A Special Town Meeting is being held in New Fairfield tonight about the proposed blight ordinance. The meeting is at 7pm in the Community Room.   Feedback received from a public hearing was incorporated into the final proposal.  A portion was taken out that the Director of Social Services would no longer be part of  a Blight Prevention Board.  A resident, appointed by the First Selectman, would be a member of the Board.  Any farm with a current agricultural sales tax exemption permit from the state Department of Revenue Services, would be exempt from the ordnance.  The amount of missing siding on a house was increased from 10 to 25-percent.  Another change is that it would apply to inoperable motor vehicles, rather than abandoned cars.  The Board approved the draft by a 2 to 1 vote.