The Associated Press reported that a maintenance foreman saw smoke coming from the sealed wall, which had blocked off an area where a 2003 fire had occurred. The sealed areas are about four to five miles from the area being mined now.
The foreman sprayed the area with fire extinguishers, notified headquarters and was sent to a hospital for observation as a precaution, Thomas Hoffman, vice president of investor and public relations for CONSOL told Associated Press.
Mine officials shut off the mine's electricity, sprayed water through the gaps in the seal and used boreholes established during last year's firefighting efforts to pump nitrogen into the area to displace the oxygen and make the atmosphere inert to avoid combustion or a thermal event.
Hoffman said it did not appear that a fire had started in the sealed area.
Electricity was restored Tuesday and mine officials planned to pump additional nitrogen into the area and repair the seal. Plans to build a second seal as an extra safety measure were expected to be submitted to state and federal mine safety officials.
The mine was closed in February last year after a devastating fire and reopened for production early this year.
The sealed section, which Hoffman said is about four to five miles from the area being mined now, had been filled with nitrogen last year to smother the fire and prevent it from recurring.