Whenever fifty-one percent of the resident property owners of any territory adjacent to, or within a radius of seven miles of a city shall petition for the creation of a benefit district for the purposes of this act, it shall be the duty of the township boards of the townships in which said benefit district is located to organize such benefit district and to define the limits thereof as set forth in said petition. If said benefit district is located entirely within one township, the township board, and where said benefit district is located in two or more townships, the township trustees of said townships shall constitute the board of directors of said benefit district and shall be authorized to execute contracts in accordance with the purposes of this act for said district.