Marine UXO
Marine unexploded ordnance surveys, magnetic anomaly mapping and integrated seabed investigation.
Kordil supports offshore and nearshore projects with geophysical surveys to locate, map and assess targets that may require further investigation for unexploded ordnance (UXO). We combine marine magnetometer and gradiometer measurements with side-scan sonar, multibeam bathymetry, sub-bottom profiling and accurate positioning to build a clear picture of seabed conditions and potential buried ferrous objects.
Supporting offshore project planning
Historical military activity can leave unexploded munitions in marine environments. Construction, dredging, anchoring and seabed intervention therefore require a project-specific understanding of potential hazards. Geophysical investigation helps project teams identify areas and targets for specialist review before intrusive work begins.
Survey scope is agreed around the project footprint, available historical information, water depth, seabed conditions and intended works. Kordil's survey results support the wider UXO risk-management process; they do not replace a specialist risk assessment or constitute an explosive ordnance clearance certificate.
Integrated survey methods
- Marine magnetometry and gradiometry: mapping disturbances in the magnetic field associated with ferrous objects, including objects that may be buried beneath the seabed.
- Side-scan sonar: imaging exposed objects, debris, seabed textures and acoustic shadows to support target interpretation.
- Multibeam bathymetry: providing seabed topography and spatial context for survey planning, interpretation and subsequent investigation.
- Sub-bottom profiling survey: investigating sediment layers and buried acoustic features below the seabed, supporting burial-depth assessment and correlation with magnetic and sonar targets where the data allow.
- Positioning and data integration: bringing sensor observations into an agreed coordinate reference system, with navigation and sensor offsets considered during processing.
Combining these datasets helps distinguish isolated targets from wider debris fields and understand where magnetic and acoustic observations coincide. Detection performance depends on target properties, burial, sensor geometry, environmental conditions and survey coverage. No single sensor can identify every potential hazard.
Kordil’s proprietary Marine UXO survey data and integrated interpretation.
Magnetic profiles and mapped anomalies are correlated with side-scan sonar contacts. A correlated target is a finding for assessment, not confirmation that an object is UXO.
Sub-bottom profiling and burial-depth assessment
Sub-bottom profiling complements seabed imaging by investigating sediment layers and acoustic reflectors beneath the seabed. It can help assess whether a target or associated feature is buried and support estimation of its depth below the seabed where a clear response is resolved. Results are interpreted alongside magnetometry or gradiometry, side-scan sonar and multibeam data.
Kordil Subbottom Processing software supports the processing and interpretation of sub-bottom survey records for burial-depth detection and assessment. The workflow relates interpreted subsurface features to the seabed and the project survey data, supporting investigation of buried objects and engineering features. Burial-depth estimates depend on data resolution, sediment conditions, sound-velocity assumptions and the clarity of the target response; they are reported with relevant limitations.
Download the Kordil Subbottom Processing datasheet (PDF).
Diver support and handheld gradiometers
Survey maps and target registers support dive planning and the relocation of selected targets. Kordil can support diving teams with georeferenced target information, surface survey coordination and follow-up measurements. A diver-held handheld gradiometer, such as Marine Magnetics Argos, assists with localising ferrous anomalies during an authorised underwater investigation, including when visibility is poor or the object is not immediately visible.
Diver observations can be correlated with the original magnetic and acoustic findings and added to the target record. Any approach to a suspected munition must follow the project-specific UXO specialist's procedures. Geophysical survey and diver support are distinct from explosive ordnance disposal.
Port and harbour inspections
Integrated surveys are also applicable to port and harbour inspections, including berths, approach channels, turning basins, quay surroundings and dredging footprints. Multibeam bathymetry maps seabed levels and morphology; side-scan sonar images exposed objects; magnetometry or gradiometry identifies ferrous anomalies; and sub-bottom profiling investigates buried features where conditions permit.
Kordil Subbottom Processing contributes to interpreting subsurface records and assessing burial depth in these inspection programmes. Combined results support maintenance planning, dredging preparation, assessment of seabed obstructions and selection of targets for further inspection. Existing harbour infrastructure can influence magnetic measurements, so interpretation takes account of the local setting and available asset information.
From acquisition to a reviewable target register
Our work covers survey preparation, field data acquisition, processing, quality control and interpretation. Survey coverage, navigation quality, noise and data gaps are reviewed so that limitations remain visible in the final assessment. Targets are assigned consistent identifiers and correlated across the available datasets.
The interpretation records what the data show and where uncertainty remains. Magnetic anomalies may also originate from cables, scrap metal, wreckage or other infrastructure. Acoustic appearance alone cannot establish whether an object contains explosives. Where required, the findings are passed to competent UXO specialists for further assessment and an authorised investigation plan.
Typical project applications
- Offshore cable and pipeline routes and landfall approaches
- Port development, harbour works and dredging areas
- Offshore wind and other marine energy developments
- Foundation, piling, drilling and anchoring footprints
- Pre-construction debris surveys and follow-up target relocation
Survey deliverables
Deliverables are agreed to suit the client's engineering and GIS workflow and may include georeferenced anomaly maps, side-scan sonar mosaics, bathymetric context, survey coverage plots and a target register. The register can include target coordinates, supporting imagery, magnetic observations, interpretation notes and recommended priorities for specialist review. A technical report documents the equipment, methods, processing, quality checks and survey limitations.
Discuss your Marine UXO survey
Send us the project location, survey boundary or route, water depths, proposed seabed activities and any available historical or geophysical information. We can help define the survey scope, suitable sensor combination and reporting requirements.
