Prior to the completion of proceedings for the annexation or inclusion of unincorporated territories to or within a city which is a part of a separation of grade district the city council shall adopt a resolution containing the following:
(a)
A description of the unincorporated territory involved in the annexation or inclusion proceedings.
(b)
A statement that unless excluded by the city council all portions of such unincorporated territory shall upon annexation to or inclusion within the city be included within the district, and naming the district.
(c)
A statement of the time and place at which objections to inclusion within the district will be heard, which time shall not be less than 30 days after the adoption of the resolution.