Neb. Rev. Stat. § 19-2409

Any city of the first class, city of the second class, or village may pave, repave, macadamize, gravel, curb, and gutter streets, avenues, or alleys and do any grading or work incidental in connection therewith and install water mains and sewer lines, either sanitary or storm or a combination sewer, in any improvement district or make any one, or a combination, of the above improvements, as a single project by following the Combined Improvement Act, if the total estimated costs do not exceed the dollar limitations in section 19-2408 .