Idaho Admin. Code r. 58.01.13.200

Current through September 2, 2024

Section 58.01.13.200 - REQUIREMENTS FOR WATER QUALITY PROTECTION

The following design and performance standards are intended as the minimum criteria for protection of public health and waters. These standards apply to all facilities unless the Department determines that other site-specific criteria, including an alternative design approved under Section 205, are appropriate to protect water quality and the public health.

01.Professional Engineer. Plans and specifications for construction, alteration or expansion of any cyanidation facility must be prepared by or under the supervision of an Idaho licensed professional engineer and bear the imprint of the engineer's seal. Construction must be observed by an Idaho licensed professional engineer or a person under the supervision of an Idaho licensed professional engineer.

02.Plans and Specifications. Final plans and specifications for the construction of a cyanidation facility must be submitted to and approved by the Department before construction may begin. All construction must be in compliance with the plans and specifications approved by the Department. Within thirty (30) days of the completion of such construction, modification or expansion, complete and accurate plans and specifications depicting that actual construction, modification or expansion does not deviate from the original approved plans and specifications must be submitted to the Department.

03.Manufacturer's Specifications. Manufacturer's specifications for materials and equipment necessary to meet the requirements of Subsection 100.03.r. and Sections 200 through 205 for containment of process water must be submitted to the Department with the plans and specifications required in Subsection 200.02 before construction may begin.

04.Siting and Preparation. All cyanidation facilities including, but not limited to, the process building, laboratories, process chemical storage and containment facilities, plumbing fixtures that support process water, untreated or treated process water ponds, tailings impoundments, ore stock piles, and spent ore disposal areas must be appropriately sited and prepared for construction. Siting criteria must ensure that, at a minimum, the facilities are structurally sound and that containment systems can be adequately protected against factors such as wild fires, floods, land slides, storm water run-on, erosion, migrating stream channels, high ground water table, equipment operation, subsidence of underground workings, public access and public activities. All sites must be properly prepared prior to construction of foundations and facilities. Vegetation, roots, brush, large woody debris and other deleterious materials, top soil, historic foundations and plumbing, or other materials that may adversely affect appropriate construction and long term stability, must be removed from the footprint of the cyanidation facility unless approved by the Department.

05.Process Water Storage Sizing Criteria. All aspects of the cyanidation facility that entrain, utilize, treat, discharge, pump, convey, or otherwise contain process water, treated process water, or run-off water from any portion of the cyanidation facility must be included in the water balance. Each pond, tailings impoundment, and ditch containing process water must be designed to maintain a minimum two (2) foot freeboard during storage or conveyance of the design climatic events plus maximum expected normal operating levels. Leach pad design must provide containment of the maximum expected operating flows plus storm flows from the design climatic event. At a minimum, a cyanidation facility must be designed to contain the maximum expected normal operating water balance and the volume of run-on and run-off water associated with a climatic event that has a one percent (1%) annual exceedance probability. Snowmelt events will be considered in determining the maximum flow volume during the design climatic event. Contingency plans for managing excesses of all water included as a part of the water balance must be described in the water management strategy. Each structure that impounds process water or process-contaminated water must include a means of passing excess water unless otherwise approved by the Department.

06.Minimum Plans and Specifications. Unless the Department approves an alternative design under Section 205, the plans and specifications for any portion of a cyanidation facility that will contain process water must satisfy the applicable general design criteria in Subsection 200.06 and the design criteria in Sections 201 through 204 for the type of facility receiving process water. These provisions establish minimum pollutant control technologies and define the site and operating conditions that must be evaluated.

a. Cyanidation facility design must:

i. Minimize releases of pollutants into ground water or subsurface migration pathways so that any release will not cause unauthorized degradation of waters.

ii. Preclude any differential movement or shifting of the subgrade, soil layer, liner or contained material that endangers containment integrity as a result of the proposed range of operating conditions for each component and anticipated seismic activity at the site.

iii. Include additional containment of process water, as requested by the Department, in areas where ground water is considered to be near the surface. Ground water is considered to be near the surface if:

(1) The depth from the surface to ground water is less than one hundred (100) feet and the top one hundred (100) feet of the existing formation has a hydraulic conductivity greater than 10^-5 cm/sec;

