Well construction requirements - General

1. Construction requirements listed in this section apply to all wells installed for activities related to mining. 2. The department may grant a deviation from the requirements through a technical revision, if the operator proves that alternative requirements are reliable, ensure mechanical integrity, and will protect ground water. 3. Injection and production wells must be generally constructed as follows: a. Annular seals must be installed to protect the casing against corrosion, ensure the casing's structural integrity, stabilize the upper formations, protect against contamination or pollution of the well from the surface, and prevent migration of ground water from one aquifer or water-bearing strata to another in accordance with the following requirements: (1) The drill hole must have a sufficient annular opening to allow for one and one-half inches [38.1 millimeters] of grout around the casing and couplings as per section 33.1-18-01-06. The department may approve an alternative casing design if it provides an equivalent degree of ground water protection; (2) Before placing the annular seal, the well bore must be under static conditions and all loose drill cuttings, rock chips, or other obstructions must be removed from the annular space by circulating the borehole with water or drilling mud slurry; (3) Grout must be placed to fill all voids as required in subsection 10 of section 33.1-18-01-06 using a bottom-up trimmie grouting method. Grout must be injected into the subsurface in a sequence beginning at the bottom of the void and progressing upward in two-foot [.61-meter] increments; (4) Sealing material must consist of neat cement grout or bentonite grout mixtures meeting the following requirements: (a) Cement grout must be composed of high sulfate-resistant Portland cement and no more than six gallons [22.71 liters] of clean water for each ninety-four-pound [42.64-kilogram] sack of cement to yield a slurry weight of approximately thirteen pounds per gallon. Cement grout must conform to the requirements of subsection 10 of section 33.1-18-01-06; (b) Bentonite grout must conform to subsection 10 of section 33.1-18-01-06 requirements. High-solids bentonite clay grout, bentonite chips, or bentonite tablets must be commercially prepared specifically for the purpose of sealing water wells; (c) The sealing material must be thoroughly mixed before applied so there are no balls, clods, or other features that could reduce the seal's effectiveness; (d) Special quick-setting cement, cement accelerators, retarders, fluid-loss additives, dispersants, extenders, loss-of-circulation materials, and other additives, including hydrated lime to make the mix more fluid or bentonite to make the mix more fluid and reduce shrinkage, may be used, if approved by the department; and (e) Used drilling mud or drill cuttings from the borehole may not be used as sealing material; b. Well casing must conform to the requirements in subsections 2 and 3 of section 33.1-18-01-06. The casing must be of sufficient strength and diameter to prevent casing collapse during installation, convey liquid at a specified injection/recovery rate and pressure, and allow for sampling. Casing must be installed to avoid damage to casing sections and joints. All joints in the casing above the perforations or screens must be watertight. Casing must be equipped with centralizers placed at a maximum spacing of one per forty feet [12.19 meters] to ensure even thickness of annular seal and gravel pack; and c. Well development must be by methods that will not cause damage to the well or cause adverse subsurface conditions that may destroy barriers to the vertical movement of water between water-bearing strata.