CIRIA report C785 – Unexploded Ordnance (UXO) risk management guide for land-based projects

Shortlisted for Brownfield Awards Category 2 - Best Scientific/Technical/Digital Advance

The Background: Curtins has been involved in dozens of projects on which UXO risk management has played a prominent role; from former military sites, to unexpected encounters of UXO on urban sites. The company’s approach to this hazard was either guided by external UXO specialists or internally, by staff with suitable experience and knowledge. Whilst individually these attributes were reasonably well covered within the company, experience of the necessary combination of both was limited. With this skills gap and the company’s project experience, the publication of CIRIA’s first UXO guidance (C681) in 2009 was welcomed and immediately became a point of reference. In practice however, uncertainty remained, particularly around the point at which an UXO specialist should be engaged in the risk management process.
This uncertainty directed staff to adopt a precautionary approach that, over time, was perceived by practitioners across all disciplines involved in ground engineering as being disproportionate to the background threat UXO poses on construction projects.

The Opportunity: With UXO risk management a key point of internal discussion, when CIRIA invited applications to lead the development of a new, shorter form of UXO guidance, Curtins readily committed to the invitation to tender. This commitment was also supported by an informal meeting with an international UXO specialist at a CIRIA-led conference on UXO that an individual from Curtins was speaking at. This specialist, who would ultimately become an author on the new guide, questioned how the UK with its history of leading the world in the development of standards (including in the field of UXO risk management overseas) could be struggling with this subject ‘at home’.

The Ambition: Following a successful tender, Curtins (the project lead) assembled a team - ‘the authors’. Together with CIRIA’s project manager, they quickly agreed the main ambition of the new guidance was to demystify and make more accessible the process of UXO risk management for land-based projects in the UK, across all stages of a project’s lifecycle (off-shore UXO risk management being covered under separate CIRIA guidance). Curtins saw a key motivation for the guidance being to foster a more balanced or proportional response to the hazard UXO presents. Without proportionality workers would be exposed to real risk or unnecessary costs through the risk being ‘ignored’ or ‘eliminated’ respectively.
The Contributors: Development of the guidance was collaborative; primarily between the authors and the project steering group that met at regular intervals during the contract; the latter being central to CIRIA’s peer review process. Other contributors whose input the authors sought included; the Health and Safety Executive, regional police forces (who 
are invariably first responders to UXO incidents), other international UXO specialists and from as diverse cross section of the construction sector as possible through a survey.

The Survey: The survey was promoted by Curtins as a means to verify the perception that responses to UXO risk management are polarised and to obtain an impression of the existing guidance’s impact on the construction sector. Advertised through CIRIA’s mailing list and the Project Steering Group’s networks to obtain as broad a base of feedback as possible, the survey mainly drew on people working within the contaminated land sector but also included; main contractors, demolition contractors and UXO specialists. Over 100 respondents completed the survey and when asked, “Do you have concerns with the way UXO risks are managed in the UK construction industry?” 65% responded, ‘yes’. The free-form text section of the survey also drew out some key themes; a sense of uncertainty relating to UXO risk management, generic and overly conservative recommendations with specialist reporting and dissatisfaction with some UXO specialist’s services.

The Process: A running question through the guide’s development was how to rationalise the existing risk assessment protocols within C681 (CIRIA’s first UXO guidance), the basis of which was sound, with new guidance that made the process more accessible. Through the iterative process of developing the guide, various options were considered that included: the scoring of risk – that the authors viewed as being too much of a distraction from the analysis at the core of risk assessment; and, the use of a proforma risk assessment – that the project steering group viewed as being too proscriptive and liable to misuse. The authors ultimately noted that once the process of UXO risk assessment started, it had a tendency to ‘run-away’ and therefore, it was the beginning of the risk management process that needed greatest focus to increase engagement. These early stages of risk assessment are where the competency of non-UXO specialists was more easily demonstrated and, like other land-based hazards, often where the strongest lines of evidence emerge. The Guidance: This attention to the early stages of risk assessment was drawn out within the new guidance through a distinction between ‘hazard screening’ and ‘preliminary risk assessment’. The logic followed that if no indicators of UXO were present on a site, then the assessment of risk to planned activities wasn’t strictly necessary. Hazard screening is an essential part of risk management but this step was embedded within the preliminary risk assessment protocol of C681
and so, even where no evidence of UXO was present, there was a tendency to follow-on and consider the exposure of planned activities (or likelihood of an encounter). As well as likely to be unnecessary, this follow-on was more likely to draw non-UXO-specialists into areas they were less competent in dealing with. Related to, and alongside a focus on the early stages of risk assessment, the new guidance sought to address the subject of ‘background threat’ within the UK. To this end the guidance is broken down into two sections; theory and practice, with the former available to those who want to develop a fuller understanding of the background threat with the UK. This section includes emphasis on; the emotive and interesting nature of the hazard (compared to slope instability for example, that has resulted in more fatalities and injuries since 1949, the date of the last known UXO fatality), the fact the likelihood of an encounter varies widely across different land areas and the reasons for the background threat in Germany and the continent not being comparable to the UK. Guidance on detailed risk assessment is limited to advice on how to more effectively review these reports, a specialist’s work.

The Reception: Through a number of presentations following the guide’s publication the need for clearer guidance on UXO risk management within the contaminated land sector has been reinforced. Some feedback from early adopters and attendees at these events indicates that the guidance helps address the sector’s need and, whilst the background threat will only decrease with the passage of time, the need for UXO risk management within the UK will remain for decades to come. Curtins and the authors hope this guidance offers increased clarity to non-UXO-specialists around this interesting and evocative topic.

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