There is hereby established a "City of Fort Lauderdale Police and Firefighters' Retirement System", comprising a comprehensive amended retirement plan for the police and fire employees, who have received their State Certification, other than the general employees. The purpose of this Plan is to establish amended terms and conditions under which retirement benefits will be provided to eligible employees of the city. The benefits under the Plan shall be in addition to amounts received as federal social security benefits, except where social security benefits are specifically applied as offsets in the case of disability benefits hereunder; the benefits under this Plan shall also be in addition to benefits received by any Member from any other private or public retirement system. The effective date of the provisions of this division shall be January 3, 1973.