(6) incur temporary debt in anticipation of receipt of funds; provided that a Horace Mann
school shall obtain the approval of the local
school committee and appropriate local appropriating authorities and officials relative to any proposed lien or encumbrance upon public
school property or relative to any financial obligation for which the local
school district shall become legally obligated; and provided further, that notwithstanding any general or special law to the contrary, the terms of repayment of any
charter school's debt shall not
exceed the duration of the
school's
charter without the approval of the board;