That was no uninformed observer sipping water and chatting with Nick Garza and Doug White earlier this week as the two workmen prepared to descend into the tunnels beneath Langdon Street to repair steam pipes.
That was Tunnel Bob, and he was very knowledgeable about what Garza and White, who work for Dirty Ducts, of Fitchburg, were encountering below.
"He knew what he was talking about. He knew where this tunnel got smaller and where he had to crouch down," said Garza, describing how the denizens compared notes about the tunnels.
Tunnel Bob — really Robert Gruenenwald — is one of those campus apparitions that new students occasionally hear about, but few see. His 6-foot 6-inch frame notwithstanding, Gruenenwald, 55, has always seemed comfortable below the geographical and social radar.
More of a surprise than a threat, he has been making unauthorized patrols of the labyrinth of heating and cooling steam tunnels beneath campus since the 1970s. The tunnels themselves have criss-crossed below surface since the late 1800s.
University officials have made it clear that Gruenenwald is not welcome in the tunnels, citing and fining him three times this year and numerous times in the past for "unauthorized presence."
In an interview, Gruenenwald said he stopped on Langdon Wednesday to "check out" the workers after spotting the open vent. He said he still occasionally enters the tunnels these days, but "usually nobody sees me go in. I am very careful."
Tunnel access these days is barred by locks and chains, and the tunnels themselves present such dangers as asbestos exposure and potential burns, Garza said.
Wednesday was not Garza's first chat with Tunnel Bob.
"We were doing a night shift job about a year ago across campus and he just showed up in the tunnel," recalled Garza. "It was about midnight or 1 a.m."