The legislative body may order the revolving fund reimbursed, in whole or in part, when the following conditions exist:
(a)
It has appropriated and expended or advanced any sum out of the fund to pay or to secure the payment of the cost of improvement of a street or other public way pursuant to this article, or the cost of acquiring land, rights of way, or other property necessary for such purposes.
(b)
The cost, either in whole or in part, of the improvement is a lien assessed upon property abutting upon the improvement according to frontage or benefits, or upon property in districts according to benefits, and assessments are levied and collected for the cost.