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Brimstone undertook a UXO drone survey on 316 hectares of land for a solar park project in the UK, resulting in multiple UXO finds at a depth of 1 metre.

Brimstone was instructed by the client to survey 316 hectares of land for Cleve Hill Solar Park. Situated on the north Kent coast, the solar park will generate renewable power through photovoltaic panels, providing clean power to UK homes. At the time of surveying, this was the UK’s largest solar farm to date.

We deployed to the site to complete a UXO survey before any ground-intrusive work started. Due to the large nature of the site, we opted to use our state-of-the-art UAV to carry out the survey. This method allows for a faster rate of surveying, whilst maintaining data quality.

Cleve hill magnetometry map for faversham
Cleve hill magnetometry map

Completing the UXO survey

We were able to survey all 316 hectares in just 25 days. This would have taken over 150 days had we used the conventional push-cart method instead. Using the UAV was also deemed most suitable as the site had a high-water table which would have been unsuitable for our push-cart system, and we also had a responsibility to protect the local farmer’s crops.

Following the field collection, the data was sent back to Brimstone head office to be processed by our in house geophysics team. The data underwent several steps to reduce noise and improve the survey quality. In the later stages of data processing, we used a specialist computer model to look at the signals measured by the equipment. These signals were then compared against a bank of known UXO signals.

The data processing software presented us with a list of possible UXO targets. Estimations of depth and mass were made, and their locations were offered in coordinates accurate to 5 centimetres.

The UXO survey resulted in a total of 1606 targets being identified on the site as needing further investigation. We recommended an investigation of the targets, and that intrusive works should not continue or be started within the surveyed areas until this process had been completed.

Investigating the targets

Our explosives engineers attended the site to investigate the identified targets. This resulted in several 30mm projectiles being found at a depth of 1 metre. This highlights just how advanced our UAVs are, with the capability to detect small items of ordnance. The projectiles were removed from site and safely disposed of by our engineers.

Once the site had been thoroughly investigated, we were able to hand it back over to the client with an ALARP certificate, providing clearance to the surveyed area.

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