(a) who is a member of the uniformed force of the department of sanitation or similar department or agency of a city, and is a member of a pension or retirement system maintained by such city; and

(b) who, by reason of a plan or option selected by him or otherwise made applicable to him pursuant to or by the administrative code or charter or other local provisions of law governing the rate of contribution and eligibility for service retirement of members of such uniformed force who are members of such city-maintained pension or retirement system:

(1) is required to make contributions to such system at a rate calculated on the basis of a service-fraction of not less than one one-hundredth of his final compensation under such system; and

(2) is eligible for retirement for service upon completion of a minimum of twenty-five years of service in such uniformed force as a member of such system; and

(c) who has completed at least twenty-five years of service in such uniformed force as a member of such system; shall, upon retirement for service, receive, on account of the first twenty-five years of service in such uniformed force, a pension or retirement allowance which shall, subject to the provisions of this section, be equal to one-half of his annual salary or compensation when so retired. 3. Where a city-maintained pension or retirement system for such members of such uniformed force of such city provides, upon retirement for service, for a retirement allowance consisting of a pension (with or without a pension for-increased-take-home-pay) plus an annuity which is the actuarial equivalent of the member's accumulated contributions or accumulated deductions at the time of his retirement, then in that event there shall be added by the city, whenever required, a further pension of such amount which, together with the member's annuity, shall be sufficient to provide him with a retirement allowance equal to one-half of his annual salary or compensation when so retired. For the purpose only of determining the amount of the additional pension contributions by the city that may be required, the member's annuity, if any, shall be computed, as it would be, (a) if it were not reduced by the actuarial equivalent of any outstanding loan, (b) if it were not increased by the actuarial equivalent of any additional contributions, (c) if it were not reduced by reason of the member's election to decrease his annuity contributions in order to apply the amount of such reduction in payment of his contributions for old-age and survivors insurance coverage, (d) as it would be without any optional modification. 4. Where additional retirement benefits are payable under the city-maintained pension or retirement system, such additional benefits shall be paid, for service in addition to and in excess of twenty-five years of service, in addition to the minimum retirement benefits required to be paid by this section. 5. The provisions of this section shall not apply to members of the New York state employees' retirement system.