CANADA - Monitoring changing conditions

- survey of submerged pipelines for movement and coating damage ...

A pipeline in northern Canada was laid across a fast flowing river - over 1 mile (1600 metres) wide, with a max. depth of 50 ft (15 metres).

There had been indications of severe bottom scouring and the owners were worried about movement of the pipeline and possible coating damage.

The C-Scan survey was carried out in February, when the river was covered by ice and temperatures were down to -40oC. Readings were taken at 100 metre intervals and stakes driven into the ice at the precise ‘overhead’ positions. These were then tied in to existing survey markers on the bank and thus the amount of downstream ‘ bow’ determined. Depth readings were also recorded and found to be accurate to better than 5% at 10 metres. The line coating was found to be undamaged.

A total of 4 miles (6,500 metres) of submerged line was surveyed in extreme conditions in under 7 days.