Download Acronyms and Abbreviations

Frequently Asked Questions can be found below. 

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What does UXO mean?

The most commonly used definition of Unexploded ordnance (UXO) is:

“Explosive ordnance that has been primed, fused, armed, or otherwise prepared for use and used in an armed conflict. It may have been fired, dropped, launched or projected and should have exploded but failed to do so.”

The term UXO also includes:
“Explosive ordnance that has not been used during an armed conflict, that has been left behind or dumped by a party to an armed conflict, and which is no longer under control of the party that left it behind or dumped it. Abandoned explosive ordnance may or may not have been primed, fused, armed or otherwise prepared for use.”

UXO can range in size from small arms ammunition to large unexploded bombs weighing more than 2000 kg (unexploded aerial delivered bombs are often referred to as unexploded bombs or UXBs’) and all have the potential to cause significant harm to those who encounter them. They can be found on the surface but are more usually buried underground with no surface markers to indicate their presence.


Where does UXO come from?

UXO found on land in the UK typically originates from one of three principal sources:

  • Munitions deposited as part of military training exercises.
  • Munitions dumped as part of a deliberate act, accidental disposal or disposed of ineffectively due to poor working practices during munitions storage and manufacture.
  • Ordnance resulting from wartime activities including enemy bombing events during WWI and WWII, long range shelling, munitions deliberately placed as a means of area denial (mine fields, pipe mines etc) and munitions from other home defence activities (anti-aircraft batteries, coastal artillery emplacements etc).

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

CIRIA Report C681 - Unexploded ordnance (UXO) A guide for the construction industry. 

This report is an independent construction industry guide produced by the Construction Industry Research and Information Association. It focuses on the needs of the construction industry if there is a suspected UXO on site and covers issues such as what to expect from an UXO specialist. 

You can purchase a copy of C681 here:  (http://www.ciria.org/ItemDetail?iProductcode=C681&Category=BOOK)


What guidance is available for marine projects which may encounter UXO?

CIRIA Report C754 – Assessment and management of Unexploded ordnance (UXO) risk in the marine environment.

This report from 2015 is an independent guide produced by the Construction Industry Research and Information Association (CIRIA). It focuses on the risk of encountering UXO during inshore or offshore projects and gives guidance as to how the risk can be assessed and managed.

You can purchase a copy of C754 here:  (https://www.ciria.org/ItemDetail?iProductCode=C754&Category=BOOK)


How can Fellows help with UXO Risk Management?

Fellows can support you through the whole UXO Risk Management lifecycle whether on land or in water. You can find out more information about our products and services here. 


Do I need a UXO survey at my site?

Not necessarily. It all depends on where your site is located, its history and the likelihood of finding an item of unexploded ordnance. A preliminary desktop risk assessment is the best way to determine if you require a physical site survey. 

For example, if your site is located in a major town or city that was bombed heavily during the war, there is a good chance that a physical site survey will be required. If however, the site is located in an isolated area of countryside, with no history of military activity a desktop risk assessment may determine that no action is required.

Fellows would be happy to advise you further in this. Please get in contact if you have any questions, or you can start the process by ordering a Preliminary Desk top study here. 

The Construction Industry Research and Information Association (CIRIA) reports that over 15,000 items of ordnance were found on UK construction sites from 2006 to 2009. This equates to over 5000 a year.


What are the different kinds of site survey?

There are principally two types of survey for UXO risk mitigation. Intrusive and non-intrusive surveys. 
A non-intrusive survey uses a magnetometer or echo pulse locator to detect metal objects in the ground. This type of survey can be very effective at finding large items of ordnance, particularly on green field sites with little or no magnetic contamination. The effectiveness of these techniques is limited on sites that have been previously developed and have high levels of metallic contamination. In this case, an intrusive survey will be more appropriate.  

Non-intrusive survey systems can be configured with different numbers of sensors dependent upon the areas to be surveyed and can be mounted on a number of platforms dependent upon the size of the survey area. Small sites are typically undertaken by pedestrian surveys and large sites can be surveyed by motorised platforms. Non-intrusive surveys can be employed for both land and marine environments and provide rapid and cost effective surveys over large areas of site.

Intrusive Surveys are undertaken when clearance is required for structures that penetrate into the ground beyond depths that can be cleared by other methods (typically >3-4m). The intrusive survey consists of a magnetometer probe being inserted into the ground either via hydraulic rams from a specialist vehicle (Cone Penetration Testing) or a rotary drilling rig or other hole forming method in conjunction with hand-held locators that can be inserted into the drilled hole. Dependent upon the soil types the survey holes can be uncased or cased with a non-ferrous casing to prevent the survey holes collapsing.


Is there a legal requirement to undertake a UXO RA?

No, the management and control of UXO risks in the UK construction industry is not mandatory, however, issues regarding risk management at a site are addressed within existing legislation. The most comprehensive and widely referenced UXO guidance for the construction industry is CIRIA C681 – Unexploded Ordnance (UXO) a guide for the construction industry (Published in 2009).

The approach described within CIRIA C681 follows UK HSE guidance and is based upon the ALARP (As Low As Reasonably Practicable) approach. This approach also recommends that proactive risk mitigation measures are employed whenever possible and reactive measures are only employed as a last option. 


Do I need to consider UXO during site or ground investigation?

On sites at an early stage of development or where the scope of work involves only Site or Ground Investigation works it may only be appropriate for a UXO Engineer to carry out initial surface scans of potential Bore-Hole, Window Sampling or Trial Pit areas. 

The UXO Engineer can also supervise deeper survey of these positions by utilising a staged ‘down hole’ magnetometer survey to ensure the position is clear and no anomalies with ordnance like qualities are present.

Boreholes may be cased with non-ferrous (stainless steel or plastic) casings if required or traditional casing may be ‘pulled’ or raised allowing surveying of the bottom of the borehole without interference from the magnetic casings.


Do I need to consider UXO during marine development work?

Both inshore and offshore projects need to understand the threat that marine UXO can present to people and equipment.

The rise in ports and harbours development work has seen increasing numbers of marine development and construction companies encountering UXO during seabed survey, intrusive operations or dredging.

As the offshore energy industry expands in UK and European waters, construction in the marine environment - ranging from installation of wind turbine foundations to cable laying – is taking place on an unprecedented scale. Throughout this process it is imperative that developers take account of and address site-specific risks, both to the safety of personnel and to the successful completion of a project.

The UXO threat is posed by the sizeable legacy of unexploded ordnance left behind on the seabed by two World Wars, years of munitions dumping and military training and testing. Several European offshore wind projects have experienced costly delays relating to the mismanagement of UXO risks especially during construction, highlighting the need for a more robust and coordinated approach to the assessment and mitigation of this risk.

Furthermore, as projects move from the early construction phases into a prolonged period of operations and maintenance (O&M) activity, management teams must be made aware of the on-going threat posed by the prospective migration of seabed UXO throughout the lifecycle of a project. The importance of responsible management is further underlined by a range of European and national legislation that makes project directors fully accountable should a UXO-related incident occur on site.

With a management team consisting entirely of ex Royal Navy Bomb Disposal personnel, Fellows are uniquely placed to assist with the unique demands of offshore ordnance risk management. 

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