What is CIRIA C681?

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One unintended outcome from construction activity is that UXO is occasionally discovered. When it is, it usually generates considerable media interest and can cause major disruption to the public.

UXO finds can also be costly in terms of delays and increased costs and there are the obvious health and safety concerns involved in encountering unexploded weaponry.

Fortunately, experience shows that the number of casualties resulting from UXO encounter in the UK is low. However, as it is a low probability but high consequence event, appropriate allowance should be made at the design stage for assessing the risk of encountering UXO and for mitigating that risk.

In the UK, there is no specific legislation that requires the construction industry to undertake a UXO Risk Assessment or UXO Risk Mitigation measures before construction or development work begins.

However, clients do have a legal obligation under CDM2015 to provide specific health and safety information needed to identify hazards and risks associated with design and construction work.

Under the Health and Safety at Work Act 1974 every employer must also ensure (as far as reasonably practicable) the health and safety of their employees and that of other persons who are affected by their work activity, and must have in place a safe system of work.

Therefore, pre-planning and accessing your site for UXO risk before development works commence is essential to mitigate any potential safety risks or concerns.

As a result, all employers with employees working on or visiting a site where there may be risk from UXO have a statutory duty to make sure that a safe system of work is in place for their staff that adequately addresses the risk from UXO.

^{The above content has been repurposed from the CIRIA C681 guide for the construction industry.}

10lb Practice Bombs which were recovered from a UK airfield by 1st Line Defence

What guidance is available for the construction industry about UXO risk?

For more information about the risk management process, including best practices, case studies and a detailed guide to UXO risk in the UK – it is recommended that the 2009 document ‘C681 Unexploded Ordnance (UXO) A Guide for the Construction Industry‘ is viewed.

The principal purpose of this document is to provide the UK construction industry with a set and defined process for the management of risks associated with UXO from WWI and WWII aerial bombardment, and current / historic military activity.

It focuses on the needs of the construction professional if there is a suspected UXO on-site and covers issues such as what to expect from an UXO specialist. 1st Line Defence conform to the recommendations for good practice set out in this guide, and our management team were part of the original steering group for this document.

CIRIA C681 was updated / supplemented in 2019 by a more concise version of the original document – ‘Unexploded ordnance (UXO) risk management guide for land-based projects (C785)‘. The document was part authored by Phil Baptie, Director of Research at 1st Line Defence, and acts as a shorter more accessible handbook for management of UXO risk on UK construction projects.

What is the CIRIA C681 risk management process?

CIRIA have outlined a four-stage risk management process for constructors, click on the following link to download an overview of the UXO Risk Mitigation Strategy we follow – in accordance to C681 Guidelines.

The risk management process includes the following stages and we can assist you at each stage of the process:

Stage 1: Preliminary UXO Risk Assessment

This is a basic risk assessment to determine a risk level for your project and advice whether further investigation is required.

If you require multiple Preliminary UXO Risk Assessments, contact us directly to check whether any discounts are available.

Useful info: In 2022, 55% of all Preliminary UXO Risk Assessments resulted in ‘no further action’ being recommended. If your site falls into this category no further action would be necessary.

Stage 2: Detailed UXO Risk Assessment

If any risk or need for further research is identified during the Preliminary assessment, we would recommend that a Detailed UXO Risk Assessment is commissioned – which is a comprehensive and in-depth desktop study report which fully examines the history of a project.

This detailed desktop study report includes specialist analysis of historical records including bombing maps, previous military use, location history and land use, reports and records of air-delivered bombs, frequency of access, consideration of any mitigating factors plus the extent and nature of proposed construction plans.

If the level of risk is ‘low’, no further action will be required unless future changes are proposed, for example – if deeper foundations and excavation of the site is required at a later date.

Stage 3: UXO Risk Management

If the level of risk on your site has been identified as ‘medium’ or ‘high’, we will provide a UXO risk mitigation plan detailing the services required to address the risk.

If the risk mitigation solution proposed isn’t suitable, you may be required to review development plans, however – in the majority of cases we will be able to identify a suitable solution.

Stage 4: UXO Support

Once the risk mitigation solution has been approved, we will deploy UXO Specialists to investigate your project – this might involve a UXO Survey or proactive on-site UXO Support.

If an item of UXO is encountered, the risk level for your site will need to be reviewed and if necessary – amend the risk mitigation plan.

If no UXO is encountered during this stage you will receive a verification report and no further action will be required.