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Home My WebLink AboutDWQ-2025-001293Appendix H Permit # UGW350010 Operations & Maintenance Manual East Waste Rock Extension Water Collection System Operations & Maintenance Manual Rio Tinto Kennecott Utah Copper East Waste Rock Extension Water Collection System December 2016 III Contents Section Page 1.0 Context and Purpose ........................................................................................................... 1-1 1.1 Context ............................................................................................................................. 1-1 1.2 Purpose ............................................................................................................................ 1-1 1.3 Disclaimer ........................................................................................................................ 1-1 2.0 Design and Operation ......................................................................................................... 2-1 2.1 Overview of EWRE Water Collection System................................................................... 2-1 2.2 Typical Component Designs for the EWRE Water Collection System .............................. 2-2 2.2.1 Toe Drains ........................................................................................................... 2-2 2.2.2 Storm Water Detention Basins ........................................................................... 2-5 2.2.3 Cut-Off Walls ....................................................................................................... 2-5 2.2.4 Weir boxes .......................................................................................................... 2-7 2.2.5 Storm Water Weir/Flume and Lower Concrete Lined Canal ............................ 2-10 2.2.6 Branch Connection Vault and WCRW Main Line .............................................. 2-10 2.2.7 Settling Basin .................................................................................................... 2-11 2.3 Atypical Designs of the EWRE Water Collection System ............................................... 2-14 2.3.1 Copper 4 ............................................................................................................ 2-15 2.3.2 Copper 3 ............................................................................................................ 2-15 2.3.3 Copper 2 ............................................................................................................ 2-16 2.3.4 Copper 1 ............................................................................................................ 2-17 2.3.5 Lost Creek and Keystone ................................................................................... 2-17 2.3.6 North Keystone ................................................................................................. 2-19 2.3.7 South Crapo ...................................................................................................... 2-21 2.3.8 Crapo ................................................................................................................. 2-21 2.3.9 South Congor and Midas .................................................................................. 2-21 2.3.10 WRCW Branch Vault Diversion Box (Station 2134+00) .................................... 2-23 2.3.11 South Area Dumps (SAD) Box ........................................................................... 2-23 2.3.12 Storm Water Inlet Structure at Canal ............................................................... 2-24 2.3.13 Lower Concrete Lined Canal ............................................................................. 2-25 3.0 Inspection and Maintenance ............................................................................................... 3-1 3.1 Overview .......................................................................................................................... 3-1 3.2 Guidance for Inspection ................................................................................................... 3-1 3.2.1 Dump Face .......................................................................................................... 3-1 3.2.2 Down Drains ........................................................................................................ 3-1 3.2.3 Toe Drain ............................................................................................................. 3-2 3.2.4 Storm Water Detention Basin ............................................................................. 3-3 3.2.5 Cut-off Wall ......................................................................................................... 3-6 3.2.6 Weir Box .............................................................................................................. 3-7 3.2.7 Branch Connection Vault .................................................................................... 3-9 3.2.8 Storm Water Vault, Lower Concrete Lined Canal and Datalogger Station ......... 3-9 3.2.9 Old Bingham Tunnel ......................................................................................... 3-11 3.2.10 Settling Basin .................................................................................................... 3-12 3.2.11 Lower Concrete Lined Canal ............................................................................. 3-14 3.2.12 WRCW Branch Vault Diversion Box (WRCW Vault Station 2134+00) ............... 3-14 3.2.13 South Area Dumps (SAD) Box ........................................................................... 3-15 iii CONTENTS (CONTINUED) 3.2.14 Storm Water Inlet Structure at Lower concrete lined Canal ............................ 3-15 3.3 Compliance Sampling Locations and Frequency ........................................................... 3-16 4.0 Training .............................................................................................................................. 4-1 4.1 General Requirements ..................................................................................................... 4-1 5.0 Reference Information ........................................................................................................ 5-1 5.1 UDWQ Construction Permit ............................................................................................. 5-1 5.2 Dam Safety Permit ........................................................................................................... 5-1 5.3 Groundwater Discharge Permit ....................................................................................... 5-1 5.4 Project Contacts ............................................................................................................... 5-1 5.5 Project Quality Assurance and Quality Control ............................................................... 5-2 5.6 Revision History ............................................................................................................... 5-2 Appendices A EWRE Geology, Seeps, and Springs Map B Drainage Basin Photographic Logs C South Area Water Services East Side Collection System – East Waste Rock Extension Groundwater Discharge Permit Inspection and Supplemental Inspection Forms D Drainage Basin As-Built Drawings E XML Terrain Files and AutoCAD Design Files F Redline Design Drawings G Survey Monument Documentation H EWRE Compliance Monitoring Transition Documentation I State Inspection Reports J Quality Assurance and Quality Control Documentation K Operations and Maintenance Manual Microsoft Word Document File L CH2M HILL Hydrology Report Tables 1-1 Applicable operating permits related to groundwater and surface water management 2-1 Storm water detention basin dimensions 2-2 East Waste Rock Extension water collection system conveyance description and size 2-3 Atypical designs of the EWRE water collection system 3-1 Inspection frequency and guidance 5-1 EWRE project contact information Figures 1-1. Rio Tinto Kennecott Utah Copper facilities map. 1-2. Copper area structures overview. 1-3. Keystone area structures overview. 1-4. Crapo area structures overview. 2-1. EWRE water collection system schematic (typical). 2-2. EWRE water collection system flow diagram. 2-3. Type 1 and Type 2 toe drain details. 2-4. Type 3 toe drain detail. iv CONTENTS (CONTINUED) 2-5. Typical toe drain showing clean-outs, rip-rap ditch and the access road. 2-6. Typical toe drain under construction. 2-7. Typical cut-off wall. 2-8. (A) WRCW by-pass valve located in each cut-off wall; (B) manipulated with valve tool; (C) valve tool attaches to valve stem for manipulation. 2-9. (A) Space frame with baffle and v-notch; (B) weir box with space frame and B. 2-10. Lost Creek-Keystone weir box and carrier pipe leak detection. 2-11. Photograph of a newly constructed weir box and auxiliary components. 2-12. Typical datalogger display showing real-time flow rate through the weir V-notch. 2-13. Photograph of a newly constructed WRCW branch connection vault. 2-14. The WRCW Mainline terminates in the settling basin; from the settling basin, WRCW is conveyed to the Midas Pump Station. 2-15. Mine water drainage process and instrumentation diagram. 2-16. Storm water in the Copper 3 drainage connects to the lower concrete lined canal through a pre- existing storm water flume. 