EE & ANOTHER WERE SANDBLASTING A 30,000 GL HORIZONTAL DIESEL TANK WHEN THE LTA OCCURRED. THE LADDER HE WAS USING WAS MOVED INSIDE THE DIKE & PROPPED UP AGAINST THE TANK. EE DID NOT WAIT FOR LA DDER TO BE SECURED. THE LADDER SLID OUT @ BOTTOM& STOPPED BY BASE. IMPACT THREW EE OF BUT LADDER STAYED UPRIGHT. HE FELL ON SIDE, BROKE ELBOW & PELVIS. HE HAD SURGERY & HAVING PHYSICAL THERPY