Commencing October 1, 2002, each person whose employer participated in the Employees’ Retirement System pursuant to Sections 36-27-7 and 36-27-7.1, whose effective date of retirement for purposes of receiving benefits from the Employees’ Retirement System is prior to October 1, 2001, and who is receiving a monthly allowance or is eligible to receive a monthly allowance from the Employees’ Retirement System, shall receive a cost-of-living increase as described in Section 36-27-180. Beneficiaries of deceased members or deceased retirees of employers participating in the Employees’ Retirement System pursuant to Sections 36-27-7 and 36-27-7.1, shall be entitled to the increase the retiree has attained under the provisions in Section 36-27-180. In no case shall the COLA be less than fifteen dollars ($15) per month.