The Liberty District became a Conference for the 2013-2014 Season, but still comprises eight teams: Fairfax, Hayfield, Langley, Madison, McLean, Washington and Lee (W&L), and Yorktown. W&L, Hayfield and Yorktown moved over from the old National District. Jefferson, Marshall, and Stone Bridge moved out to join Region 5A. All schools have turf fields.
Here is a link to a Liberty District historical summary in Wikipedia.
Here are links to the athletics home page for some Liberty Conference schools.