THE EE WAS LIFTING A STEEL INSPECTION PLATE LID OFF THE SCALE DECK TO PUMP WATER OUT FROM BELOW THE SCALE. HE TRIEDF TO LIFT THE LID & IT APEARED TO BE STUCK, SO HE JERKED HARDER TO OPEN THE L ID. WHEN DOING SO, HE FELT LIKE A RIPPING PAIN IN HIS LWOER BACK. HE IS NOW ON RESTRICTED WORK ACTIVITY, SO AS NOT TO AGGRAVATE HIS BACK CONDITION.