2025 West Best Projects
Best Specialty Construction: Portland UG Network Willamette River Crossing
Portland UG Network Willamette River Crossing
Portland, Ore.
BEST PROJECT
Submitted by Michels Corp.
Owner PacifiCorp
Lead Design Firm AECOM
General Contractor Michels Pacific Energy Inc.
Trenchless Subcontractor Michels Corp.
As part of the EPA Harbor Superfund Mile 11 Cleanup initiative, the project team installed two parallel horizontal directional drills beneath Portland’s Willamette River. Scope called for replacing electric circuits originally laid on the riverbed and drilling to depths of 253 ft below river water level while navigating extreme urban constraints and complex geology.
Both drills crossed an existing 14-ft combined sewer outfall tunnel, with HDD-2 maintaining just 10.9 ft of clearance. Although industry norms specify 15-ft spacing for parallel drills, the team stacked bores vertically on the east side and positioned them just 5 ft apart on the west—threading through a narrow 29-ft easement between deep foundation piles.
Photo courtesy Michels Corp.
Geological challenges included contaminated fill, alluvium, cobbles and boulders extending 194 ft deep. The team employed innovative telescoping surface casing systems, combining pneumatic pipe ramming with retractable Direct Pipe technology to advance through unstable formations.
Photo courtesy Michels Corp.
During electrical duct conduit installation, which required a 500-ft bend radius, the entry point would overcome it, so the team developed an alternative that would mitigate the challenges. The 48-in. casing was cut prior to pipe-pull operations, and a 500-ft-radius overbend was welded to the end of the pipe string. This overbend was then pulled 24 linear ft below the surface, which accommodated the conduit radius requirements and reduced the excavation depth.
