Tetra Tech Unexploded Ordnance (UXO) assessment and site support enabled the survey, for a UK oil field, to proceed safely and on-time.
Before conducting an onshore seismic survey on the Wytch Farm Oil Field in Dorset, UK, Rees Onshore Seismic, on behalf of Perenco UK Ltd., needed to be confident that the site was free of UXO (Unexploded Ordnance). UXO poses an extreme threat to life and equipment. Tetra Tech provided desktop studies that enabled the seismic team to begin work safely in reduced-risk areas. Onsite UXO specialists then worked to release the land in the higher risk areas safely.
During the Second World War, Dorset was transformed into a large holding area for troops prior to operations in Europe. Airfields, camps, storage, and training areas were quickly constructed, but due to circumstances, the exact placement of these facilities was not well documented.
Another area of significant concern for the survey was the Ministry of Defence (MOD) Armoured Fighting Vehicle Gunnery Range. The British military has been actively using this range for over 100 years, and the timeframe to work in this area was short.
To get the survey up and running safely and quickly, the UXO specialists performed a series of detailed desktop studies and used a ‘micro-site’ research technique to determine areas of very low risk. The seismic survey began safely, in these areas, without any onsite UXO support required.
Tetra Tech proceeded simultaneously with a series of Wide Area Assessments to identify additional low-risk regions of the survey site, allowing the survey to continue moving forward safely.
Once the client began work in areas deemed to contain an elevated likelihood of encountering UXO, Tetra Tech provided site support to ensure the project timeframe was not affected.
Benefits
- 613 seismic source points cleared
- 757 seismic receiver points cleared
- 32 items of expended ordnance investigated, deemed safe, and removed
The UXO project coordinators worked closely with the MOD to identify a narrow window of opportunity that would allow the 3D Seismic Survey to take place during the short summer stand-down period when the range was not in operation. To complete the survey on the gunnery range in time, Tetra Tech pulled together a team of UXO specialists dedicated to on-time delivery – even if that required working in shifts 24 hours a day. Tetra Tech established a Safe System of Works for the set-out and collection of seismic receiver nodes and source points. It included UXO awareness training and reference guides. To ensure safety on the range, each survey team was always led by a UXO specialist. And as most of the survey team spoke limited English, all training material was translated into Polish, and interpreters were used throughout the project.
By identifying low-risk areas to be surveyed, through the combination of micro-site research and Wide Area Assessments, onsite UXO support was used only where necessary. When needed, project coordinators deployed a team of UXO specialists who were both flexible and proactive, which kept the project on track. Tetra Tech delivered the UXO support required, and the survey project proceeded safely and on-time.
At a glance
Client
Rees Onshore Seismic
Completion date
2019
Location
Dorset, UK
Services
Crew personnel classroom training and on-site practical instruction, detailed desktop study, UXO site support, wide area assessment
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The project featured in this article was undertaken by RPS, A Tetra Tech Company and originally published on RPSgroup.com. In March 2026 RPS rebranded to Tetra Tech.