2-17. Copper 2 and Copper 1 storm water branch canal. 2-18. Lost Creek drainage directional boring outlet. 2-19. Keystone drainage directional boring outlet. 2-20. Keystone detention basin straddling the Bingham Tunnel. 2-21. Photograph showing the 14-inch-diameter HPDE pipe conveying WRCW under the Mine Access Road in the North Keystone drainage basin. The coarse quartzite finger drain directs WRCW flow toward the North Keystone segment of toe drain. 2-22. The North Keystone storm water conveyance pipe will eventually be covered by waste rock and will require prope 2-23. Photograph showing the Crapo storm water branch line connection to a pre-existing branch canal. 2-24. Photograph showing tunnel discharge from the Old Bingham Tunnel (OBT). The tunnel discharge from the OBT is conveyed to the combined South Congor and Midas weir box, but enters below the V-notch flow measuring point. 2-25. WCRW branch vault (Station 2134+00) can divert water into the lower concrete lined canal when maintenance is required at the Settling Basin. 2-26. South Area Dump (SAD) box. 2-27. Storm water inlet structure by Copper 3. 3-1. Photographic overview of EWRE water collection system components. 3-2. Photograph of a newly constructed segment of the toe drain; toe drain features include the clean outs, rip rap ditch and access road. 3-3. Photograph of a newly constructed storm water detention basin; features include desilting area, check dam, storm water detention basin, outlet box, spillway and silt fences. 3-4. Photograph of a newly constructed spillway. The spillway connects the storm water detention pond to the cut-off wall. 3-5. Photograph of a newly constructed cut-off wall. The spillway connects the storm water detention pond to the cut-off wall; the cut-off wall includes a storm water inlet grate and a valve vault. 3-6. Photograph of a newly constructed cut-off wall. The valve port allows access to manipulate the WRCW flow valves. 3-7. Photograph of a newly constructed weir box and auxiliary components. 3-8. Photograph of a newly constructed WRCW branch connection vault. 3-9. Photograph of a newly constructed storm water vault, level indicator and lower concrete lined canal. 3-10. Photo of the Old Bingham Tunnel (OBT) entrance. 3-11. Settling Basin isometric projection and cross sectional view. 3-12. Section of the lower concrete lined canal. v CONTENTS (CONTINUED) 3-13. (A) WRCW branch vault diversion box (Station 2134+00); (B) diversion gate valve. 3-14. Compliance monitoring well and sampling location map. 3-15. Seeps, springs and geology map. vi SECTION 1 1.0 Context and Purpose 1.1 Context Rio Tinto Kennecott Copper (RTKC) and its Bingham Canyon Mine are required to effectively manage waste rock contact water (WRCW) and the discharge to groundwater, surface water, sediment and debris associated with the waste rock dumps on property. These requirements are outlined in Section 5 under the applicable permits associate with the operation. The agencies and permits are listed in Table 1. Table 1-1. Applicable operating permits related to groundwater and 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 best meet obligations to the public and regulatory agencies specifically related to the East Waste Rock Extension (EWRE) (Figure 1-1), an integrated system of toe drains, detention basins, cut-off walls and conveyance lines were constructed throughout 2015 and 2016 (Figures 1-2, 1-3, 1-4). The effort was completed to accommodate continuation of mining and waste rock placement while carefully managing the surface and groundwater capture and conveyance. 1.2 Purpose This Operations and Maintenance (O&M) manual is designed to provide the operator with clear instructions and reference material for the proper care and upkeep of the EWRE project groundwater and surface water control infrastructure. 1.3 Disclaimer This operation and maintenance manual was created to (1) fulfill the construction permit condition for the EWRE project which requires 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 capture system. This manual is applicable only to the infrastructure associated with the EWRE project. 1-1 SECTION 2 2.0 Design and Operation 2.1 Overview of EWRE Water Collection System The EWRE water collection system affectively captures WRCW through a toe drain system on top of low-permeable bedrock and directly at the toe of the relaxed waste rock slope. The WRCW is moved by gravity through HDPE pipes and lined concrete structures. Secondary containment of all WRCW conveyance is in place down gradient of the cut-off walls to minimize the potential for a release of WRCW to the environment. The system is also designed to capture surface water (up to a 100 year- 24-hour event) off of the face of the waste rock dump. Key features of the EWRE water collection system include the following: • The system captures surface and alluvial water (groundwater) up gradient of the cut-off walls; WRCW reporting to the toe of the waste rock is collected in subsurface toe drains filled with coarse quartzite, keyed into bedrock, and conveyed in a system of HDPE pipes (double contained down gradient of the cut-off wall) separate from surface water. • The toe drain is the primary collection point for WRCW and the cut-off wall acts as the secondary collection point in the event the toe drain under performs. • WRCW from the toe drains and all drainages from Copper 4 to Midas is transported via gravity to the Midas Pump Station (MPS), and then pumped to the existing ACC plant for copper recovery. • The cut-off wall locations permit gravity flow from the cut-off wall collection piping via the down gradient collection system piping. • Secondary containment and leak detection exists for all WRCW piping and structures down gradient of the cut-off walls. • Storm water is collected in detention basins and released slowly to the storm water piping system so as not to overwhelm the associated piping and concrete lined canal. • WRCW and storm water flows are recorded on data loggers using weirs, flumes and level indicators. • WRCW water samples can be collected at the weir boxes. The collection system is described from top to bottom. A conceptual representation of the EWRE water collection system design is shown in Figure 2-1. 2-1 SECTION 2 DESIGN AND OPERATION Figure 2-1. EWRE water collection system schematic (typical). 2.2 Typical Component Designs for the EWRE Water Collection System The photographic representation of the typical water capture system components for the EWRE are shown on Figure 2-2. Specific details of the typical EWRE water collection system components are presented below. 2.2.1 Toe Drains The toe drains are designed to intercept waste rock contact water (WRCW) moving along the bedrock contact as it reports directly from the toe of the waste rock. The toe drains are composed of two parallel, 12-inch-diameter perforated corrugated HDPE pipes placed along the lower permeability layer at the bedrock contact. There are three types of toe drains: • Type 1 is a more robust design, clay down on the down gradient side of the toe drain is 8 feet thick, and was used primarily at drainage bottoms in the collection system where flow reporting from the waste rock is anticipated to be greatest and in cases where slope parallel with the toe drain is < 1% (Figure 2-3). • Type 2 was used throughout the majority of the collection system and where flow from waste rock is anticipated to be less active and/or significantly diminished or slopes are ≥ 1%. Clay down gradient of the toe drain is 2 feet thick (Figure 2-3). 2-2 SECTION 2 DESIGN AND OPERATION • Type 3 was used on steep slopes greater than 45 degrees and incorporated no imported clay. Type 3 was used where constructability of Type 2 toe drains was not achievable (Figure 2-4). Figure 2-3. Type 1 and Type 2 toe drain details. Figure 2-4. Type 3 toe drain detail. Note: This toe drain detail is applicable to ground slopes greater than 1:1 (45°), such as the south slope of the Lost Creek drainage and the south slope of the Keystone drainage. 