Mui Wo Waste Incinerator (1st generation) [1958-c.1987]
Henri McKerr-Kastan let us know the location of this one via Annemarie Evans's Facebook page. He sent this map, which has the incinerator marked just below the circle that was the landing pad:
He says it's about where the swimming pool is today.
I think it's the smoking chimney shown at the left of this photo from 1983: