After bonds have been sold to finance the construction of an off-street parking facility, all payments of the assessments, principal and interest, for the facility and any other revenue pledged for the facility’s debt retirement, shall be deposited in a separate fund for bond redemption established to retire the bonded debt, principal and interest, issued for the construction of the facility. The funds deposited shall be invested and paid as provided by state law unless otherwise directed by ordinance of the council.