All exploration drill holes shall be properly plugged and abandoned by the holder of any coal option contract or coal mining lessee according to the following requirements:

(1) No drill holes shall be plugged and abandoned until the method and manner of plugging has been approved by the department. Drill holes not necessary for hydrological monitoring measurements shall be plugged and abandoned as soon as practical following drilling and probing. Hydrological monitoring holes shall be cased and capped while in use.

(2) All drill holes in which gas is present, or which exhibit artesian ground water flow, or which encounter ground water zones, shall be plugged with grout, cement or approved gel. These plugs shall extend a minimum of 100 feet above and below all ground water zones or to the top and bottom of the hole.

(3) Plugs below the water level of the drill hole must be made by a method which precludes dilution of the plugging material.

(4) All exploration drill holes must have surface plugs sufficient to effect a permanent seal. The top of the plug must be installed deeper than three feet below the original surface with a permanent identification monument in the soil above the plug.

(5) Unused drilling supplies and debris extraneous to drilling operations must be removed from the premises and the excavation must be backfilled to its approximate original land surface. Each drill site shall be graded to its approximate original contour and shall be left in a stable condition. Within thirty days after completion of all exploration activities, the lessee shall file a sworn statement on a form provided by the department setting forth in detail the methods used in sealing all drill holes and restoring the premises to a stable condition.