2024-05-17_REVISION - M1977493 (4)

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G-2.8.6 Tenmile Tunnel The Tenmile Tunnel is a water conveyance structure that runs from the west abutment of 3 Dam on the north end to Robinson Lake on the south end. There is a vertical decant inlet into the tunnel from the water pool on the west side of Tenmile TSF that is known as the Tenmile Riser. By operating valves at a bulkhead within the tunnel, water can be directed either to Robinson Lake or Mayflower TSF. G-2.8.7 East Side Channel — Robinson Section The East Side Channel (ESC) has been completed along the east side of Robinson TSF. The channel currently conveys process water from the Robinson Pond water pool and areas tributary to the Robinson Pond through the 2 Dam Spillway to Tenmile TSF. G-2.8.8 East Tailing Delivery Line The East Tailing Delivery Line (ETDL) extends from the mill area to 3 Dam and is now used to convey process water to the SDP treatment system. The line consists primarily of 36-inch-diameter and 42-inch- diameter concrete and HDPE pipe that is installed on the ground surface. G-2.8.9 DSM Interceptors The DSM Interceptors are several separate interceptor systems that collect process water from impacted areas and discharge into the ETDL. The system includes the South Camp Interceptor, North Camp Interceptor, and the McNulty Interceptor. G-2.8.10 5 Dam (Mayflower) Seepwater Pump System The 5 Dam Seepwater Pump System consists of a seepage collection system at the toe of 5 Dam, a pump station and a pipeline that conveys this water to the water pool on Mayflower TSF. The discharge elevation of this system is periodically raised as the height of 5 Dam increases. G-2.8.11 3 Dam Seepwater Pump System The 3 Dam Seepwater Pump System consists of a seepage collection system along the toe of 3 Dam, a pump station and a pipeline that conveys this water to the Sludge Densification Plant (SDP) for treatment. This pumping system will eventually be decommissioned as the elevation of Mayflower TSF increases. At that time 3 Dam seepage will be collected in Mayflower TSF. G-2.8.12 Mayflower Barge Pumping System The Mayflower Barge Pumping System consists of two pump barges. The Plant Barge is used to convey water from the water pool on Mayflower TSF to the PDWTP for treatment and release to Tenmile Creek downstream of 5 Dam. The Mill Barge is used to convey water from the Mayflower TSF water pool to Robinson Lake via Supply Canal No. 2 and the Tenmile Tunnel. G-2.9 Future Modifications to Water Handling Systems Some modifications to the process water handling system will be required as production at the mine continues. The modifications include the eventual decommissioning and inundation of the 3 Dam Pump Station and seepage collection system by Mayflower TSF, as described above. Under the current configuration, the 5-Shaft Pump System dewaters a portion of the existing underground mine workings and maintains the underground water levels well below the apex of the Mosquito Fault. As the open pit is developed, however, it will progress to depths below the current dewatering level of the 5-Shaft system. When this occurs, a new system to dewater the open pit will be required. Because of the impacted nature of this water, the new pit dewatering system will deliver impacted mine and pit water to the ETDL, which will convey it to the SDP for first-stage treatment and discharge it into the process water circuit. Exhibit G G-7 May 2024