A stream of raw sewage and rain water flooded the basement of Grays Hall last month, prompting a federal Labor Department inquiry into lingering sanitation concerns University officials said yesterday.

OSHA is pursuing an anonymous complaint about the site, which houses offices used by the Linguistic Department according to a September 25 letter from the Occupational Safety and Health Administration (OSHA) obtained by The Crimson.

The letter addressed to Dean of the Faculty A. Michael Spence states that employees are "being exposed to raw sewage from bathroom drains backing up and rain water leaking into basement creating mildew and mold growth."

But clean-up work in the offices is mostly completed said Michael N. Lichten, director of physical operations for the Faculty of Arts and Sciences.

Lichten said the spill--caused by a rainstorm in August that flooded Cambridge sewage and water lines--spread from a basement bathroom, leaving a small pool of sewage about 25 feet in diameter in a hallway and two offices.

While the basement was pumped out, vacuumed and deodorized immediately the carpet remained damp for about two weeks, Lichten said.

"Being a basement, it's taken somewhat of a time period for the carpeting to dry out," he said.

Late last week, however, Lichten said he received a call from Linguistics Chair Calvert Watkins complaining that the staff remained concerned about the spread of bacteria, mold or spores.

Watkins could not be reached for comment yesterday, and a receptionist referred all calls to the department to him.

But Lichten said that in response to the department chair's inquiry the University contracted workers to disinfect and deodorize the carpet. Inspectors from the University Environmental Health and Safety Office also conducted tests on the site but found no contaminants he added.

Lichten said he had not seen the letter from OSHA saying he received a call about it from Spence just this week.

"We're acting very properly here, I feel we're getting the mess cleaned up," Lichten said. But he said he understood employees concerns over hygiene.

"When people see raw sewage spill out of a pipe or toilet on their floor or carpet, it takes a lot of convincing to [let them know it is] cleaned up afterward," he said.

OSHA officials in Boston said they will not inspect the site and have turned the matter over to University personnel.

"We didn't feel we needed to make an inspection," said John V. DiRienzo, an OSHA safety complaints officer."It is probably something that has to do withdrains backing up in bathrooms. It should behandled by University maintenance."

Lichten said he had "no idea what soever" ofclean-up costs because a separate office takescare of them but he estimated that total damagesto dozens of sites in FAS buildings from the floodcould easily reach $20,000 or $30,000