1. A. Before drilling a storage well for storing liquid or gaseous hydrocarbons, or any other substances under the jurisdiction of the Commission, in an underground cavity, the applicant shall demonstrate to the Commission that the proposed storage will preserve the structural integrity of the host rock, including halite, and the overlying sediments. The evidence presented shall include:

   1. 1. An investigation to determine the feasibility of a storage system at the particular site; and
   2. 2. An assessment of the stability of each proposed cavity design, particularly with regard to the size, shape and depth of the storage cavity, the amount of separation between storage cavities, and the amount of separation between the storage cavity and the periphery of the host rock.

2. B. The design of a solution-mined storage system shall be based on site-specific geologic and engineering parameters including type of storage use, location of each cavity, number of cavities, cavity capacity, and maximum development diameter of each cavity. The design shall ensure that project development can be conducted in a reasonable, prudent, and systematic manner and shall stress physical and environmental safety and the prevention of waste. The design and solution mining shall be continually reviewed throughout the construction phase to account for any new subsurface information and shall include provisions for protection from damage caused by hydraulic shock. The original development and operational plans shall be modified, as necessary, to conform with good engineering practice. The design shall incorporate the standards outlined below:

   1. 1. The minimum separation between the nearest outer walls of adjacent storage cavities as measured in any direction shall be established considering:

      1. a. The properties of the host rock;
      2. b. The elevation of the top and bottom of the adjacent cavities;
      3. c. Their maximum development diameter relative to the spacing of the cavities; and
      4. d. Other considerations deemed appropriate for the specific site; however, in no case shall such separation at any time during the storage project be less than 200 feet.
   2. 2. The walls of a storage cavity shall be no less than 200 feet from the boundary of the lands included in the storage project on which the chambers are located.
   3. 3. If the design involves the intentional subsurface connection between 2 adjacent storage cavities under 1 property (that is, a “U”-tube storage-cavity system), the minimum separation between cavities specified in subsection (B)(1)(d) shall not apply.

3. C. The borehole shall be dually cased from the surface into the cavity in accordance with R12-7-110 and R12-7-111. At least 2 strings of casing shall be fully cemented from the surface into the host rock either during the primary cement job or by remedial action. The Commission may administratively grant an exception to the requirement for 2 strings of cemented casing if the applicant can show that the exception is reasonable, justified by site-specific geologic or engineering parameters, is no less stringent, and consistent with the intent of these rules regarding physical and environmental safety, conservation of the resource, and the prevention of waste.

   1. 1. The final cemented casing string shall have tensile and collapse strengths, as approved by the Commission, for the setting depth and shall be set a minimum of 200 feet into the formation to be used for the storage cavity.
   2. 2. The casing seat of the final cemented casing string shall be pressure-tested after drilling at least 10 feet into the formation below the casing seat. The test pressure calculated at the casing seat shall equal the proposed maximum operating pressure at that point and shall not exceed 0.9 psi per foot of depth.
   3. 3. After the wellhead has been installed and before products are stored, the system shall be pressure-tested as a unit.
   4. 4. All tests required in this subsection shall meet the integrity standards set in R12-7-179(D).
4. D. Storage facilities in existence prior to June 1, 1978, shall not be required to meet the planning and construction requirements of subsections (B) and (C), except for future expansions or additions.

Historical Note

Adopted effective August 31, 1978 (Supp. 78-4). Amended effective September 29, 1982 (Supp. 82-5). Amended (and subsections (A)(1)(h) through (m) moved to Section R12-7-182) effective January 2, 1996 (Supp. 96-1)