2021-08-06_PERMIT FILE - C1982056A

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through a riprapped discharge basin and channel to the existing culvert. For all pipeline construction, soil material will be removed and temporarily windrowed on one side of the trench, with trenched material placed to the other side. Once the pipeline is placed, properly bedded, connected to the main l ORT/FCM-2 Transfer Pipeline, and leak tested, trenched material will be backfilled and compacted, and soil material will be replaced over the excavation and reseeded. It is anticipated that when the pipeline is no longer needed to support mining and related operations, it will be plugged below grade and abandoned in-place. Reclamation of the wells, when no longer needed, will involve plugging and sealing the well consistent with approved sealing practices, consistent with applicable State Engineer requirements. TORT Monitoring Borehole Installation and Pumphouse Modifications (MR09-238) In order to accurately monitor water levels in the EMD sump area, TCC plans to drill and case a monitoring borehole at the TORT location. The new IORT Monitoring Borehole will be drilled on the existing IORT facilities pad, and will involve no new surface disturbance. The borehole will be collared with an 8 -inch ID surface casing, extending to a depth of approximately 40 feet. The borehole will then be drilled as a 6.25 -inch borehole to a depth of approximately 1,365 feet, and cased with 3 -inch ID cemented in-place casing. The casing will extend approximately 4 feet above the ground surface, and be fitted with a locking cap to prevent unauthorized access. The 10 -RT Monitoring Borehole will be used for regular monitoring of mine water levels in the EMD. When no longer needed to monitor water levels, the IORT Monitoring Borehole will be plugged and sealed in compliance with State Engineer requirements, the casing will be cut-off below grade, and the associated disturbance will be reclaimed along with the rest of the 1 ORT facilities area. The addition of the second l ORT Dewatering Borehole resulted in the need for changes to the pumping and control systems for the l ORT dewatering installation. To accommodate pumping and control equipment for the two IORT Dewatering Boreholes, the existing IORT Pumphouse and foundation pad will be demolished, and replaced with a larger Pumphouse and foundation pad with support piers. Specifically, the existing 16 x 14 foot wood -frame building and 14 x 24 foot concrete pad will be replaced by a 25 x 43 foot concrete pad with 12 — 1 -foot diameter concrete piers extending to a depth of approximately 12 feet, and a 25 x 30 foot pre -fabricated steel building. The Pumphouse expansion will occur on the existing 10 -Right facilities pad and will involve no new surface disturbance. Other associated work will include placement of the existing electrical transformer on the northeast corner of the new pad, and completion of the necessary plumbing and electrical hook-ups. When the pumping installation is no longer needed to support ongoing or future operations, the TORT Pumphouse, foundation pad, and associated equipment will be removed for salvage or demolished, and the associated disturbance area reclaimed along with the rest of the l ORT facilities area. 1ORT/FCM-2 Transfer Pipeline and 1ORT/6MN Transfer Pipeline (MR07-224, MR08-230, MR16-299) A water line was installed from the IORT dewatering facility to FCM-2 to route water back into the mine for underground operations. The location of this water line is shown on Figure 16I, 1996 Seismic Lines and Mine Water Discharge Return Line, East Mine District. Approximately 6,740 feet of 8 -inch HDPE pipe was buried at 5 to 6 feet below grade from the TORT dewatering facility to FCM-2. This pipe will be left in place when no longer needed to support ongoing mining and related operations. TC is proposing to install an additional water line paralleling the existing TORT/ FCM-2 transfer pipeline. The pipeline will tie in near the junction of the IORT/6MN and the existing IORT/ FCM-2 transfer pipeline. The new pipeline will be approximately 6,590 feet of 10 -inch HDPE pipe, buried at a depth of 5 to 6 feet below the existing grade and paralleling the existing IORT/FCM-2 pipeline to the Barricade Chamber. In addition, an 8 foot diameter CMP riser will be installed next to the existing CPM riser at the junction of the IORT/6MN pipeline and the 1ORT/Barricade Chamber pipeline. The new pipeline will tie into the existing pipeline to distribute the pressure of pumping and not exceed the rating of the pipe. No new disturbances are expected. As part of the 6MN Facilities project, TC established a new pipeline running approximately 6,040 feet from the l0RT/FCM-2 Transfer Pipeline to the 6MN Mine Water Storage Reservoir and Million -Gallon Tank. The pipeline is constructed of 10 -inch HDPE pipe, buried to a depth of approximately six feet, with one sub -grade crossing (bored under) of Fish Creek. Details of the Fish Creek pipeline crossing are presented in Exhibit 490, 6MN Mine MR16-299 2.05-50.8 06/16/16