La. Admin. Code tit. 43 § XVII-3313

Current through Register Vol. 50, No. 9, September 20, 2024

Section XVII-3313 - Site Assessment

A. Applicability. This Section applies to all applicants, owners or operators of solution-mining wells. The applicant, owner or operator shall be responsible for showing that the solution-mining operation shall be accomplished using good engineering and geologic practices for solution-mining operations to preserve the integrity of the salt stock and overlying sediments. In addition to all applicants showing this in their application, as part of the compliance review found in subsection 3309 K, the commissioner may require any owner or operator of a solution-mining well to provide the same or similar information required in this Section. This shall include, but not be limited to:

1. an assessment of the engineering, geological, geomechanical, geochemical, and geophysical properties of the salt stock;

2. stability of the salt stock and overlying and surrounding sediments;

3. stability of the cavern design (particularly regarding its size, shape, depth, and operating parameters);

4. the amount of separation between the cavern of interest and adjacent caverns and structures within the salt stock;

5. the amount of separation between the outermost cavern wall and the periphery of the salt stock; and

6. an assessment of well information and oil and gas activity within the vicinity of the salt dome which may affect the solution-mining cavern.

B. Geological Studies and Evaluations. The applicant, owner, or operator shall do a thorough geological, geophysical, geomechanical, and geochemical evaluation of the salt stock to determine its suitability for solution-mining, stability of the cavern under the proposed set of operating conditions, and where applicable, the structural integrity of the salt stock between an adjacent cavern and salt periphery under the proposed set of operating conditions. A listing of data or information used to characterize the structure and geometry of the salt stock shall be included.

1. Where applicable, the geologic evaluation shall include, but should not be limited to:

a. geologic mapping of the structure of the salt stock and any cap rock;

b. geologic history of salt movement;

c. an assessment of the impact of possible anomalous zones (salt spines, shear planes, etc.) on the solution-mining well or cavern;

d. deformation of the cap rock and strata overlying the salt stock;

e. investigation of the upper salt surface and adjacent areas involved with salt dissolution;

f. cap rock formation and any non-vertical salt movement.

2. The applicant shall perform a thorough hydrogeological study on strata overlying the salt stock to determine the occurrence of the lowermost underground source of drinking water immediately above and in the vicinity of the salt stock.

3. The applicant shall investigate regional tectonic activity and the potential impact (including ground subsidence) of the project on surface and subsurface resources.

4. The proximity of all existing and proposed solution-mining caverns to the periphery of the salt stock and to manmade structures within the salt stock shall be demonstrated to the Office of Conservation at least once every five years (see §3309.K) by providing the following:

a. an updated structure contour map of the salt stock. The updated map should make use of all available data. The horizontal configuration of the salt caverns should be shown on the structure map and reflect the caverns' maximum lateral extent as determined by the most recent sonar caliper surveys; and

b. vertical cross-sections of the salt caverns showing their outline and position within the salt stock... Cross-sections should be oriented to indicate the closest approach of the salt cavern wall to the periphery of the salt stock. The outline of the salt cavern should be based on the most recent sonar caliper survey.

C. Core Sampling

1. Unless specifically exempted by the commissioner, at least one well at the site of the solution-mining well (or the salt dome) shall be or shall have been cored over sufficient depth intervals to yield representative samples of the subsurface geologic environment. This shall include coring of the salt stock and may include coring of overlying formations, including any cap rock. Cores should be obtained using the whole core method. Core acquisition, core handling, and core preservation shall be done according to standard field sampling practices considered acceptable for laboratory tests of recovered cores.

2. Repealed.

D. Core Analyses and Laboratory Tests. Analyses and tests shall consider the characteristics of the injected materials and should provide data on the salt's geomechanical, geophysical, geochemical, mineralogical properties, x-ray diffraction, microstructure, and where necessary, potential for adjacent cavern connectivity, with emphasis on cavern shape and the operating conditions. All laboratory tests, experimentation, and numeric modeling shall be conducted using methods that simulate the proposed operating conditions of the cavern. Test methods shall be selected to define the deformation and strength properties and characteristics of the salt stock under cavern operating conditions. Test results, analyses, and operating recommendations shall be summarized in an interpretive report.

