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on the Fish Creek pipeline crossing are presented in Exhibit 490, 6MN Mine Water Storage Reservoir — Design <br />Drawings. Pipeline construction will involve placement of sediment control materials (straw wattles or silt fence) <br />downslope of the disturbance at any location where the pipeline corridor is within 50 feet of a drainage or stream <br />buffer zone; removal and windrowing of available soil material (total soil material volume for the pipeline project is <br />estimated at 11,150 cy) to one side of the 50 foot pipeline construction corridor; excavation of the pipeline trench <br />using a track -hoe, with temporary placement of the excavated material on the opposite side of the trench; <br />placement, connection, and bedding of the pipe; backfilling and compaction of the excavated material around the <br />pipe; re -spreading of the soil material; and re -seeding using the standard rangeland seed mixture. Because the soil <br />materials will be replaced immediately after pipeline placement, as construction advances, stabilization measures <br />are not necessary. <br />Where the pipeline crosses under Fish Creek, jacking pits will be excavated adjacent to the creek, while <br />maintaining a minimum 5 -foot buffer between the near edge of the pits and the crest of the stream bank, and the <br />pipeline will be bored or jacked under the creek. Protective measures (BMP's) at the crossing location will include <br />placement of stream buffer zone markers at any point where the pipeline corridor is within 50 feet of the stream <br />buffer zone prior to any activity; completion of the work during low -flows; placement of silt fence or anchored <br />straw bales at least 50 feet downstream to catch any sediment released prior to initiation of work; placement of <br />sediment control materials (straw wattles or silt fence) around the entire side and near stream perimeters of the <br />jacking pit disturbance areas; restrictions on storage or transfers of petroleum products within the buffer zone, and <br />reclamation of the affected areas immediately following completion of pipeline installation. Construction and <br />sediment control details are shown by the design drawings in Exhibit 490. <br />With construction of the 6MN Mine Water Storage Reservoir, the temporarily direct connection from the 10 -Right <br />Mine Dewatering Pipeline to the 6MN Million -Gallon Tank will be replaced with an inlet line from the 10 -Right <br />Mine Dewatering Pipeline to the 6MN Reservoir, and a pumped outlet line from the Reservoir to the 6MN Million - <br />Gallon Tank. The 6MN Storage Reservoir will be used to provide back-up storage for TCC's 10 -Right Mine <br />Dewatering Well (also previously identified as the EMD Dewatering Facility), allowing the well to pump <br />continuously at full capacity, providing buffer storage for pump maintenance or failure, and limiting the distance <br />over which the mine water must be transferred. <br />As a separate, but related project, TCC will establish a new pipeline running approximately 6,200 feet from the 19 - <br />Right Dewatering borehole to the 6MN Storage Reservoir. The pipeline will be constructed of up to 12.5 -inch <br />HDPE pipe, buried to a depth of approximately five feet, with two trenched crossings of unnamed ephemeral <br />drainages. The 19 -Right Mine Dewatering Pipeline will discharge to the 6MN Reservoir near the eastern edge of <br />the Reservoir. Pipeline construction will involve placement of sediment control materials (straw wattles or silt <br />fence) downslope of the disturbance at any location where the pipeline corridor is within 50 feet of a drainage; <br />removal and windrowing of available soil material (total soil material volume for the pipeline project is estimated at <br />5,750 cy) to one side of the 50 foot pipeline construction corridor; excavation of the pipeline trench using a track - <br />hoe, with temporary placement of the excavated material on the opposite side of the trench; placement, connection, <br />and bedding of the pipe; backfilling and compaction of the excavated material around the pipe; re -spreading of the <br />soil material; and re -seeding using the standard rangeland seed mixture. Because the soil materials will be replaced <br />immediately after pipeline placement, as construction advances, stabilization measures are not necessary. <br />The 6MN Storage Reservoir is designed as a closed reservoir, with no discharge, and provision for adequate <br />operating free -board to allow for storage of runoff from a small upslope drainage area. The 6MN Mine Water <br />Storage Reservoir will be constructed south of the current 6MN Shaft pad and northwest of the NW Mains <br />Ventilation installation. The reservoir embankment will be an earthen dam constructed of suitable fill material <br />excavated from the reservoir basin and placed and compacted consistent with engineering design specifications and <br />construction recommendations. The engineering designs are based on site geotechnical investigations, which <br />included drilling of six, 4 -inch hollow -stem auger test holes; examination and testing of soil samples; placement of <br />1.5 -inch slotted PVC pipe in two of the auger holes to measure water levels (piezometers); and excavation of seven <br />shallow (6-11 feet in depth) test pits. The location of the 6MN Mine Water Storage Reservoir geotechnical <br />investigations is shown on Map 24 (sheet 2 of 3), Surface Facilities and Freshwater Systems, and by the detail <br />drawings in Exhibit 490, 6MN Mine Water Storage Reservoir — Design Drawings. <br />MRI 1-259 2.05-45.13 11/17/11 <br />