Where the Board finds that because of unusual circumstances of shape,
topography or other physical features of the proposed subdivision
or because of the nature of adjacent developments, extraordinary hardship
may result from strict compliance with this chapter, it may waive
certain requirements of this chapter so that substantial justice may
be done and the public interest secured, provided that no such waiver
shall be granted which will have the effect of nullifying the intent
and purpose of the Official Map, Zoning Ordinance, this chapter, or ordinances of the City.