It has been four months since Pinggu District Government signed the river repair contract, but the contract did not say 15 working days. What do you think is the way?

Just sue directly. If a lawsuit is filed, it is a civil complaint, and it is only necessary to fulfill the agreement. If the agreement is not fulfilled within the time limit, the bank shall pay interest for the same period. Finally, I suggest that you find a special lawyer to help you go through the proceedings, and you can find more parties, so that the lawyer's fees will not be shared equally.