A SUBSIDENCE OCCURRED AT THE 4020 DRIFT A SMALL HOLE OPENED UP IN THE FLOOR. THE HOLE WAS THREE FEET WIDE, FIVE FEET LONG AND FIVE FEET DEEP. THE AREA WAS FLAGGED OFF AND THE APPROPRIATE AGENC IES WERE NOTIFIED AND WE WERE TOLD IT WAS OK TO FILL IT WITH MUCK AND MOVE ON. NO OTHER PROBLEMS WERE ENCOUNTERED.