(1) For the purpose of covering in whole or in part the costs of any of the improvements, authorized in sections 14-384 to 14-3,127, or costs incident to such improvements, including grading done in combination with any other improvements, a city may:

(a) Assess the property within an improvement district or the property benefited by change of grade or grading when not made in combination with other improvements, to the full extent of the special benefits conferred upon the respective lots, tracts, and parcels of land; or

(b) If the city council finds that there are common benefits enjoyed by the public at large without reference to the ownership of property abutting or adjacent to the improvement or improvements, or that there is a common benefit to the property embraced within such district or districts, assess the costs of such improvement or improvements against all the property included in such district or districts.

(2) All such assessments shall be:

(a) Done according to such rules as the city council sitting as a board of equalization shall adopt for the distribution or adjustment of the costs of the improvement or improvements; and

(b) Equalized, levied, and collected as special assessments.

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