In July of 2025, inspectors hired by the Nippon Dynawave Packaging Company to assess the condition of a tank at the firm's Washington State paper mill in Longview delivered some bad news. The tank contained "white liquor," a highly corrosive solution of sodium hydroxide (lye) and sodium sulfide used to break down wood pulp in the initial stages of papermaking. The inspection by Applied Technical Services LLC showed that the wall thickness of the tank had deteriorated in the lower portions below the minimum safe wall thickness, and the tank was in danger of collapsing. The inspector's report stated that the tank was "not fit for continued service unless corrected."
However, despite the urgency of the report, apparently no repairs were made to the tank, and it continued to be used until the following May 26. On that date, a digestor that used the tank's output was taken out of service, but white liquor continued to flow into the tank until it reached its capacity in excess of 900,000 gallons. Just to make clear what a lot of liquid that is, 900,000 gallons would fill a cube fifty feet (15 meters) high, long, and wide.
A little after 7 A. M. that day, a wall of the tank collapsed, sending most of that 900,000 gallons cascading through a parking lot, breaking down building walls, and flowing into meeting rooms where workers were already gathering for the day. A total of 11 people died in the accident, and several more workers and first responders were severely injured, suffering chemical burns.
The facts relating to the tank inspection were released as part of a preliminary report by the U. S. Chemical Safety Board, the national agency charged with investigating major accidents involving chemicals. The board's chairman, Steve Owens, stated "we are greatly concerned that the tank was not promptly removed from service or properly repaired after the clear findings in the inspection report."
And the findings were definitely clear. The Wikipedia page on the disaster reproduces a graph of average wall thickness versus height for the tank. At the "course" (basically a circumferential row of steel plates) that was at a height of between 7.5 and 15 feet, the calculated minimum safe thickness was 0.5 inches. But the measurements, presumably performed by some type of externally applied thickness-measuring device, showed that the average thickness was as low as 0.25 inches to 0.3 inches. Clearly, the tank, and the plant and its workers, were living on borrowed time.
News reports failed to reveal why the inspection was made, but clearly there were concerns about the tank's integrity that inspired it. What appears to be inexcusable is the fact that the plant's management did nothing about the critical safety issue discovered by the report until the tragedy occurred.
The plant is still out of service following the accident. Company officials reached for comment refused to comment on "individual findings or documents." But clearly, wrongful-death lawsuits filed against the company have received a boost from the Chemical Board findings.
Maintaining a safe environment in a complex chemical plant is a continual battle against thousands of hazards that are kept at bay only by constant vigilance, enforcement of rigid rules, and inspections such as the one that revealed the tank's too-thin walls. The physics behind the strength-of-materials engineering that sets limits for tank wall thinning has been known since the nineteenth century. And modern nondestructive inspection methods now provide safety engineers with abundant data that can flag hazardous conditions such as the one in Tank G at the Longview plant.
But all the instrumentation and safety manuals in the world will not prevent an accident if those in charge don't take the actions required to avert it. And in this case, for whatever reason, action was not taken.
If the tank was the main source of white liquor for the whole plant, repairing it would probably have meant shutting down the entire facility. Well-run plants schedule maintenance downtime into their operating calendar for just such repairs, but it is not known whether Nippon Dynawave had such a schedule or whether their policy was simply to run things until something major broke.
The facility is over seventy years old, according to Wikipedia. While age itself is not necessarily an indication of hazardous conditions, older plants can give rise to outmoded habits and customs that simply wouldn't be tolerated in newer facilities. The pressure to keep a facility running at all costs is always present when a large investment is at stake, and it is management's job to see that this pressure is resisted to the extent of calling for periodic maintenance shutdowns to allow for repairs such as were needed on the tank that collapsed.
It's significant that the failure occurred under conditions of maximum stress when the tank was filled with more than the usual amount of white liquor. This condition might not have occurred for months, but sooner or later something was going to give, and it was the unfortunate fate of the eleven workers who died to be there when it happened.
This accident is unusually simple in that only a couple of coincidental factors had to come together for it to happen: dangerous wall thinning and an unusually heavy load on the tank. It would also have been relatively simple to avoid: take the tank out of service and repair it before it busts. But for whatever reason, that was not done.
The firm operating the plant now faces months of losses from a shutdown following the accident and huge legal and regulatory problems as well. It's an old lesson, but one that can never be repeated enough: when something really dangerous is discovered in a facility, safety officials should have the power to do anything necessary up to and including calling for a plant-wide shutdown in order to address it. A management structure that doesn't permit this is just as dangerous as having a wall of a tank full of lye that's way too thin.
Sources: I referred to an AP report on the U. S. Chemical Board preliminary investigation at https://apnews.com/article/nippon-dynawave-longview-chemical-tank-rupture-washington-3da9aff673419848f5cc29e076baabeb and the Wikipedia article "2026 Longview, Washington paper mill chemical tank collapse."
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