1. There shall be filed with the petition a bond in an amount fixed and with sureties approved by the auditor, conditioned for the payment of all costs and expenses incurred in the proceedings in case the district is not finally established.2. No preliminary expense shall be incurred before the establishment of such proposed improvement district by the board in excess of the amount of bond filed by the petitioners. In case it is necessary to incur any expense in addition to the amount of such bond, the board of supervisors shall require the filing of an additional bond by the petitioners and shall not proceed with the preliminary survey or authorize any additional expense until the additional bond is filed in a sufficient amount to cover such expense.S13, §1989-a2; C24, 27, 31, 35, 39, §7430, 7431; C46, 50, 54, 58, 62, 66, 71, 73, 75, 77, 79, 81, §455.10, 455.11 89 Acts, ch 126, §2CS89, §468.9Referred to in §357.1A, 468.7