7 Del. Admin. Code § 7102-65.0

Current through Register Vol. 28, No. 4, October 1, 2024

Section 7102-65.0 - Construction requirements for Class I non-hazardous wells

65.1 All Class I wells shall be sited in such a fashion that they inject into a formation which is beneath the lowermost formation containing an underground source of drinking water within one-quarter (1/4) mile of the well bore.

65.2 All Class I wells shall be cased and cemented to prevent the movement of fluids into or between underground sources of drinking water. The casing and cement used in the construction of each newly drilled well shall be designed for the life expectancy of the well and shall be new and unused for Class I wells. The number, thickness, type of materials, and length of casing shall be sufficient to protect the quality of drinking water resources and the integrity of the well and the confining strata. The final string of casing shall be made of seamless mild steel pipe having a minimum 0.500 inch wall thickness. An applicant who proposes to use pipe composed of other than 0.500 inch wall seamless mild steel for the final casing shall demonstrate that the proposed material and thicknesses will not compromise the integrity or operation of the well. All casing shall be consistent with the standards of the American Petroleum Institute Specification 5CT or American Society of Testing and Materials standard ASTM A53 / A53M - 12 Standard Specification for Pipe, Steel, Black and Hot-Dipped, Zinc-Coated, Welded and Seamless. In determining and specifying casing and cementing requirements, the following factors shall be considered:

65.2.1 Depth to the injection zone;

65.2.2 Injection pressure, external pressure, internal pressure, and axial loading;

65.2.3 Hole size;

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

65.2.5 Corrosiveness of injected fluid, formation fluids, and temperatures;

65.2.6 Lithology of injection and confining intervals; and

65.2.7 Type or grade of cement.

65.3 All Class I injection wells shall inject fluids through tubing with a packer set immediately above the injection zone, or tubing with an approved fluid seal as an alternative. The tubing, packer, and fluid seal shall be designed for the expected service.

65.3.1 The use of other alternatives to a packer may be allowed with the written approval of the Department. To obtain approval, the operator shall submit a written request to the Department, which shall set forth the proposed alternative and all technical data supporting its use. The Department may approve the request if the alternative method will reliably provide a comparable level of protection to underground sources of drinking water. The Department may approve an alternative method solely for an individual well or for general use.

65.3.2 In determining and specifying requirements for tubing, packer, or alternatives the following factors shall be considered:

65.3.2.1 Depth of setting;

65.3.2.2 Characteristics of injection fluid (chemical content, corrosiveness, and density);

65.3.2.3 Injection pressure;

65.3.2.4 Annular pressure;

65.3.2.5 Rate, temperature and volume of injected fluid; and

65.3.2.6 Size of casing.

65.4 Appropriate logs and other tests shall be conducted during the drilling and construction of new Class I wells. A descriptive report interpreting the results of such logs and tests shall be prepared by a knowledgeable log analyst and submitted to the Department. At a minimum, such logs and tests shall include:

65.4.1 Deviation checks on all holes constructed by first drilling a pilot hole, and then enlarging the pilot hole by reaming or another method. Such checks shall be at sufficiently frequent intervals to assure that vertical avenues for fluid migration in the form of diverging holes are not created during drilling.

65.4.2 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, which may arise from time to time as the construction of the well progresses. In determining which logs and tests shall be required, the following logs shall be considered for use in the following situations:

65.4.2.1 For surface casing intended to protect underground sources of drinking water:

65.4.2.1.1 Resistivity, spontaneous potential, and caliper logs before the casing is installed; and

65.4.2.1.2 A cement bond, acoustic cement evaluation log, or density log after the casing is set and cemented.

65.4.2.2 For intermediate and long strings of casing intended to facilitate injection:

65.4.2.2.1 Resistivity, spontaneous potential, porosity, and gamma ray logs before the casing is installed; and

65.4.2.2.2 A cement bond, acoustic cement evaluation log, or density log after the casing is set and cemented.

65.5 At a minimum, the following information concerning the geologic formation shall be determined or calculated for new Class I wells:

65.5.1 Identification of the lowermost USDW. The applicant will be required to identify the base of the lowermost USDW at the injection well location. During construction, the applicant shall conduct tests and collect water samples, as needed, to identify the depth at which the TDS concentration of the aquifer exceeds 10,000 ppm. This demonstration shall be made using water samples, geophysical logs, drilling records and drill cuttings.

65.5.2 Demonstration of Confinement. The applicant shall conduct logging and testing as needed to demonstrate that the injected fluid will not migrate from the injection zone either vertically or horizontally into a USDW. The geologic layers overlying the injection aquifer shall serve as confining layers, preventing the upward movement of injected fluids into a USDW. Confinement shall be demonstrated using the appropriate geophysical logs, drilling records, cutting samples and core samples. Core samples shall be analyzed in a laboratory for porosity and vertical hydraulic conductivity.

65.5.3 Selection of Monitoring Zones. The applicant shall be required to monitor in the vicinity of the injection well bore for upward movement of injected fluid. During construction, the applicant shall identify at least two (2) monitoring zones. One zone shall be at the base of the lowermost USDW, and the second will be an early-warning monitor zone below the lowermost USDW and above the primary confining unit. The monitoring zones must have adequate water production to allow periodic sampling, and the applicant shall identify the zones and provide technical justification for their selection using drilling records, cutting samples and geophysical logs.

65.5.4 Characteristics of the Injection Formation:

65.5.4.1 Fluid pressure;

65.5.4.2 Temperature;

65.5.4.3 Fracture pressure;

65.5.4.4 Other physical and chemical characteristics of the injection matrix; and

65.5.4.5 Physical and chemical characteristics of the formation fluids.

65.6 In addition to complying with these regulations, all injection wells must be constructed in a manner that is in accordance with the State of Delaware Regulations Governing the Construction and Use of Wells.

65.7 For Class I injection well permit approval, reasonable assurance is required that the project will function in compliance with these Regulations. Prior to applying for a Class I injection well permit, an exploratory well must be drilled and documented on the project site. The Department shall require an exploratory well for projects located in an area where available information concerning geologic or hydraulic confinement is deficient; or where existing information indicates that geologic or hydraulic confinement may be poor or incomplete (See Section 68.0).

7 Del. Admin. Code § 7102-65.0

21 DE Reg. 978 (6/1/2018) (Final)