Guyed towers, lattice towers, utility towers and monopoles in existence at the time of adoption of this bylaw may be reconstructed, altered, extended or replaced on the same site by special permit, provided that the Zoning Board of Appeals finds that such reconstruction, alteration, extension or replacement will not be substantially more detrimental to the neighborhood and/or the Town than the existing structure. In making such a determination, the ZBA shall consider whether the proposed reconstruction, alteration, extension or replacement will create public benefits such as opportunities for co-location, improvements in public safety and/or reduction in visual and environmental impacts. No reconstruction, alteration, extension or replacement shall exceed the height of the existing facility by more than 20 feet not to exceed the 150 feet permitted in § 240-13.3C(4).