Aerators, left, and ultraviolet treatment equipment are seen in the new Monteagle, Tenn., wastewater treatment plant.

Monteagle, Tenn., and state officials say damage estimates from a malfunction early Tuesday that flooded the building's basement at the town's new Wastewater Treatment Plant #3 won't be known until they find the cause.

Crews still are cleaning up and disinfecting as they hunt down what caused the basement of the new, multi-million-dollar sewer plant to flood four feet deep in sewage, Monteagle Mayor Marilyn Campbell Nixon said Friday.

Meanwhile, operators at the plant will keep treating incoming wastewater manually.

"It's the best it can be in this situation," Nixon said.

She said many of the electronics probably will have to be cleaned or, more likely, replaced before the plant can go back online, but there was no timeline on Friday.

"Hopefully, by Monday we'll have a better idea," she said.

Tennessee Department of Environment and Conservation spokeswoman Meg Lockhart said new sewer treatment plants have a typical "break-in" period when problems can crop up, but "the magnitude of this incident was considerably greater than what anyone would have expected."

Lockhart said that, while the exact cause is unknown, officials have determined the floor drains in the basement were not equipped with "backflow-preventer valves" and a sump pump operating in the basement could allow sewage to enter the basement under the right circumstances.

She said officials are investigating how those mechanisms failed, but plant operators were not at fault.

The plant's malfunction will have no impact on the 2005 moratorium that was lifted Aug. 7 with the opening of the new plant, Lockhart said.

She said the town of Monteagle has followed all of the requirements of its state permit for the new plant, officials immediately notified TDEC when they became aware of the problems and "they have been aggressive in addressing the problems they have been facing."