2-3 SECTION 2 DESIGN AND OPERATION Within each drainage basin, the perforated 8” toe drain piping connects to a solid wall 14-inch-diameter HDPE conveyance pipeline. This piping extends down gradient from the toe drain through the cut-off wall and reports to a collection weir box. Two oblique angled 14-inch-diameter capped HDPE pipe cleanouts are located approximately every 500-feet of toe drain, in addition to the cleanouts at branch connection. Photographs of the completed and ‘in construction’ toe drain are shown in Figures 2-5 and 2-6, respectively. Figure 2-5. Typical toe drain showing clean-outs, rip-rap surface water ditch and the access road. Figure 2-6. Typical toe drain under construction. Upstream of the toe drain are finger drains built with coarse non-acidic (non-reactive) rock (quartzite) drainage (NARD) material. In most cases, the coarse quartizte fingers drains were keyed into bedrock; however, in a few locations, the finger drains were placed in drainage lows once all soils were removed to bedrock. The locations of the coarse quartzite finger drains are illustrated on the EWRE Geology, Seeps and Springs Map (Appendix A). Clean outs Rip rap ditch Access Road Bedrock keyway Perforated toe drain pipe Coarse quartzite Geotextile fabric Clay backfill 2-4 SECTION 2 DESIGN AND OPERATION 2.2.2 Storm Water Detention Basins Storm water detention basins are located in all drainages associated with EWRE. The size of each detention basin was determined based on the modeled peak storm water flow rates reporting from the waste rock face. Basic design criteria used is based on a 100-year, 24-hour storm event and the planned, reclaimed waste rock and site topography. At a minimum, the storage provided in each detention basin will be sufficient to detain the estimated peak storm volume (Table 2-1). The detention basins are designed to drain to a topographic low point, and are bounded at the inlet by a pervious rock embankment approximately 6 feet tall designed to capture sediment and debris. A primary outlet box is located at the basin’s topographic low point. The detention basin is designed to drain in a 24-hour period. The primary outlet box is generally 4 feet tall, and includes a variably-sized inlet orifice (Table 2-1), a fiberglass top grate, and a 24-inch-diameter HDPE outlet pipe. The primary outlet box directs storm water into a 24-inch-diameter HDPE outlet pipe through the cut-off wall storm water collection vault and ultimately the canal. In the event the outlet box fails or cannot keep up with a given storm event, the detention basin embankment contains an emergency overflow (between 4 and 9 feet above the basin floor), which directs storm water via a pervious rip rap rock spillway to a second grated inlet on the wet-side of the cut-off wall. The detention basins are slightly oversized to accommodate sediment buildup, and include a staff gauge near the topographic low to visually monitor sediment accumulation. Table 2-1. Storm water detention basin dimensions Basin Basin Volume (acre-feet) Average Basin Depth (feet) Basin Floor Elevation (feet) Outlet Box Top Elevation (feet) Emergency Overflow Weir Elevation (feet) Berm Top Elevation (feet) Copper 4 6.3 6.7 5,635 5,642 5,644 5,645 Copper 3 1.9 3.3 5,635 5,639 5,640 5,641 Copper 2 2.8 5.7 5,610 5,617 5,618 5,620 Copper 1 2.3 4.3 5,603 5,607 5,608 5,610 Lost Creek 1.9 5.4 5,578 5,585 5,686 5,588 Keystone Upper 0.9 5.1 5,554 5,563 5,564 5,566 Keystone Lower 2.6 5.8 5,534 5,541 5,542 5,544 North Keystone 5.6 3.8 5,560 5,565 5,566 5,568 South Crapo 4.1 3.8 5,549 5,553 5,554 5,556 Crapo 1.9 4.4 5,525 5,532 5,533 5,535 South Congor 3.4 4.2 5,530 5,534 5,535 5,538 Midas 7.4 3.7 5,540 5,544 5,545 5,547 2.2.3 Cut-Off Walls The cut-off walls are designed to serve as a secondary capture system for alluvial groundwater, with the toe drains functioning as the primary capture system. Figure 2-7 shows a typical cut-off wall in cross section. 2-5 SECTION 2 DESIGN AND OPERATION Figure 2-7. Typical cut-off wall. Cut-off walls are located in each of the major drainages (Figures 1-2, 1-3, 1-4), and are keyed into bedrock for structural support and to enhance capture effectiveness. Additionally, the upgradient wet- side of the cut-off walls are protected from WRCW by a HDPE liner. Three pipes pass through each cut-off wall: 1. A French drain with a perforated 8-inch-diameter HDPE pipe runs parallel to the base of each cut-off wall, along the surface of the bedrock. This French drain captures WRCW originating between the toe drain and the cut-off wall or WRCW in the event the toe drain under performs. The 8-inch- diameter HDPE pipe, passes through the valve vault at the cut-off wall, becomes double contained inside a 12-inch-diameter HDPE pipe at the cut-off wall and gravity drains to the weir box. 2. The 14-inch-diameter HDPE pipe from the toe drain, passes through the valve vault at the cut-off wall, becomes double contained inside a 24-inch-diameter HDPE pipe at the cut-off wall and gravity drains to the weir box. 3. The 24-inch-diameter HDPE pipe from the storm water detention basin outlet structure enters the cut-off wall storm water vault, passes through the storm water vault to exit via another 24-inch- diameter HDPE pipe, and gravity drains to the lower concrete lined canal. The water can be diverted to the storm water line in the event the 14-inch-diameter WRCW line requires repair (Figure 2-8). Storm water arriving at the cut-off wall via the spillway overflows into the storm water vault, and is then carried through the cut-off wall and downgradient to the lower concrete lined canal via a 24-inch diameter HDPE pipe. Before storm water enters the canal, it passes through either a weir box or flume where flow is measured. 2-6 SECTION 2 DESIGN AND OPERATION Figure 2-8. (A) WRCW by-pass valve located in each cut-off wall; (B) manipulated with valve tool; (C) valve tool attaches to valve stem for manipulation. 2.2.4 Weir Boxes Waste rock contact water from the toe drain and the cut-off wall are comingled in weir boxes. A weir box is an HDPE lined concrete structure that includes a baffle for stilling the water, a V-notch weir (Figure 2-9) and level indicator for flow measurement, leak detection, and a data logger. On the upgradient side of the weir box, WRCW reports from the 14-inch-diameter HDPE pipe from the toe drain (double contained within a 20-inch-diameter HDPE pipe) and the 8-inch-diameter HDPE pipe from the base of the cut-off wall (double contained within a 12-inch-diameter HDPE pipe). On the downgradient side of the weir box, a 14-inch-diameter HDPE pipe (double contained in a 20-inch-diameter HDPE pipe) of combine WRCW gravity drains to the WRCW main line. (A) (B) (C) 2-7 SECTION 2 DESIGN AND OPERATION Leak detection is located outside of the weir box in three (visible) vertical 18-inch-diameter HDPE pipes (Figures 2-10 and 2-11). The three 18-inch-diameter leak detection inspection pipes are connected to the secondary WRCW pipes and concrete weir box via 3-inch HDPE pipes. Signage in the field indicates which leak detection 18-inch-diameter HDPE pipe correlates to which respective pathway. The real-time flow datalogger collects flow data at the V-notch weir or flume. The datalogger and digital station are powered by a solar panel (Figure 2-11). Data acquisition is acquired manually at the data logger (Figure 2-12). Figure 2-9. (A) Space frame with baffle and V-notch; (B) weir Box with space frame. Figure 2-10. Lost Creek-Keystone weir box and carrier pipe leak detection. Baffle V-notch weir Baffle V-notch weir Inlet Outlet Weir Box Leak detection Toe drain WRCW Cut-off wall WRCW (A) (B) Leak detection piping 2-8 SECTION 2 DESIGN AND OPERATION Figure 2-11. Photograph of a newly constructed weir box and auxiliary components. Weir box Leak detection Solar panel Datalogger Battery Level indicator Bolt penetrations through the weir liner are problematic to seal. A space frame (Figure 2-9A) was used to eliminate the need to penetrate the liner in order to mount the baffle and v-notch plates. If water is found in the leak detection sumps, test water quality to determine if it matches WRCW characteristics and to rule out malfunctioning leak detection piping as displayed in Figures 2-10 and 2-11. 2-9 SECTION 2 DESIGN AND OPERATION Figure 2-12. Typical datalogger display showing real-time flow rate through the weir V-notch. 2.2.5 Storm Water Weir/Flume and Lower Concrete Lined Canal Water reporting from storm water detention basin outlet boxes is conveyed via 24-inch-diameter HDPE pipe through the cut-off walls to the lower concrete lined canal, which ultimately conveys flow to Zone 2 of the Large Reservoir. Storm water weirs and flumes with level indicators are present where the 24-inch-diameter HDPE pipe connects to the lower concrete lined canal. In some instances, the new system used historic existing branch canals. The lower concrete lined canal originates in the Copper 3 drainage (Figure 1-2). The EWRE system ties into the south dumps at the South Area Drainage (SAD) box. Storm water exits the SAD box via a 36-inch-diameter HDPE storm water overflow line. The line increases in diameter to a 42-inch line at the Copper 4 drainage. The Copper 4 drainage does not have a means of flow measurement and is connected via hard pipe at the Copper 4 deep branch connection. Water from south dumps and the Copper 4 drainage enter the lower concrete lined canal at an outlet box at the head of the canal. The canal is sized to manage storm water from all EWRE basin simultaneously during a 24-hour 100-year event. 2.2.6 Branch Connection Vault and WCRW Main Line The WRCW branch connection vaults are situated parallel to the storm water main line and lower concrete lined canal, and receive WRCW from the dual contained 14-inch-diameter HDPE branch line(s) (Figure 2-13). The branch lines tie into the 16-inch-diameter HDPE WRCW main line pipe (double contained within a 24-inch-diameter HDPE pipe). This 16-inch-diameter HDPE pipe diameter increases in diameter to 24-inch at the Crapo branch connection vault. A typical branch connection vault is accessible via a metal hatch (Figure 2-13). Dual containment of the WRCW main line Real-time flow rate Opening the hatch and exposing the opening in the lid of the box will require fall protection. Entering the vault will require conformance with confined space entry protocol. 