THE EE WALKED OUT TO A D6 CATERPILLER BULLDOZER THAT HAD BECOME STUCK IN A TAILING AREA. AFTER ATTACHING HE CHAIN TO THE DOZER SO THAT IT COULD BE PULLED OUT +6 EE TRIED TO PULL HIS LEGS UP OU T OF +6 MID-THIGH DEEP TAILING. WHEN +6 EE TRIEDTO PULL HIS LEGS UP OUT OF THE TAILINGS HE FELT SOMETHING GIVE IN HIS BACK. EE HAD HAD PREVIOUS BACK INJURY.