EE WAS CHARGING COOLANT IN #309 785 CAT ROCK TRUCK. AS HE WAS CLIMBING THE ACCESS LADDER HIS FOOT SLIPPED DUE TO OIL ON HIS BOOT & WET STEPS. HE FELL TO THE GROUND ONTO HIS BACK. THE EE CONTIN UED TO WORK AT HIS REGULAR JOB UNTIL 7/2/02. AT THIS TIME THE INCIDENT BECAME REPORTABLE DUE TO DAYS LOST.