No grant for a project (other than so much of a grant as is used for a preliminary energy audit, energy audit, or technical assistance or a grant the total project cost of which is $5,000 or less, excluding costs for a preliminary energy audit, energy audit, or technical assistance) shall be made under this part or part 1 unless the Secretary finds that all laborers and mechanics employed by contractors or subcontractors in the performance of work on any construction utilizing such grants will be paid at rates not less than those prevailing on similar construction in the locality, as determined by the Secretary of Labor in accordance with sections 3141–3144, 3146, and 3147 of title 40; and the Secretary of Labor shall have with respect to the labor standards specified in this section the authority and functions set forth in Reorganization Plan Numbered 14 of 1950 (15 F.R. 3176; 5 U.S.C. Appendix) and .section 3145 of title 40