I think I know the spot Duncan is talking about.  It was an eye sore for a long time and it's now a totally productive garden. 

China Creek Co-op did something very similar.  A slope right at the base of Vancouver Community College was once a live stream (which is still running underground) but became a landfill.  I think about 10 years ago the China Creek Housing Co-op turned the landfill into a garden.  Those who turnover their soil today still find reminants of it but it's an absolutely incredible garden area now.