N.C. Gen. Stat. § 87-9
Nothing in this Article shall operate to prevent the Department of Transportation from complying with any act of Congress and any rules and regulations promulgated pursuant thereto for carrying out the provisions of the Federal Highway Act, or shall apply to any person, firm or corporation proposing to submit a bid or enter into contract for any work to be financed in whole or in part with federal aid road funds in such manner as will conflict with any act of Congress or any such rules and regulations promulgated pursuant thereto.
Neither shall anything in this Article prevent the State of North Carolina or any of its political subdivisions or their contractors from complying with any act of Congress and any rules and regulations promulgated pursuant thereto for carrying out the provisions of any federal program to assist in the planning, financing, or construction of drinking water or waste water processing, collection, and disposal systems and facilities.
N.C. Gen. Stat. § 87-9