The Soylent System is a huge Solaris slaughterhouse plant that was first connected to Karellen's Lab before being moved to the ground. Erich Van Houten was one of the facility's superintendent, but he resigned out of guilt. In actuality, there are many Soylent System facilities, not just in Solaris, but also on the surface of the earth. However, it is very unlikely that the ones on the surface are public - it is likely that they are almost impossible or difficult to find, and may be underground.