(a) This Part IV of this subtitle (Reformed Contributory Pension Benefit) applies to: (1) an individual who becomes a member of the Employees’ Pension System or the Teachers’ Pension System on or after July 1, 2011; and (2) except as provided in § 23–215.1 of this subtitle, a member of the Employees’ Pension System or Teachers’ Pension System who separated from employment on or before June 30, 2011, and subsequently becomes employed in a position eligible for membership in the Employees’ Pension System or the Teachers’ Pension System on or after July 1, 2011. (b) This Part IV does not apply to an employee of: (1) a participating governmental unit that was participating in the Employees’ Pension System prior to July 1, 2011, and that has not elected to participate in the Alternate Contributory Pension Selection under § 31–116.1 of this article; or (2) a former participating governmental unit, other than Frederick County, that has withdrawn from the Employees’ Pension System.