DWQ-2024-007418

GROUND WATER QUALITY DISCHARGE PERMIT UGW350017
STATEMENT OF BASISKennecott Utah Copper LLC (Kennecott)Copperton Concentrator
South Jordan, Utah
October2024
Introduction
The Division of Water Quality (DWQ) under the authority of the Utah Ground Water Quality Protection Rules 1(Ground Water Rules) issues ground water discharge permits to facilities which
have a potential to discharge contaminants to ground water2. As defined by the Ground Water Rules, such facilities includeminingoperations.3The Ground Water Rules are based on an anti-degradation
strategy for ground water protection as opposed to non-degradation; therefore, discharge of contaminants to ground water may be allowed provided that current and future beneficial uses
of the ground water are not impaired and the other requirements of Rule 317-6-6.4.A are met.4 Following this strategy, ground water is divided into classes based on its quality5; and
higher-quality ground water is given greater protection6 due to the greater potential for beneficial uses.
DWQ has developed permit conditions consistent with R317-6 and appropriate to the nature of the mined materials, facility operations, maintenance, best available technology7 (BAT) and
the hydrogeologic and climatic conditions of the site, to ensure that the operation would not contaminate ground water. Basis for Permit RenewalThis Permit is being renewed in accordance
with R317-6-6.8 which states that a permit may be terminated or a renewal denied if any one of the four items below applies:Noncompliance by the permittee with any condition of the Permit
where the permittee has failed to take appropriate action in a timely manner to remedy the Permit violation;The permittee’s failure in the application or during the Permit approval process
to disclose fully all significant relevant facts at any time;A determination that the permitted facility endangers human health or the environment and can only be regulated to acceptable
levels by plan modification or termination; orThe permittee requests termination of the Permit.Basis for Modification and Permit Issuance
Under Rule 317-6-6.4A, DWQ may issue a ground water discharge permit if:
The applicant demonstrates that the applicable class TDS limits, ground water quality standards protection levels and permit limits established under R317-6-6.4E will be met;
The monitoring plan, sampling and reporting requirements are adequate to determine compliance with applicable requirements;
The applicant is using best available technology to minimize the discharge of any pollutant; and
There is no impairment of present and future beneficial uses of ground water.
Permit Changes and Modifications
Management RevisionsIn addition to renewal, the following facilities are included and will be regulated under thisPermit including the associated Best Available Technology (BAT, Table
2), Permit limits and requirements for monitoring, release reporting (Table 2A) and cleanup (Appendix A).
The 48-inch and 60-inch tailings lines, along with associated vent stacks, drop boxes, bubble dissipaters, and splitter box;
the 48-inch buried steel process water return line;
the 3B surge basinand;
Monitoring and tracking of process water flows into and out of Retention PondsIII and IV located at the eastern footprint of the Copperton Concentrator
The tailings pipeline system consists of two, approximately 13-mile parallel pipelines that deliver whole tailings slurry to the north splitter box. The tailings lines (48-inch and
60-inch) convey tailings slurry from the Copperton Concentrator north to the tailings impoundment using a gravity flow system. The gravity flow system requires the tailings lines to
have open vent stacks along the pipeline to ensure proper hydraulic fluid flow. The vent stacks are also used as inspection ports and access points for monitoring and cleaning activities
associated with the tailings line preventative maintenance program. The tailings lines also incorporate a series of drop boxes along the length of the corridor. The drop boxes reduce
the velocity of the tailings slurry and adjust for elevation change along the corridor.
The process water return system extends from the Magna Reservoir to the Copperton Concentrator. This system consists of Pump Stations 3A and 3B, approximately 12 miles of 48-inch diameter
steel with reinforced concrete pipeline, and associated infrastructure. Pump Station 3B is a booster station that is located mid-line and incorporates a concrete surge basin to buffer
pump operations and process upsets as well as provide adequate suction head pressure to the booster pumps. The surge system at Pump Station 3B provides water storage above the pump
station to maintain minimum pump suction inlet pressure, provide reserve capacity to buffer pump starts and stops between the pump stations, and absorb surges from upset conditions.
The pumping system hydraulics cause pressure surges and pressure spikes with each start and stop. The system is designed to absorb these changes in pressure.
Retention Ponds I to IVare permitted to receive storm water and process water upset flow as listed in Table 2 and are clay lined with a pump out performance standard. Retention pond
IV can receive excess flow from the Byron Jackson Pump Station. In the past, excess overflow from the pump station hasalso been sent to the tailings lines with the potential to cause
surge events of water in the tailings lines. Those surges could trigger tailings line releases. To minimize any potential for future events related to these surges, modifications have
been made that limit flows from the pump station to the tailings lines. As part of this enhanced water management, process water that is routed to Retention Pond IV is now pumped out
in less than seven days and redirected in a controlled fashioninto the tailings lines.Compliance ScheduleKennecott has complied with all prior compliance schedule obligations including
the installation of nine monitoring wells which are specifically identified in this permit renewal. During the previous permit term, the Contaminant Investigation was completed and a
Potential Corrective Action with a Ground Water Compliance Monitoring Plan was submitted on September 14, 2020 and approved by DWQ on October 22, 2020. This approved plan is incorporated
by reference as part of this permit renewal.BackgroundPermit HistoryThe Ground Water Discharge Permit Application for the facility was initially submitted to DWQ in October 2000 (Kennecott
Utah Copper, 2000). UGW350017 was initially issued to Kennecott Utah Copper in 2004 in accordance UAC R317-6-6.4. The Permit was most recently renewed in 2017. This is the fourth
renewal of the UGW350017Permit. To assure adequate ground water quality protection, the facility was designed to employ discharge minimization and control technology with ground water
monitoring to prevent any impairment of present and future beneficial uses of the ground water.
