The intent of the special public interest overlay districts established in the following sections is to protect and enhance specific lands, uses and structures that, by virtue of their type or location, have characteristics that are distinct from the lands and structures outside such overlay districts. It is the intent of the board of commissioners to permit, insofar as possible, those uses and structures that would otherwise be permitted, provided that reasonable and necessary conditions are met that insure the protection and enhancement of said lands, uses and structures.