74:55:01:31.  Well construction requirements. The method for well construction shall be stated in the permit application. Construction requirements listed in this section apply to all wells installed for activities related to in situ leach mines. The secretary may grant a deviation from the requirements through a technical revision, if the operator supplies documentation of reliability, mechanical integrity, design, and construction to protect ground waters of the state. Injection and production wells shall be generally constructed as follows:

 

          (1)  Annular seals shall be installed to protect the casing against corrosion, ensure structural integrity of the casing, stabilize the well bore, 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:

 

               (a)  The drill hole shall be of sufficient diameter for adequate sealing and, at any given depth, at least three inches greater in nominal diameter than the outside diameter of the outer casing at that depth. The secretary may approve an alternative casing design if it provides an equivalent degree of ground water protection;

 

               (b)  Before placing the annular seal, the well bore shall be under static conditions and all loose drill cuttings, rock chips, or other obstructions shall be removed from the annular space by circulating the borehole with water or drilling mud slurry;

 

               (c)  The annular sealing material shall be pressure-grouted as required in § 74:02:04:28;

 

               (d)  Sealing material shall consist of neat cement grout or bentonite grout mixtures meeting the following requirements:

 

                      (i)    Cement grout shall be composed of high sulfate resistant Portland cement and shall conform to the requirements of § 74:02:04:53;

 

                      (ii)   Bentonite grout shall conform to the requirements of § 74:02:04:53.01. The bentonite grout shall be a sodium bentonite material that has been commercially manufactured and specially formulated for use as a well casing seal;

 

                      (iii)  The sealing material shall be thoroughly mixed before placement so there are no balls, clods, or other features that could reduce the effectiveness of the seal;

 

                      (iv)   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 secretary; and

 

                      (v)    Used drilling mud or drill cuttings from the borehole may not be used as sealing material;

 

          (2)  Well casing shall conform to the requirements of §§ 74:02:04:42 to 74:02:04:45, inclusive, and § 74:02:04:48. The casing shall 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 shall be placed with sufficient care to avoid damage to casing sections and joints. All joints in the casing above the perforations or screens shall be watertight. Casing shall be equipped with centralizers placed at a maximum spacing of one per forty feet to ensure even thickness of annular seal and gravel pack; and

 

          (3)  Well development shall be done 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.

 

          Source: 8 SDR 71, effective December 24, 1981; 13 SDR 129, 13 SDR 141, effective July 1, 1987; transferred from § 74:03:11:31, July 1, 1996; 34 SDR 279, effective May 12, 2008.

          General Authority: SDCL 34A-2-93(15).

          Law Implemented: SDCL 34A-2-32.

 

          74:55:01:31.01.  Well construction requirements -- Injection wells. The following construction requirements apply to injection wells and are in addition to the requirements listed in § 74:55:01:31:

 

          All injection wells shall be constructed to prevent the migration of fluids to unauthorized zones. The casing and annular sealing material used in the construction of each newly drilled well shall be designed for the life expectancy of the well. In determining and specifying casing and annular sealing requirements, the following factors shall be considered:

 

          (1)  Depth to the deepest injection zone;

          (2)  Injection pressure, external pressure, internal pressure, axial loading, and related information;

          (3)  Hole size;

          (4)  Size and grade of all casing strings including well thickness, diameter, nominal weight, length, joint specification, and construction material;

          (5)  Corrosiveness of injected fluids and formation fluids;

          (6)  Lithology of injection zone and confining zones; and

          (7)  Type and grade of cement used to seal the annular space between the outer casing and borehole.

 

          Source: 34 SDR 279, effective May 12, 2008.

          General Authority: SDCL 34A-2-93(15).

          Law Implemented: SDCL 34A-2-32.