That (a) whe the bonds are sold, the proceeds shall be deposited in a bank or trust company, or combined bank and trust company, except as hereinafter provided, pursuant to an escrow agreement approved by the attorney who approved the bonds; to the extent such deposit is not insured by the Federal Deposit Insurance Corporation it shall be secured in such manner as may be approved by the governing body. The bond proceeds may also be invested by the governing body in securities of the United States Government, and interest received from such investments shall be deposited in the aforesaid account.
(b) There shall be set aside into a "Parking Improvement (No.) Special Fund," hereinafter created, a sum from bond proceeds equal to all interest which will accrue on said bonds until the date when the first improvement assessments in connection therewith will become due and payable. The remainder may be disbursed from time to time in payment of costs of the improvement, except that payments on account of the construction contracts shall not exceed 90 per cent of the amount certified in writing by the engineer as having been earned for materials furnished and/or labor performed by a contractor, the retained 10 per cent to be disbursed only upon final acceptance of the finished work of such contractor. If, after completion, acceptance and payment of the work of all contractors, and the payment of all costs of the improvement, as herein defined, there shall remain an unexpended balance in the aforesaid bank account, such balance shall be transferred to the "Parking Improvement (No.) Special Fund" created and maintained in connection with the improvement. [As added by Priv. Acts 1970, ch. 276, § 8]