At the Ngauranga Freezing Works, (a.k.a. abatoir, meatworks, slaughterhouse) which disappeared in the 1970s, and the only clue now to its existence is the former rail tunnel under the motorway to the main railway line which can be seen in the Google Streetview.
This establishment was noted for the red-stained water in the harbour where the waste was discharged -- which wouldn't be popular with today's environmental consciousness.
For more, see the book Wellington Transport Memories. (Russ Bidgood pic)