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Baseline Hydrologic Monitoring Plan — Hansen Project 21 <br />2.3.3 Hydrostratigraphy <br />Cyprus and their consultants identified four principal aquifers in the Hansen area (Geo- Hydro, 1980): <br />• The uppermost aquifer, the Thirtynine Mile Andesite, is under water table conditions (unconfined). <br />The Thirtynine Mile Andesite is underlain in some locations by relatively impermeable bentonite <br />which prevents hydraulic connection with the lower aquifers. <br />• Tallahassee Creek Conglomerate. <br />• Wall Mountain Tuff. A discontinuous aquifer of relatively high transmissivity which underlies <br />portions of the Tallahassee Creek Conglomerate. In the Hansen area, the Wall Mountain Tuff is <br />under artesian conditions. <br />• Echo Park Formation. Deepest aquifer, lies directly above the Precambrian basement (which is <br />essentially impermeable). <br />2.3.4 Groundwater Flow <br />A preliminary potentiometric surface map was developed based on (1) water levels in monitoring wells <br />installed by Cyprus Mines and (2) water levels report on driller's logs filed with the Colorado Division of <br />Water Resources. The preliminary potentiometric surface map (Plate 3) indicates that groundwater <br />generally flows northeastward, eastward, and southeastward away from Waugh Mountain and toward <br />Cottonwood Creek and the Arkansas River. Extensive groundwater characterization by Cyprus near the <br />Hansen deposit indicates that the paleochannel that controlled mineral deposition in the Echo Park <br />Formation may also control groundwater flow today, and that flow directions in the Echo Park Formation <br />near the Hansen deposit are toward the south - southeast. <br />Water level contours developed by Cyprus and Wright Water Engineers are included on the preliminary <br />potentiometric surface map (Plate 3). Further characterization of vertical and horizontal flow directions <br />and hydraulic gradients will be developed from the groundwater monitoring program. <br />2.3. S Seeps and Springs <br />Seven springs have been mapped within the greater Taylor Ranch CUP boundary by the USGS at the scale <br />of a 7.5- minute (1:24,000) topographic quadrangle map. Two additional springs are located within one <br />mile of the Project boundary (Table 5). A seep and spring survey will be conducted as described in <br />Section 6. Water quality and flow data collected from the seep and spring survey will provide additional <br />baseline hydrologic data for the Project. The survey will be conducted after spring snowmelt and before <br />the summer rainy season (Section 2.1). <br />4153A.140129 Whetstone Associates t <br />