CLAREMORE, Oklahoma - For the third time in about a year, a Claremore fire station has closed down.

The first time was a hazmat issue. The second time was mold.

Now, Claremore firefighters say the smell was so bad inside the station, they couldn't even work there.

The firefighters are back at station three, after sewage gas leaked in the station.

“Over the last few weeks, our personnel started to notice a sewer odor in the building,” said Chief Sean Douglas. “It came on pretty sudden on a Friday afternoon."

The smell was so strong, firefighters moved to station one.

Chief Douglas says plumbers have found multiple possible sources of the leak, but the main one appears to be an abandoned sewer vent pipe.

"Years ago when they put the generator in, they damaged the pipe somehow and they did a temporary patch," explained Douglas.

That's now been capped off and smell is gone, but firefighters say it's not the first time the smell has disappeared only to come back again.

"It's been a sporadic deal,” stated the chief. “We are trying to address it and get it taken care of."

Last year, we told you about an unknown substance found in the ditch by the station, which forced firefighters out.

During that time, mold was found inside, and remediation took six months.

At this time, it doesn't smell in the station, but if that smell does come back, there's one more advanced test that can be run to get to the bottom of it.

The chief says the sewage pipe may have been damaged during construction to get rid of the mold.