When a local improvement district has been established and an assessment or installment is delinquent, in addition to the interest to be paid on the assessments or installments as previously fixed by the City Council, a penalty shall be assessed on the assessment or installment in the amount of nine percent (9%) upon both the principal and the interest due. The collection of such delinquent installments shall be enforced in the manner provided by law. (Ord. 2520, 8/25/09; Ord. 1297, 1987)