§ 1313. Additional member contributions. Upon election by the state of New York, the retirement system shall require additional member contributions to be paid by all eligible employees. The additional member contributions to be paid by eligible employees shall be of a level so that no additional contributions shall be paid by the state or participating employers in the retirement system to cover the cost of such additional benefits. Additional member contributions made pursuant to this section shall be in addition to member contributions made pursuant to other provisions of this chapter.