In granting any variance or special exception, the Board may attach such reasonable conditions and safeguards, in addition to those expressed in this chapter, as it may deem necessary to implement the purposes of the Planning Code and Zoning Ordinance, which conditions and safeguards may relate to, but are not limited to, the harmonious design of buildings, planting and its maintenance as a sight or sound screen, lighting, noise, safety and the minimizing of noxious, offensive or hazardous elements.