Who was Nina Ireland — and where did she get $48 million to give to UCSF?

UCSF can credit its largest-ever estate gift to road building and an unconventional woman with a familiar San Francisco story.
The estate of Nina Ireland, who died from emphysema at 67 in October, gave $48 million to the University of California, San Francisco, the school announced last week. UCSF’s press release, however, gave few clues about Ireland beyond the fact that she had made other substantial gifts to UCSF while alive. A quick Google search turned up a few more details: Ireland apparently grew up in Birmingham, Ala., attended secondary schools there and in Chatham, Va, and attended Rollins College in Florida.
But where did that money originate and how did someone of Ireland’s means avoid the limelight afforded well-heeled San Francisco names like Hambrecht, Hellman, de Young and Robertson?