Parties in the federal court case demanding better protection for Hanford workers from chemical vapors have asked for another trial delay.
It is the fifth delay requested by plaintiffs and defendants in the case this year as they continue to try to reach a settlement out of court.
The parties met for mediation Sept. 18-19 but did not reach an agreement.
They are asking U.S. Judge Thomas Rice to postpone the trial from July 2018 to Aug. 29, 2018. Trial preparation deadlines that start next month also would be delayed if the request is granted.
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The parties agreed in January to pursue mediation, with the trial then set for October 2017.
The state of Washington, Hanford Challenge and union Local 598 sued the Department of Energy and its tank farm contractor, Washington River Protection Solutions, in September 2015.
The state has argued that workers have been sickened for decades at Hanford from inhaling chemical vapors associated with waste held in underground tanks. Hanford Challenge said that some workers have developed serious respiratory and neurological illnesses from chemical exposure.
Reports of possible chemical exposures have significantly dropped since the tank farm contractor began requiring workers to wear supplied air respirators for most work within the tank farms.