The approval of a petition and consequent amending of the Zoning Map by an overlay of the OPD District shall be issued upon and include as conditions thereto the building, site and operational plans for the development as approved as well as all other commitments offered or required with regard to project value, character or other factors pertinent to assuring that the project will be developed basically as presented on the official submittal plans and shall be mapped and recorded as provided for conditional uses under Article XXIII of this chapter. Such plans, however, need not necessarily be completely detailed at the time of overlay zoning, provided they are of sufficient detail to satisfy the Plan Commission and Common Council as to the general character, scope, and appearance of the proposed development. Such preliminary plan shall at least designate the pattern of proposed streets, the basic pattern of land use, and the size and arrangement of lots and illustrate a "typical" example of the development proposed. The approval of such preliminary plans shall be conditioned upon the subsequent submittal and approval of more specific and detailed plans as the development progresses.