When the international engineering and construction Group, Costain, had to inspect the upstream end of a scour pipe at Scar House Reservoir in Yorkshire they took the innovative and cost saving decision to hire a VideoRay Remotely Operated Underwater Vehicle (ROV) complete with BlueView sonar attachment from Atlantas Marine, rather than using conventional divers.
The scour pipe passed through the base of a gravity dam, at a depth of 47m below top water level. The altitude of the site and depth of the dive would limit 'bottom time' to 5 minutes and the safe system of work demanded at least lifting equipment and a decompression chamber. The price quoted for completion of the survey using divers was in excess of £15K.
The ROV was launched easily from the crest of the dam by one operative and flown to the bottom of the dam to complete the inspection. Live video and sonar images were fed back to a screen on the surface and recorded for future reference. Said Tom Lewis from Costain: "The quality of the images obtained was impressive given the low light conditions at this depth. The sonar capability gave further useful detail beyond the visible spectrum. Without a limitation on bottom time, it was also possible to inspect other elements of the dam, adding value to our client"
Atlantas Marine with the VideoRay Pro 3 GTO ROV and BlueView multibeam sonar not only helped Costain to locate and inspect the scour pipe on the valve tower, but also removed all health and safety risks associated with diving and saved them money. By engaging Atlantas Marine's services the cost incurred was less than 10% of the best price obtained for completing the survey by diving, and they also gained other useful information as a bonus!