DWQ-2025-001295

Appendix I Permit # UGW350010
Operations & Maintenance Manual South Waste Rock Reclamation Detention Basins
Rio Tinto Kennecott Copper

Operations and Maintenance Manual
South Waste Rock Reclamation Detention Basins

Groundwater Discharge Permit #UGW350010
Bingham Canyon Mine and Water Collection System

November 2018
Revision 2

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Contents
1.0 Context and Purpose ........................................................................................................... 1
1.1 Context ............................................................................................................................. 1
1.2 Purpose ............................................................................................................................ 1
1.3 Disclaimer ......................................................................................................................... 1
2.0 Design & Operation .............................................................................................................. 2
2.1 General Overview ............................................................................................................. 2
2.2 Detention Basin Specifications ......................................................................................... 4
2.3 Cut-off Wall Design ........................................................................................................... 5
3.0 Inspection & Maintenance .................................................................................................... 6
3.1 Overview .......................................................................................................................... 6
3.2 Basin Components ........................................................................................................... 6
3.2.1 Rock Weir: ................................................................................................................. 8
3.2.2 Outlet Structure: ......................................................................................................... 8
3.2.3 Pipe Outlets: .............................................................................................................. 8
3.2.4 Rip Rap Overflow Weir: .............................................................................................. 8
3.2.5 Distribution Boxes: ..................................................................................................... 8
3.3 Cut-off Wall Components .................................................................................................. 9
3.3.1 Concrete Wall, Box and Valves .................................................................................10
3.3.2 Finger Drains and Contact Water Capture at Cut-off Wall .........................................10
3.3.3 Storm Water Conveyance .........................................................................................10
3.4 Inspection Checklist: ........................................................................................................10
3.5 Sediment Removal ..........................................................................................................11
4.0 Training ...............................................................................................................................11
5.0 Reference Information .........................................................................................................12
5.1 UDWQ Construction Permit .............................................................................................12
5.2 Dam Safety Permit ..........................................................................................................12
5.3 Groundwater Discharge Permit ........................................................................................12
5.4 Project Contacts ..............................................................................................................12
6.0 Revision History ..................................................................................................................13

Appendices
A. Detention Basin As-Built Specifications (Hardcopy & CD)
B. As-Built Survey & Drawings (Hard Copy & CD)
C. Inspection Checklist (Hard Copy & CD)
D. Photo Documentation (CD)
E. Hydro Report (CD)
F. Data Files (DWG & XML) (CD)
G. Quality Assurance Reports (CD)
H. Operations & Maintenance Manual (CD)

1.0 Context and Purpose
1.1 Context
Rio Tinto Kennecott Copper (RTKC) and the Bingham Canyon Mine are required to effectively
manage surface water, sediment and debris associated with the waste rock dumps on property.
These requirements are outlined in detail under the applicable permits associate with the
operation. The agencies and permits are listed in Table 1.
Table 1. Applicable Operating Permits Related to Surface Water Management
Agency Permit
Utah Department of Environmental Quality -
Division of Water Quality
Groundwater Discharge Permit No.
UGW350010 Bingham Canyon Mine and Water Collection System
Utah Department of Environmental Quality -
Division of Water Quality
UPDES Permit No. UT0000051
Storm Water Pollution Prevention Plan
Utah Department of Natural Resources - Division of Oil, Gas and Mining Permit No. M/035/0002 Mining and Reclamation Plan

In order to better meet our obligations to the public and regulatory agencies related to surface
water management along the vicinity of the Bingham Canyon Mine south dump, the detention
basins were designed and constructed between the fall of 2014 and fall of 2017. The effort
increases basin capacity in conjunction with waste rock placement and subsequent reclamation
activities thereby decreasing the risk of offsite release of waste rock contact water, sediment
and debris.
1.2 Purpose
This Operations and Maintenance manual is designed to provide the operator with clear
instructions and reference material for the proper care and upkeep of the detention basins
associated with the south end waste rock placement facilities.
1.3 Disclaimer
This operation and maintenance manual was created to 1) fulfill the construction permit
condition for basins constructed during 2014 through 2017 requiring an O&M manual in order to
operate the system and 2) provide general guidance to the South Area Water Services (SAWS)
operators and maintenance staff as part of the handover of the newly constructed basins. This
manual is not all inclusive of the Bingham Canyon Mine Water Collection System originally
constructed in the mid 1990’s and modified in 2016 which included toe drains, french drains,
cut-off walls, detention basins, and associated system of piping from Bingham Canyon to Queen
cut-off wall.

