(c) Reimbursement From Assessments. - If a city contracts with a private party to construct a project on behalf of the city as provided in G.S. 160A-239.7, the city council may agree to impose one or more assessments pursuant to this Article in order to reimburse the private party for actual costs incurred by the private party related to the project and documented to the city. The city council shall not be obligated to reimburse a private party any amount in excess of assessment revenues actually collected less the city's related administrative costs. A reimbursement shall not include reimbursement to the private party for any interest costs, whether actual or imputed, of the funds invested by the private party in the project except in the event that an abeyance in the collection of assessments is permitted pursuant to G.S. 160A-239.5. If an abeyance in the collection of assessments is permitted, the amount to be reimbursed may include an inflationary factor applicable for the period of the abeyance.