N.C. Gen. Stat. § 87-90
The Environmental Management Commission or Department shall have the right to conduct such investigations as it may reasonably find necessary to carry on its duties prescribed in this Article, and for this purpose to enter at reasonable times upon any property, public or private, for the purpose of investigating the condition, installation, or operation of any well or associated equipment, facility, or property, and to require written statements or the filing of reports under oath, with respect to pertinent questions relating to the installation or operation of any well: Provided, that no person shall be required to disclose any secret formula, processes or methods used in any manufacturing operation or any confidential information concerning business activities carried on by him or under his supervision. No person shall refuse entry or access to any authorized representative of the Environmental Management Commission who requests entry for purposes of inspection, and who presents appropriate credentials, nor shall any person obstruct, hamper or interfere with any such representative while in the process of carrying out his official duties, consistent with the provisions of this Article.
N.C. Gen. Stat. § 87-90