1

2.0 Design & Operation
2.1 General Overview
The basins are designed to 1) receive surface water and sediment off the face of the dump and
2) passively move alluvial and waste rock contact water (WRCW) through the basin system
where the waters are conveyed by pipe via gravity to the cut-off wall where the water then
continues via pipe to the east side collection pipe and ultimately the Process Plant and/or Large
Reservoir.
Key basin design criteria and operation:
• The basins are designed and sized appropriately to manage precipitation events above
the cut-off wall for ≥25 year-24 hour rain event. In addition, basin capacity has been
established below the cut-off wall so that the composite capacity for each respective
drainage is ≥100 year-24 hour rain event;
• If the precipitation event is within the design criteria, basins are designed to route all
water through the east side collection system piping;
• The basins are designed to gravity drain within a 24 hour period;
• All surface water for events not exceeding the design capacity will rout water via gravity
into the east side collection system piping system (Under the current design, storm
water that exceeds the basin capacity will report to Butterfield Canyon drainage);
• Basin design and capacity accounts for sedimentation but requires routine removal of
the sediment in order to maintain minimum capacity.
The basins are not designed or sized to:
• Manage large amounts of debris (waste rock, cover soils, vegetation);
• Receive water from the dump flattops;
• Operate without routine inspection and maintenance.
Additionally, the basins are designed to drain in a 24 hour period. Ponded water in excess of the
24 hour period should be addressed as soon as possible in order to minimize the potential
infiltration of WRCW to ground.
Exhibit 1 is a basic overview map identifying South Dump detention basin locations and names.
More detailed drawings are included in Appendix B and photographs of the completed detention
basins are included in Appendix D.
In Order to accommodate detention basins and waste rock reclamation, the relocation of cut-off
walls was required in three drainages. The new wall design is similar to the existing walls
located in the SWRR drainages. The cut-off walls are keyed into bedrock in order to intercept
WRCW. Perforated pipe runs along the footing of the wall in order to best facilitate and convey
the WRCW capture. In most cases a French drain containing coarse non-reactive rock and
perforated pipe extends along the top of bedrock from the original cut-off wall location to the
new further facilitating the conveyance and capture of WRCW.
2

