Curtins commissioned to lead on Unexploded Ordnance guide

Unexploded Ordnance, or UXO, is a legacy of the First and Second World Wars as well as UK military activities (training and defensive), and is one of many ground hazards affecting construction works around the country. Unexploded Ordnance is just as likely to be present at former airfields and munitions factories that have returned to nature over time as it is in more obvious locations, such as docklands.

Whilst the intensity of aerial bombing on the UK was around 20 times less than in Germany, the size of the UK’s land mass and extensive military history mean that UXO encounters on construction sites are occurring relatively frequently. Increased demand for housing, including on former military land, together with deeper urban developments (basements) are two reasons Unexploded Ordnance incidents may be increasing, or at least, being maintained at a steady rate annually [1].

In this context – and through our experience working on urban sites; former and current industrial land and historic and active military sites – we have asked, and continue to ask ourselves, the following questions:

  • How do we as ‘designers’ discharge ours and our client’s responsibilities (Duty of Care and CDM Regulations 2015) with respect to UXO hazards and risk?
  • How do we as ‘supervisors’, i.e. ground investigation, respond to UXO incidents?

We have also been at the ‘sharp’ end with Unexploded Ordnance incidents occurring during projects from Plymouth to Sheffield and beyond.

Guidance on managing UXO risk was published by CIRIA in 2009 (Unexploded Ordnance (UXO) – A Guide for the Construction Industry; C681) that established a clear framework for both ‘UXO specialists’ and ‘non UXO specialists’ to follow and be measured against.  As an aside, this guidance is being used as a framework by which other nations and their technical advisors are managing demining programmes (including UXO) that are moving into ‘residual risk’.

This guidance (C681) clarifies that:

  • UXO is a ground hazard affecting the UK
  • Unexploded Ordnance risk should be assessed on all projects

This informs both the requirement for an adequate emergency procedure to be in place (in a similar manner to other, potentially severe incidents, e.g. buried utility strikes) and for the ‘risk’ this hazard presents to be assessed.

C681 also clarifies that, as part of a Preliminary Risk Assessment process, “…the majority of sites in the UK will be identified as having a low probability of finding a UXO…” but goes on to state that “…this {Preliminary Risk Assessment} is an important step to help construction professionals to assess sites with potential UXO risk.”.

In practice; the hazard UXO presents is often downplayed with myths persisting, e.g. the assumption that Unexploded Ordnance is ‘stable’, and the risk often ignored, forgotten or inappropriately assessed.

With the view to improve awareness and demystify the UXO risk assessment process, CIRIA have sought to develop a short guide that Curtins have been commissioned to lead on. The short guide is intended to cover the essentials; to serve as a practical guide for clients, designers and supervisors.

The guide is intended to be completed in December 2018, with publication in early 2019, but in the meantime over the next few months, we are running a survey to gauge how well mainstreamed the subject of Unexploded Ordnance is within the UK construction sector – Can we be more methodical? Are we pushing our luck?

Please share your experience and thoughts via the survey here or get in touch direct via

[1] 11 EOD regiment have, on average, cleared 61 UXO items {excluding small arms ammunition} from the UK since 2010 – just one licensed EOD operator.