There is hereby created a Trustees’ Fund which shall be credited with all cash and securities deposited with the City Treasurer to protect the City against loss on account of certain obligations, and with all money and/or securities deposited with the City Treasurer pending information or accrual of time for its application.  The City Treasurer shall receive into such fund installment payments on municipal assessments against real property, including payments which are too small to be entered on the Lien Docket as a credit, it being provided that a payment shall be too small for such entry when it is less than one‑third of the total amount to be paid as shown on the open lien docket.  When such deposits in the Trustees’ Fund make an amount sufficient for entry the Treasurer shall make application thereof as a payment on such assessment, make a proper entry thereof in his books, and the Auditor shall make a proper entry thereof in his books.  The amounts deposited in the Trustees’ Fund shall be applied as provided in the receipt showing the terms of deposit.  The City Treasurer shall upon receiving a deposit under the provisions of this Section issue a receipt therefor, a copy of which shall be filed with the City Auditor and be credited to the Trustees’ Fund.  No cash or collateral securities shall be returned by the City Treasurer without written approval of the City Auditor.  The City Treasurer upon returning cash or collateral securities shall take a receipt from the depositor in duplicate, the original of which shall be filed with the City Auditor, who is hereby authorized to credit the City Treasurer with the amount of the receipt.  In cases where deposits are made by persons interested in local improvements no refund shall be made unless the contemplated improvement is not made or the owner of the property for account of which the deposit was made promptly pays or bonds the assessment.  If the improvement is made and the owner fails to pay and/or bond the assessment within twenty (20) days after its entry in the open lien docket the deposit shall be applied to a payment pro tanto of the assessment and the Treasurer and Auditor shall make proper book entries thereof.