If in any case of a labor dispute between a public utility employer and its employes, the collective bargaining process reaches an impasse and stalemate, with the result that the employer and employes are unable to effect a settlement, then either party to the dispute or the Pennsylvania Labor Relations Board may request the Governor, in writing, to appoint a mediator. Upon the filing of any such request, the Governor shall consider the same, and if in his opinion, the collective bargaining process has failed and such dispute, if not settled, is likely to cause the interruption of the supply of a public utility service on which a community is so dependent that severe hardship would be inflicted on a substantial number of persons by a cessation of such service, the Governor shall appoint a mediator from among the mediators employed by the Department of Labor and Industry to attempt to effect a settlement of such labor dispute.