Section 4-113. Power to exchange lands no longer used for public purpose

The
  board  of  estimate  is  authorized  by  a  three-fourths  vote upon the
  application of any agency of the city to whose use any lands of the city
  have been assigned and upon the determination of such  board  that  such
  real  property  of the city as shall be specified in such application is
  no longer needed for departmental or public purposes, to convey any such
  land, with  or  without  the  improvements  thereon,  and,  in  exchange
  therefor,  the  mayor  is  authorized  to acquire other land of equal or
  greater value of private owners lying within the same borough;  provided
  that  the  mayor  shall  determine that such lands of private owners are
  needed for a public purpose. To determine the value of the land  of  the
  city,  and  of  the  land to be exchanged therefor, the board shall have
  such property of the city and the mayor shall have the property  of  the
  owners  duly appraised by three discreet and disinterested appraisers to
  be appointed by such board  and  the  mayor.  The  appraisers  shall  be
  residents  of  the  borough  in  which such lands are situated, and such
  appraisal shall be made within three months prior to the  date  of  such
  exchange.  The  corporation  counsel,  as  directed by a resolution duly
  adopted and certified by the board and by  order  of  the  mayor,  shall
  approve  the  form of all legal instruments necessary on the part of the
  city to effect such exchange in law, and the board and the  mayor  shall
  designate  and  authorize  the proper officer to execute and deliver any
  and all legal instruments necessary to  effectuate  such  exchange.  The
  land  so  acquired  by  the  exchange  shall  be  assigned to the agency
  requiring the use of the same upon proper appplication therefor.