The City Finance Department shall issue an invoice for the costs incurred in mitigating or causing the mitigation of the effects of a release. Payment shall be due and payable within fifteen (15) days after the billing date. Failure to pay after sixty (60) days from the billing date shall result in an additional ten percent (10%) late charge. Unpaid bills may be referred to a collection agency after ninety (90) days delinquency or be assessed against the parcel of land involved in the incident pursuant to section 38773.5 of the Government Code and shall thereafter be transmitted to the Tax Collector for collection. (Prior code § 3-4-10)