(2) Open fractured or faulted geologic conditions exist in the bedrock from the surface to the ground water; or

(3) There is an inability to document that all borings beneath the cyanidation facility have been adequately abandoned.

iv. Not locate new process component containing process water within one thousand (1,000) feet of any dwelling that is occupied at least part of the year and not owned by the permittee. This does not apply to modifications at a facility that predates such a dwelling.

v. Include measures for preventing wildlife contact with process water having a WAD cyanide concentration in liquid fraction exceeding fifty (50) mg/L. The Department may require additional measures if wildlife mortality is observed.

vi. Implement measures to protect birds, other wildlife and livestock from adverse effects of cyanide process water and other pollutants.

vii. Include a quality assurance/quality control plan for the construction of containment systems that provides a process for documenting owner acceptance of all underlying components of the containment system prior to construction of the overlying components.

b. Liner systems must:

i. Have a structurally stable subgrade for the overlying components and contained material. The subgrade should be constructed to resist consolidation, excessive differential settlement that compromises liner performance, and uplift resulting from pressures inside or outside the containment unit to prevent distortion of overlying components.

ii. Have a smooth rolled and compacted soil layer, or equivalent layer approved by the Department, in intimate contact with the overlying geomembrane liner with the following characteristics:

(1) A minimum thickness of twenty-four (24) inches compacted to ninety-five percent (95%) of maximum dry density according to Standard Proctor Test ASTM D698 or Modified Proctor Test ASTM D1557;

(2) Soil placed in a minimum of four (4) lifts that each have a compacted thickness of six (6) inches and a hydraulic conductivity less than or equal to 10^-6 cm/sec;

(3) An uppermost lift of soil that does not contain particles in excess of point seven five (0.75) inches (nineteen (19) mm) in largest dimension unless larger particles are consistent with the manufacturer's specifications for the overlying liner and approved by the Department;

(4) No putrescible, frozen, or other deleterious materials.

(5) No angular, sharp material regardless of diameter; and

(6) Soil placed within two percent (2%) of optimum moisture content to achieve the specified compaction and hydraulic conductivity.

iii. Include the following if an equivalent layer replacing the soil layer described in Subsection 200.06.b.ii. is proposed:

(1) A layer that is not a geomembrane and has a liquid flow rate no greater than that of twenty-four (24) inches of compact soil with a hydraulic conductivity less than or equal to 10^-6 cm/sec;

(2) Materials with appropriate chemical properties and sufficient strength and thickness to prevent failure due to pressure gradients (including static head and external hydrogeologic forces), physical contact with the waste, process water, or process-contaminated water to which they are exposed, climatic conditions, the stress of installation, and the stress of daily operation;

(3) Materials that provide appropriate shear resistance of the upper and lower component interface to prevent sliding of the upper component including on slopes;

(4) Certification from an Idaho licensed professional engineer that the liquid flow rate per unit area through the equivalent layer is no greater than the liquid flow rate through two (2) feet of compacted soil with a hydraulic conductivity less than or equal to 10^-6 cm/sec, considering the maximum hydraulic head anticipated on the liner system and the thickness of the equivalent layer replacing the two (2) feet of compacted soil; and

(5) Plans and specifications for an equivalent layer that substantially reflect the manufacturer's specifications and standards for construction, operation and maintenance unless otherwise approved by the Department.

iv. Include geomembrane liners consisting of high density polyethylene, linear low-density polyethylene, or equivalent, rated as having a resistance to the passage of process water equal to or less than a hydraulic conductivity of 10^-11 cm/sec. Each geomembrane liner will be constructed of materials with appropriate chemical properties and sufficient strength and thickness to prevent failure due to pressure gradients (including static head and external hydrogeologic forces), physical contact with the waste or leachate to which they are exposed, climatic conditions, the stress of installation, and the stress of daily operation and permanent closure.

v. Be constructed according to manufacturer's standards, or Department-approved design standards, and protect against damage from cracking, sun exposure, ice, frost penetration or heaving, wildlife, wildfires, and damage that may be caused by personnel or equipment operating in or around these facilities.

vi. Have an appropriate coefficient of friction against sliding plus a factor of safety for each interface constructed on a slope.

vii. Have minimum factors of safety, and the logic behind their selection, for the stability of the earthworks and the lining systems.

viii. Include redundant systems for failures in primary power or pumping systems.

ix. Have liner material that meets the manufacturer's quality assurance/quality control performance specifications.

