31682. The board of retirement of a county of the 13th class, as defined by Sections 28020 and 28034, as amended by Chapter 1204 of the Statutes of 1971, may elect to provide, by resolution, a vested supplemental retirement benefit of one hundred eight dollars and forty-four cents ($108.44) per month to all current and future retired members and their survivors eligible for an optional settlement or a survivors allowance under this chapter.Prior to the adoption of a resolution by the board of retirement to provide the supplemental retirement benefit provided for in this section, the cost of funding this supplemental retirement benefit into perpetuity shall be determined by a qualified actuary.This section shall not be operative until such time as the board of supervisors shall, by majority vote, adopt a resolution making the provisions of this section applicable.(Added by Stats. 1990, Ch. 914, Sec. 1. Section operative as prescribed by its own provisions.)