Subject to the limitations on applicability contained in C.R.S. tit. 31, art. 30, pt. 10(C.R.S. § 31-30-1001 et seq.), as amended in 1979, the rank escalation benefits provided in this article shall continue uninterrupted from and after January 1, 1980. This section constitutes the election by the city pursuant to C.R.S. § 31-30-1014(4)(b)(II) to continue full rank escalation retirement benefits for all firefighters hired by the city prior to April 7, 1978, who elect to remain covered by this local plan. A rank escalation retirement benefit fund is established into which sufficient funds shall be deposited to defray the payment of such benefits. The board shall be the custodian of such fund but shall arrange for the management, investment and administration of the fund by the retirement association pursuant to agreement between the two entities. The board shall biennially, or more often if deemed necessary, arrange for an actuarial study of the fund. (Code 1979, § 15-137)