Section 14. The department shall require the cities and towns, if within 3 years no construction has been started within the smart growth zoning district, to repay to the department all monies paid to the city or town under this chapter for said smart growth zone. The 3 years shall commence on the date of the payment of the zoning incentive payment for said smart growth zoning district. All monies returned to the department under this section shall be returned to the trust fund.