(a) Commencing October 1, 1998, there is provided to certain persons identified in subsection (b) who are currently receiving benefits, whose effective date of retirement was prior to October 1, 1998, for purposes of receiving benefits from the Employees' Retirement System, and to certain beneficiaries of deceased members and deceased retirees who are currently receiving survivor benefits if the effective date of retirement or death for the deceased member or retiree was prior to October 1, 1998, for purposes of receiving benefits from the Employees' Retirement System shall receive a cost-of-living increase of not less than thirty dollars ($30) per month and the increase shall be more if determined as follows:
(1) Four percent of the current gross benefit paid to the retirees and to certain beneficiaries of deceased members and deceased retirees.
(2) Two dollars ($2) per month for each year of service attained by the retiree for each retiree selecting the maximum retirement allowance or option one.
(3) Two dollars ($2) per month for each year of service attained by the retiree reduced by the retiree's option election factor for each retiree selecting option two, three, or four unless the beneficiary under the option selected is deceased on July 1, 1998, in which case the increase shall not be reduced.
(4) Two dollars ($2) per month for each year of service attained by the deceased member or deceased retiree reduced by the survivor's option factor for each beneficiary receiving monthly benefits from the Employees' Retirement System.
(b) The benefits provided in this section are limited to those retirees whose participation in the Employees' Retirement System was based on Section 36-27-6, and whose employer at the time of retirement was a local board of education or a state supported institution of higher education. The benefits granted in this section shall not apply to any other participants in the Employees' Retirement System.