Arizona Administrative Code
Title 18 - ENVIRONMENTAL QUALITY
Chapter 9 - DEPARTMENT OF ENVIRONMENTAL QUALITY - WATER POLLUTION CONTROL
Article 3 - AQUIFER PROTECTION PERMITS - GENERAL PERMITS
Part D - TYPE 3 GENERAL PERMITS
Section R18-9-D304 - 3.04 General Permit: Non-stormwater Impoundments at Mining Sites

Universal Citation: AZ Admin Code R 18-9-D304

Current through Register Vol. 30, No. 38, September 20, 2024

A. A 3.04 General Permit allows discharges to lined surface impoundments, lined secondary containment structures, and associated lined conveyance systems at mining sites.

1. The following discharges are allowed under the 3.04 General Permit:
a. Seepage from tailing impoundments, unleached rock piles, or process areas;

b. Process solution temporarily stored for short periods of time due to process upsets or rainfall, provided the solution is promptly removed from the facility as required under subsection (D);

c. Stormwater runoff not permitted under A.R.S. § 49-245.01 because the facility does not receive solely stormwater or because the runoff is regulated but not considered stormwater under the Clean Water Act; and

d. Wash water specific to sand and gravel operations not covered by R18-9-B301(A).

2. Facilities that continually contain process solution as a normal function of facility operations are not eligible for coverage under the 3.04 General Permit. If a normal process solution contains a pollutant regulated under A.R.S. § 49-243(I) the 3.04 General Permit does not apply if the pollutant will compromise the integrity of the liner.

B. Notice of Intent to Discharge. In addition to the Notice of Intent to Discharge requirements specified in R18-9-A301(B), an applicant shall submit:

1. A description of the sources of inflow to the facility. An applicant shall include a representative chemical analysis of expected sources of inflow to the facility unless a sample is not available, before facility construction, in which case the applicant shall provide a chemical analysis of solution present in the facility to the Department within 90 days after the solution first enters the facility;

2. Documentation demonstrating that the facility design and operation under subsections (C) and (D) have been reviewed by a mining engineer or an Arizona-registered professional engineer before submission to the Department; and

3. A contingency plan that specifies actions proposed in case of an accidental release from the facility, overtopping of the impoundment, breach of the berm, or unauthorized inflows into the impoundment or containment structure.

C. Design, construction, and installation requirements. An applicant shall:

1. Design and construct the impoundment or secondary containment structure as specified under R18-9-D301(C)(1);

2. Ensure that conveyance systems are capable of handling the peak flow from the 100-year storm;

3. Construct the liner as specified in R18-9-D301(C)(4)(a);

4. Develop and implement a Quality Assurance/Quality Control program that meets or exceeds the liner manufacturer's guidelines. The program shall address site and subgrade preparation, inspection procedures, field testing, laboratory testing, repair of seams during installation, and final inspection of the completed liner for functional integrity;

5. If the facility is located in the 100-year flood plain, design the facility so it is protected from damage or flooding as a result of a 100-year, 24-hour storm event;

6. Design and manage the facility so groundwater does not come into contact with the liner;

7. Ensure that the facility design addresses any significant geologic hazard relating to static and seismic stability. The applicant shall document any design adjustments made for this reason in the Notice of Intent to Discharge;

8. Ensure that the site preparation includes, as appropriate, clearing the area of vegetation, grubbing, grading, and embankment and subgrade preparation. The applicant shall ensure that supporting surface slopes and foundation are stable and structurally sound;

9. Ensure that the liner is anchored by being secured in an engineered anchor trench. If regularly exposed to sunlight, the applicant shall ensure that the liner is ultraviolet resistant; and

10. Use compacted clay subgrade in areas with shallow groundwater conditions.

D. Operational requirements. The permittee shall:

1. Maintain the freeboard required in subsection (C)(1) through design, pumping, or both;

2. Remove accumulated residues, sediments, debris, and vegetation to maintain the integrity of the liner and the design capacity of the impoundment;

3. Perform and document a visual inspection for cracks, tears, perforations and residual build-up at least monthly. The operator shall conduct and document an inspection after the facility receives significant volumes of stormwater inflow;

4. Report cracks, tears, and perforations in the liner to the Department, and repair them as soon as practical, but no later than 60 days under normal operating conditions, after discovery of the crack, tear, or perforation;

5. For facilities that temporarily contain a process solution due to process upsets, remove the process solution from the facility as soon as practical, but no later than 60 days after cessation of the upset; and

6. For facilities that temporarily contain a process solution due to rainfall, remove the process solution from the facility as soon as practical.

E. Recordkeeping. A permittee shall maintain the following information for at least 10 years and make it available to the Department upon request:

1. Construction drawings and as-built plans, if available;

2. A log book or similar documentation to record inspection results, repair and maintenance activities, monitoring results and facility closure;

3. Capacity design criteria;

4. A list of standard operating procedures;

5. The Quality Assurance/Quality Control program required under subsection (C)(4); and

6. Records of any unauthorized flows into the impoundment.

F. Reporting requirements.

1. If the liner is breached, as evidenced by a drop in water level not attributable to evaporation, or if the impoundment breaches or is overtopped due to a catastrophic or other significant event, the permittee shall report the circumstance to the Department within five days of discovery and implement the contingency plan required in subsection (B)(3). The permittee shall submit a final report to the Department within 60 days of the event summarizing the circumstances of the problem and corrective actions taken.

2. The permittee shall report unauthorized flows into the impoundment to the Department within five days of discovery and implement the contingency plan required in subsection (B)(3).

G. Closure requirements.

1. The permittee shall notify the Department of the intent to close the facility permanently.

2. Within 90 days following closure notification the permittee shall comply with the following requirements, as applicable:
a. Remove liquids and any solid residue on the liner and dispose appropriately;

b. Inspect the liner for evidence of holes, tears, or defective seams that could have leaked;

c. If evidence of leakage is discovered, remove the liner in the area of suspected leakage and sample potentially impacted soil. If soil remediation levels are exceeded, the permittee shall, within 60 days notify the Department and submit an action plan for the Department's approval before implementing the plan;

d. If there is no evidence of holes, tears, or defective seams that could have leaked:
i. Cover the liner in place or remove it for disposal or reuse if the impoundment is an excavated impoundment,

ii. Remove and dispose of the liner elsewhere if the impoundment is bermed, and

iii. Grade the facility to prevent the impoundment of water; and

3. Notify the Department within 60 days following closure that the action plan has been implemented and the closure is complete.

Disclaimer: These regulations may not be the most recent version. Arizona may have more current or accurate information. We make no warranties or guarantees about the accuracy, completeness, or adequacy of the information contained on this site or the information linked to on the state site. Please check official sources.
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