Section 11.1.  Power of council to assess.
   (a)   The council shall have power to determine, with or without a petition therefore, that the whole or any part of the expense of any public improvement or repair shall be defrayed by special assessment upon the parcels or property especially benefited and so declare by resolution.  Such resolution shall state the estimated cost of the improvement, what portion of the cost shall be paid by special assessment, what portion, if any, shall be a general obligation of the city, the number of installments in which assessment may be paid, the interest to be charged, and designate the districts or land and premises upon which special assessment shall be levied.
   (b)   No such improvement shall be made if the owners of more than two-thirds of the property to be assessed shall object thereto in writing, but if the council shall determine and declare by a resolution unanimously adopted that the proposed improvement is immediately necessary for the public health, welfare and safety, such improvement may be made, and such special assessment may be levied, therefor, notwithstanding such objections thereto.  The whole amount to be levied upon the premises subject to special assessment shall not be limited by the assessed valuation of the property subject to such special assessment.