(a) The county board of each county may, subject to a referendum in the townships affected as provided in this Section, adopt a plan for altering the boundaries of townships, changing township lines, dividing, enlarging, or consolidating townships, or creating new townships, so that each township shall possess an equalized assessed valuation of not less than $10,000,000 as of the 1982 assessment year.
     (b) No alteration or change in boundaries shall be effective unless approved by a referendum in each township affected. The election authority shall submit to the voters of each township affected, at a regular election to be held not less than 60 days after the plan is adopted, the question of approving the alteration or change. The alterations or changes, if approved by the voters, shall take effect on the date of the next township election and shall be applicable to that election. If there is doubt as to the township clerk with whom nomination papers for that election should be filed, the county board shall designate the clerk. In the alteration of boundaries, a county board may not disturb urban or coterminous townships in existence on October 1, 1978.