If a site is free from significant ferrous contamination, a non-intrusive UXO magnetometer can be used to detect sub-surface ferrous anomalies. The detector is walked across the surface, so the ground isn’t disturbed making it a quick and effective way of surveying a site. This geophysical survey ‘non-intrusive’ approach is an effective, tested and reliable way of reducing risk.

The survey is undertaken by a specialist two-person team, either walkover or vehicle mounted. Data from each survey is logged and sent back to the geophysical team for processing and interpretation.

Our bespoke software allows a ‘false colour’ map of the site to be produced showing all ferrous anomalies. The data can be filtered to permit the modelling and selection of discreet targets. From this, a coordinated ‘target list’ is produced of anomalies which model similar to buried UXO. These are recommended for physical investigation.

Survey Suitability

The survey is very effective on ground which is relatively ‘clean’ and which does not contain too much background ferrous contamination. Areas with significant amounts of Made Ground such as ‘brownfield’ sites, which have either been previously developed or in-filled, are often too contaminated. Scrap and materials such as brick, clinker, rebar and reinforced concrete impede the accurate detection of potential UXO. Certain surface features such as chain link fencing, vehicles and pylons can also influence the data collection. The depth that the survey is effective to is also a consideration. If deep intrusive piles are planned, an Intrusive UXO Magnetometer Survey would always likely be more appropriate. Contact Us to find out more about this type of survey.

Parameters of Survey

In optimum ground conditions, the system can detect a buried 50kg German iron bomb at a depth of around 4m below ground level (the 50kg being the most commonly dropped high explosive bomb). In most circumstances, a non-intrusive survey would not be appropriate for clearance ahead of deep piled foundations. The survey is also effective at detecting shallower buried items of Land Service Ammunition (items such as grenades, mortars and projectiles).

  • A walkover survey can typically cover around 2ha per day
  • 1st Line Defence always recommend that a trial is undertaken at a site where the suitability of this type of survey is unclear

Target Investigation Phase

Once a non-intrusive survey has been completed, the data processed and a target list created, phase two is to undertake Target Investigation.

A UXO search team of bomb disposal experts is mobilised to locate and physically excavate/investigate a selection of targets. Any UXO-related anomalies are identified, classified and arrangements made for their safe removal/disposal. Specialist GPS equipment allows each mapped anomaly to be located as quickly as possible, with software providing our UXO engineers estimates of depth and mass.

Our search teams are highly trained in identification and hazard assessment; we will deploy as many clearance specialists as required to ensure a site is made safe as quickly and efficiently as possible.

Need some advice? Looking for a UXO expert?

Contact us if you need more information or have questions or queries. We are always happy to assist or advise where we can.

Call: 01992 245020 or Email: info@1stlinedefence.co.uk