Natural gas utilities in the U.S. Northwest are returning to normal operations after Enbridge Inc. restarted one of two natural gas transmission pipelines impacted by a rupture in British Columbia.

Puget Sound Energy Inc., Cascade Natural Gas Corp. and Avista Corp.'s Avista Utilities on Oct. 11 allowed its residential, business and industrial customers to resume normal gas usage as their supply recovers. The three utilities provide gas service to a combined 1.4 million customers, mostly in Washington and Oregon.

Enbridge brought back online a 30-inch-diameter pipeline that runs parallel to the 36-inch pipeline that ruptured Oct. 10 near Prince George, British Columbia. The shutdown of the lines after the event had prompted gas utilities that were supplied by the pipelines to conserve gas use.

The smaller line was found to be fit for service after an integrity assessment. The ruptured pipeline remains shuttered.

"Enbridge initiated our restart plan to safely and gradually bring the line's pressure up to approximately 80% of normal operating capacity," Enbridge said in an Oct. 11 update. "Natural gas is now safely flowing to our customers through the single line."

Fortis Inc.'s FortisBC Inc., which serves communities in British Columbia, said its gas supply will remain limited until the ruptured pipeline is repaired and placed back in service. FortisBC customers are still supposed to restrict gas use until further notice.

Enbridge is working with regulators to investigate the cause of the accident and replace the damaged pipeline segment. The company does not have a timetable yet for the segment's restoration and return to service.