The Navy already spent millions cleaning the ship because they were originally going to sink it as an artificial reef. After protests about the cost and continuing threat of toxic pollution coming from the ship the Navy abandoned those plans and sold it for recycling. Plans to “clean” and then sink three additional carriers were also scrapped.

BAN’s calls to the Navy to end its plans to sink the carrier began in 2008, following the Navy’s report to Congress in which the military branch clarified its intent to sink the ship as an artificial reef. By July 2009, the Navy had already spent $6.4 million removing asbestos from the vessel in preparation for ship scuttling.

BAN last year published a report, “Jobs and Dollars Overboard: The Economic Case against Dumping U.S. Naval Vessels at Sea,” which calls the Navy’s SINKEX program a significant waste of taxpayer dollars.
Link

I even saw a T.V. show (on Discovery maybe?) that went into the efforts to clean the Forrestal in preparation for its sinking as an attraction for divers.