N.C. Gen. Stat. § 74-80
All exploration holes shall be abandoned by adequately plugging them with cement from the bottom of the hole upward to a point three feet below ground surface. The remainder of the hole between the top of the plug and the surface shall be filled with cuttings or nontoxic material.
If multiple aquifers are encountered that have alternating usable quality water and salt water zones, or if other conditions determined by the Department to be potentially deleterious to surface or ground water are encountered, the conditions must be isolated immediately by cement plugs. Each such hole shall be plugged with cement to prevent water from flowing into or out of the hole or mixing within the hole. Usable quality water is ground water that is used or can be used for a beneficial purpose, including, domestic, livestock, irrigation or industrial uses.
Alternative plugging procedures and materials may be utilized when the applicant has demonstrated to the Department's satisfaction that the alternatives will protect ground waters and comply with the provisions of this Article. In the event that a hole is more suitably plugged with a nonporous material other than cement, the material shall have sealing and lasting characteristics at least equal to cement.
All other excavations or disturbances made in connection with exploration activities shall be adequately reclaimed so as to protect the natural resources of the surrounding area and to prevent the release of toxic substances.
Abandonment shall be undertaken as soon as practicable after exploration, except if multiple aquifers or other conditions potentially deleterious to surface or ground water are encountered. In any event, all abandonment shall be accomplished no later than 30 days following completion of exploration activity in an area of affected land.
N.C. Gen. Stat. § 74-80