2010-06-04_PERMIT FILE - C1982056A (9)

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18 -Left Mine Water Transfer Piaeline (TR09 -70) • The 18 -Left Mine Water Transfer Pipeline (18LT Pipeline) will originate from a permitted mine dewatering borehole at the 18 -Left Shaft location, and extend approximately 8,200 feet to the southeast, connecting to the existing Fish Creek Mine Water Transfer Pipeline just to the east of the Fish Creek Water Treatment Facility. The 18LT Pipeline will be a 12 -inch HDPE pipeline with thermally welded joints, buried below the frostline at a depth of approximately 5 feet. The pipeline will be installed under Routt County Road 27 by boring the pipeline under the road, and a crossing of Fish Creek will be either trenched through, or bored under the creek. Manholes, consisting of 8 -foot diameter x 10 -foot high CMP culverts, fitted with locking lids and access ladders, will be installed at either end of the pipeline for access to pipeline valving. Pipeline construction will involve placement of sediment control materials (straw wattles or silt fence) downslope of the disturbance at any location where the pipeline corridor is within 50 feet of a Stream Buffer Zone or non- qualifying ephemeral drainage; removal and windrowing of available soil material to one side of the 40 foot pipeline construction corridor; excavation of the pipeline trench, with temporary placement of the excavated material on the opposite side of the trench; placement, connection, and bedding of the pipe; backfilling and compaction of the excavated material around the pipe; re- spreading of the soil material; and re- seeding using the standard rangeland seed mixture. Because the soil materials will be replaced immediately after pipeline placement, as construction advances, stabilization measures are not necessary. Where the pipeline crosses under Routt County Road 27, boring or jacking pits will be excavated and the pipeline will be bored or jacked under the road. The Fish Creek crossing has been located to take advantage of a deeply incised stream channel, minimizing potential impacts to the narrow riparian fringe which exists along this section of the creek. To the extent feasible, the trenched crossing will be completed during the winter low -flow period. A temporary upstream flow barrier will be established in the channel, and normal streamflows will be transferred around the work area by pumping from the resulting pool above this upstream barrier to well below the crossing work area. If the Fish Creek pipeline crossing is completed by boring the pipeline under the creek, the surface protective measures, as outlined above, will not be • necessary. Specific protective measures (BMP's) will be used at the crossing location including placement of stream buffer zone markers, silt fence or anchored straw bales at least 50 feet downstream to catch any sediment; placement of sediment control materials (straw wattles or silt fence) around the entire side and near stream perimeters of the boring /jacking pits; restrictions on storage or transfers of petroleum products within the buffer zone, and reclamation of the affected areas immediately following completion of pipeline installation. Soil materials will be replaced following completion of pipeline installation, and reseeding of the disturbed areas will be completed during the first appropriate planting period following soil material replacement. Fresh -Water System Modification TCC's fresh -water system was modified to incorporate the million- gallon storage tank currently being used by Colorado Yampa Coal Company. A water -line was constructed which ties -in the million- gallon tank, the existing well, and the new fresh -water borehole. The location of this system is shown on Map 24, Surface Facilities. Installation of the water -line required excavating a trench approximately 7 to 15 feet in depth. As shown on Map 24, Surface facilities, the majority of the ditch work occurred within previously disturbed areas. For the section of pipe laid in the disturbed area, a work corridor, approximately 30 feet wide, was used. The material excavated from the trench was placed adjacent to it, and after the pipe was placed the trench was backfilled. For the undisturbed area the topsoil, approximately 2 feet in depth, was removed from the work area, and temporarily stockpiled adjacent to it. After the trench was excavated, the water line placed, and the trench backfilled, the topsoil was replaced. • A borehole, approximately 150 feet in depth, was drilled into the mine workings and cased. The borehole is approximately 12 inches in diameter, and the casing is a nominal 8" diameter. The annular space was grouted from TR09 -70 2.05 -50.7 01/26/10