3

2.2 Detention Basin Specifications
Detailed basin dimensions are provided in Appendix A. A summary of key basin dimensions for
quick reference based upon as-built survey data are included below in Table 2. Basins per
respective drainage are identified beginning with downstream locations and progressing
upstream. Basins below the lower most cut-off wall in a specific drainage are identified as a
whole number (i.e. 51) while basins above the lower most cut-off wall in a specific drainage are
identified with a decimal point, increasing in value moving upstream (i.e. 3.1, 3.2).
Table 2. Overview of Detention Basin Specifications
Basin ID Capacity (ac-ft) Outlet Elevation
(ft)
Spillway Elevation (ft) Outlet Orifice Dimension1
(in)
Peak Outflow 100yr-24hr
(CFS)
Grate Material2
Yosemite
6.1 2.17 5800.1 5809.5 12 4.20 Galvanized
6.2 3.52 5845.0 5864.1 6 4.17 Galvanized
6.3 2.36 5874.1 5892.0 8 7.11 Galvanized
6.4 0.90 5903.0 5913.6 12 18.78 Galvanized
Saints Rest
51 0.73 5778.2 5786.4 8 2.61 Galvanized
5.1 3.79 5843.1 5857.0 6 3.15 Galvanized
South Saints Rest3
41 0.52 5792.4 5800.8 8 2.00 Stainless
4.2 0.77 5827.8 5841.8 6 3.13 Stainless
4.3 0.87 5846.6 5858.7 6 3.28 Stainless
4.4 2.74 5871.4 5886.6 6 3.63 Stainless
4.5 2.20 6054.0 5918.8 10 7.67 Stainless
Castro
3.1 4.87 6166.0 6179.6 6 2.60 Galvanized
3.2 4.45 6161.3 6179.0 6 2.70 Galvanized
3.3 10.16 6151.3 6172.0 6 2.90 Galvanized
Butterfield 1
21 4.83 6054.0 6073.0 6 3.64 Galvanized
2.1 0.75 6113.1 6126.5 8 5.57 Galvanized
2.2 4.18 6161.1 6180.3 8 5.05 Galvanized
2.3 0.94 6195.3 6207.9 10 6.74 Galvanized
2.4 1.37 6222.4 6237.3 10 6.72 Galvanized
Olsen
12 2.77 6146.4 6165.4 6 4.15 Galvanized
11 1.82 6220.0 6233.0 8 4.91 Galvanized
1.1 3.16 6275.5 6293.6 8 4.98 Galvanized
1.2 3.49 6307.9 6326.6 8 5.12 Galvanized
1.3 1.50 6340.0 6352.7 9 5.68 Galvanized
Queen
0.1 2.03 6491.9 6511.0 7 5.62 Galvanized
0.2 1.35 6539.7 6559.0 7 6.04 Galvanized
Notes.
1 - All detention basin outlet structures (excluding 3.1 and combination cut-off walls) are constructed with the same
dimensions and inlet/outlet pipe sizing, however each 18” lower outlet pipe has an orifice plate that varies in size and
can be changed out to modify the performance of the outlet structure.
2 – Outlet structure grates are either stainless steel or galvanized steel based upon drainage water quality.
3 - Basin 4.1 was in the original design and resided on the ridge above 4.2 but was omitted during construction due to
lack of capacity and difficulty to access and was later replaced with 4.5.
4

2.3 Cut-off Wall Design
The cut-off walls are designed to capture WRCW and convey that water via gravity to the
contact water mainline. The wall accepts contact water from 1) a french drain (perforated pipe
embedded in coarse non-reactive rock) leading up the drainage or 2) perforated pipe adjacent
to the wall footing and atop bedrock. The contact water perforated piping is atop bedrock but
below surface grade. This allows for segregation of contact water from storm water and
optimum performance of the storm water basins. Ultimately contact water and storm water are
comingled prior to entering the mainline collection pipe.
In some cases, the cut-off walls are designed to detain surface water and act as the lower
embankment of the detention basin. The inlet box is slotted the entire height of the box. Water
exits the box through an 18” outlet pipe. In the event the pipe at the bottom of the box plugs,
water can exit through a 12” overflow pipe that routs water back into the primary 18” pipe. In the
event both pipe outlets become plugged, water will exit over the wall through an overflow weir
notch.

5

3.0 Inspection & Maintenance
3.1 Overview
The detention basins, although not designed to primarily capture and route waste rock contact
water (WRCW), do play an important role in protecting the structures and piping that are
designed to manage WRCW. If storm water, sediment and debris were to overwhelm cut-off
walls and associated infrastructure, the potential for the release of WRCW to the environment
would greatly increase. The detention basins are designed to minimize adverse impacts to the
primary acid rock drainage (ARD) collection system as well as convey WRCW through and
require routine inspection and maintenance.
Inspection frequency is guided by groundwater discharge permit # UGW350010. The permit
only specifically requires quarterly inspection, however best practice recommends a more
frequent inspection following large rain events. Table 3 provides inspection guidance and
frequency.
Table 3. Inspection Frequency and Guidance
Inspection Type Frequency Guidance
UDWQ Groundwater Discharge Permit #UGW3500101 Quarterly Appendix A, Groundwater Discharge Permit # UGW350010 Significant precipitation event2 Varies Rain depth ≥10 year-24 hour as indicated by the Copper drainage rain gage
Notes.
1 – Required by groundwater discharge permit #UGW350010
2 – Not required by the groundwater discharge permit. Refer UPDES Permit (0000051) Statement of Basis (p. 21)
and Part I.E as well as 40 CFR 440.131(c) for guidance

