(a) The board is granted the following powers and duties:

(1) To provide for the collection of all moneys provided in this chapter;

(2) To pay the administrative expenses of the board;

(3) To hear and decide all applications for retirement benefits under this chapter;

(4) To make payment of all retirement benefits that may be determined to be due under the terms of this chapter;

(5) To make all necessary rules and regulations, not inconsistent with the laws of the state, for its government and for the government of the employees of the board;

(6) To determine and fix rules of eligibility of persons to receive retirement benefits;

(7) To make refunds and repayments to persons who may be entitled to receive them; and

(8) To keep all records of its meetings.

(b) The board shall also have all powers necessary for the purpose of administering this chapter.

(c) (1) Subject to the terms and limitations of this subsection, the board of commissioners is authorized to adopt from time to time a method or methods of providing for increases in the maximum monthly retirement benefit payable under Article 5 of this chapter for persons theretofore or thereafter retiring under this chapter. Such method shall be based upon:

(A) The recommendation of the actuary of the board of commissioners;

(B) The maintenance of the actuarial soundness of the fund in accordance with the standards provided in Code Section 47-20-10 or such higher standards as may be adopted by the board; and

(C) Such other factors as the board deems relevant.

Any such increase may be uniform or may vary in accordance with the time of retirement, length of service, age, nature of the retirement, or such other factors as the board of commissioners shall determine.

(2) Any provision of paragraph (1) of this subsection to the contrary notwithstanding, no benefit increase shall be awarded under this subsection greater than 1.5 percent in any six-month period.