Northwest Pipeline has asked FERC for the green light to put in service the southern 15.5 miles of the final pipeline loop (Muddy Creek Loop) of its Rockies expansion project. The pipeline said it was unable at this time to seek operation for the entire 30-mile loop because testing had revealed a number of cracked welds on the line.

All of Northwest’s $154 million Rockies expansion project, with the exception of the Muddy Creek Loop, began service on Nov. 1. The entire project involves the addition of approximately 91 miles of pipeline looping on segments of Northwest Pipeline’s mainline and 24,924 horsepower of new compression in Wyoming and Idaho. The project was designed to expand the physical north-flow capacity and to replace existing north-flow displacement capacity on the pipeline [CP01-438].

Northwest isolated the Muddy Creek Loop into several segments after hydrostatic testing revealed a pressure loss on the 30-mile line. Further testing identified 42 cracked welds on the loop, the pipeline told FERC. Final repairs on the 15.5-mile segment of the loop are expected to be completed by Nov. 13, Northwest said.

Repairs and inspection of the remaining segments of the Muddy Creek Loop (total 14.5 miles) will be finished by the end of the month. At that time, Northwest said it will ask FERC for the authorization to place the rest of the loop in operation, completing the entire Rockies expansion program.

Northwest’s Rockies expansion will replace 175,000 Dth/d of required north-flow displacement volumes from the Muddy Creek compressor station in Wyoming to an interconnect with PG&E Gas Transmission-Northwest at Stanfield, OR. It also will replace all 191,000 Dth/d of north-flow displacement capacity from the Green River compressor to Muddy Creek.

The project is expected to reduce the need for Northwest to routinely invoke operational flow orders on its system. Northwest has had to rely heavily on displaced capacity over the years to move gas supplies northward to market areas in the Pacific Northwest due to the limited availability of northbound capacity on its system.

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