Such written agreement shall be filed within ten days from the date of its execution in the superior court for the judicial district in which the municipality executing such agreement is located. The clerk of such court shall forthwith refer such agreement to a state referee for approval as a fair and reasonable agreement. If the referee finds such agreement fair and reasonable he shall certify to the same and the clerk of the superior court for such judicial district shall annex such certificate to such agreement and only at that time shall the agreement be binding upon the parties executing such agreement. If such referee finds said agreement not fair and reasonable, the clerk of the superior court of such judicial district shall forthwith notify the parties and such agreement shall be null and void and of no effect.