The county commissioners of counties of the fourth, fifth, sixth, seventh and eighth class shall have the power and their duty shall be to:
(1) Erect, equip, maintain, repair, alter and add to institutions for the care of dependents. A plan for the erection or substantial alteration of an institution must be approved as to suitability by the Department of Human Services.
(2) Pay the necessary expenses of land and buildings for the care of dependents and farms.