The contractor shall within 90 days of the issuance of the assessment submit to the Director of Public Works a list of all unpaid assessments, and it shall be the duty of said Director to notify the Tax Collector of each assessment that is delinquent, and the lot and block number against which such assessment is levied, and it shall be the duty of the Tax Collector to note such delinquency on each annual tax bill, in accordance with Section 107 of the Charter of the City and County of San Francisco.