(a) In order to hasten work, the board may borrow money at a rate of interest as provided for in a resolution of the commissioners, may issue negotiable bonds therefor, signed by the members of the board, and may pledge all assessments for the repayment thereof. It may also issue to the contractors who do the work its negotiable evidences of debt, bearing interest at such rate or rates as determined by the board.
(b) No bonds issued under the terms of this act shall run for more than thirty (30) years. All issues of bonds may be divided so that a portion thereof may mature each year as the assessments are collected, or they may all be made payable at the same time, with proper provision for a sinking fund.