Section 5-346. Petition and notice

When the mayor shall have authorized the
  acquisition  of  additional  real  property  in  connection   with   any
  improvement, such additional real property shall be separately described
  in  the notice of application to condemn by the supreme court and in the
  petition presented on any such application, and separately shown on  the
  rule  map  attached  to  the  petition  and  on  the  damage  map in the
  proceeding, and such notice and petition shall state what  part  of  the
  real  property to be condemned is required for the improvement, and what
  part thereof  is  to  be  acquired  as  additional  real  property.  The
  acquisition  of  such  additional  real property, when authorized by the
  mayor, shall be deemed to be for a public purpose.