Section 5. The amount of group life insurance on each employee and the amount of group accident death and dismemberment insurance on each employee shall be established by the appropriate public authority and shall be not less than two thousand dollars except that those employees desiring to elect optional coverage in excess of the amount or amounts so established may do so as provided in section eleven A. The schedules of hospital, surgical, medical, dental and other health insurance benefits and the amount to be provided each employee and his dependents shall be determined by the appropriate public authority subject to the amount of the appropriation made available for such purpose, provided, however, that to the extent such schedules exceed the schedule of benefits established under section eleven of this chapter, the premium applicable to such excess coverage shall be withheld from each payment of salary or wages of such employee and the governmental unit shall make no contribution applicable to such excess coverage. As determined by the rules and regulations of the appropriate public authority all insurance coverages authorized by this chapter may be considered as separable for any employee, retired employee or deferred retiree who applies for any part of such coverage.