I'd swear that I read it was a 70 year contract somewhere; DEIS, townhall meeting material, hidden secret documents that have made it to the surface? Also, aren't Zachary and Cintra owned by the same Spanish company?
As far as I know, H.B. Zachry is not Spanish-owned. Cintra, IIRC, is owned by Ferrovial SA, which is a Spanish company itself.