Upon the receipt by a participating county of responsive construction bids, the board and the department may borrow funds for project costs after the project has been certified pursuant to Section 1970 from the Pooled Money Investment Account pursuant to Sections 16312 and 16313 of the Government Code, or from any other appropriate source. In the event any of the revenue bonds, notes, or bond anticipation notes authorized by this chapter are not sold, the department shall commit a sufficient amount of its support appropriation to repay any loans made for an approved project.