2-10 SECTION 2 DESIGN AND OPERATION and the weir box branch connection drain directly into the branch connection vault; thus, water flowing into the branch connection vault is indicative of a leak in the respective conveyance piping. Many branch connection vaults contain automated leak detection sensor that are connected to strobe lights on the associated weir box datalogger station for the respective drainage basin. In the case of branch connection vaults that are located in close proximity to one another, such as Crapo and South Crapo, only one leak detection strobe is used per datalogger. A leak from a secondary pipe will enter the vault triggering the strobe once water comes in contact with the sensor. Water will continue down the secondary pipe associated with the outlet triggering each downstream probe as the water accumulates. The main line pipe conveys WRCW from the EWRE water collection system, as well as flows from the existing system south of Copper 4, to the Midas Pump Station (MPS). The WRCW main line pipe is buried, and is located parallel to and adjacent to the existing lower concrete lined canal (Figures 1-2, 1- 3, and 1-4). Figure 2-13. Photograph of a newly constructed WRCW branch connection vault. 2.2.7 Settling Basin The WRCW Mainline terminates in the settling basin (Figure 2-14). The settling basin also receives inflow directly from the comingled flows of South Congor, Midas and the Old Bingham Tunnel (OBT). From the settling basin, the WRCW is conveyed to the MPS. In the event the MPS cannot receive additional Branch connection vault Air backflow Access hatch for leak detection Lower concrete lined canal 2-11 SECTION 2 DESIGN AND OPERATION WRCW, WRCW in the settling basin can be diverted directly to the lower concrete lined canal. The settling basin also has a fail-safe overflow pipe that directs water to the lower concrete lined canal in the event the outlets of the settling basin are plugged or malfunctioning, thus preventing WRCW spills to ground. The settling basin is also equipped with leak detection for the HDPE liner, as well as the WRCW piping reporting to the settling basin. Sediment accumulation in the settling basin is estimated to be considerable in the first one to two years of operation as the WRCW collection system (e.g., finger drains, toe drain, piping,) rinses free of fine sediment. Further guidance is provided in Section 3.2.10. Figure 2-14. The WRCW Mainline terminates in the settling basin; from the settling basin, WRCW is conveyed to the Midas Pump Station. Piping for specific components of the EWRE water collection system are detailed in Table 2-2. The table describes the function of each pipe, as well as the pipe diameter and dual lining diameter (if applicable). Figure 2-15 is a design drawing detailing the typical and atypical components of the EWRE water collection system. 2-12 SECTION 2 DESIGN AND OPERATION Table 2-2. East Waste Rock Extension water collection system conveyance description and size EWRE Water Collection Piping Description of Piping Pipe Diameter (inches) DR Rating Dual Lining Diameter (inches) DR Rating Toe Drain Pipe Two parallel perforated HDPE pipes; union at tow drain branch connection 12 17 None None Toe Drain Clean Out Pipes Two oblique capped HDPE pipes; each attached to single toe drain pipe 12 17 None None Toe Drain Branch Connection Pipe Solid wall HDPE pipe; transitions at cut-off wall 14 26 None None Storm Water Outlet Box Inlet Orifice Upgradient penetrating port through concrete See Table 2-1 N/A None None Storm Water Outlet Box Outlet Pipe Downgradient penetrating pipe through concrete; terminates at storm water vault and lower concrete lined canal 24 26 None None Cut-off Wall French Drain Pipe Perforated HDPE pipe; transitions at cut-off wall 8 26 None None Toe Drain WRCW from Cut-off Wall to Weir Box Solid wall HDPE pipe; terminates at weir box 14 26 20 32.5 Cut-off Wall WRCW to Weir Box Solid wall HDPE pipe; terminates at weir box 8 26 12 32.5 Weir Box Outlet Pipe Solid wall HDPE pipe; terminates at branch connection vault 14 26 20 32.5 Branch Connection Vault Inlet from Weir Box Solid wall HDPE pipe 14 26 20 32.5 Branch Connection Vault Outlet (WRCW main line upgradient of Crapo) Solid wall HDPE pipe; terminates at settling basin 16 26 24 32.5 Branch Connection Vault Outlet (WRCW main line downgradient of Crapo) Solid wall HDPE pipe; terminates at settling basin 24 26 36 32.5 Storm water main line from SAD box to Copper 4 Solid wall HDPE pipe 36 17 None None Storm water mainline from Copper 4 to lower concrete lined canal Solid wall HDPE pipe 42 26 None None 2-13 SECTION 2 DESIGN AND OPERATION 2.3 Atypical Designs of the EWRE Water Collection System While the majority of the components present in each drainage are constructed identically, there are a few distinct differences within the drainages. These atypical design components are summarized in Table 2-3, and described in subsequent sections below. Table 2-3. Atypical designs of the EWRE water collection system Drainage Unique Feature Copper 4 (Section 2.3.1) Storm water branch line ties into storm water mainline at storm water branch connection; no weir is present. Copper 3 (Section 2.3.2) Storm water branch line ties into canal at head of canal through pre-existing flume. Copper 2 (Section 2.3.3) 1. Two toe drain branch lines report to the cut-off wall. 2. Storm water branch line ties into pre-existing branch canal and comingles with Copper 1 storm water flow; flow measured at pre-existing flume. 3. Branch vault leak detection light located on the Copper 1 datalogger station Copper 1 (Section 2.3.4) Storm water branch line ties into pre-existing branch canal and comingles with Copper 2 storm water flow; flow measured at pre-existing flume. Lost Creek (Section 2.3.5) 1. WRCW branch lines comingle at Lost Creek/Keystone weir for one combined flow. 2. Storm water passes under Mine Access Road via HDPE pipe to storm water detention basin. 3. Commingled Lost Creek-Keystone storm water enters at pre-existing flume Keystone (Section 2.3.5) 1. WRCW branch lines comingle at Lost Creek/Keystone weir for one combined flow. 2. Storm water passes under Mine Access Road via HDPE pipe to storm water detention basin. 3. Commingled Lost Creek-Keystone storm water enters at pre-existing flume 4. There are two detention basins in the drainage straddling the Bingham Tunnel North Keystone (Section 2.3.6) 1. Finger drain of NARD material located west of Mine Access Road collects WRCW; this finger drain leads to HDPE pipe that passes under the Mine Access Road. The HDPE pipe under Mine Access Road opens into another NARD drain east of the Mine Access Road; this NARD drain leads to the toe drain. 2. Surface water from the Mine access road is captured in a rip rap basin and routed under the road, past the toe drain and reports to the detention basin. Care to properly abandon this pipe will be required before the waste rock is placed in this location to prevent the transport of WRCW across the toe drain. South Crapo (Section 2.3.7) None Crapo (Section 2.3.8) 1. Storm water branch line ties into pre-existing branch canal; flow measured through pre-existing flume. 2. Storm water routed under the toe drain road via culvert. 3. The WRCW main line increases in pipe diameter from 16-inch-diameter to 24-inch-diameter 4. At branch connection diversion located downgradient of the Crapo branch connection vault permits WRCW to be segregated from the WCRW main line into the lower concrete lined canal. 2-14 SECTION 2 DESIGN AND OPERATION South Congor (Section 2.3.9) 1. WRCW branch lines comingle at South Congor/Midas weir for one combined flow, which also includes flow from Old Bingham Tunnel. The flow from the Old Bingham Tunnel enters the weir below the V-Notch. No leak detection for flow from the Old Bingham Tunnel. 2. Combine WRCW flow goes direct to Settling Basin and not WRCW Mainline. 3. Storm water combined for South Congor and Midas; flows combine at weir. Midas (Section 2.3.9) 1. WRCW branch lines comingle at the South Congor/Midas weir for one combined flow. 2. WRCW flow out of the weir box includes flow from the Old Bingham Tunnel (OBT). The OBT flow is not accounted for in the combined South Congor/Midas flow as OBT flow enters the weir box below the V-Notch. There is no leak detection for the OBT conveyance pipe. 3. Combine WRCW flow goes direct to Settling Basin and not WRCW Mainline. 4. Storm water combined for South Congor and Midas; flows combine at weir. Structure Unique Feature WRCW Branch Vault (Station 2134+00) (Section 2.3.10) 1. Valve to divert WRCW to lower concrete lined canal. South Area Dumps (SAD) Box (Section 2.3.11) 1. 16-inch-diameter pipe with 6-inch-diameter orifice accepts base flow (approximately 100 gallons per minute) water from the South Area Dumps. 2. Portal to access 32-inch-diameter HDPE WRCW pipe and insert “pig.” Storm Water Inlet Structure at Canal (Section 2.3.12) 1. Energy dissipation structure that directs water from the 42-inch-diameter storm water pipe into the canal in the Copper 3 drainage. Lower concrete lined canal (Section 2.3.13) 1. Curbing to extend top of canal near Copper 1 and Copper 2, where a flat grade of less than 1%. 2.3.1 Copper 4 Appendix B provides a photo log documenting the construction process of the Copper 4 drainage. The one unique feature of the Copper 4 drainage basin is the following: 1. There is no storm water weir in the Copper 4 drainage; rather, the 24-inch-diameter HDPE storm water branch line ties directly into the 42-inch-diameter storm water mainline via a branch connection. 