2007-11-01_PERMIT FILE - C1982056A (4)

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established to increase the productivity of the land, nor are the management practices established for haying this area. The land is treated as unimproved rangeland utilized for grazing by the lessee. TCC's mining and subsiding of Fish Creek and its alluvial valley floor will not impact those AVF's located downstream of the operation. The subsiding of the valley floor above Panels 17-Right and 18-Right will result in the formation of pools, and these should be similar to those formed over Panel 9-Right in the Eastern Mining District and Panels 13- and 14-Right in the Northern Mining District. It is anticipated that the Fish Creek channel will respond in the same manner as the Foidel Creek channel (see PR 03) for the entire length where it goes over Panels 17-Right and 18-Right. The entire length of Fish Creek overlying the panels was surveyed to look for outcrop areas. The survey showed that approximately 1,260 feet of channel in Section 10, TSN, R86W has a rock outcrop (Fish Creek Sandstone) exposed. This would be an area that could experience surficial cracking, and be a potential site recharging the bedrock. However, the cover is greater over these panels, and has additional shale between the mine and the surface. This shale is the unit over which the alluvial materials were deposited. The combination of greater depth and thicker shale deposits will minimize the potential for surficial cracking to occur during and after mining. TCCe does not anticipate any significant loss of flow in Fish Creek as a result of its mining operations. If one were to look at the worst case of flow disruption in Fish Creek, it would be prudent to assume that the same loss as experienced in Foidel Creek would occur. Also, it should be understood that the loss would be experienced over each of the panels and not all at once, thus limiting the volume of water that would enter the bedrock system. As presently shown on Map 23, mining will progress from the south to the north in the Northern Mining District. Panel 17-Right is the first panel in this part of the NMD that will result in subsidence potentially impacting Fish Creek and its alluvial valley floor. Fish Creek meanders over the panel for approximately 2,300 feet. Using the above-referenced relationship of stream length to recharge volume, results in approximately 14 ac-ft of water potentially recharging the bedrock. In reference to Panel 18-Right, Fish Creek meanders over the panel for .approximately 1,700 feet. This will result in approximately 10 ac-ft of water potentially recharging the bedrock. Given the volume of water that passes through the Fish Creek system, any loss during the year is not significant to the irrigation systems on lower Fish or Trout Creeks. Table 72 B, NMD Recharge Time Estimate, provides the number of days it would take to fill in the additional fracture volume resulting from subsiding the bedrock. Again, it should be recognized that this is a very conservative estimate due to the character of the stream. The data presented assumes that sandstone bedrock can be found for the entire length of Fish Creek overlying the panels, and this is not the case. The section in which the sandstone unit is exposed is the approximate 1,260 feet of channel in Section 10, TSN, R86W. The remainder of the channel is alluvial material overlying the Lewis Shale. Given the nature of the shale, it will swell to fill in any cracks that may occur. TCC is the immediate downstream user of irrigation water, and does not foresee any impacts to its agricultural operations due to the potential loss of water from the system. In the event that significant losses occurred during the irrigation season, TCC has sufficient water rights to augment and loss. In reference to water quality impacts, the ongoing downstream monitoring at Station 900 on Foidel Creek does not show any changes that can be attributed to subsidence over Panels 8- and 9-Right. Refer to TCC's recent Annual Hydrology Reports to review this data. In order to validate that no impacts will be realized to the AVF located downstream of its operation, TCC will continue to utilize its current downstream surface and alluvial water monitoring stations. These stations are presented on Map 13A, Hydrologic Monitoring Program. The stations will be monitored as per the existing monitoring schedule. These stations are located along Fish Creek in Section 5, TSN, R86W. In addition to the current hydrologic monitoring program, TCC will initiate a program directed at the segment of Fish Creek to be impacted by mining in the NMD. This environmental program is presented in Exhibit 4e-8, NMD-Fish Creek MR07-224 2.06-25.6 10/17/07