((a)) ** .—** At the request of a federal agency, a mixed-ownership Government corporation (as defined in chapter 91 of title 31), or the District of Columbia, the Administrator of General Services may—

((1)) acquire land for a building or project authorized by Congress;

((2)) make or cause to be made (under contract or otherwise) surveys and test borings and prepare plans and specifications for a building or project prior to the Attorney General’s approval of the title to the site; and

((3)) contract for, and supervise, the construction, development, and equipping of a building or project.

((b)) ** .—** An amount available to a federal agency or instrumentality for a building or project may be transferred, in advance, to the General Services Administration for purposes the Administrator determines are necessary, including payment of salaries and expenses for preparing plans and specifications and for field supervision.