Ken Glass, Oak Ridge Public Works environmental compliance officer, said levels of technetium 99 in the wastewater system in west Oak Ridge are dropping, but it’s not clear how long UCOR might have to ship sludge from the Rarity Ridge Wastewater Treatment Plant to an out-of-state landfill. Above, Glass stands near a chlorine contact tank at the treatment plant on Monday, Jan. 4, 2016. (Photo by John Huotari/Oak Ridge Today)

Note: This story was last updated at 9:55 a.m.

The radioactive nuclide that was first detected in the city’s wastewater lines more than two years ago near the demolition project at the former K-25 Building doesn’t affect drinking water, and it’s not believed to pose any threat to residents or municipal employees, officials said this month.

The levels of the radionuclide, technetium 99, are dropping at several measuring spots in the sewer system in west Oak Ridge, but it’s not clear how long UCOR, the federal government’s cleanup contractor, might have to ship sludge from the Rarity Ridge Wastewater Treatment Plant to an out-of-state landfill.

Officials said UCOR has already hauled away about 80,000 gallons of sludge using a 5,000-gallon tanker truck about once every one or two months since 2014. The sludge, which is about 3 percent to 4 percent solid, comes from a part of the plant known as a digester, and the shipments vary depending upon how much is processed at the plant each month.

Officials don’t know yet when the shipments might end. The sludge is now being taken to the Perma-Fix Northwest treatment facility in Richland, Washington. The last shipment was this month. [Read more…]