If a consolidated employer is a participating member in the public employees' retirement system under chapter
41.40 RCW prior to the consolidation or in the public safety employees' retirement system under chapter
41.37 RCW prior to the consolidation:
(1) All existing employees of the consolidated employer who are active members of the public employees' or public safety employees' retirement system immediately prior to the consolidation shall continue to be members of that retirement system while employed by the consolidated employer.
(2) All existing employees of the consolidated employer who are active members of a first-class city retirement system under chapter
41.28 RCW immediately prior to the consolidation shall cease to be members of that system at the time of the consolidation and, if eligible, shall immediately become members of the public employees' or public safety employees' retirement system. However, any such active member may, by a writing filed with the consolidated employer within thirty days after the consolidation or within thirty days after March 15, 1984, whichever is later, irrevocably elect instead to continue to be a member of the first-class city retirement system, thereby forever waiving any rights under the public employees' or public safety employees' retirement system based upon employment with the consolidated employer.
(3) Only prospective periods of qualifying service under the public employees' or public safety employees' retirement system may be established under this section.