UXO can pose a real danger to construction and development projects across the UK. CIRIA C681 focuses on the needs of construction professionals and reduces the risk of an unexpected UXO encounter, keeping you and your project as safe as possible.

This blog takes an in-depth look at CIRIA C681 and the UXO guidance it provides.

What Is CIRIA C681?

If you work in construction, you’ll likely have heard of CIRIA, or the Construction Industry Research and Information Association.

They’re the independent, not-for-profit body at the forefront of construction research. Their work ranges from biodiversity enhancements on building sites to a set framework for reducing risk from unexploded bombs.

450,000 bombs were dropped on Britain during the Blitz, with a significant proportion failing to explode. There are also a considerable amount of explosives left over from allied action, such as ordnance manufacturing and Home Guard activities. In addition, tons of UXO have been left over from more recent military training, creating the potential for a UXO incident. This could occur during a construction or development project, so it’s safest to research the site thoroughly before beginning any work.

Surprisingly, there’s no UK legislation defining the steps you must take to check for UXO before construction or development work begins. However, there are legal obligations under the Health and Safety at Work Act 1974 and CDM2015 to ensure the health and safety of employees. This is where CIRIA C681 comes in, with an industry guide for the management of risk associated with UXO.

The four stages of CIRIA C681 are:

  1. Preliminary UXO Risk Assessment
  2. Detailed UXO Risk Assessment
  3. Risk Mitigation
  4. Implementation

This UXO guidance is focused on WWI and WWII aerial bombardment, though it’s broadly applicable to other forms of unexploded ordnance.

Breaking Down CIRIA C681

The first unwritten step is to get in contact with UXO specialists who can help you follow through with C681. Brimstone manages a team of EOD-trained personnel, who use their experiences from the British Army, Royal Navy and Royal Air Force to mitigate the risk of UXO.

Step One: Preliminary UXO Risk Assessment

UXO specialists begin with a preliminary assessment to determine your site’s risk level. They investigate any military activity on or near your site to calculate the likelihood of you encountering UXO, eventually presenting you with a risk rating and any recommended further action.

Brimstone relies on primary and secondary sources instead of automated systems, and delivers an accurate assessment within 24 hours, letting your project continue smoothly and safely.

Step Two: Detailed UXO Risk Assessment

If the researchers decide more analysis is needed, they’ll move on to the second step of CIRIA C681. If your site is a former military site, you will need to start the process with this type of assessment.

The research team will investigate how any military action could have led to contamination on your site, factoring in modern construction and human activity. With detailed modelling and granular research, Brimstone can discern the type of UXO that could be on your land and how deeply it would have penetrated the soil.

Taking Action

If your site returns a low risk rating after an assessment, this is deemed ‘acceptable’ and you can continue with your project. However, if it comes back as high or moderate, you will need to take further action.

Step Three: Risk Mitigation

The UXO specialists will work with you to find a solution to the problem. If a viable solution can’t be found, then you may have to make changes to your development plan. Fortunately, Brimstone are usually able to find workable solutions that take your project budget and site characteristics into account.

Step Four: Implementation

The UXO engineers will join you onsite to implement the rest of the plan. With Brimstone, this could involve a non-intrusive survey, with drones, carts and towed-array systems used to sense ferrous metals without breaking the surface.

Alternatively, we might deploy one of our rigs to site, which allows us to clear piles up to 25m beneath the ground and model targets in three dimensions.

Should we uncover any anomalies, we’ll move onto a thorough investigation and disposal process, aided by our 250kg explosive magazine, used for nationwide disposal tasks.

Working With Brimstone

By working with us, you will have followed CIRIA C681 to the letter.

If you would like support on your project or further UXO guidance, get in touch with our commercial team today, or explore our website to learn more.

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