What are UXO surveys?

UXO contamination refers to areas (on land or seabed) where unexploded munitions are suspected or confirmed to be present. These may result from historical conflicts, military testing ranges or munitions dumping at sea.

UXO clearance is the process of identifying, confirming and safely removing or neutralising explosive threats following detection in a UXO survey. It’s a critical safety step in offshore energy, telecommunications, dredging and marine infrastructure projects.

A UXO survey is a geophysical investigation carried out to detect and map potential UXO threats. Offshore and marine UXO surveys typically use a combination of magnetometers, gradiometers, sub-bottom profilers and side-scan sonar to scan the seabed and sub-seabed for anomalies. Data from these surveys is used to create a UXO survey map and inform risk assessments and clearance operations.

UXO clearance surveys are often required as part of environmental and geotechnical due diligence before:

• Offshore wind farm construction
• Marine cable and pipeline installation
• Port or harbour expansion
• Dredging operations
• Subsea infrastructure development

Common underwater UXO survey equipment includes:

• Magnetometers or gradiometers to detect magnetic anomalies from ferrous objects
• Side-scan sonar to produce high-resolution images of the seabed
• Sub-bottom profilers to identify buried objects
• Positioning systems like Pyxis INS + USBL for pinpoint accuracy
• Data acquisition and visualisation software for UXO mapping
• MiniPod submersible GNSS units for precise surface positioning of towed assets

applied acoustics’ Nexus 2 and Pyxis systems can be used in UXO survey offshore work in shallow and deep water. These systems offer features like Multi-Fire common interrogate capability, MiQ bi-directional data telemetry and Sigma 2 digital spread spectrum technology for maximum performance and positional stability.