For purposes of preserving the integrity of the Official Map, no permit shall be issued for any building or structure in the bed of any street or public drainageway, flood control basin or public area reserved pursuant to this Ordinance as shown on the official map, or as shown on a plat filed pursuant to this Ordinance before the adoption of the Official Map, except as provided herein. Whenever one or more parcels of land, upon which is located the bed of such mapped street, public drainageway, flood control basin or public area, cannot yield a reasonable return to the owner unless a building permit is granted, the Board may, in specific cases by an affirmative vote of a majority of the full authorized membership, direct the issuance of a permit for a building or structure in the bed of such mapped street, public drainageway, flood control basin or public area reserved herein which will as little as practicable increase the cost of opening such street, or which shall cause a minimum change in the Master Plan of streets.
The Board shall impose reasonable requirements as a condition of granting the permit so as to promote the health, safety and general welfare of the public.