Commercial sewer and drain cleaning. Rodded out the floor sink in the southwest corner of the kitchen. It was only the sink that backed up in the whole kitchen. It should have only been a 20’ run to open to the grease trap, but I think the line runs clear to the other end of the kitchen and ties back in to the grease line there, and comes all the way back to the grease trap. Rodded out approximately 50 to 60 ‘ to open the line. The grease trap was not full. Blockage was in the line. I continued to run hot water for 20 minutes after opening to try and melt the grease into the trap. Everything is operating as it should.