Issuance of permits for buildings or structures. 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 as shown on the Official Map or
shown on a plat filed pursuant to this chapter before 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
or public drainageway, flood-control basin or public area reserved
pursuant to this section cannot yield a reasonable return to the owner
unless a building permit is granted, the Joint Land Use Planning Board,
acting as the Board of Adjustment may, in a specific case, by an affirmative
vote of a majority of the full authorized membership of the Board,
direct the issuance of a permit for a building or structure in the
bed of such mapped street, public drainageway, flood-control basin
public area reserved pursuant to this section, which will, as little
as practicable, increase the cost of opening such street or tend to
cause a minimum change to the Official Map, and the Board shall impose
reasonable requirements as a condition of granting the permit so as
to promote the health, morals, safety and general welfare of the public.