EE was dropping hammers off at our C-conationer located at Vulcan Pit in Knippa, TX. Pulled on a drill hammer to get it out of pickup and felt a pop in his back. He finished unloading the hammers and returned home. Rested that day and woke up the next day with back hurting. Tried to work on the 9th. Could only make 1/2 day before he went to doctor. No witness.