Within thirty days after a petition is filed, the commission shall give due notice of the time and place of a public hearing thereon. At the hearing all interested persons shall be heard.

If it appears to the commission that additional land should be included in the district, the hearing shall be adjourned and a new notice given covering the entire area and a new date fixed for further hearing, unless waiver of notice by the owners of the additional land is filed with the commission.

No district shall include any portion of a railroad right-of-way, or another similar district. The lands included in a district need not be contiguous.