All proceedings to make any improvements, except emergency work or repairs requiring prompt attention and ordinary maintenance work, shall be begun by the adoption of a resolution by the Board declaring the necessity of such improvement, and stating the nature thereof, the estimate of the probable cost thereof, and the method of payment therefor. When payment is to be made by special tax bills or other evidence of special benefit assessments upon real property, or out of the Improvement Fund, as herein provided, reimbursed by collection of such assessments, the resolution shall state the proposed method of making such assessments to pay therefor. Any error or inaccuracy in the estimate of the probable cost of any such improvement as compared with the actual cost of the work shall not affect the validity of the proceedings or of any special benefit assessments made or special tax bills issued to pay for such work.

Upon the adoption of such resolution, the Board shall provide for and give adequate notice of a public hearing or public hearings in respect to all improvements to be paid for by special benefit assessments and all other improvements the total estimated cost of which shall be seven thousand five hundred dollars or more. Such public hearing or public hearings shall be held not less than ten nor more than thirty days after the adoption of such resolution, and all persons interested in such improvement shall be given an opportunity to be heard. After such hearing or hearings, the Board may determine that it is or is not in the public interest that such improvement or any part thereof be made.

After such hearing or hearings, if the Board determines to proceed with such improvement or any part thereof, the Executive Director shall cause plans and specifications for the proposed improvement to be prepared and submitted to the Board for approval. Such plans and specifications shall not limit the materials to be used to those of any particular producer or manufacturer, but shall be so arranged as to permit materials and processes to enter into competition.

When improvements are to be executed by contract, the District shall advertise for bids upon such notice and competition as may be prescribed by ordinance. All bids may be rejected. Except for such right of rejection, the Executive Director shall let the contract to the lowest responsible bidder and shall cause the contract to be formally executed by the contractor and by the Executive Director. Such contract, before it becomes binding and effective, shall be confirmed by ordinance adopted by the Board. All contracts for improvements which involve labor shall contain provisions that the prevailing rates of pay shall be paid to skilled and unskilled labor employed thereon and that there shall be no discrimination in the selection or employment of labor because of race, creed, or color; and such provisions shall be stated in the invitations for bids and shall be included in proposals or bids for the work.

All ordinances and contracts for improvements shall specify how the same are to be paid for. In case payment is to be made in whole or in part to the contractor in special tax bills or other evidence of special assessments, the District or subdistrict, as the case may be, shall in no event be liable for or on account of the work to be so paid for.

Upon the completion of any work, the payment for which is to be made by special tax bills, the Board shall by ordinance direct the issuance of said tax bills. When said ordinance is approved, the tax bills authorized thereby shall become a lien upon the property charged therewith upon filing with the Recorder of Deeds of the City of St. Louis or the Recorder of Deeds of St. Louis County, as the case may be; provided, however, there shall be no priority between special tax bills issued under the Plan, regardless of the date of such bills. They shall be payable to the party entitled thereto either at the office of the Secretary-Treasurer or at some bank or trust company in the City of St. Louis or St. Louis County at the option of the party so entitled. They shall be promptly registered in the offices of the Director of Finance and Secretary-Treasurer and delivered to the person entitled thereto. They shall be prima facie evidence of what they contain and of their own validity, and no mere informality or clerical mistake in any of the proceedings shall be a defense thereto. Such tax bills shall mature at such times and bear such rate of interest as may be prescribed by the ordinance directing the issuance thereof, and at the request of the property owner may be made payable in annual installments, not exceeding ten.

If any such special tax bill or special benefit assessment shall fail to be valid in whole or in part, or if for any cause, mistake, or inadvertence the amount assessed shall not be sufficient to pay the cost of such improvements, the Board shall be and is hereby authorized to cause such assessment to be reassessed and to enforce or authorize the enforcement of its collection.

All real property located within any benefit subdistrict established by the Board, whether publicly or privately owned, shall be liable for special benefit assessments made or special tax bills issued against such property. Any such assessment or tax bill shall constitute a personal obligation of the owner of such property as well as a lien against the property and may be collected by suit or other proceedings in any court of competent jurisdiction, and such assessment, tax bill, or judgment thereon, against public property shall be paid out of the general treasury of the public body, agency, corporation, or authority owning such property.

There is hereby created a fund to be known as the "Improvement Fund." Any moneys in said fund may be used to pay the cost of any improvement or to purchase any special tax bills issued for any improvement. Said fund may be established and maintained from any or all of the following sources:

1. Appropriations from the general funds of the District when available.
    

2. The proceeds from bond issues as provided in this Plan.
    

3. Collections of special benefit assessments or special tax bills, and any interest thereon, levied or issued for work or condemnation of land theretofore paid for out of said Improvement Fund.
    

4. The proceeds from the sale of special tax bills.
    

5. Any other source permitted by law.

Whenever the Board shall authorize the cost of any improvement or the purchase of any tax bills issued for any improvement to be paid out of the Improvement Fund, any special benefit assessment and interest thereon that may be levied and collected on account of such improvement or the proceeds from the collection of any such tax bills and interest thereon shall be credited to and be paid into said fund.

Upon recommendation of the Executive Director, the Board may, from time to time, by ordinance, make further provision, not inconsistent herewith, for special benefit assessments, the issuance of special tax bills, the collection thereof, and all matters incidental thereto.