Whenever under the provisions of this act the political subdivision is authorized to acquire property rights and a reasonable price cannot be agreed upon, or whenever the owner is legally incapacitated or is absent or is unable to convey valid title or is unknown, the political subdivision is hereby authorized and empowered to acquire, by condemnation, any lands, rights, easements, franchises and other property, deemed necessary or convenient for the attainment of the purposes hereinbefore set forth.
53 P.S. § 5210