THE PLANT WAS SHUT DOWN @ 4 AM FOR HOLIDAY WEEKEND. AN EE RETURNED ABOUT 10:30 AM TO USE WAREHOUSE TO WORK ON HIS VEHICLE & SMELLED SMOKE. HE TRACED THE SMOLDERING LIGNITE TO THE DUST COLLECTO R & WATERED DOWN THE HOT SPOT & THE FLOOR BENEATH IT. VARIOUS COMMUNICATIONS WERE MADE & THE FIRE DEPT HOSED DOWN THE COLLECTOR FROM 1:30-2:00 PM. CAUSE OF FIRE HAS NOT BEEN DETERMINED. MSHA