2.3.2 Copper 3 Appendix B provides a photo log documenting the construction process of the Copper 3 drainage. The one unique feature of the Copper 3 drainage basin is the following: 1. Storm water in the Copper 3 drainage connects to the lower concrete lined canal through a pre- existing storm water flume, shown in Figure 2-16. 2-15 SECTION 2 DESIGN AND OPERATION Figure 2-16. Storm water in the Copper 3 drainage connects to the lower concrete lined canal through a pre-existing storm water flume. 2.3.3 Copper 2 Appendix B provides a photo log documenting the construction process of the Copper 2 drainage. The two unique features of the Copper 2 drainage basin are the following: 1. The Copper 2 cut-off wall is unique in that two branch lines from the toe drain report to the cut-off wall. This is due to two low-elevation sections in the toe drain above the Copper 2 drainage basin. The two toe drain branch lines comingle below the wall in a single branch connection to the Copper 2 weir box. 2. The Copper 2 storm water branch line and the Copper 1 storm water branch line connect in a storm water vault upgradient of a pre-existing branch canal (Figure 2-17) to the lower concrete lined canal. The comingled flow of Copper 2 and Copper 1 storm water flow is measured with a data logger installed in a pre-existing flume. 2-16 SECTION 2 DESIGN AND OPERATION Figure 2-17. Copper 2 and Copper 1 storm water branch canal. 2.3.4 Copper 1 Appendix B provides a photo log documenting the construction process of the Copper 1 drainage. The one unique feature of the Copper 1 drainage basin is the following: 1. The Copper 1 storm water branch line and the Copper 2 storm water branch line connect in a storm water vault upgradient of a pre-existing branch canal (Figure 2-17) to the lower concrete lined canal. The comingled flow of Copper 1 and Copper 2 storm water flow is measured with a datalogger installed in a pre-existing flume. 2.3.5 Lost Creek and Keystone Appendix B provides photo logs documenting the construction process of the Lost Creek and Keystone drainages. The Lost Creek and Keystone drainages basins are steeply incised drainages separated by a relatively narrow ridge. As such, the drainage basins are near to each other, and share three atypical design features. The three unique features of the Lost Creek and Keystone drainage basins are the following: 1. The WRCW branch lines from each respective cut-off wall comingle at a shared Lost Creek and Keystone weir box. As such, there are four dual-contained input pipes in the stilling portion of the weir box, five leak detection pipe surrounding the shared weir box, and the datalogger measures combined Lost Creek and Keystone WRCW flow through the V-notch. 2. Storm water and WRCW from upgradient portions of each respective drainage basin is conveyed under the Mine Access Road through a 24-inch-diameter HDPE pipe, and a 14-inch-diameter HDPE pipe, respectively. The 24-inch-diameter HDPE pipes drain into energy dissipation channels immediately upgradient of each respective storm water detention basin (Figures 2-18 and 2-19), and Copper 1 storm water inflow Copper 2 storm water inflow Branch Canal 2-17 SECTION 2 DESIGN AND OPERATION the WRCW 14-inch-diameter HDPE pipe continues to the cut-off wall. The conveyance pipes under the MAR were installed through directional drilling boreholes. 3. The combined flow of the Lost Creek and Keystone storm water branch lines is measured with a datalogger installed in the pre-existing Lower Keystone flume that drains to the lower concrete lined canal. Figure 2-18. Lost Creek drainage directional boring outlet. Storm water outlet WRCW clean out Mine Access Road Storm water outlet WRCW clean out 2-18 SECTION 2 DESIGN AND OPERATION Figure 2-19. Keystone drainage directional boring outlet. 4. Two detention basins were constructed in the Keystone drainage in an effort to avoid construction and impounding water atop the Bingham Tunnel (Figure 2-20). As a result, additional concrete inlet and outlet structures are incorporated into the surface water conveyance structures which are not typical of other EWRE detention basins. Figure 2-20. Keystone detention basins straddling the Bingham Tunnel. 2.3.6 North Keystone Appendix B provides a photo log documenting the construction process of the North Keystone drainage. The one unique feature of the North Keystone drainage basin is the following: 1. West of the Mine Access Road, in the upgradient portion of the North Keystone drainage basin, a coarse quartzite finger drain was installed to collect WRCW. This finger drain leads to a 14-inch-diameter HDPE pipe, which conveys the WRCW under the Mine Access Road. The 14-inch-diameter HDPE pipe opens into another coarse quartzite finger drain east of the Mine Access Road (Figure 2-21), which directs WRCW flow toward the North Keystone segment of toe drain. 2. The surface water drain moves water off the Mine Access Road, past the toe drain and into the North Keystone detention basin. The surface water conveyance pipe (Figure 2-22) will be covered by waste rock as part of the EWRE dump footprint, at which time the pipe will act as WRCW conveyance. Storm water inlet Bingham Tunnel Storm water inlet Storm water outlet Storm water outlet 2-19 SECTION 2 DESIGN AND OPERATION Figure 2-21. Photograph showing the 14-inch-diameter HPDE pipe conveying WRCW under the Mine Access Road in the North Keystone drainage basin. The coarse quartzite finger drain directs WRCW flow toward the North Keystone segment of toe drain. Figure 2-22. The North Keystone storm water conveyance pipe will eventually be covered by waste rock and will require proper abandonment to ensure effective WRCW capture. IMPORTANT The North Keystone storm water conveyance pipe must be properly abandoned in order to ensure WRCW is not conveyed across the toe drain and water collection system. Toe drain Coarse quartzite finger drain North Keystone WRCW conveyance pipe North Keystone storm water conveyance line 2-20 SECTION 2 DESIGN AND OPERATION 2.3.7 South Crapo Appendix B provides a photo log documenting the construction process of the South Crapo drainage. No atypical water collection system design features are present in the South Crapo drainage basin. 2.3.8 Crapo Appendix B provides a photo log documenting the construction process of the Crapo drainage. There are four atypical features of the EWRE water collection system in the Crapo drainage basin. The four unique aspects are the following: 1. Storm water generated in upgradient areas of the Crapo drainage basin is routed under the toe drain road via culvert toward the Crapo storm water detention basin. 2. The Crapo storm water branch line ties into a pre-existing branch canal (Figure 2-23), where flow is measured with a datalogger installed in a pre-existing flume. 3. At the Crapo WRCW branch connection vault, the WCRW main line increases in pipe diameter from 16-inch-diameter to 24-inch-diameter. The WCRW main line remains 24-inch-diameter HDPE pipe to the settling basin. 4. At branch connection diversion located downgradient of the Crapo branch connection vault (Station 2134+00) permits WRCW to be segregated from the WCRW main line into the lower concrete lined canal (see Section 2.3.10). This feature will be used when repairs are necessary to the settling basin. Figure 2-23. Photograph showing the Crapo storm water branch line connection to a pre-existing branch canal. 2.3.9 South Congor and Midas Appendix B provides photo logs documenting the construction process of the South Congor and Midas drainages. Branch canal Storm water branch line l Concrete slab 2-21 SECTION 2 DESIGN AND OPERATION The South Congor and Midas drainages basins are steeply incised drainages separated by a relatively narrow ridge. As such, the drainage basins are near to each other, and share four atypical design features. The four unique features of the South Congor and Midas drainage basins are the following: 1. The WRCW branch lines from each respective cut-off wall comingle at a shared South Congor and Midas weir box. As such, there are four dual-contained input pipes in the stilling portion of the weir box, five leak detection pipe surrounding the shared weir box, and the datalogger measures combined South Congor and Midas WRCW flow through the V-notch. 2. The WRCW flow out of the weir box includes tunnel discharge from the Old Bingham Tunnel (OBT) (Figure 2-24). The OBT flow is not accounted for in the combined South Congor and Midas flow, as the OBT flow enters the weir box below the V-Notch. Additionally, no leak detection for the OBT conveyance pipe was installed. 3. The combine South Congor, Midas, and OBT WRCW is conveyed directly to the settling basin, by- passing the WRCW Mainline. 4. Storm water generated in the South Congor and Midas drainage basins is combined in a storm water weir; the combined South Congor and Midas storm water flow is discharged to the lower concrete lined canal. Figure 2-24. Photograph showing tunnel discharge from the Old Bingham Tunnel (OBT). The tunnel discharge from the OBT is conveyed to the combined South Congor and Midas weir box, but enters below the V-notch flow measuring point. Tunnel discharge Old Bingham Tunnel Entrance 2-22 SECTION 2 DESIGN AND OPERATION 2.3.10 WRCW Branch Vault Diversion Box (Station 2134+00) This WRCW branch vault behaves similarly to all other WRCW vaults but in addition contains a gate valve that, once closed, will divert water into the lower concrete lined canal. The necessity of this feature became apparent during EWRE construction when repairs, modifications or maintenance was required at the Settling Basin. Access to the valve is inside the vault and requires a confined space entry. Figure 2-25. WCRW branch vault (Station 2134+00) can divert water into the lower concrete lined canal when maintenance is required at the Settling Basin. 