Section 100. Apportionment of city's expense of improvements

The common
  council may,  by  ordinance  approved  by  the  board  of  estimate  and
  apportionment,  fix  and  determine  the  amount  and  proportion of the
  expense which shall be borne by the city at large for opening, altering,
  grading, curbing or paving a  street,  or  for  constructing  therein  a
  public  sewer  which  is not less than two feet in diameter.  The amount
  and proportion of the expense of such improvements which shall be  borne
  by  the  city at large shall be included in the budget and raised by tax
  the same as other general city charges or may be  financed  pursuant  to
  the  local  finance  law.    An  amount sufficient to pay, when due, any
  obligations  issued  to  pay  the  portion  of  the  expense   of   such
  improvements  borne  by  the  city  at  large, together with the accrued
  interest thereon, shall be included in the tax budget and raised by  tax
  the  same  as  other  general city charges, and such obligations as they
  mature, together with the interest thereon, shall be  paid  out  of  the
  moneys  so  raised  by tax.   The proportion of the expense which is not
  borne by the city shall  be  assessed  and  charged  upon  the  property
  affected by such improvement in the form and manner provided by law.