No later than thirty days after satisfactory completion of any additional work or portion of any additional work by a contractor on a public works project, the state or municipality shall issue a change order to the contract for the full dollar amount of the work not in dispute between the state or municipality and the contractor. If the state or municipality does not issue such a change order within the thirty days, interest must accrue on the dollar amount of the additional work satisfactorily completed and not in dispute until a change order is issued. The state or municipality shall pay this interest at a rate of one percent per month. For the purposes of this section, additional work is work beyond the scope defined in the contract between the contractor and the state or municipality.