2.3.11 South Area Dumps (SAD) Box The South Area Dump (SAD) box accepts water from the south dump drainages (Yosemite to Queen) via a 36-inch-diameter HDPE pipe (Figure 2-26). Base flow from the south dumps is typically less than 100 gallons per minute (gpm) and is accepted through the WRCW outlet line. The WRCW outlet is a 16-inch- diameter dual lined HDPE pipe with an 8-inch-diameter orifice. Should a storm event exceed the 100 gpm flow threshold into the SAD box, the comingled flow will rout through a 36-inch-diameter overflow pipe. The SAD box has an HDPE liner but does not have leak detection due to the chemical nature of the contact water. Contact water from the south dump drainages is of better water quality compared to contact water north of Copper 4 drainage. Additionally, a port was installed upgradient of the connection box for pigging the line and temporarily stopping the flow for repairs or cleaning (Figure 2-26). WRCW diversion to lower concrete lined canal Station 2134+00 Diversion valve 2-23 SECTION 2 DESIGN AND OPERATION Figure 2-26. South Area Dump (SAD) box. 2.3.12 Storm Water Inlet Structure at Canal The storm water inlet box (Figure 2-27) receives water from the south area dumps (Yosemite to Queen Drainages) via a 36-inch-diameter HDPE pipe and dissipates the energy of the water as it is introduced to the canal. The HDPE pipe is 36-inch-diameter from the SAD box to the Copper 4 branch line, at which time the HDPE pipe becomes 42-inch-diameter. A gate valve at the outlet structure allows for the drainage of standing water behind the structures energy dissipation baffle. Figure 2-27. Storm water inlet structure by Copper 3. SAD Box “Pig” port Standing water outlet Energy dissipation baffle 2-24 SECTION 2 DESIGN AND OPERATION 2.3.13 Lower Concrete Lined Canal The lower concrete lined canal was originally constructed in the 1990’s and is permitted under groundwater discharge permit #UGW350010 to convey both storm water and process water under upset conditions. The lower concrete lined canal, while still functional, was refurbished as part of the EWRE project and modified in sections to accommodate the capacity needed under the modeled 100- year 24-hour storm event. Surface water reports to the lower concrete lined canal from the detention basins via HDPE pipe and/or sections of pre-existing branch canal. Water flow can be measured through pre-existing flumes or newly constructed weirs. Flow is recorded at the same data loggers that capture WRCW flow in the weir boxes. 2-25 SECTION 3 3.0 Inspection and Maintenance 3.1 Overview Inspection frequency is guided by groundwater discharge permit # UGW350010. The groundwater discharge permit specifically requires quarterly inspection; however, best practice recommends inspection following large rain events. Table 3-1 provides inspection guidance and frequency. Table 3-1. Inspection frequency and guidance Inspection Type Frequency Guidance UDWQ Groundwater Discharge Permit #UGW350010 1 Quarterly Groundwater Discharge Permit # UGW350010 Significant precipitation event 2 As Needed Rainfall period ≥10 year-24 hour as indicated by the Copper drainage rain gage Other As Needed Examples for inspection may include a Health and Safety incident, Dump/Slope movement, or at the request of regulatory agency Notes: 1 Required by the groundwater discharge permit 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. 3.2 Guidance for Inspection Inspection checklists for evaluating the primary and auxiliary components of the EWRE water collection system are provided in Appendix C. Final as-built drawings of each drainage basin the respective water collection system components are provided in Appendix D. The following sections are descriptions of what to assess and evaluate during the inspection process, conditions that may result in a need for maintenance, and potential mitigation and repair recommendations. 3.2.1 Dump Face A visual inspection of the dump face (Figure 3-1) is required for each respective drainage basin. Examples of potential issues with the dump face may include the following: • Erosional gullies and/or debris flows developing • Seeps or wet spots observed • Settling, bulging or slumping observed • Horizontal or vertical cracks developing 3.2.2 Down Drains Visual inspection of the down drains is required for each respective drainage basin. Examples of potential issues with the down drains may include the following: • Erosion and channel development along the sides of the down drain If evidence of any of these items is observed on the dump face, document the findings in the inspection checklist, photograph, and notify RTKC Mine operations for support and resolution. If evidence of any of these items is observed on the down drains, document the findings in the inspection checklist, photograph, and notify RTKC Mine operations for servicing. 3-1 SECTION 3 INSPECTION AND MAINTENANCE • Disturbed rip-rap channels altering drainage Figure 3-1. Photographic overview of EWRE water collection system components. 3.2.3 Toe Drain 3.2.3.1 Access Road Inspection of the toe drain access road (Figure 3-2) is required for each respective drainage basin. Examples of potential issues with the access road may include the following: • Rutting related to weather and driving in wet conditions • Channeling related to running water and erosion • Maintenance of the surface water rip rap ditch adjacent to the access road 3.2.3.2 Toe Drain Clean Outs Inspection of the toe drain clean outs (Figure 3-2) is required for each respective drainage basin. Examples of potential issues with the clean outs may include the following: • Access to the clean out port has changed due to rock, debris or erosion Dump face Check dam Stormwater detention basin Outlet box Toe drain Spillway Cut-off wall Weir box Mitigation may include redirecting surface water through engineered structures and/or regrading the access road. Mitigation may include repair, removal of rock/debris, construction of a protective berm, and/or regrading the area around the clean out. Silt fence 3-2 SECTION 3 INSPECTION AND MAINTENANCE • The clean out cover or pipe is damaged (e.g., struck by debris or equipment) 3.2.3.3 Rip Rap Ditch and Energy Dissipation Inspection of the rip rap ditch (Figure 3-2) and energy dissipation system (not installed as of October 31, 2016) are required for each respective drainage basin. Examples of potential issues with these components may include the following: • Erosion along the sides of the rip rap channel • Rip rap channel full of sediment and debris • Rock in the rip rap channel has moved or is missing • A significant volume of water is ponded in the rip rap channel Figure 3-2. Photograph of a newly constructed segment of the toe drain; toe drain features include the clean outs, rip rap ditch and access road. 3.2.4 Storm Water Detention Basin 3.2.4.1 Check Dam Integrity Inspection of the check dam (Figure 3-3) is required for each respective drainage basin. Examples of potential issues with the check dam may include the following: • Erosion in upgradient portions of the drainage basin have caused excessive silting • Check dam embankment material has moved or is missing • The silt fence is damaged and/or full of sediment Access road Rip rap ditch Clean outs Toe drain For design and maintenance support, contact the Facility Environmental Engineer Silt fence is advised to prevent silt plugging the desilting basin and outlet structure while vegetation becomes established. 3-3 SECTION 3 INSPECTION AND MAINTENANCE 3.2.4.2 Storm Water Detention Basin Inspection of the storm water detention basin (Figure 3-3) is required for each respective drainage basin. Excess silt, sediment and debris can decrease basin capacity or lead to system failure (i.e., plugged outlets). A staff gauge is included in each basin to easily conduct visual observations. In addition, as built drawings (Appendix D), XML terrain files and AutoCAD design files (Appendix E), redline design drawings (Appendix F), and documentation of cut-off wall survey monuments (Appendix G) are all available for reconstruction of the detention basin to original design schematics. Examples of potential issues with the storm water detention basin may include the following: • The storm water detention basin is not draining • The storm water detention basin has excessive silt 3.2.4.3 Outlet Box Inspection of the outlet box (Figure 3-3) is required for each respective drainage basin. Examples of potential issues with the outlet box may include the following: • The low flow orifice is blocked by sediment, vegetation or debris • The silt fence is damaged and/or full of sediment 3.2.4.4 Embankments and Spillway Inspection of the embankments (Figure 3-3) and spillway (Figure 3-4) are required for each respective drainage basin. Examples of potential issues with these components may include the following: • Displacement or movement of spillway or embankment material • Embankment instability, potentially caused by burrowing animals/tunneling • Erosion along the edges of the spillway or through the embankments If the low flow orifice to the outlet box is blocked greater than 10 percent of the diameter, then the orifice requires cleanout maintenance. The storm water detention basin may not be draining due to a blocked overflow structure, or it may be draining, but a seep/spring has developed in the basin. If a seep is identified, estimate the flow rate and report the finding to the Facility Environmental Engineer (Table 5-1). If sediment is greater than 1.5 feet at the staff gauge, the storm water detention basin should be scheduled for sediment removal and clean out. Potential maintenance to embankments and spillways may include removal/replacement of embankment and spillway material, especially if erosion along the edge of the rip-rap channel begins to develop. 