The inspection checklist for the south dump detention basins is discussed in section 3.3 and
included in Appendix C.
3.2 Basin Components
The basins are fairly simple by design. Alluvial water, storm water and sediment report from the
dump toe, face or the native hillside and enter the drainages containing the detention basins
and cut-off walls. The water passes through the rock weir in front of the outlet structure while
coarse sediment is trapped behind the rock weir. Water then exits the detention basin through
the outlet structure. Peak flow for a given rain event is regulated by the outlet structure and
appropriately sized orifice plates so as to not overwhelm the capacity of the main collection pipe
along the east side collection road. If the detention basin is overwhelmed due to either the size
of the precipitation event or sediment and debris plugging off outlets, water then exits the basin
through the overflow weir, reporting to the next basin in line. The basins for each respective
drainage are designed to manage up to a 100 year-24 hour rain event. By design, in some
cases when rain events are large, water will exit some basins via the overflow weir and report to
the next basin.
Flow diagrams for the drainages are located with the as-built drawings in Appendix B.

6

Exhibit 2. Basin Components Illustration

Key
1. Rock Weir. See dwg. # 10199-C-321.
2. Outlet Structure. See dwg. # 10199-C-322 & 10199-C-323.
3. Rip Rap Overflow Weir. See dwg. # 10199-C-321.
4. Basin Embankment. See dwg. # 10199-C-321.
5. Pipe Outlet. See dwg. # 10199-C-321.

1
4
2 3
5
3
2
3
Facing down stream
Facing up stream
4
7

3.2.1 Rock Weir:
The rock weirs are four (4) feet tall. They are designed to filter out medium to coarse particulate
and prevent the concrete outlet structure from becoming plugged with sediment and debris.
Sediment may accumulate behind the rock weir over several rain events and seasons. If
sediment depth reaches two (2) feet behind the rock weir then the basin should be scheduled
for sediment removal. Use of the digital terrain model (DTM) file will assist in achieving the
basins original shape and capacity. Care should be taken to maintain the integrity of the rock
weir. In the event of a significant precipitation event that overwhelms one or more detention
basins, the rock weir can be dismantled to remove fine grained particles and reconstructed.
Details regarding the rock weir specifications are found in Appendix B, drawing # 10199-C-124.
If not all the rocks for the weir cannot be salvaged, material that meets specification may need
to be sourced to supplement reconstruction. Generally, the rock used for the weir needs to be
resistant to erosion and non-reactive with the water found in the drainage.
3.2.2 Outlet Structure:
All outlet grates and orifices must be inspected following significant storm events as outlined in
Table 3. The grates and piping inlets (orifices) must be clear of vegetation, sediment and debris
in order to function as designed. In order to combat outlet plugging from floating debris, the
Yosemite drainage incorporated “T”s that will allow head pressure to push water through the
submerged pipe inlet while sediment floats on the surface, reducing the potential of debris
blocking the inlet. Water can also flow in from the top of the “T”. A clean out access pipe is also
included immediately down gradient of the outlet structure.
3.2.3 Pipe Outlets:
Pipe outlets are within the outlet structure should remain free of excess sediment and debris in
order to provide proper functionality. If the rip rap at or below the pipe outlet show signs of
deterioration (i.e. rock movement, erosion adjacent to the channel, etc.) repairs must be made.
3.2.4 Rip Rap Overflow Weir:
The rip rap overflow weirs are designed to move water from out of the basin to the next
containment structure without damaging the integrity of the embankment. In many cases and in
larger rain events, the basins are designed to move water through the overflow weir in addition
to the outlet structure. The overflow weir will also move water should the outlet structure
become plugged by sediment and debris. If an overflow weir shows indications of erosion
adjacent to the rock channel, at the inlet or outlet, repairs must be made.
3.2.5 Distribution Boxes:
The distribution boxes are designed to accept water from two sources (i.e. cut-off wall and
sediment basins) and route the water through a common pipe into the main east side collection
pipe. These boxes also provide access for pipe cleaning. The boxes must be kept clean, free of
sediment and debris. The inspection schedule needs to be the same as the cut-off walls and
basins.
8

