(i) all regular member contributions which such member would have been required to pay to the retirement system for such period of suspension if he or she had been in service during such period of suspension; and

(ii) if such member is a participant in a special plan, the additional member contributions attributable to participation in such special plan which he or she would have been required to pay to the retirement system for such period of suspension if he or she had been in service during such period of suspension; and

(iii) an amount equivalent to the additional costs to the employer of providing retirement service credit to such member for such period of suspension, as determined by the actuary for the retirement system. c. The deductions for the additional member contributions referred to in paragraph b of this subdivision shall be made in accordance with such equitable method and over such equitable period of time as shall be prescribed by the executive director of the member's retirement system with the approval of the board of trustees. d. The additional member contributions referred to in subparagraph (i) of paragraph b of this subdivision shall be paid into the account established by the retirement system for the deposit and accumulation of such member's regular member contributions. The additional member contributions referred to in subparagraph (ii) of paragraph b of this subdivision shall be paid into the contingent reserve fund of such retirement system and shall be subject to the provisions of law which govern additional member contributions in the special plan in which such member is a participant. The additional member contributions referred to in subparagraph (iii) of paragraph b of this subdivision shall be paid into the contingent reserve fund of such retirement system and shall not be subject to any retirement system right or privilege of such member, unless such right or privilege is granted by other provisions of law which specifically refer to additional member contributions made pursuant to subparagraph (iii) of paragraph b of this subdivision. e. At any time prior to completion of the deductions for the additional member contributions referred to in paragraph b of this subdivision, payment of the remainder of the total of such additional contributions required by such paragraph may be made in a lump sum.