Section 57. The department may make advances of funds to local urban renewal agencies for up to seventy-five per cent of the estimated cost of surveys and plans and administrative expenses in preparation of projects which may be assisted under this section, and contracts for such advances of funds shall be made upon the condition that such advances of funds shall be repaid out of any moneys which become available to such agency for the undertaking of the project or projects under this section and section fifty-six.

The contracts referred to in section fifty-six shall provide for a state grant-in-aid equal to one half of the net cost of each project as determined by the department. Any such contract shall provide that no state grant-in-aid shall be made until the city or town shall have appropriated the funds required for the entire project cost excluding funds otherwise available.

From time to time the department shall certify to the state comptroller, and the state treasurer shall, within thirty days after such certification, pay to the several cities and towns, from any amounts appropriated therefor, the amounts due them in accordance with the provisions of section fifty-six and of the following clauses:—

(a) The total state grant-in-aid for any approved project shall not exceed one half of the net cost of project, including advances for surveys, planning and administrative expenses, with respect to which a contract under the provisions of section fifty-six and this section has been signed.

(b) The total amount of urban renewal assistance grants or urban revitalization and development grants to be paid under the provisions of this section shall be payable in twenty equal annual installments, except that the department may deduct any advances of funds for surveys and plans and administrative expenses from the commonwealth's share before determining said twenty equal annual installments, and may adjust the annual payment upon final determination of the net cost of each approved project.

(c) The total amount of urban renewal assistance grants to be paid under the provisions of this section shall not exceed one million dollars in any one fiscal year or a total of twenty million dollars in the aggregate, including amounts authorized by the department to be advanced for the estimated expenses as provided in the first paragraph.

(d) The total amount of urban revitalization and development grants to be paid under this section shall not exceed $4,400,000 in any 1 fiscal year or a total of $60,000,000 in the aggregate, including amounts authorized by the department to be advanced for the estimated expenses as provided in the first paragraph.