The board of local improvements or committee on local improvements, as the case may be, shall submit to the corporate authorities, during the months of May and October of each year, for 3 years following the completion of any public work, a written report of its condition based upon a careful examination of the public work by the board of local improvements, or by the committee on local improvements, as the case may be, or by its representative, who shall be an experienced and capable person of good character. This section shall not apply to municipalities having a population of less than 100,000.