Heavy rains to blame for Husky oil spill into Saskatchewan River
Ground movement was apparently to blame for Husky Energy's pipeline rupture that occurred in late July, spilling about 1,400 barrels of heavy oil and diluent into the North Saskatchewan River.
A geotechnical report prepared by Stantec blamed heavy rains, poor drainage and a weak clay foundation for ground movement that caused the pipe to buckle. A metallurgical survey of the pipeline ruled out corrosion or material defects as a possible cause.
The coated 16 inch pipe had a wall thickness of 7.9 mm, transporting about 273 m³/hr of heavy crude and diluent at 5,500 kPa. The line was pigged on a monthly basis and continuously treated with both corrosion inhibitors and biocide (to protect against microbiologically induced corrosion). The fracture was about 380 mm (or 15 inches) in length. An adjacent condensate line had also buckled but did not fail.
Husky called the failure “a sudden, one-time event in a section of the pipe that had buckled due to the force of ground movement.” There was a 10 hour time delay between when alarms were first sounded in the control room Wednesday evening and when the spill was discovered the next morning. The company says it is reviewing its leak detection procedures. The pipeline had been in operation since 1997 without incident. The pipe had undergone inspections five times in its history, the most recent in January 2015.
Husky has spent about $90 million cleaning up the shorelines, recovering an estimated 1,200 barrels of oil.
The company says its cleanup operations on the North Saskatchewan River are complete but monitoring activities will continue through the winter and into 2017. The province of Saskatchewan has yet to decide whether it will charge Husky for the spill.