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,~ <br />Schwar[zwxlder Mine Hydrologic Evaluation of Hine Closure and Reclamation <br />~.3 Seeps <br />Numerous seeps exist on and below mine property, where groundwater surfaces at the contact of alluvium <br />and the underlying, relatively impermeable hornblende gneiss unit. The natural seeps below mine property <br />are located along the south side of the access road. along the road cut bank, where the alluvium thins and <br />groundwater is forced to the surface. Numerous hydmphyllic grasses (phreatophytes) are associated with <br />these seeps. Within the property boundary, seeps have been observed emanating from depressions or luw <br />points in the alluvium and till. <br />Historically. a seep existed in the till near the mine parking lot. The "parking lot seep" was removed when <br />the emergency storage ponds were reclaimed and the area was regraded. Seeps also existed historically <br />near ti1W9 and Sump 3. This seep, the "Sump 3 Seep", is still in existence as of fall X007. Water quality <br />in the seeps is discussed in Section 7.~3. <br /> <br />5.1 Conceptu~-I H~•drolo~ic Model <br />1'he conceptual model for groundwater flow prior to mining is sho~yn in Figure 1~. Qefore 1953. <br />groundwater in bedrock occurred in both local (shallow) and regional (deep) tlo~ti systems. Recharge to <br />groundwater occurred by infiltration of precipitation and snowmelt in the upper portions of the watershed <br />and either flowed in the shallow subsurface where it discharged into Ralston Creek. or entered the deeper <br />regional system and flowed toward the e:i`st. F3ecause the deep bedrock is relatively impermeable, most of <br />the infiltrating precipitation flowed in the shallow, weathered bedrock (in the upper 50 tt or less helow the <br />water table> where permeabilities are somewhat higher. At depth, hydraulic gradients in bedrock were not <br />significantly influenced by Ralston Creek. or other surface features. <br />r <br />N <br />O <br />z <br />SW ~ <br />m <br />m <br />r <br />N <br />-~ <br />O <br />z <br />o <br />o N E <br />c <br /> <br />m <br />1 <br />- iooo <br />esoa <br />. eooo <br />ssoo <br />- 5000 <br />- 4500 <br />X000 <br />Figure 15. Conceptual Model of Groundwater Flow-Pre-Mining <br />Whetstone Associates <br />~tll)~)I~.Q71116 <br />