Whenever real property is acquired by the government of the District of Columbia or the Washington Metropolitan Area Transit Authority for a program or project which is not subject to sections 4630 and 4631 of this title, and such acquisition will result in the displacement of any person on or after , the Mayor of the District of Columbia or the Washington Metropolitan Area Transit Authority, as the case may be, shall make all relocation payments and provide all assistance required of a Federal agency by this chapter. Whenever real property is acquired for such a program or project on or after such effective date, such Mayor or Authority, as the case may be, shall make all payments and meet all requirements prescribed for a Federal agency by subchapter III of this chapter.January 2, 19711971-01-02