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To safely complete the North Fork Nooksack Line Lowering in dry conditions, Barnard implemented a massive dewatering system of 45-ft.-deep wells that pumped 30,000+ gallons per minute.

When the migration of the North Fork Nooksack River in Western Washington put a 30-in.-dia. natural gas pipeline at risk of exposure, Northwest Pipeline, Inc. contracted with Barnard to lower the endangered span. The pipeline crossed the river at a depth of 24 ft. below the ground surface and transitioned to a depth of 4 ft. just 200 ft. from the riverbank. Barnard lowered approximately 1,700 ft. of pipeline to the river crossing elevation and also performed removal, slurry filling, and nitrogen inerting along a previously retired 26.-in.-dia. pipeline. Construction occurred in sensitive riparian habitat that required waterbody and wetland restoration.


Location: Deming, Washington

Owner & Engineer: Northwest Pipeline, Inc.

Contract Type: Fixed Lump Sum (competitive bid) and Fixed Unit Price (competitive bid)

Status: Completed


  • 54,000 CY of material excavated and replaced
  • 1,550 ft. of pipeline removed
  • 1,900 ft. of slurry fill placed
  • Construction in sensitive riparian habitat
  • Strict oversight by numerous regulatory agencies, including the Federal Energy Regulatory Commission, U.S. Fish & Wildlife Services, U.S. Army Corps of Engineers, and Environmental Protection Agency

1,700 LF of 30-in.-dia. pipeline lowered

122 dewatering wells

3.5 miles of nitrogen inerting on previously retired pipeline

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