3-4 SECTION 3 INSPECTION AND MAINTENANCE Figure 3-3. Photograph of a newly constructed storm water detention basin; features include desilting area, check dam, storm water detention basin, outlet box, spillway and silt fences. Outlet box Silt fence Storm water detention basin Check dam Desilting area Silt fence Embankment Spillway 3-5 SECTION 3 INSPECTION AND MAINTENANCE Figure 3-4. Photograph of a newly constructed spillway. The spillway connects the storm water detention basin to the cut-off wall. 3.2.5 Cut-off Wall Inspection of the cut-off walls (Figures 3-5 and 3-6) are required for each respective drainage basin. Examples of potential issues with the cut-off walls may include the following: • Cracks have developed and/or are enlarging in the cut-off wall concrete • The cut-off wall has been damaged (i.e., equipment strikes or storm debris) • Sediment has built-up behind the wall • Associated cut-off wall piping is plugged, damaged or broken (evidence of a problem will not likely be visible at the cut-off wall proper, but rather in other areas along the storm water or WRCW flow paths) • The storm water inlet grate is damage or clogged by vegetation or debris • Associated cut-off wall pipe valves are stiff, leaking or damaged Storm water inlet grate Spillway Cut-off wall 3-6 SECTION 3 INSPECTION AND MAINTENANCE Figure 3-5. Photograph of a newly constructed cut-off wall. The spillway connects the storm water detention pond to the cut-off wall; the cut-off wall includes a storm water inlet grate and a valve vault. 3.2.6 Weir Box 3.2.6.1 Weir Box Integrity Inspection of the weir box (Figure 3-7) is required for each respective drainage basin. Examples of potential issues with the weir box may include the following: • The above ground concrete weir box curbing and/or surface grating is damage • Weir box signage is missing or damaged • Scale, debris, or sediment (at quantities that potentially may disrupt flow measurement) has accumulated in the weir box • The weir box piping, liner, V-notch, and/or baffle is damaged • The weir box piping has developed scale (at quantities that potentially may disrupt flow measurement) Spillway Valves Storm water inlet grate Cut-off wall Embankment In order to maintain accurate flow readings, it is recommended that level indicators be calibrated approximately every six months. In addition, the v- notch may begin to scale and require cleaning in order to accurately represent water level. Scale removal from the v- notch and calibration of the level indicator should be done in conjunction. 3-7 SECTION 3 INSPECTION AND MAINTENANCE Figure 3-6. Photograph of a newly constructed cut-off wall. The valve port allows access to manipulate the WRCW flow valves. Figure 3-7. Photograph of a newly constructed weir box and auxiliary components. Valve access port Spillway Storm water vault Cut-off wall Weir box Leak detection Solar panel Datalogger Battery Level indicator 3-8 SECTION 3 INSPECTION AND MAINTENANCE 3.2.6.2 Data Logger Inspection of the data logger stations (Figure 3-7) is required. Visually inspect the components of the data logger station to identify wear and tear, broken or missing parts, and to confirm all display components are functional. During the inspection, examine the solar panel for damage and clean off dust. If the data logger is not functioning, operational troubleshooting may be required. See the Reference Links in Section 5 for guidance on the operation of the datalogger and service contact information. 3.2.6.3 Leak Detection Sump Inspection of the leak detection sumps (Figure 3-7) should be performed quarterly, or if there is suspected pipe damage along the WRCW flow path. If water is detected in any of the leak detection sumps, notify the facility environmental engineer (Table 5-1) as sample collection will likely be required. 3.2.7 Branch Connection Vault Inspection of the branch connection vault (Figure 3-8) is required for each respective drainage basin. Examples of potential issues with the branch connection vault may include the following: • Presence of standing water inside the vault • Presence of sediment inside the vault • Damage to the metal hatch, vent pipe or bollards • Leak detection sensor malfunction Potential maintenance to the branch connection vault may include determining the source(s) of standing water and/or sediment, draining/cleaning the branch connection vault, and repair of any damaged components. If flowing water is observed in the branch connection vault, there is a break in the pipe upstream that will require immediate repair. Notify the facility environmental engineer (Table 5-1) if flowing water is observed. 3.2.8 Storm Water Vault, Lower Concrete Lined Canal and Datalogger Station Inspection of the storm water vault, lower concrete lined canal, and datalogger station (if applicable) (Figure 3-9) is required for each respective drainage basin. Examples of potential issues with the storm water vault and lower concrete lined canal may include the following: • Damage to or development of cracks in the concrete vault or canal • Accumulation of sediment or debris • Datalogger malfunction The leak detection sensor should be tested annually to confirm functionality; in order to test the sensor and datalogger station strobe, the sensor must be submerged in water. A confined space permit is required to enter the branch connection vault. Potential maintenance to the storm water vault and lower concrete lined canal may include concrete repair and debris/sediment clean out. Inspect the components of the data logger station to identify wear and tear, broken or missing parts, and to confirm all display components are functional. Examine the solar panel for damage and clean off dust. Calibration of the storm water level indicators is recommended annually in order to maintain accurate measurements. If the data logger is not functioning, operational troubleshooting may be required (see reference links in Section 5 for service contact information). 3-9 SECTION 3 INSPECTION AND MAINTENANCE Figure 3-8. Photograph of a newly constructed WRCW branch connection vault. Branch connection vault Air backflow Access hatch for leak detection Bollard Lower concrete lined canal 3-10 SECTION 3 INSPECTION AND MAINTENANCE Figure 3-9. Photograph of a newly constructed storm water vault, level indicator and lower concrete lined canal. 3.2.9 Old Bingham Tunnel Inspection of the Old Bingham Tunnel (OBT) is required. Examples of potential issues with the OBT may include the following: • Collapse or failure of the tunnel entrance • Accumulation of rock or debris in the tunnel discharge area • Plugging of the tunnel discharge orifice Lower concrete lined canal Storm water vault and level indicator Datalogger Solar panel Potential maintenance to the OBT may include tunnel entrance repairs, excavation of rock and/or debris, and removing accumulated sediment from the discharge and drainage area. Battery 3-11 SECTION 3 INSPECTION AND MAINTENANCE Figure 3-10. Photo of the Old Bingham Tunnel (OBT) entrance. 3.2.10 Settling Basin The Settling Basin (Figure 3-11) should be drained and inspected on a quarterly basis for two years starting 4Q2016 to establish a performance baseline. In order to perform the inspection, the following steps need to be taken: • Place the WRCW into bypass by closing the valve at the WRCW Branch Vault diversion (Station 2134+00). Cross reference section 2.3.10 for additional details. • Pump down the Settling Basin in manual to low shut-off. • Remove the remaining water; use of a vacuum truck is strongly recommended due to the likely presence of silt. • Remove the excess silt and water with a vacuum truck. Consult with the facility environmental engineer for proper disposal of sediment and water. • IMPORTANT. When vacuuming, always keep separation between the hose intake and the liner so as not to damage the liner. The corner welds are stronger and better anchored than the center liner; vacuuming should be preferentially focused in these areas. In order to maintain space between the hose tip and the liner, incorporate a basket or similar implement. Tunnel discharge Old Bingham Tunnel entrance 3-12 SECTION 3 INSPECTION AND MAINTENANCE Figure 3-11. Settling Basin isometric projection and cross sectional view. Examples of potential issues, other than accumulated sediment, occurring in the Settling Basin may include the following: • The concrete Settling Basin curbing and/or surface grating is damage • Signage is missing or damaged • Scale or debris (at quantities that potentially may disrupt flow measurement) has accumulated in the Settling Basin • The piping is damaged • The piping has developed scale (at quantities that potentially may disrupt flow measurement) When vacuuming always keep separation between the hose intake and the liner so as not to damage the liner. 