North Dakota Administrative Code › Title 43 - Industrial Commission › Article 43-02 - Mineral Exploration and Development › Chapter 43-02-02.2 - In Situ Leach Mining Rules › Section 43-02-02.2-26 - Well construction requirements - General

Current through Supplement No. 393, July, 2024
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;