3.3 Cut-off Wall Components
Cut-off wall components require inspection similar to the detention basin outlet structures. Some
components (finger drains) are below grade and cannot be readily inspected. The cut-off wall
manages both contact and non-contact water.
Exhibit 3. Cut-off Wall Components Illustration

Dry side facing up gradient
Wet side facing down gradient

2
1
1
4
3
2 6
1
5
3
4
Key
1. Concrete cut-off wall keyed into bedrock. See dwg. # 10199-C-305, 306, 315, 308 & 327.
2. Overflow weir notch. See dwg. # 10199-C-305, 306 & 315.
3. Surface water inlet box. See dwg. # 10199-C-327 & 328.
4. Hand wheel and slide gate valve. See dwg. # 10199-C-327.
5. Outlet box and piping. See dwg. # 10199-C-327.
6. Outlet pipe cleanout port. See dwg. # 10199-C-327.
9

3.3.1 Concrete Wall, Box and Valves
The concrete wall is keyed into bedrock and designed to facilitate in the capture of all water
moving down the drainage, contact and non-contact water. The wall contains an overflow weir
(notch in the wall) to allow overflow of storm water in the event the outlet box and associated
piping are overwhelmed or plugged. The inlet box has grating from the ground surface to the top
of the box allowing for the free flow of water into the box as sediment and debris accumulate
against the grating. A hand wheel atop the box operates the slide gate valve on the low level
inlet at the back of the inlet box. A secondary inlet pipe is located near the top of the inlet box in
the event the low level inlet becomes inoperable.
3.3.2 Finger Drains and Contact Water Capture at Cut-off Wall
The information provided in this section pertains to finger drains installed at the toe of the
reclaimed waste rock slope (and extending beyond) in the Yosemite, South Saints Rest,
Butterfield 1 and Olsen drainages. These finger drains are designed to capture WRCW at the
highest point in the drainage and direct that water to the cut-off wall and collection system.
Where practical, a finger drain is installed from the location of the legacy cut-off wall to the new
cut-off wall along the drainage bottom against bedrock. The finger drain is 8” perforated pipe
embedded in 2” non-reactive rock and wrapped in geotextile to prevent fine silt from plugging
the pipe and ability to accept water.
The newly installed cut-off walls in Yosemite, Butterfield 1 and Olsen drainages incorporated
perforated pipe below grade to capture WRCW in conjunction with the concrete wall. Along the
footing of each cut-off wall resides a 4” perforated pipe embedded in 2” non-reactive rock and
wrapped in geotextile. All water collected at the wall will enter the coarse rock channel and
perforated pipe and report to the 12” HDPE pipe. In the case of the Upper Yosemite cut-off wall,
Butterfield 1 and Olsen, the piping system passes through the cut-off wall and ultimately reports
to the main collection line. In the case of the Lower Yosemite cut-off wall, the 4” pipe reports to
the inlet box where it comingles with the surface water that enters the box through the grate.
3.3.3 Storm Water Conveyance
Storm water enters the inlet box through the grating and enters the 12” collection pipe on the
floor of the back wall of the box. The outlet pipe does not have an orifice plate but does contain
a slide gate valve. The valve typically stays in the fully open position and is only closed for
maintenance purposes. In the event the 12” pipe inlet were to become plugged, a secondary 12”
pipe is located approximately 5’ below the top of the box. In the event both pipes were to
become plugged or otherwise fail, storm water would exit pass through the overflow weir notch
atop the wall and adjacent to the outlet box. A hatch resides on the down gradient side of the
box to allow access to the associated piping. Immediately down gradient of the wall are
cleanouts for the 12” inch pipe.
3.4 Inspection Checklist:
Detention basin inspections should be conducted on a routine basis in conjunction with
inspections of the east side collection system. An inspection checklist for the south dump
detention basins is included in Appendix C. In the event of a significant precipitation event, more
frequent inspections are advised (See Table 3 for guidance).
10