07.Process Buildings, Process Chemical Storage Containment Areas and General Facility Criteria. Storage, handling and use of all process chemicals, process wastes, process water and pollutants associated with the cyanidation facility must be conducted within a clean, safe and secure work space to prevent unauthorized discharges to soils, ground water or surface water. The plans and specifications must contain sufficient detail, including pump capacity and plumbing for evacuation of collection sumps, triggering systems for sump evacuation, and monitoring and reporting requirements and, where appropriate, provide for:

a. Structural integrity of the foundation, walls and roof for process and process chemical storage buildings;

b. Restriction of public access;

c. Protection of wildlife;

d. Internal sumps and spill cleanup plans;

e. Grouted and sealed concrete stemmed walls and floors in the process buildings and process chemical storage and containment facilities;

f. Vapor barriers and frost protection;

g. Segregation of process chemicals according to compatibility;

h. Communication systems;

i. Fire suppression systems, internal and external; and

j. Quality assurance/quality control for construction activities and construction materials.

08.Cap and Cover Criteria. Caps and covers used as source control measures for facilities must be designed and constructed to minimize the interaction of meteoric waters, surface waters, and ground waters with wastes containing pollutants that are likely to be mobilized and discharged to waters. Caps and covers designed for permanent closure must demonstrate permanence applicable to the permittee's designed and approved permanent closure plan.

09.Plumbing and Conveyance Criteria. Plumbing and conveyance systems must:

a. Be structurally sound and chemically compatible with the materials being conveyed;

b. Provide adequate primary and secondary containment; and

c. Be protected against heat, cold, mechanical failures, impacts, fires, and other factors that may cause breakage and result in unauthorized discharges.

10.Operation and Maintenance Plans. Operation and maintenance plans must be submitted to the Department for review and approval. Operation and maintenance plans must include, but are not limited to:

a. An overall plan that includes techniques for evaluating the integrity and performance of all containment systems;

b. Schedule for inspections of all containment systems;

c. Schedule for inspections on piping and conveyance systems that carry process water;

d. Response plans that detail specific actions that will result in mitigation of compromised or damaged containment systems; and

e. Response plans that detail specific thresholds identified under Subsection 200.11, the locations and frequency at which the thresholds will be monitored, and actions that will result in mitigation of an exceedance of any threshold.

11.Water Quality Monitoring and Reporting. The water quality monitoring plan submitted with the application must be reviewed and, if appropriate, approved by the Department. The approved water quality monitoring plan must:

a. Provide for physical, chemical and biological monitoring, including measurements of surface water flow, wildlife and bird mortality, and aquatic indicator species in potentially affected surface and ground water, as appropriate;

b. Provide for sampling locations and frequency;

c. Provide an assessment of the existing surface and ground water conditions prior to construction of the proposed cyanidation facility;

d. Be site specific and dependent on location, design and operation of the cyanidation facilities included in the overall operating plan;

e. Specify compliance points and associated water quality compliance criteria;

f. Specify monitoring points and threshold concentrations that provide for early detection of discharges of pollutants;

g. Provide analytical methods and method detection limits for chemical analysis used in the determination of water quality;

h. Provide a quality assurance quality control plan for data collection and analysis;

i. Provide for appropriate and timely analytical data analyses including evaluations of water quality and quantity trends;

j. Provide an annual environmental monitoring and data analysis report of water quality and quantity trends;

k. Provide for the reporting and re-sampling of monitoring locations where detectable and statistically significant changes in water quality are found. The permittee must propose a statistical method to determine the significance of the changes in water quality; and

l. Provide for anticipated changes or modifications to monitoring plans, which may be the result of a phased approach to cyanidation facility construction, operations and permanent closure.

