may exit elsewhere away from the site of impact – depending of course on the underlying geology. Consequently, there is a potential risk away from the site of the impact and a big unknown is the stability of any explosives. This is not something that you would want to hit with an excavator during development! In this situation we would then recommend the involvement of UXO specialists to  further assess risks and suggest mitigation measures.


Conversely, we also worked with an organisation who are developing a technology to safely disarm munitions in conflict zones. Our role in this was to determine the risks from explosive residues in soils following disarming/destruction of the munitions. This required specialist laboratory analysis as most labs do not accept materials with explosive residues present. It also required strict adherence to safety protocols in the field. The munitions used actually underwent detonation and despite being over 500m away, we could feel the ground shake despite being only small artillery pieces (105mm calibre). This therefore as well as giving us useful experience in assessing risks from soils contaminated with explosive residues, gave us a new perspective on the potential risks from UXO, which would have many times the explosive power of what we encountered!

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