3.5 Sediment Removal
There are two types of sediment deposition associated with the detention basins requiring
maintenance, chronic and acute. Chronic sediment deposition includes sediment that can
accumulate over multiple precipitation events occurring over weeks, months and even years.
Acute sediment deposition may take place over one large rain event or several larger events in
in a short period of time. In either case, maintenance will be required to remove the sediment
and return the basin to its original capacity. A DTM file is provided that will assist the GIS
equipped equipment to restore the basin to its original shape and capacity. If the DTM is not
compatible with the selected contractor, detailed electronic as-built files are included with the
O&M.
Care should be taken to not damage the outlet structures and piping. Use hand tools as needed
to complete the close proximity maintenance.
4.0 Training
Training for the operation of the basins consists of the following components:
• A complete read of the O&M and thorough review of the materials provided in the
Appendices;
• A site tour with a member of the construction team and/or operations team familiar with
the cut-off walls, basins and associated structures.
If, in the future, a knowledge gap is identified, contact a member of the RTKC Water Quality
team and arrange for training support should knowledgeable members of the construction team
and operations team not be available.
11

5.0 Reference Information
5.1 UDWQ Construction Permit
The detention basin design and specifications were reviewed and approved by Mr. Woodrow
Campbell, P.E. of the Utah Department of Environmental Quality – Division of Water Quality.
Periodic field visits were conducted during the construction activities including three final
inspections based upon project phasing and completion:
• Saints, South Saints and Castro detention basins - December 15, 2014 for.
• Yosemite detention basins and cut-off walls - 3Q2016.
• South Saints Rest detention basin 4.5, Butterfield 1 cut-off wall and detention basins,
Olsen cut-off wall and detention basins and Queen detention basins - October 23, 2017.
5.2 Dam Safety Permit
The embankments associated with the detention basins were reviewed and approved through
the Utah Department of Natural Resources – Water Rights – Dam Safety. Under the advisement
of the Assistant State Engineer, the basins were lumped together by drainage and issued a
permit number accordingly. The combined basins per drainage are classified as a small dam –
low hazard with cumulative capacities by drainage of less than 20 acre-feet.
Drainage Permit # Water Rights Yosemite UT53811 a6714 (base water right 59-42)
Saints Rest UT53799
South Saints Rest UT53800
Castro UT53802
Butterfield 1 UT53803
Olsen UT53804 Queen UT53876
5.3 Groundwater Discharge Permit
The detention basins and associated piping are considered a component of the groundwater
control structures associated with the Bingham Canyon Mine and Water Collection System
Groundwater Discharge Permit # UGW350010 under the sections Part 1.D.3 and Part 1.D.2
with additional detail provided in Appendix A.
5.4 Project Contacts
Name Title Contact Information Engineering and Projects (Construction Team) Jared Barlow Project Manager [phone]
Dave Hales Project Engineer/Design & Interface [phone]
Zeb Kenyon Project Engineer/Design & Permitting [phone]
Operations Team (South Area Water Services)
Jason Doyle Superintendent – Tailings & Water Services [phone]
Guillermo Salcedo Supervisor – SAWS Operations [phone] Environmental Team (Permit and Compliance) Brian Vinton Principle Advisor – Water Quality [phone]
12

6.0 Revision History
Rev. # Description of Change(s) Prepared by Date
0 Original release of O&M to capture basins completed in December 2014 for Saints Rest (5.1 & 51), South Saints Rest (4.4, 4.3, 4.2 & 41) and Castro (3.3, 3.2 & 3.1) and to fulfillDWQ construction permit obligations.
Zeb Kenyon, RT T&I March 2015
1 Updated to incorporate basin and cut-off wall
completion in Yosemite drainage and fulfill DWQ construction permit obligations.
Zeb Kenyon,
Rio Tinto G&I
December 2016
2 Updated to incorporate basin and cut-off wall completion in South Saints Rest, Butterfield
1, Olsen and Queen drainages and fulfill DWQ construction permit obligations.
Zeb Kenyon, Rio Tinto G&I November 2018
13
DWQ-2020-015204