Any junkyard lawfully in existence on the effective date of this chapter any portion of which is within a controlled area and which is not in any of the classes specified in § 1205(a)(2), (3) and (4) of this title shall be screened, if physically and economically feasible, by the Department at locations on the highway right-of-way or in areas acquired for such purposes outside the right-of-way, so as not to be visible from the main-traveled way of the highway of the interstate or primary systems. Any such junkyard which the Department determines cannot, as a practical matter, be screened pursuant to this section shall be relocated, removed or disposed of by the owner thereof.