USA: Railway Supply previously reported on the freight-safety standoff between Portland and Union Pacific over the fire-damaged Centennial Mills warehouse; the demolition itself finally began Monday, Aug. 17, with a controlled explosion rather than the crane work that had marked the site’s first week of preparation.

The fire-damaged Centennial Mills warehouse in Portland, Oregon, adjacent to Union Pacific tracks
The fire-damaged Centennial Mills warehouse in Portland, Oregon. Illustrative photo. Photo: City of Portland.

Contractors detonated the building’s rooftop water tower Monday afternoon, the first step in what officials warned would be an atypical demolition because the structure remains at risk of sudden collapse, according to the City of Portland. “This is a complex demolition. Because the building is at risk of collapse, the work requires specialized engineering, equipment, and demolition expertise to protect workers, adjacent infrastructure, the railroad, and the surrounding community,” said Eric Kutch, director of Portland Permitting and Development.

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The chemical the city named for the first time

Where earlier city statements referred generally to “hazardous materials,” Portland’s own emergency update now specifies that Union Pacific moved rail cars containing residual chlorine through the collapse zone on Aug. 12 — a departure, the city says, from the safety plan the railroad had previously shared. Union Pacific has said it suspended running loaded rail cars carrying toxic and poisonous inhalation hazards, but has not answered additional questions about the cars that passed through the area since. Nearby buildings were asked to shut off their HVAC systems Monday as a precaution against dust during the detonation.

Weeks, not days, before the area reopens

City officials estimate the full demolition could take two more weeks, meaning nearby closures — including Fields Park and a stretch of Northwest Naito Parkway — will likely remain in place well past the initial explosion. Tests at the site confirmed the presence of lead and asbestos, raising additional dust-safety concerns during teardown. The announcement does not specify a firm date for reopening the Seattle–Portland Amtrak Cascades corridor, which has been suspended since the Aug. 2 fire.

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