Compliance monitoring for this facility is a combination of ground water monitoring and periodicinspections. Ground water monitoring is performed at wells located downgradient of the
concentrator and tailings lines; monitoring parameters, and protection limits are listed in Table 1 of the Permit. Inspections are conducted at tanks, pumps, ponds, pipes, and reservoirs
to verify the condition and operation of the equipment, and identify and correct maintenance issues that could lead to a release of process fluids to the environment. Appendix A of
the Permit is the Process Material Pipeline Spill Prevention, Minimization, and Response Plan and describes maintenance and inspection procedures for pipelines as well as spill clean-up
procedures.
Description of Facility
The Copperton Concentrator and tailings lines facilities are comprised of:
The coarse ore stockpile and grinding mill;
Copper-Molybdenite flotation, concentrate re-grind and concentrate thickening tanks;
Molybdenite recovery plant;
Copper concentrate and tailings thickening tanks;

Water supply reservoir;
The 48-inch and 60-inch tailings lines, along with associated vent stacks, drop boxes, bubble dissipaters, and splitter box;
the 48-inch buried steel process water return line;
the 3B surge basin;
the tailings line launder; and
other associated facilities including those identified in the Permit (e.g., Table 2).
Figure 1 provides a generalized overview of the facility.
The Copperton concentrator was completed in 1988. Modernization and expansion of the facility was completed in 1992 and was designed to process a capacity of 200,000 tons of ore per
day. Ore is transported from the Bingham Mine via a conveyor belt to the coarse ore stockpile. The ore is fed to Semi-Autogenous Grinding (SAG) mills which crush the ore for separation
and floatation to concentrate metal recovery. Tailings are slurried via a 13 mile pipeline to the tailings impoundment adjacent to the Great Salt Lake.Water used by the Copperton facilities
is acquired from the Process Water Reservoir (PWR) and various storage tanks. The PWR is a two chamber lined reservoir with a 7.5 million gallon capacity. The sources of water for
the PWR are reclaim water from the tailings pond and smelter via the process water return line, thickener overflow, molybdenite plant effluent, north end surface drainage and springs,
existing deep wells and the Bingham Tunnel. The concentrator facilities require approximately 55,000 gpm for milling purposes.Hydrogeologic and site conditions
The Copperton Concentrator facilities, including the process water and tailings pipelines, are located predominantly on bedrock with portions in unconsolidated valley-fill alluvium at
the base of the Oquirrh Mountains. The process water and tailings pipelines are in a corridor running north south along the Oquirrh Mountains, extending approximately 13 miles between
the Copperton Concentrator and tailings impoundment adjacent to the Great Salt Lake (Figure 2). The base of the Oquirrh Mountains constitutes a portion of the primary recharge area
of the principal, basin–fill (alluvial) aquifer of the Salt Lake Valley (Anderson, et al., 1994, pg. 23 and Plate 4). Hydrogeologic conditions along the 13 mile pipeline corridor vary
due to the geologic complexities summarized above.
There are no perennial streams near these facilities and surface water runoff only exists during high intensity storms or snow melt.
There are two aquifers in the vicinity of the Copperton Concentrator facilities, the bedrock and principal alluvial. The bedrock aquifer is composed of Paleozoic sandstones and quartzite
and Tertiary volcanic rocks. Flow within the bedrock aquifer is assumed to be primarily by fracture flow and provides recharge to the overlying principal aquifer.
The principal aquifer is unconfined and composed of interbedded volcanic and quartzitic gravels, clays and cemented gravels. The principal aquifer extends eastward from the foot of
the Oquirrh Mountains and is bounded at its base by the Jordan Narrows formation. Aquifer thickness increases to the east, thins to the north and remains fairly constant to the south.
Near the concentrator the principal aquifer is approximately 150 feet thick. Two production wells owned by Copperton Improvement District, approximately one-half mile northeast from
the concentrator, are used as a source of drinking water for the town of Copperton. The wells are screened in volcanic gravels of the principal aquifer. The area around the Copperton
Concentrator provides recharge to the principal aquifer of the Jordan Valley.
In the Salt Lake Valley ground water flow is generally from the mountain front toward the Jordan River. Ground water flow from the Copperton Concentrator facilities and pipeline corridor
is generally east and turns north in the vicinity of the Bennion area and as water moves closer to the Great Salt Lake (Anderson, et al., 1994 pgs. 23-24, Figure 12). The concentrator
has three wells for culinary and fire use. The wells are screened in the bedrock aquifer South and southwest of the Copperton Concentrator. To the north, downgradient (east) of the
tailings pipeline corridor, a variety of private water supply wells and municipal production wells are present including those that serve the Kearns Improvement District, Magna, and
West Jordan.
