Underwater tools protect the environment

The ingenious answer came from Global Diving and Salvage, which created a unique sampling system that is mounted on a Saab Seaeye Cougar XT ROV that can penetrate a sealed container and extract a sample without creating a leak point.

It came about from the US Coastguard’s need to determine if oil was still present aboard the SS Montebello, a tanker torpedoed in 1941 off the coast of California. Global fitted out the Cougar with a range of tools to perform 3D modelling, sonar inspection, thickness gauging, a backscatter investigation, the physical sampling of the ship’s fuel tanks and sediment sampling of the general area.

However, first Global had to clean off areas which had accumulated 70 years of debris using a wire wheel and barnacle buster on one of the Cougar’s manipulator arms.

A Tracerco neutron backscatter system was used to help determine the likelihood of oil in the wreck’s cargo holds. This backscatter tool is a non-invasive contents sensing device, something like an x-ray that emits neutron particles capable of passing through insulation material and carbon steel to determine the presence of content. It was mounted on a skid attached to the ROV and integrated with the vehicle’s control package. The ROV’s thrusters held the system steady whilst the operation was carried out.

Due to a 275m water depth and the potential risk of leakage of the tank contents, the development of Global’s unique sampling tool system to extract a sample was paramount to the success of the operation. The innovative feature meant that when the hole was drilled through the tank and a sample taken, the hole was then sealed, all in one leak-proof operation without fittings or valves. Happily, no oil was found and the wreck was declared not to be an environmental hazard.