If, at the conclusion of the hearing, written protests not withdrawn have been filed by the owners of more than fifty (50) percent of the net land area proposed to be assessed, the city council shall abandon the proceedings for the formation of the district and shall not reinstitute proceedings to form substantially the same district for a period of one year from the date on which the hearing is concluded, unless the protests have been overruled by the affirmative vote of not less than four-fifths of the members of the city council. (Prior code § 85.05.570)