Guyed towers, lattice towers, utility towers and monopoles in existence at the time of adoption of this section may be reconstructed, altered, extended or replaced on the same site by special permit, provided that the SPGA finds that such reconstruction, alteration, extension or replacement will not be substantially more detrimental to the neighborhood and/or the City than the preexistent nonconforming structure. In making such a determination, the SPGA shall consider whether the proposed reconstruction, alteration, extension or replacement will create public benefits such as opportunities for collocation, improvements in public safety, and/or reduction in visual and environmental impacts.