EE WAS WALKING NEAR 8000 DRAGLINE CARRYING TOOL BAG, STEPPED INTO SNOW-COVERED HOLE AND JARRE BACK. EE THOGUHT HE AGGRAVATED AN OLD INJUR-HAD BACK SURGERY ON 4-5-00. DID NOTHING MORE THAN REPO RT INCIDENT ON TIME CARD. BACK CONTINUED TO BOTHER EE. SAW DR. ON 12-26-00. FOUND HE HAD INJURED SAME AREA IN BACK AGAIN. EE SCHEDULED FOR BACK SURGERY ON 1-9-01. HAS MISSED NO WORK TO DATE.