EMPLOYEE WENT DOWN IN PLANT TO FILL 5 GALLON BUCKETS WITH SLURRY AND TAKE TO THE LAB FOR TESTING. THE TAILGATE WOULD NOT OPEN SO HE LIFTED BUCKETS (70 LBS. APPROX) OF SLURRY OVER THE TOP OF TA ILGATE. HE FELT SOMETHING PULL IN HIS LOWER BACK. HE REPORTED IT ON THE SAME DAY AND FELT HE WOULD BE OKAY. HE REQUESTED TO GO TO THE DOCTOR ON 1/7/2004.