EE WAS USING A 20 LB. JACKHAMMER WITH A SPADE BIT TO BREAK UP HARDENED CLINKER DUST SPILLED UNDER THE CEMENT CLINKER BINS & FEED CONVEYORS. HE LIFTED THE JACKHAMMER TO MOVE TO ANOTHER AREA & A S HE TOOK A STEP HIS FOOT SLIPPED ON THE RAIN WET SURFACE. THIS CAUSED HIS LEGS TO SPREAD AWKWARDLY AS HE TRIED TO STOP THE FALL. HE 1ST REPORTED TO SUPERVISOR 3/5/03. HERNIA REPAIR SET 3/28.