Work will resume in the group of Hanford tank farms where three of the recent chemical vapor incidents have occurred, but workers will wear respirators.
The respirators are a temporary measure while Hanford officials work on solutions to protect workers from vapors vented from the underground tanks, according to tank farms contractor Washington River Protection Solutions.
Since March 19, about 26 Hanford workers have been sent for medical evaluations after reporting a concern, smelling unusual odors or experiencing symptoms that could be caused by vapors from Hanford's underground waste tanks.
The tanks hold radioactive and hazardous chemical waste and a study of chemicals in the head space of the tanks identified more than 1,200. Filters remove radioactive particles but not chemicals in vapors released into the atmosphere.
Workers have reported symptoms such as coughing, a sore throat, a metallic taste in the mouth or headaches. But some previous tank farm workers have developed serious long-term medical problems, including neurological conditions.
All workers who recently have been evaluated at Kadlec Regional Medical Center or the Hanford medical provider have been cleared to return to work. The most recent case was reported Thursday when a Hanford worker who did not work for the tank farm contractor requested a medical evaluation related to an earlier vapor incident.
However, even though workers have been medically cleared to return to work, they will not be working in the tank farms until laboratory results from their medical evaluations are back, giving them more information about their health. A Hanford Atomic Metal Trades Council shop steward filed a stop work order for that restriction for those employees Wednesday.
Any employee may call a halt to work at Hanford if unsafe working conditions may be present.
A Hanford Atomic Metal Trades Council safety representative also filed a stop work order Monday for Mission Support Alliance workers who work at or near Hanford tank farms until workers could receive more information from Washington River Protection Solutions on vapor incidents.
Mission Support Alliance provides support services at the tank farms such as crane and rigging work, information technology, weed spraying and janitorial service. Scheduled work has been rearranged to allow workers to continue their jobs in other areas until the stop work order related to the tank farms is lifted.
The stop work order originally was for work in the tank farms and within 100 yards of a tank farm, but that has been modified to include only work within the tank farms by Mission Support Alliance employees, said Rae Weil, spokeswoman for the support services contractor.
Workers for Washington River Protection Solutions and Mission Support Alliance workers who might be assigned to work in or near the tank farms were given additional briefings Thursday about tank vapor incidents.
Respirators with cartridge filters are required in the complex of A Farm tanks, which include A, AX, AY and AZ tank farms and may be worn voluntarily in other tank farms. Employees in the A Farms reported symptoms and smells on March 19, 25 and 27.
Waste retrieved from single-shell tanks is being moved to a double-shell tank, which requires transfers of waste among some of the A Farm tanks.
Washington River Protection Solutions is looking at a wide range of possible improvements to better protect workers, including different personal protection equipment for workers to wear, additional monitoring equipment, and air sampling and engineering changes to tank farm equipment, said spokesman John Britton.
Washington River Protection Solutions also is reinstituting its Chemical Vapors Safety Team, which includes workers and management. Any worker can attend the team's meetings to give input and ask questions, Britton said.
The contractor also has named Doug Greenwell, a senior manager in the strategic planning and technology group, as the project manager to oversee vapor control improvements.
The source of tank vapors smelled at multiple tank farms remains under investigation. A pump pit that needed repair in the A Farms and liquid that had collected in old, contaminated equipment at the S Tank Farm have been identified as possible sources.
In addition, herbicides were being sprayed near the T Tank Farm and south of the U Tank Farm. Some workers near the U Tank Farm reported odors similar to herbicides or pesticides.
A third Hanford contractor, CH2M Hill Plateau Remediation Co., also had a stop work order issued Tuesday at the 200 West Pump and Treat Facility because of concerns about odors. But the odors were not related to the tank farm.
The plant uses biological processes similar to a municipal sewage treatment plant to treat contaminated groundwater. The process creates odors similar to ammonia. The stop work order was lifted Wednesday.
-- Annette Cary: 582-1533; email@example.com; Twitter: @HanfordNews