(a) All existing and new Class I wells shall be constructed to prevent the movement of fluids into any underground source of drinking water, permit the use of testing devices and workover tools, and permit continuous monitoring of injection tubing and long string casing, as required under Sections 6(h)(i) and 6(h)(ii) of this chapter.
(b) All well materials shall be compatible with the wastes that may be contacted. The applicant shall submit data necessary to document compatibility.
(c) Casing and cement used in the construction of each newly drilled well shall be designed for the life expectancy of the well. The applicant shall provide all information required to make a determination based on these factors: - (i) Depth to the injection zone.
- (ii) Injection pressure, external pressure, internal pressure, and axial loading.
- (iv) Size and grade of all casing strings (wall thickness, diameter, nominal weight, length of joints, joint specifications and construction material).
- (v) Corrosiveness of injected fluid, formation fluids, and temperatures.
- (vi) Lithology of injection and confining intervals.
- (vii) Type or grade of cement.
(d) Construction requirements for Class I hazardous waste wells. - (i) For casing and cementing requirements, the applicant shall provide all information necessary to make a determination of adequacy based on quantity and chemical composition of injected fluids.
- (ii) One surface casing string shall, at a minimum, extend into the confining zone below the lowest Underground Source of Drinking Water and be cemented by circulating cement from the base of the casing to the surface, using a minimum of one-hundred twenty percent (120%) of the calculated annular volume. The administrator may require more than one- hundred twenty percent (120%) when the geology or other circumstances warrant a greater percentage.
- (iii) At least one long string casing, using a sufficient number of centralizers, shall extend to the receiver and shall be cemented by circulating cement to the surface in one or more stages:
- (A) Of sufficient quantity and quality to withstand the maximum operating pressure.
- (B) In a quantity no less than one hundred twenty percent (120%) of the calculated volume necessary to fill the annular space. The administrator may require more than one hundred twenty percent (120%) when the geology or other circumstances warrant a greater percentage.
- (iv) Circulation of cement may be accomplished by staging. The administrator may approve an alternative method of cementing in cases where the cement cannot be recirculated to the surface, provided the operator can demonstrate by logs that the cement is continuous and does not allow fluid movement behind the casing.
- (v) Casings, including any casing connections, must be rated to have sufficient structural strength to withstand, for the life the well, the maximum burst and collapse pressures which may be experienced during the construction, operation, and closure of the well. Casings shall also be rated to withstand the maximum tensile stress which may be experienced at any point along the entire length of the casing during construction, operation, and closure of the well.
- (vi) At a minimum, cement and cement additives shall be of sufficient quantity and quality to maintain mechanical integrity over the design life of the well.
- (vii) For tubing and packer, the applicant shall provide all information necessary to make a determination of adequacy based on these factors:
- (B) Characteristics of the injection fluid, including chemical content, corrosiveness, temperature, and density.
- (E) Rate (intermittent or continuous), temperature, and volume of injected fluid.
- (G) Tubing tensile, burst, and collapse strengths.
- (viii) During the drilling and construction of a Class I hazardous waste well, appropriate logs and tests shall be run to determine or verify the depth, thickness, porosity, permeability, and rock type of, and the salinity of any entrained fluids in all relevant geologic units to assure compliance with the performance standards of Section 16 of this chapter, and to compile baseline data against which future measurements may be compared. A descriptive report interpreting results of such logs and tests shall be prepared by the operator and submitted to the administrator. At a minimum, such logs shall include:
- (A) Deviation checks made during drilling of all Class I hazardous waste wells. Such checks shall be done at sufficiently frequent intervals to determine the location of the borehole.
- (B) Such other logs and tests as may be needed after taking into account the availability of similar data in the area of the drilling site, the construction plan and the need for additional information that may arise as construction of the well progresses. At a minimum, the following logs shall be required:
- (I) When installing the surface casing: resistivity, spontaneous potential, and caliper logs shall be run before the installation of the casing. A cement bond log and variable density log and temperature log are required after the surface casing is installed and before the well is deepened.
- (II) When installing the long string casing: resistivity, spontaneous potential, porosity, caliper, gamma ray and fracture finder logs are required before the casing is installed. After the casing is installed and cemented, a cement bond log and variable density log are required before the well is completed.
- (III) The administrator may allow the use of an alternative to the logs described above, when, in the administrator's opinion, the alternative will provide equivalent or better information.
- (C) A mechanical integrity test as described in Section 6(h)(i) of this chapter.
- (D) Whole core or sidewall cores of the confining zone and receiver and formation fluid samples from the receiver shall be taken. The administrator may accept cores from nearby wells if the operator can demonstrate, to the administrator's satisfaction, that core retrieval is not possible, and the other cores are representative of the conditions in the well. The administrator may require the operator to core other formations in the borehole.
- (ix) The fluid temperature, pH, conductivity, pressure, and static fluid level of the discharge zone shall be recorded during construction.
- (x) At a minimum, the following information about the injection and confining zones shall be calculated or determined during construction:
- (A) The physical and chemical characteristics of the rock itself; and
- (B) Physical and chemical characteristics of the formation fluids.
- (C) Upon completion of construction, but still prior to operation, the operator shall conduct either pump tests or injectivity tests to verify the hydrogeologic characteristics of the discharge zone.
(e) Fluid seals are not allowed in place of a packer in any Class I well.
020-27 Wyo. Code R. § 27-12