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Retaining Wall <br />TCC installed a Hilfiger -type retaining wall at its' Batch Loadout Facility (BLO). The location is shown on Map <br />24. The retaining wall function to stabilize the slope at this location to limit any erosion between the access to the <br />BLO and the railroad tracks. The wire basket and rock retaining wall will be buried as part of final reclamation. <br />Geotechnical Investigation - Batch Weigh System (MR95-114) <br />TCC will conduct a geotechnical investigation of the proposed construction site for a Batch Weigh train loading <br />system and associated facilities. Detailed designs and a technical revision application for construction of the batch <br />weigh system will be submitted separately from the minor revision application addressing the geotechnical <br />investigation work for the project. The geotechnical investigation for these facilities will entail drilling fourteen <br />shallow holes. The proposed drilling site locations are shown on Figure 20 in Volume 4 of Permit C-82-056. <br />Drilling will be conducted with a self -leveling track -mounted portable drilling rig (CME 45 mounted on <br />Bombardier Snow Cat). Four -inch diameter continuous flight power augers will be utilized. Drillholes will be <br />driven to bedrock with core samples obtained as necessary to evaluate construction requirements for the proposed <br />facilities. Bedrock is known to occur at depths ranging from 20-60 feet in the vicinity of this project. No drilling <br />fluids will be utilized in association with the rig and no structures or preliminary site preparation work will be <br />necessary to support the drilling effort. <br />Thirteen proposed drill -sites are located on previously disturbed areas and one site is located in an area of <br />undisturbed native topsoil. Drilling is estimated to take approximately three 3-6 hours per hole, depending upon the <br />depth to bedrock. No topsoil salvaging operations are proposed in association with the drilling program, as drilling <br />will likely occur under frozen ground conditions during the month of February 1995 and no significant adverse <br />impacts to the topsoil resource are anticipated. All drill -sites are located in areas to be further disturbed during <br />construction of the Batch -Weigh system facilities. Topsoil will be salvaged, as appropriate, during the initial <br />construction phase of the Batch -Weigh system. <br />The track -mounted equipment utilized for the geotechnical investigation will produce minimal disturbance in <br />traveling over frozen ground and drilling for short durations. Particular care will be taken to access the site with <br />undisturbed native soils during a period when frozen ground conditions are prevalent. To the extent possible, <br />cuttings generated during the drilling process will be returned to the drillholes prior to abandonment to minimize <br />potential sediment transport from each site. In the event an aquifer is intercepted during drilling at any site, the <br />affected drillhole will be sealed using a grout plug in the aquifer zone and then will be backfilled to the surface with <br />cuttings. In the event formation water is encountered during drilling and liberated on the surface, silt fences will be <br />erected as secondary sediment control measures to minimize the transport of sediment off site. <br />Construction of the Batch -Weigh system and associated facilities is anticipated to commence during March 1995. <br />In the event construction initiates on schedule, permanent sediment control measures and topsoil salvage <br />operations, as detailed in the technical revision application for this project will be completed as the initial phase of <br />construction activities. In the event construction is significantly delayed, the associated geotechnical investigation <br />drill sites will be evaluated and appropriate temporary sediment control measures will be implemented as necessary <br />to ensure off-site sediment transport is controlled. <br />Loadout Slope Stabilization (MR12-262 <br />Evidence of localized slope instability was observed in an area approximately 300-500 feet east of the Batch Weigh <br />Loadout following spring snowmelt and runoff in 2011. The area of concern is an existing disturbance area between <br />the Overland Conveyor and the Railroad Spur, to the north. In order to evaluate and address the concern, TC contracted <br />with Northwest Colorado Consultants (NWCC) to complete field investigations and develop recommendations for <br />stabilization of the area of concern. The field investigations indicated that the relatively steep slope, perched <br />groundwater conditions, and an underlying claystone bedrock could be contributing factors to the observed unstable <br />slope conditions. hi order to address the existing unstable slope and provide for the long-term stability of this area, <br />NWCC recommended installation of a drilled pier retaining structure and regarding of the slope to approximately a <br />2H:1 V configuration. <br />MR12-262 2.05-48 04/08/12 <br />