All moneys deposited in the equipment rental operating account and in the equipment rental reserve account including amounts included therefor in the annual budget of the city, and not expended as provided in this chapter, will remain in the fund from year to year and shall not be transferred to any other fund or expended for any purpose whatsoever, except as provided in this chapter; provided, however, that any money in the equipment rental fund not currently required may be invested by the finance director. (Ord. 3095 § 9, 1976.)