Background Ground Water QualityOnly limited data are available regarding background water quality in the vicinity of the pipelines to be permitted. One of the purposes of the Compliance
Monitoring Plan and the Contaminant Investigation Plan is to obtain additional data to inform DWQ’s future permitting and enforcement decisions as to this facility. Ground water in the
immediate area of the Copperton Concentrator is not classified. The water quality for the principal basin-fill aquifer of the Salt Lake Valley has been classified by the Utah Geological
Survey (Wallace and Lowe, 2008) and is generally Class II Drinking Water Quality downgradient of the Copperton Concentrator facilities (refer to Figure 3) with TDS values that range
from 512 to 2588 mg/L. There is an area of Class IA Pristine Ground Water (TDS < 500 mg/L) near Kearns and UT Hwy 173. The area north of Hwy 201 is Class III, Limited Use Ground Water
(TDS values >3000 mg/L).Additional aquifer characterization is required for DWQ to better understand whether the pipeline facilities may potentially impact these groundwater resources.A
history of releases over the previous several permit terms has resulted in several Notices of Violation (NOV) and Enforcement Actions. These NOVs and compliance orders have resulted
in changes to operations and maintenance of the concentrator and process water lines and pumps. These changes have largely been effective in minimizing the scale and frequency of releases
from either portion of the pipeline and the concentrator itself. As a result of these releases, Kennecott has fully complied with the permit and R317-6-6.8 requirements and has demonstrated
that these previous releasesdid not impact groundwater.
Basis for Specific Permit Conditions
Best Available Technology and Performance Monitoring
Best Available Technology (BAT) is defined in R317-6-1.3 as "... the application of design, equipment, work practice, operation standard or combination thereof at a facility to effect
the maximum reduction of a pollutant achievable by available processes and methods taking into account energy, public health, environmental and economic impacts and other costs." For
this Permit BAT is implemented through a discharge minimization approach with a monitoring component to assess impacts to ground water quality from the operation of the Copperton Concentrator
facilities. This approach is coupled with the use of appropriate containment technology for process waters associated with the operation of the facility.
BAT includes concrete process fluids basins, HDPE lined process water ponds and asphalt lined storage pads. Table 2 in the Permit lists the BAT, including the function, containment,
inspection and work practice for each facility covered by the Permit. Kennecott conducts periodic inspections throughout the facility to document proper operation of all structures
that have the potential to release process fluids. In addition, the entire length of the tailings line corridor is driven twice daily to inspect for leaks from tailings lines, vents,
and drop boxes. A spill of any volume reaching a drainage bottom as identified onFigure 4 is reported to DWQ within 24 hours.
Performance (BAT) and Ground Water Monitoring
Performance monitoring is a requirement for each facility in the Permit and has been established for each permitted facility listed in Table 2 and Appendix A. For therecently installed
Permitted pipelines, ground water monitoring wells were installed to establish compliance monitoring in accordance with R317-6-6.4.C.2 and R317-6-6.9A. These compliance points serve
the purpose of monitoring for potential impacts to ground water resulting from permitted releases along the pipelines, unpermitted releases from the pipelines, and undetected releases
resulting from joint settlement, cracks, and other potential pipeline failures. As discussed above, limited data are available regarding background water quality in the vicinity of the
new facilities. The intent of the Compliance Monitoring and the Contaminant Investigation Plans is to obtain additional data to inform DWQ’s future decisions regarding BAT performance
and any necessary ground water monitoring.
Permit Limits for New/Pipeline Wells
Permit Limits will be established on a well-by-well basis for each new ground water monitoring well installed to monitor the tailings/process water pipelines. Permitted releases from

the pipelines are considered to have a de minimis actual or potential effect on ground water quality. As a result, Permit limits will be established as the background concentrations
in the monitoring well.
Contaminant Investigation
A contaminant investigation was completed as part of the previous permit to assess if there have been any ground water impacts associated with prior releases from thetailings and process
water pipelines in accordance with R317-6-6.15 and characterized the nature and extent of any pollutants resultingfrompastreleases.List of figures
1)Copperton Concentrator Site Map
2)Tailings Pipeline Corridor Location Map
3)Salt Lake Valley Aquifer Classification Map
4)Drainage Bottoms Map
references
Anderson, P.B., Susong, D.D., Wold, S.R., Heilweil, V.M., and Baskin, R.L., 1994, Hydrogeology of Recharge Areas and Water Quality of the Principal Aquifers Along the Wasatch Front and
Adjacent Areas, Utah: U.S. Geological Survey Water-Resources Investigations Report 93-4221
Kennecott Utah Copper, 2000, Copperton Concentrator Ground Water Discharge Permit Application, October, 2000: DWQ files, DWQ-2000-001101
Wallace, J. and Lowe, M., 2008,Ground-Water Quality Classification for the Principal Basin-Fill Aquifer, Salt Lake Valley, Salt Lake County, Utah: Utah Geological Survey, August, 2008