2009-05-12_GENERAL DOCUMENTS - C1981025

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thin alluvium of the old stream channel. This would likely result in drainage of ground water beneath the embankment. Piezometers were installed in geotechnical investigation holes above, under, below, and upstream of the proposed refuse pile. Piezometer D-1 A, placed below, and piezometer D-2A, placed upstream, were reclaimed with the approval of Technical Revision 23 on February 23, 2004. The water in these two alluvial monitoring wells has water chemistry different from that in North Thompson Creek. Monitoring suggests that there may be some degradation of water quality in the alluvial materials between the mine waste pile and North Thompson Creek from leaching of waste materials. However, it may not be significant as surrounding groundwater has relatively higher conductivity. During mining operations, waste water from the coal wash plant was recycled back into a coal washing facility after fines settled out in upper and lower settling ponds. This water recycling system increased the total dissolved solids in the water through exposure of the water to fines and through evaporation. The ponds that were used in this water recycling system were unlined and were located on, or were hydrologically adjacent to, the North Thompson Creek alluvium. Thus, these ponds posed a potential for the degradation of the alluvial water quality, and may still be reflected in the higher conductivity of samples from piezometer D-2A. Mining has ceased, the washing facilities have been removed, and the ponds have been reclaimed. Thus any such impacts to these alluvium materials are likely to diminish with time. The water used at the loadout site was pumped from wells completed in the Roaring Fork alluvium. The withdrawal of this ground water was small and was covered under a plan of augmentation that minimized impact to the quantity of alluvial ground water. All such withdrawals were suspended with reclamation of the site. Alluvial groundwater regimes have likely been restablished in these highly permeable materials. Flood irrigation has been reestablished on the alluvial valley floor. There has been no evidence of any adverse impacts to the ground water quality at the loadout site. 2. Surface Water The determination has been made that there is no impact to Middle Thompson Creek. Surface disturbances in the Middle Thompson Creek drainage included two flow monitoring flumes, a portal, an air shaft, and roads. The roads have been stabilized, and have been permitted for retention. All of the other disturbances were small, and have been reclaimed. There has been no mine water discharged to Middle Thompson Creek. Except for flow measurements, there has been no monitoring of surface waters in the Middle Thompson Creek drainage. The determination has been made that there is no impact to the Roaring Fork River from disturbances at the loadout site. The loadout site has been reclaimed. Surface water inflows to North Thompson Creek within the permit area include the discharges from the portals of both Mine No. 1 and Mine No. 3, surface water runoff North Thompson Creek C-1981-025 Permit Renewal 05 12 May 2009 19