N.Y.C. Admin. Code § 24-258: § 24-258 The board.

(a) The board shall be convened by the chairperson or in the chairperson's absence the assistant commissioner of environmental compliance, or at the request of any three members thereof.

(b) If a member of the board has presided over the initial hearing, he or she shall not be disqualified from reviewing the hearing.

(c) Five members of the board, at least two of who shall not be city officials, shall constitute a quorum.