Behind the Scenes: Detailed UXO Risk Assessments at Brimstone

At Brimstone, we navigate the risks of unexploded ordnance in conjunction with our clients, who are working to clear sites before they begin the groundworks of their project. This process usually starts with a UXO Risk Assessment.

Have you ever wondered what goes into creating a Detailed UXO Risk Assessment and how we arrive at our risk ratings? In this interview, we sit down with Alfie Hanford, one of our Project Researchers, to discuss the process our team undertakes to create a bespoke Detailed Risk Assessment and the methodologies used to reach our recommended outcomes.

Q: What is a Detailed UXO Risk Assessment?

A Detailed Unexploded Ordnance (UXO) Risk Assessment, also known as a Stage 2 Risk Assessment, is an in-depth look at your project site to evaluate the range of ways enemy action or military activity could have led to UXO contamination and how modern construction methods, including human factors, affect the likelihood of encountering UXO.

Q: When we receive a site that requires a Detailed UXO Risk Assessment, what is the first thing you do?

As soon as the order for a Detailed UXO Risk Assessment is placed, we commence a search for all available records pertaining to either the site itself or the wider area. For example, if a site is located within a former or current airfield, a station plan must be obtained from RAF Hendon in order to accurately access the site, amongst other research. While our in-house archive is extensive, if a site is located in an area for which we hold no original bombing records, a trip to the national or relevant local archives is typically required.

In addition to this, we must ensure that we have WWII-era photographic coverage of the site. A member of the Research team will then carry out a preliminary investigation into the site if a Stage 1 UXO Risk Assessment has not been completed already.

Q: What do you look for when assessing the site?

The factors under consideration are similar to those in the Preliminary UXO Risk Assessment, however, at a Detailed stage, the focus is on whether an unexploded bomb (UXB) could feasibly strike the site and remain unencountered until the present day.

The key factors to consider are the local bombing density, whether the site was bombed and if this caused damage, and whether the wartime conditions on site were conducive to the detection of UXO; is it likely that a UXB strike, or evidence of such, would have been observed and dealt with at the time?

Q: What resources do you use?

Our key resources include any available bomb maps, damage maps and written records, as well as post-WWII historic aerial photography and historic OS mapping. We also have an extensive in-house geodatabase and a library containing books that cover the length and breadth of the country. However, as all our assessments require bespoke analysis, we will try to uncover relevant information and evidence in any way possible. A thorough internet search for all available anecdotal and official evidence is also undertaken.

Q: What are the key factors that determine the risk rating the site receives?

There are three main factors that must be considered in order to determine the overall risk rating on site.

• Firstly, the likelihood of UXO contamination – is there an elevated likelihood that the site will have been struck by a German UXB or become contaminated with British/Allied UXO without being dealt with at the time?
• Secondly, the likelihood of such UXO remaining on Site – have post-WWII ground works mitigated the risk from UXO?
• And last, but perhaps most importantly to our clients, is the likelihood of UXO encounter – the likelihood of UXO contaminating the site may be elevated, but if the works proposed by the client are unlikely to encounter this UXO, the overall risk will be deemed as low.

Q: Does the process differ depending on the site location?

The process of assessing each site largely remains the same across the country, however, the resources we have at our disposal may differ. More rural areas with lower bombing densities are less likely to have original bomb plot mapping and written records, forcing us to place more of an emphasis on historical aerial imagery and anecdotal evidence in the report.

Q: Are there any challenges you often must overcome when working on a Detailed UXO Risk Assessment?

Perhaps the most common challenge faced by UXO companies when working on a Detailed UXO Risk Assessment is the lack of official records pertaining to bombing in more rural areas, or in areas where the density of bombing is lower. While challenging, we overcome this through in-depth analysis of secondary and online sources, as well as first-hand accounts from the time, where available. The historical aerial imagery becomes even more integral to the report in these scenarios, and is relied upon to attempt to better understand whether bombing has affected the site.

Q: Why should you choose Brimstone to undertake your UXO Risk Assessment?

The Brimstone Research team has completed a wide array of UXO assessments across the UK, for a variety of specialist clients. Our work with the Defence Infrastructure Organisation (DIO) has provided us with a wealth of experience when it comes to former and current military sites (such as airfields and training areas), while the training and investment into each member of the team ensures accurate and efficient analysis on a daily basis.

All too regularly we are asked to review a competitor’s Detailed UXO Assessment, where many of the typical sources we use have been neglected (such as historical aerial imagery), and no attempt has been made to conform to the ALARP (As Low As Reasonably Practicable) Principle. Blanket Medium/Moderate or High risks are all too common. Indeed, where the risk to a site is deemed to be elevated, we always strive to zone the risk, where possible, in order to provide the client with as much Low Risk as is justifiable.

Industry leading UXO risk assessments

At Brimstone, our track record speaks for itself. We have successfully produced thousands of UXO risk assessments, delivering outstanding results and surpassing client expectations.

If you need help deciding which UXO risk assessment is right for your site, get in touch with our Commercial Team today who will be more than happy to assist you.

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