UXO Survey_
At Brimstone, we deliver UXO surveys that accurately detect and characterise potential unexploded ordnance beneath the surface, supporting safe and confident progress on site. Whether broad coverage is required across open areas or a deeper investigation at specific positions, we provide both non-intrusive and intrusive survey options to suit your project.
Our surveys are carried out by qualified specialists using industry-leading equipment, with all data interpreted by our in-house geophysics team. This ensures clear, reliable results and informed decision-making at every stage.
What is a UXO Survey?
A UXO Survey is a site-based investigation used to detect and map buried metallic anomalies that may be unexploded ordnance (UXO) beneath the ground. It provides clarity on whether hazards may be present before intrusive ground works begin, supporting safe and compliant project planning in line with CIRIA C681 guidance.
Many sites across the UK have been affected by wartime bombing, historic military training and disposal practices. Even where there is no surface evidence, buried UXO can remain. A survey confirms whether items of concern may be present so that risks can be reduced to a level that is as low as reasonably practicable.
A survey usually follows a UXO Risk Assessment where a credible risk has been identified. It is typically undertaken before piling, ground investigation, excavation or deep foundation works.
If you are unsure whether your site requires a survey, our specialists can advise based on location, planned works and site history.
There is no single approach that fits every project. The survey type depends on ground conditions, access, depth of investigation and expected risk.
Non-intrusive methods provide broad, efficient coverage where shallow risks are anticipated, while intrusive surveys are used to explore deeper anomalies or work in areas of made ground.
Non-Intrusive UXO Surveys_
Using pushcart, towed-array or drone-mounted magnetometers, we carry out non-intrusive UXO surveys to detect shallow-buried metallic anomalies, such as land service ammunition or small bombs, typically to an assured depth of 4 metres. In some cases, larger ordnance may be detected at greater depths.
Our multi-channel sensor systems enable efficient, accurate coverage of large areas, without disturbing the ground.
A five-channel system for the detection of ferro-magnetic anomalies in small to medium sized areas carried out by a specialist two-person team.
An eight-channel gradiometer system for the detection of ferro-magnetic anomalies in large areas carried out by a specialist two-person team. Towing the sensors behind an all-terrain vehicle and the wider sensor array increases time-efficiency without detriment to resolution or quality.
Our specialised drones enable us to carry out UXO surveys in areas where a pushcart or towed-array system cannot reach. Brimstone is proud to have been the first company, both within the UK and overseas, to market drones for UXO surveys, and we continue to develop our systems to ensure maximum benefits for our clients.
Collected data is processed by our geophysics team using specialist software that compares anomalies against a library of known UXO signatures. We estimate depth, mass, and location to within 5 cm accuracy, delivering clear findings and actionable recommendations.
Intrusive UXO Survey_
At Brimstone we use specialist rigs for our intrusive surveys. Our CPT rigs can survey single pile positions or clusters for any deep intrusive works on your site. For large scale excavations, we can provide a site-wide matrix clearance, offering a complete survey solution to a maximum depth of 25 metres across a large area. Our system is triaxial, meaning it can also model targets in three dimensions. This allows for more than one pile position to be cleared per one survey position, keeping costs down and projects moving along.
A key benefit of this methodology is that it can be deployed to brownfield sites or sites with areas of made ground – sites that would usually be unsuitable for a non-intrusive methodology. Additionally, greater depths can be achieved with this system when compared to the non-intrusive system.
Where anomalies are detected, the data will be analysed and assessed by our in-house geophysicists. If an anomaly models the characteristics of a UXB, our operations team will discuss and plan the next step in the UXO risk mitigation process.
Recent UXO Survey Projects_
Drone UXO Survey_
Time, safety and budgetary constraints are a factor in all construction related projects. Drone systems routinely deliver superior survey coverage, surveying up to five times as many hectares in a single day compared to the push-cart system. Drone systems are also highly suited to difficult to access areas.
Our drone systems are highly suited to accessing challenging or remote locations with ease, providing comprehensive surveying solutions in diverse environments. Penetrating down to an assured depth of 4 metres below the surface, we check for potential hazards by using magnetometry to detect ferrous materials and map magnetic signatures. We then send the results back to our experienced geophysicists for analysis.
Our radiation sensors are designed to autonomously capture gamma sources by following pre-determined flight waypoints. When they detect radiation, it immediately triggers an alert, complete with GPS coordinates, which is transmitted to the operational base station. These coordinates are then plotted on radiation maps, allowing for real-time comparison against highlighted changes in isotopes across the entire survey area.
Frequently Asked Questions_
An unexploded ordnance (UXO) survey is a specialist investigation designed to identify potential unexploded ordnance (UXO) hidden beneath the ground. Using advanced detection methods, surveys locate buried metallic objects that may pose a risk to site works.
An Intrusive UXO Survey physically probes into the ground to detect and confirm the presence of buried UXO. A Non-Intrusive UXO Survey, on the other hand, uses surface-based or aerial sensors to scan for anomalies without disturbing the soil. These can be deployed in pushed, towed, or aerial formats depending on site conditions.
Survey data is analysed by Brimstone’s in-house geophysics specialists using advanced modelling and bespoke software. This allows us to identify signals, estimate the depth and size of anomalies, and pinpoint exact locations with high accuracy.
Following analysis, clients receive a comprehensive report with clear recommendations. If potential UXO targets are identified, our engineers may be deployed for further investigation. Where no anomalies are detected, clients can move forward confidently, knowing the UXO risk has been effectively addressed.
Many UK sites have a history of wartime activity, military training, or bombing during the Second World War. An unexploded ordnance survey helps to confirm whether there is a risk on your site, ensuring you can proceed safely and in compliance with regulations.
UXO surveys are usually undertaken after a desk-based risk assessment has identified a potential risk. The survey should be completed before ground works begin, so that any hazards are identified and mitigated early.
The duration depends on the size and complexity of the site, as well as whether an intrusive or non-intrusive method is used. Smaller areas can often be surveyed in a day, while larger or more complex projects may require longer.
While not legally mandatory, health and safety regulations place a duty of care on developers and contractors to identify and mitigate potential risks – including UXO. A survey provides evidence that appropriate steps have been taken to ensure site safety.
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