For some state employees, going back to work on Monday stinks — literally, in the case of those who work in the Manuel Lujan Sr. building at 1200 S. St. Francis Drive.

And it wasn't just this Monday that a rotten smell, blamed on aging sewer pipes, greeted employees at the office. One source said the stench had been wafting through the building for three weeks.

"As far as their complaints are concerned, yes, this has been going on for a while, and I hope they can understand that we're dealing with old infrastructure," General Services Department spokesman Alex Cuellar said in an e-mail.

"If your sewer line blows at your home, it's not going to be very pleasant until it's repaired, and in an older building such as this (built in 1974), we're talking about lots of pipes, and it can sometimes take time to trace a problem to its source and effect a repair," he wrote.

The General Services Department is doing a general infrastructure assessment of the building and has found problems including cracks in the sewer lines in the walls, Cuellar said.

A plumbing contractor had to be called in first thing Monday morning after the latest problems developed, he said.

The problems with the building — a broken air conditioner among them — have sent state employees home twice in the past two weeks, said Taxation and Revenue Department Secretary Rick Homans. That department is the building's main tenant.

"This is clearly an old building that wasn't intended as an office building," Homans said. "It was to house a mainframe computer decades ago, and then was converted. I'd say it's probably on its last legs."

A couple hundred people went home early on the day the air conditioner broke, Homans said. And about 50 went home the time the smell became unbearable.

About 325 people work in the building, where state revenue is processed.

"This is not a good situation when you are dealing with broken air conditioning and sewer smells in the middle of summer in an office environment," Homans said. "There's no way you can look at that picture and find anything acceptable about it."

Homans said it will cost an estimated $7 million to $10 million to upgrade the heating, cooling and plumbing systems in the building.

The 76,262-square-foot building on St. Francis Drive is 35 years old, and its entire mechanical system, including HVAC and plumbing, is scheduled to be renovated this fiscal year.

The process could mean major disruptions for employees, who might have to be moved to other offices in shifts, Homans said.

Homans also said the building's air-conditioning chiller is so large that it will be impossible to remove.

"It will probably just live in the basement," he said.

Cuellar said the General Services Department is doing everything it can to get the problem fixed.

"We really do appreciate employees' and customers' patience, and our contractors are working as fast as they can," he said.

Contact Kate Nash at 986-3036 or knash@sfnewmexican.com. Read her blog at www.greenchilechatter.com.