THE INJURED EMPLOYEE WAS ATTEMPTING TO FUEL THE MAIN WATER PUMP. HE STEPPED UP ON THE LEFT REAR TIRE OF THE TRAILER THAT THE PUMP IS MOUNTED ON, TO REACH THE FUEL TANK. THE TIRE WAS WET FROM D EW, HE SLIPPED AND FELL OFF OF THE TIRE, LANDING ON HIS BACK ONTO A MOUND OF SAND OVER A PIPE IN THE GROUND.