The county clerk shall examine the petition, if such a petition is required, signatures and attached matter as prescribed by Kan. Stat. Ann. § 15-116, as amended, and if it appears the petition is in proper form, that the inhabitants of the territory number 250 or more and 50 or more electors of the territory have signed a petition, that the territory contains 250 or more platted lots each served by water and sewer lines owned by a nonprofit corporation and that 50 or more electors of the territory have signed the petition, or that the territory has been designated as a national landmark, the county clerk shall so report to the board of county commissioners at its next regular meeting and it shall designate a time and place for a hearing on the petition, such time to be not less than 30 nor more than 90 days from the date the petition was filed. The place of the hearing shall be at a place convenient for most of the inhabitants of the territory.