HANOVER — Two laboratory buildings at the Cold Regions Research and Engineering Laboratory were evacuated as a precautionary measure earlier this week after the accidental release of trichloroethylene vapor during renovation work at the Hanover facility, officials said on Friday.

An old pipeline at the main laboratory building that had carried the substance known as TCE decades ago was being removed, according to CRREL spokesman Bryan Armbrust. It had previously been drained of fluids but still had some “residual” TCE vapor that was released on Monday morning, Armbrust said.

“There were no fluids, just vapor,” he said.

The TCE levels were “reportedly below established federal health and safety standards,” CRREL said in a news release on Thursday, but the facility evacuated its two main lab buildings, affecting roughly 90 of the facility’s 240 employees, as a precaution.

Parts of the two labs remained vacant on Tuesday, but “full and normal operations” resumed on Wednesday, the release said. Armbrust said nobody was injured in the incident.

CRREL stopped using TCE, an industrial solvent that aided as a refrigerant for experiments in extreme cold, in 1987, but TCE vapor has long been a matter of concern at the lab on Route 10, across from the Richmond Middle School.

Thousands of gallons of chemicals were accidentally discharged at the site between 1960 and 1980, and the Army Corps of Engineers have been conducting a cleanup of the 28-acre site. Officials are monitoring an underground vapor plume of TCE, which is a carcinogen, especially over concerns it was moving toward neighboring sites.

Hanover Fire Chief Martin McMillan, who sits on a “restoration advisory board” created by the Army Corps of Engineers to monitor the CRREL cleanup, said federal officials are doing a “great job” on the cleanup and that the accidental release of TCE vapor on Monday did not cross a threshold that would have required a response by the fire department.

“I’m very familiar with the monitoring they are doing over there,” McMillan said Friday. “There was no need for us to respond to that situation over there because it was not an active spill.”

Minutes from the restoration advisory board meeting in January indicated that the most recent round of sampling for TCE vapor at the Richmond Middle School “yielded no detections.”

Future work includes sampling of at least one well on the Norwich side of the Connecticut River, across from the CRREL site, according to the minutes.