Robotic inspection goes 1/2-K deep
ROV dove 570 metres to provide data for Peruvian hydropower project
In June, ASI Marine (ASI) personnel conducted a remotely operated vehicle (ROV) underwater inspection of the Cheves Hydropower Tunnel in Peru and ended up breaking the ASI company record for the deepest flooded tunnel inspection at 570 metres water depth. The Cheves Hydropower Project is being developed by Empresa de Generacion Electrica Cheves S.A., a wholly-owned subsidiary of Statkraft, a Norwegian electricity company.
The inspected tunnel is approximately 9.8 kilometres long, with a 35-square metre- area horseshoe profile. The purpose of the inspection was to collect data inside the newly-constructed tunnel for general assessment of rock stress incidences.
The tunnel was inspected internally with an ROV equipped with an array of sensors, including sonar and video, with the purpose of collecting full coverage data at the headworks and downstream to the powerhouse. The ROV was specifically designed by ASI for this type of work and is unique in the world, the company states. Data was required for the client to undertake an engineering structural assessment of the tunnel and detect significant anomalies such as deformations, major cracks, rubble, partial collapses and rock accumulations.
Guiness Book of World Records holder
ASI responded to the client’s request, mobilizing to the remote location. To perform the inspection, ASI utilized its ASI Mohican ROV, which afforded ASI a quick response time. This system was designed by ASI for tunnel inspections and is controlled and powered from the surface, which allows the ROV to navigate through tunnels for unlimited periods of time.
The inspection was successful and comprehensive. As a result of ASI’s quick turnaround time to complete the inspection, the client was able to proceed with its operations as planned and met its structural assessment deadline of summer 2015.
In 1999, ASI obtained (and still holds) the record in the Guinness Book of World Records for the “longest flooded tunnel survey by an ROV”. The 120-kilometre tunnel inspection was carried out in the Paijanne Tunnel in Finland, by the ASI Mataro.