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RULE 2 PERMITS <br />Potential effect on spring and seep water quality <br />Based on data presented in WMC (2005) springs and seeps have variable water quality with TDS <br />concentrations ranging from 390 to 1,780 mg/l. This variable water quality reflects the source waters for <br />the springs. Springs sourced from local infiltration and shallow groundwater will generally have lower <br />TDS concentrations and springs sourced from the deeper bedrock groundwater will have higher TDS <br />concentrations. <br />No significant impacts to spring and seep water quality are anticipated. Springs lying outside of the mine <br />footprint that are sourced from local infiltration and shallow groundwater will not be affected by mining <br />and no changes in the water quality are expected. <br />Spring SPRLC-01 lies within the pit footprint and will be eliminated by mining. However, it has a <br />relatively high TDS concentration of 1,720 mg/1 which is likely representative of the deeper bedrock <br />groundwater quality. In the unlikely event that a spoil seep develops after the mine backfill re -saturates, <br />the water quality of the spoil groundwater is expected to be similar to that of the deeper bedrock so TDS <br />concentrations will be similar. Springs SPRLC-02 and SPRLC-03 are located north of the pit and spoil <br />pile and their TDS values are in the range of 390 to 770 mg/1, probably reflecting a relatively shallow <br />water source. During mining, potential seepage through the spoil pile up -gradient of the source areas of <br />these springs may result in somewhat higher TDS values. Once mining is completed, the spoil pile will <br />be removed from the Little Collom Gulch drainage as part of the mine reclamation and the North Pond <br />sediment pond will be removed following bond release. The source areas for these two springs should be <br />re-established and no long-term changes to water quality at these two springs are expected. <br />There is some potential that flow from several of the springs and seeps in the West Fork of Jubb Creek <br />and Collom Creek drainages may be affected while the mine dewatering system is operating. The TDS <br />concentration of the discharge from these springs is generally in the range of 700 to 1,100 mg/1, indicating <br />a shallow or intermediate depth source. Once the mine dewatering system is turned off, groundwater flow <br />eventually should be re-established to pre -mining conditions. It is not anticipated that there will be <br />significant water quality impacts to these springs since they lie well outside of the mine area and are <br />unlikely to be affected by the reclaimed pit. <br />Potential effect on groundwater quality <br />The main impact to pre -mining groundwater quality would be caused by flow out of the re -saturated pit <br />backfill. The water quality of the groundwater at the Collom site is summarized in WMC (2005). The <br />bedrock groundwater generally has TDS concentrations of 500 to 1,000 mg/l, a pH between 7.6 to 8.3 and <br />low concentrations of dissolved metals. The valley fill groundwater has TDS concentrations of 400 to <br />1,500 mg/l, a pH between 7.6 to 8.1 and low dissolved metals concentrations. The springs and seeps, <br />which reflect discharge from groundwater, have TDS concentrations of 390 to 1,780 mg/1, a pH between <br />7.8 and 8.3 and low dissolved metals concentrations. <br />With respect to spoil water quality, current water, rock, and soil quality analyses at the Colowyo Mine <br />predominantly show a basic environment with a pH above 7.0. This chemical environment has been <br />present in this area since quality testing was initiated. Some adverse chemical conditions have been <br />identified in the soils and overburden analyses; however, these have been discussed in the application and <br />have been adequately handled by Colowyo in the past. <br />The mine backfill will be comprised of spoil material that is not geologically or chemically different from <br />the surrounding bedrock units that currently comprise the bedrock groundwater system. The water quality <br />of the groundwater that will be contained in the mine backfill after it re -saturates is expected to be similar <br />Collom — Rule 2, Page 123 Revision Date: 11/16/16 <br />Revision No.: MR -166 <br />