E. Area of Review. A thorough evaluation shall be undertaken of both surface and subsurface activities in the defined area of review of the individual solution-mining well or project area (area permit) that may influence the integrity of the salt stock, solution-mining well, and cavern, or contribute to the movement of injected fluids outside the cavern, wellbore, or salt stock.

1. Surface Delineation

a. The area of review for an individual solution-mining well shall be a fixed radius around the wellbore of not less than 1320 feet.

b. The area of review for wells in a solution-mining project area (area permit), shall be the project area plus a circumscribing area the width of which is not less than 1320 feet. The area of review for new solution-mining wells within an existing area permit shall be a circumscribing area around the proposed solution-mining well the width of which is not less than 1320 feet. Only information outlined in §3313. E 2, not previously assessed as part of the area permit application review or as part of the review of an application for a subsequent solution-mining well located within the area permit, shall be considered.

c. Exception shall be noted as shown in §3313. E.2.c and d below.

2. Subsurface Delineation. At a minimum, the following shall be identified within the area of review:

a. all known active, inactive, and abandoned wells within the area of review with known depth of penetration into the cap rock or salt stock;

b. all known water wells within the area of review;

c. all caverns within the salt stock regardless of usage, depth of penetration, or distance to the proposed solution-mining well or cavern;

d. all conventional (dry or room and pillar) mining activity either active or abandoned occurring anywhere within the salt stock regardless of distance to the proposed solution-mining well or cavern.

e. all producing formations either active or depleted.

3. Water Samples. A representative number of water wells identified under §3313.E.2.b shall be sampled and analyzed by an accredited laboratory for chloride and total dissolved solids.

F. Corrective Action

1. For manmade structures in the area of review that penetrate the salt stock and are not properly constructed, completed, or plugged and abandoned, the applicant shall submit a corrective action plan consisting of such steps, procedures, or modifications as are necessary to prevent the movement of fluids outside the cavern or into underground sources of drinking water.

a. Where the plan is adequate, the provisions of the corrective action plan shall be incorporated into the permit as a condition.

b. Where the plan is inadequate, the Office of Conservation shall require the applicant to revise the plan, or prescribe a plan for corrective action as a condition of the permit, or the application shall be denied.

2. Any permit issued for an existing solution-mining well for which corrective action is required shall include a schedule of compliance for complete fulfillment of the approved corrective action procedures as soon as possible. If the required corrective action is not completed as prescribed in the schedule of compliance, the permit shall be suspended, modified, revoked and possibly reissued, or terminated according to these rules and regulations.

3. No permit to inject shall be issued for a new solution-mining well until all required corrective action obligations have been fulfilled.

4. The commissioner may require as a permit condition that injection pressure be so limited that pressure in the injection zone does not cause the movement of fluids into a underground source of drinking water through any improperly completed or abandoned well within the area of review. This pressure limitation shall satisfy the corrective action requirement. Alternatively, such injection pressure limitation can be part of a compliance schedule and last until all other corrective action has been taken.

5. When setting corrective action requirements for solution-mining wells, the commissioner shall consider the overall effect of the project on the hydraulic gradient in potentially affected underground sources of drinking water, and the corresponding changes in potentiometric surface(s) and flow direction(s) rather than the discrete effect of each well. If a decision is made that corrective action is not necessary, the monitoring program required in §3323 shall be designed to verify the validity of such determination.

6. In determining the adequacy of proposed corrective action and in determining the additional steps needed to prevent fluid movement into underground sources of drinking water, the following criteria and factors shall be considered by the commissioner:

a. nature and volume of injection fluid;

b. nature of native fluids or by-products of injection;

c. potentially affected population;

d. geology;

e. hydrology;

f. history of the injection operation;

g. completion and plugging records;

h. abandonment procedures in effect at the time the well was abandoned; and

i. hydraulic connections with underground sources of drinking water.

7. The Office of Conservation may prescribe additional requirements for corrective action beyond those submitted by the applicant.

La. Admin. Code tit. 43, § XVII-3313

Promulgated by the Department of Natural Resources, Office of Conservation, LR 40:330 (February 2014), Amended LR 42416 (3/1/2016), Amended LR 482309 (9/1/2022).

AUTHORITY NOTE: Promulgated in accordance with R.S. 30:4 et seq.