Amending Title 14 of The Philadelphia Code, relating to "Zoning and Planning," by amending Chapter 14-1100, entitled "Institutional Development District," by amending certain provisions of the Institutional Development District concerning permitted uses, minimum district area, gross floor area and occupied area by placing additional limitations on those provisions for Institutional Development Districts located within a certain area of the City and by providing for exceptions from certain provisions of the Wissahickon Watershed regarding impervious ground cover limitations and construction on — Open Common Ground