3-13 SECTION 3 INSPECTION AND MAINTENANCE 3.2.11 Lower Concrete Lined Canal The lower concrete lined canal (Figure 3-12) should be inspected for accumulation of sediment and debris and the elimination of sources (i.e., eroded embankments). Sediment and debris should be removed regularly in order to maintain design capacity and best performance. Should vegetation develop, remove in order to maintain best performance. Quarterly inspection should include observations for settling and cracking of the lower concrete lined canal sections. Minor cracks will not hinder performance but should be addressed in order to prevent deterioration of the structure and costlier repairs in the future. Figure 3-12. Section of the lower concrete lined canal. 3.2.12 WRCW Branch Vault Diversion Box (WRCW Vault Station 2134+00) The inspection of the branch vault diversion box (Station 2134+00) is similar to the inspection of typical WRCW vaults (See Section 3.2.7), and can be done in conjunction with the settling basin inspection since this is where the basin bypass is accomplished. This vault does not contain a leak detection sensor and associated strobe. In addition to criteria outlined in section 3.2.7, the valve requires exercise and associated bypass piping requires inspection for leaks or damage. Lower concrete lined canal 3-14 SECTION 3 INSPECTION AND MAINTENANCE Figure 3-13. (A) WRCW branch vault diversion box (Station 2134+00); (B) diversion gate valve. 3.2.13 South Area Dumps (SAD) Box The South Area Dump (SAD) Box does not have leak detection due to the relatively clean nature of the WRCW as compared to the WRCW reporting from the Copper drainages north. The important aspects to inspect in order to ensure proper function of the structure are: • If sediment and debris are present in the box they should be removed immediately. • Check for damage of the liner and pipe inlets/outlets due to sediment and debris. • If scale is present it should be removed in order to preserve capacity. IMPORTANT. When vacuuming always keep separation between the hose intake and the liner so as not to damage the liner. 3.2.14 Storm Water Inlet Structure at Lower Concrete Lined Canal The storm water inlet structure at the lower concrete lined canal should require limited maintenance. Inspect for sediment and debris that could hinder capacity and full function of the structure. Large intense rain events will be of particular interest since this is about the only time the structure will have become active. Sediment and debris will need to be removed in order to maintain full functionality. Station 2134+00 WRCW diversion flow Diversion gate valve (A) (B) 3-15 SECTION 3 INSPECTION AND MAINTENANCE 3.3 Compliance Sampling Locations and Frequency Compliance points such as cut-off walls, weir boxes, seeps and tunnels are associated with the Bingham Canyon Mine Groundwater Discharge Permit #UGW350010, and are required to be sampled on various frequencies for water quality and flow rate (Figure 3-14). The installation of the cut-off walls and toe drain associated with the EWRE required updating many of these sample points, as the legacy system was replaced and the new collection system was installed. Appendix H details the transition from the legacy east side collection system to the newly installed EWRE water collection system. The operational sample identification numbers (i.e. cut-off walls) were kept the same at the new weir boxes in cases where the legacy flow was traced to the corresponding new toe drain section, branch line and weir box. In cases where new drainages were intercepted not corresponding to the legacy system, a new identification number was assigned. Incorporated into the new system is capture of WRCW primarily at the toe drain and secondarily at the cut-off wall. Both sources for a particular drainage are collected at a shared weir box. The sample reporting from the toe drain has an “A” designation while the sample from the cut-off wall has a “B” designation. During construction, water quality from the A and B sources was typically different, in that toe drain water was more characteristic of waste rock contact water, and cut-off wall water was more characteristic of fresh water. Based upon this information, the following guidance is derived: • When the two water qualities mix in the weir box, and are introduced to an open environment with increased oxygen, water chemistry will change and increased mineral precipitation (i.e. scale) can be expected. • If water quality is to suddenly diminish in the “B” sample reporting from the cut-off wall, toe drain functionality could be in question, although all potential sources need to be considered and investigated. Typically, each weir represents a single drainage; however, flow from the Lost Creek-Keystone drainages merge into a single weir box, and flow from the South Congor-Midas drainages merge into a single weir box. Discharge water from the Old Bingham tunnel also enters the South Congor-Midas weir box, but can still be sampled at the tunnel opening. In all cases the curb is labeled with the sample identification number for easy identification, and a sample port grate allows for sample collection access. A number of seeps were identified during the EWRE project. The locations of these seeps, as well as the geology, are shown on Figure 3-15. This seeps, springs and area geology map was constructed to provide documentation of the EWRE site prior to waste rock coverage. 3-16 SECTION 4 4.0 Training 4.1 General Requirements 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 basins and structures. If, in the future, a knowledge gap is identified, contact a member of the RTKC Water Quality team (Table 5-1) and arrange for training support should knowledgeable members of the construction team or operations team not be available. 4-1 SECTION 5 5.0 Reference Information 5.1 UDWQ Construction Permit The collection system design and specifications were reviewed and approved by Mr. Woodrow Campbell, P.E. of the Utah Department of Environmental Quality – Division of Water Quality. Eight periodic field visits were conducted during the construction activities, including a final inspection on October 25, 2016. The State inspection reports are included in Appendix I. 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. 5.3 Groundwater Discharge Permit The EWRE collection system components are 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. 5.4 Project Contacts Should questions arise in the future that are not covered in this document, RTKC contacts are provided below. Table 5-1. EWRE project contact information Name Title Contact Information Tom Gibson Construction Manager 970-946-0641 Steve Ferris Project Manager 385-246-6938 Rob Watson Construction Superintendent 801-824-1146 Scott Bird Manager – HSEC & Quality 801-699-8337 Jason Hill Quality and Engineering 435-841-9413 Zeb Kenyon Environmental Compliance and Quality 801-913-2356 Jason Doyle Operations Manager - Tailings 801-652-0028 Guillermo Salcedo Operations Supervisor - SAWS 801-232-1297 Brian Vinton Principal Advisor – Water Quality 801-712-4597 5-1 SECTION 5 REFERENCE INFORMATION Reference Links: Datalogger Flow Monitoring Reference Material The Pulsar Ultra Twin UL Instruction Manual (June 2011) is available at: https://www.pulsar- pm.com/LinkClick.aspx?fileticket=BoFap_kwCtI%3d&tabid=771&portalid=0&mid=1111&language=en- GB The Pulsar datalogger software is Ultra Log 5.1, and is available at: https://www.pulsar-pm.com/support/downloads/software.aspx Midas Pump Station Reference Material The installation, operation and maintenance manual for the Goulds Pumps Model 3196 i-FRAME at the Midas Pump Station is available at: https://www.gouldspumps.com/ittgp/medialibrary/goulds/website/Products/3196-i- FRAME/InstallationOperationMaintenance_3196_i_FRAME.pdf 5.5 Project Quality Assurance and Quality Control Documentation of project quality assurance and quality control is provided in Appendix J. Quality Control was performed by Amec Foster Wheeler Environment and Infrastructure, Inc., and discrepancies were satisfactorily reported and corrected. 5.6 Revision History To assist in future updates and revisions to the EWRE O&M Manual, the native Microsoft Word file is included in Appendix K. Rev # Description of Changes Prepared by Date 0 Original release of O&M to comply with UDWQ Permit #UGW350010 Permit to Construct, Condition #2 Zeb Kenyon, RT G&I December 2016 5-2 DWQ-2020-015202 Appendix A EWRE Geology, Seeps, and Springs Map Appendix B Drainage Basin Photographic Logs Appendix C South Area Water Services East Side Collection System – East Waste Rock Extension Groundwater Discharge Permit Inspection and Supplemental Inspection Forms Appendix D Drainage Basin As-Built Drawings Appendix E XML Terrain Files and AutoCAD Design Files Appendix F Redline Design Drawings Appendix G Survey Monument Documentation Appendix H EWRE Compliance Monitoring Transition Documentation Appendix I State Inspection Reports Appendix J Quality Assurance and Quality Control Documentation Appendix K Operations and Maintenance Manual Microsoft Word Document File Appendix L CH2M HILL Hydrology Report