Managers of construction projects in the UK are increasingly having to consider factors such as the possibility of encountering buried items of unexploded ordnance (UXO) during intrusive works on their sites. The potential risks presented by the presence of UXO are well known and can be considerable in terms of both cost and safety.
However, for the vast majority of sites in the UK, the risk of encountering buried UXO will be negligible and can be screened out at a very early stage, without the need for further research or costly proactive risk mitigation measures.
For those sites which do have a viable risk, it is important to identify this as early as possible in the planning process so that mitigation measures can be budgeted and incorporated early into the overall scheme. Advanced knowledge of such risk will often enable a saving in both time and cost, and ultimately result in less downtime at a more critical stage of a project.
One of the concerns commonly raised by construction industry professionals is that when advice and risk assessments are sought from UXO specialists, either early or late into a project, the reasoning behind – and evidence for – the risk levels assessed by some companies is often not clear and justified. On occasion, the historical information presented is so minimal and the analysis so limited, that it is not clear why certain conclusions have been reached. However, once an assessment of “high” risk has been identified, and recommendations for follow-up works have been made, such measures are often not possible to ignore and can be expensive.
It is essential, therefore, that as a starting point thorough, detailed research is undertaken for a site at the earliest opportunity. It is also paramount that conclusions made from the analysis of the information found is clear, open and justified.
Taking the point of research first, in general, the amount of resources available for most areas of the UK is considerable – be the risk from German air-delivered ordnance or British/Allied weaponry. It is imperative that as much as possible is done to find any relevant historical information pertaining to a site or an area.
It is not sufficient to say that there is a risk because a town was “bombed” and not to make efforts to find out where the bombs fell, what damage they caused, what calibre were they, what the ground conditions were like, what was the land use, would the area have been checked and so on. This should generally mean a bespoke, “micro” level approach to most sites, and accessing and presenting to the client data such as historical mapping, high resolution WWII-era aerial photography, bomb plot maps and written bomb incident records, and always checking local and national archive information.
What is just as important is what is done with this information once it has been analysed and collated. It must be made very clear to a client the reasoning behind assessed risk levels so that they can understand exactly why a recommendation is being made. This also means taking into consideration factors beyond contamination such as the risk that UXO could remain on a site, the risk that it might be encountered and the risk of initiation.
Once a risk has been established, the next stage is to assess the best way that it can be mitigated. This should mean working with a client to understand exactly what is being planned for a site, and having a good knowledge of the nature of the ground conditions present so that the right methods and equipment are used and that the risk is resultantly reduced to as low as is reasonably practicable.
As UXO discoveries become increasingly common with the growing amount of new development in areas untouched since the war, early planning, good research and a pragmatic approach to risk assessment and mitigation measures are essential to both ensure safety and reduce cost.
Brett Kinsman in managing director of 1st Line Defence