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indicates that the ephemeral 006 Gulch contributes to no more than 20 percent of the flow • <br />in Hubberson Gulch, and only during the snowmelt period (April through May). <br />The previously-mentioned calculations indicate that in the reclaimed, upper portions of <br />tributaries to Dry and Sage Creeks, runoff from snowmelt could be 6 times the runoff <br />expected from rainfall events, and snommelt runoff from the reclaimed areas could provide <br />up to 20 percent of additional contributions to streamflow in Dry and Sage Creeks. <br />Historic monitoring of surface water quality at sites associated with the Seneca II-W Mine <br />have resulted in observations of a seasonal variability in levels of TDS. Generally, <br />snommelt runoff exhibits lower levels of TDS and major ions in comparison to baseflow. <br />Increases in TDS and major ions observed in streamf lows sampled during the baseflow period <br />are likely influenced by contributions to flow from ground water and springs, as <br />contributions to baseflow from precipitation events are usually short-term and of <br />compari ti vely lessor magnitudes than snommelt runoff. <br />The chemistry of runoff from reclaimed areas will be influenced by the mineralogy of the <br />replaced topsoil. Tab 9, Soils, describes properties of soils mapped in the vicinity of • <br />the Seneca II-W Mine prior to mining. These soils will be salvaged, stockpiled, and <br />redistributed on regraded spoil to provide a medium for plant growth. No toxic or acid <br />topsoil will be used for reestablishing vegetation in the reclaimed areas. Runoff from <br />these areas, either from snommelt or summer thunderstorms, will likely feature relatively <br />low concentrations of major ions and TDS, especially during the snowmelt runoff period. <br />Modeling of sediment concentrations in runoff from watersheds that will be wholly or <br />partially reclaimed resulted in predicted concentrations Less than 70 mg{l. <br />Interestingly, the predicted concentrations are less than the upper limits for this <br />parameter set forth in Peabody's NPDES permit for pond outfalls. The reader should note, <br />however, that Peabody does not anticipate use of NPDES effluent standards as hydrologic <br />criteria for band release. <br />The chemistry of water impounded in the sediment ponds (005, 006, and 009) will be greatly <br />influenced by the chemistry of waters that discharge from resatura ted Spoil. Water from <br />re sa turated spoil materials will be relatively high in TDS concentration. The impacts of <br />this spoil water on downstream surface water quality has been addressed previously in this <br />Tab (see Potential Impact of Replaced Spoil on Surface Water Quality), and were concluded • <br />to be long-term, but of minimal significance. <br />76 <br />