Good question. She was talking about doing it on the 35 acres of city-owned land. Would love a map of that area
Here you go.
http://nycfcforums.com/index.php?threads/stadium-discussion.21/page-448#post-201163
City bought a lot of the land East of City Field. It's full of chop shops and roads with insane pot holes, and no real utility infrastructure, like plumbing running into the area. Half the shops have been purchased by the NYCEDC and are closed down (whole blocks are boarded up), the other half are still operating.
West of Citi Field is owned by Sterling Equities/Related, it's the parking lot that was planned for a mall, but shot down by the courts.