Any junkyard lawfully in existence on April 15, 1971, any portion of which is within 1,000 feet of the nearest edge of the right-of-way of an interstate or primary highway, and visible from the main-traveled way, shall be screened, if 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 such highways.