A steam pipe below a slab of concrete in Beinecke Plaza burst Tuesday morning, sending a geyser of concrete and debris nearly 80 feet into the air, Yale Fire Marshal Michael Johns said. No one was hurt in the blast, but nearby buildings were evacuated and the area was cordoned off for a little over an hour.

Johns said several Beinecke Rare Book and Manuscript Library employees heard a loud blast and called the fire marshal’s office shortly after 11 a.m. Patrons and staff evacuated the building. After arriving on the scene, Yale fire officials called both Yale and New Haven police and the New Haven Fire Department to check out the incident.

For a short time after the pipe burst, there was some concern as to whether the pipe was wrapped with asbestos, Johns said. Officials from Yale’s Office of Occupational Health and Safety were called in to run field tests on the material, which turned up negative for the presence of the carcinogen.

Civilians were allowed back into the building at 12:30 p.m.

Johns said Yale fire officials also alerted Berkeley College Master John Rogers, whose administrative assistant sent an advisory e-mail warning students to keep their doors shut to prevent dirt and dust from getting in.

Johns said this accident was most likely a result of rust and old age in the pipe — it was one of three installed in 1963 — rather than a careless installation. Roberto Meinrath, Yale’s director of utilities, said tests are currently being performed on the two intact pipes and the remaining length of the damaged one to determine the exact cause and location of the problem.

“All the pipes rust, but the problem is they don’t rust uniformly,” Meinrath said. “We’re going to see if we need to do a full replacement or if we can perform some piecemeal work to get the job done.”

Johns said the steam shower was anything but routine: “In 15 years this has been the most significant [such explosion] I’ve seen.”

–Brian Ginsberg