12.Monitoring Wells Siting and Construction Plans. The applicant is encouraged to submit a report describing the purpose, objectives, location and proposed construction of monitoring wells to the Department for review and comment during the initial stages of site characterization. A monitoring well siting and construction plan must be provided upon submittal of the preliminary design report under Subsection 050.02.

a. Monitoring well siting and construction plans must provide for the following.

i. A quality assurance/quality control plan for well construction.

ii. A minimum of three (3) monitoring wells with one (1) located up gradient and two (2) located down gradient of primary components of the cyanidation facility to determine ground water flow direction.

b. Siting and planning for additional wells or replacement wells may be required in the permit application and final permit. Specifically, additional wells may be required for:

i. Large areas with multiple potential sources for pollutants;

ii. Areas with complex geology, fractured bedrock; and

iii. Areas with insufficient background hydrogeology.

c. All monitoring well construction must also conform to the well construction rules listed in IDAPA 37.03.09, "Well Construction Standards Rules."

d. Record diagrams including well construction details, well elevation and a detailed geologic log must be provided to the Department for each monitoring well.

13.Land Application. Plans and specifications must include:

a. An operation and maintenance plan including:

i. Water balance for the land application site;

ii. Pretreatment requirements and procedures;

iii. Operating season for land application;

iv. Seasonal closeout procedures;

v. Special soils or vegetative amendments;

vi. Storm water run-on/run-off controls;

vii. Best management practices for all areas impacted by the land application system; and

viii. A topographic map of the land application site and adjacent affected areas, of sufficient scale to facilitate site-specific analysis of soils, vegetation, surface water, and ground water;

b. Chemical, physical, and volumetric characteristics of the material to be land applied;

c. A complete description of the chemical and physical characteristics of the soils and applicable geology of the land application site;

d. Methods of process water treatment, distribution and disposal;

e. Hydraulic loading capacity of the soils;

f. Constituent loading capacity of the site;

g. Attenuation capacity of the vegetative covers and soils;

h. Evapotranspiration capacity of the site;

i. Testing and analytical procedures for water quality and soils samples prior to, during, and following the land application process;

j. Trend analysis of the constituent loading in the affected soils, vegetation, and water quality of the affected surface or ground water systems;

k. Reporting requirements including both frequency and form; and

l. Standby power and pumps sufficient to maintain all treatment and distribution works.

14.Temporary or Seasonal Closure. Temporary and seasonal closure plans for the entire cyanidation facility must be submitted by an applicant to the Department for review and approval prior to issuance of a final permit. Temporary and seasonal closure plans may, subject to Department approval pursuant to Section 750, be modified to provide for changes in operating conditions of the facilities and must incorporate a water management plan for the period of inactivity as well as during shut down and reactivation.

a. Prior to seasonal closure, process buildings, process chemical storage, process water ponds, tailings impoundments, spent ore disposal areas and other ancillary facilities must be stabilized and/or conditioned to prevent any emergency or unauthorized discharges to surface or ground water.

b. Subsequent to seasonal closure, process buildings, process chemical storage, process water ponds, tailings impoundments, spent ore disposal areas and other ancillary facilities must be maintained to prevent any emergency or unauthorized discharges to surface or ground water. Cyanidation facilities must be conditioned and maintained to provide:

i. Material stabilization for all solids affected by process waters;

ii. Optimum freeboard in all ponds, as dictated by the water management plan;

iii. Fully functional power and pumping systems that are ready for use; both power and pumps are to incorporate redundant systems to allow for failure of either power or a pumping system. A failed power supply or pump is not an acceptable reason for an unauthorized discharge;

iv. Protection of all containment; and

v. Sufficient availability of qualified staff to restrict public access, fully implement the water quality monitoring plan, and initiate the emergency and spill response plan.

15.Employee Education Program. Operators and staff of facilities must be properly oriented and trained to operate, maintain, and protect containment systems; waste disposal and discharge systems; and to implement monitoring and emergency and spill response plans. An applicant must submit an employee orientation and continuing training plan to the Department for review prior to issuance of a final permit. The plan must provide the format and contents for training, the general qualifications of the person(s) responsible for training and testing, and the person(s) or positions who must receive such training.

Idaho Admin. Code r. 58.01.13.200

Effective March 24, 2022