THE EE WAS CLEANING UP & SHOVELING SALT AT THE BOTTOM OF THE 16' SHAFT. AS HE PICKED UP A SCOOP OF SALT WITH A SHOVEL HE TWISTED TO THE SIDE TO THROW THE SHOVEL LOAD & FELT PAIN IN HIS LOWER B ACK. AN MRI REVEALED A RUPTURED DISK IN HIS LOWER BACK. THE EE HAD PRE-SCHEDULED VACATION & HIS FIRST DAY LOST WAS 2-18-02.