Sec. 11.6. Contested assessments.
No suit or action of any kind shall be instituted or maintained for the purpose of contesting or enjoining the collection of any special assessment, (1) unless, within thirty days after the confirmation of the special assessment roll, written notice is given to the Council of intention to file such suit or action, stating the ground on which it is claimed such assessment is illegal, and (2) unless such suit or action shall be commenced within sixty days after confirmation of the roll for such assessment.