A U.S. Department of Energy contractor says radioactivity levels have dropped at an Oak Ridge sewage treatment plant in the past two years.
Levels of radioactivity at Rarity Ridge Wastewater Treatment Plant have fallen by 90 percent as 90,000 gallons of radioactive sludge were removed to a treatment facility in Washington state.
Spokeswoman Anne Smith of URS-CH2M Oak Ridge says the contractor recently completed its 18th shipment of radioactive sludge to the Washington state facility.
Radioactive technetium-99 infiltrated pipelines leading to the sewage plant during demolition activities at the former K-25 uranium-enrichment facility. The technetium in the sewer system was discovered in early 2014. Officials have said the radioactivity doesn't pose a threat to workers at the sewage treatment plant.