Development within the Special Downtown District shall be exempt from the site plan review process; provided, however, that any construction of new structures within the Special Downtown District and/or any change to an existing structure or use within the Special Downtown District shall be subject to the site plan review process unless the Planning and Development Director, after consultation with the Director of Building, Zoning, and Licensing Services, the Commissioner of Public Works, the Fire Chief, the Police Chief, the Economic Development Director, and one representative from the Planning Board appointed by the Board Chair, certifies in writing to the Planning Board that such proposed construction or change will have no significant adverse impact on the Special Downtown District.