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44 <br />Groundwater <br />5.9.2 Regional groundwater flow <br />The overall direction of groundwater flow in the Collom synclinal basin is from south to <br />north down the dip of the south limb of the syncline. Lateral flow (east or west) occurs <br />locally where units drain into the adjacent stream drainages. The water table in the <br />basin varies from about 7,800 ft amsl on the south to about 6,500 ft amsl on the north. <br />5.1.3 Regional recharge and discharge <br />Recharge to units of the Williams Fork Formation and the Trout Creek Sandstone occurs <br />along the outcrops on the south, east, and west margins of the basin, from the saturated <br />valley fill in the streams channels, and via seepage from overlying units in the southern <br />areas. Recharge is probably highest on the south side of the basin in the Danforth Hills, <br />which, because of their elevation, tend to have lower average temperatures, more <br />precipitation, and more snow than other potential recharge areas. Discharge occurs <br />where the steeply- dipping north limb of the syncline is dissected by streams and along <br />the northern portions of the stream channels (Figure 2.2). The elevation of the Collom, <br />Straight, Williams and Good Spring drainages where they cross the north limb of the <br />syncline is about 6,500 ft. <br />Along the southern reaches of the stream channels, the deeper units of the Williams <br />Fork Formation (down to the I coal sequence) are observed to outcrop. The stream <br />channels cut through successively higher units from south to north on the south limb of <br />the syncline. The valleys provide drainage for the shallower coal and sandstone units. <br />As a result of these conditions, the southern portion of the groundwater basin consists of <br />a sequence of perched groundwater zones. In general, the groundwater levels occur <br />within the respective water - bearing units. Conditions in the southern part of the project <br />area are therefore relatively similar to those in the existing Colowyo Mine. Perched <br />groundwater zones in the upper coal seams are expected to be encountered in the <br />Collom Mine, but with a greater magnitude and frequency of sustained inflows than at <br />the Colowyo Mine as a result of the greater drainage area and the greater recharge rate. <br />On the north side of the basin, the Williams Fork units outcrop along the steeply <br />upturned north limb of the Collom Syncline. Units of the Williams Fork are also exposed <br />along the stream valleys. Groundwater in the northern area appears to discharge into <br />the valley fill of the incised drainages. <br />5.2 Site data acquisition and monitoring activities <br />The following section describes the various activities conducted to characterize <br />groundwater conditions in the Collom study area. Data for the pre - feasibility <br />hydrogeology study were obtained from previous investigations, the geologic exploration <br />program, and the hydrogeologic characterization program designed and implemented by <br />the staff of KEC, CNI, and WMC. . <br />2572 -R2 Colowyo Coal Company <br />Water Management Consultants <br />