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Status Report, Robinson Seep Investigation Climax Molybdenum Company <br />The 1,500 pS /cm contour (Figure 3.5) indicates narrowing of the seepage migration <br />pathway into a drainage approximating bedrock contours. This area also contains <br />groundwater that is >2,000 pS /cm. Note that sample locations EVS -006 (a previously <br />identified and sampled spring location) and EV -11 with readings of 1,491 and 1,480 <br />pS /cm respectively, are considered within the 1,500 pS /cm contours. The 1,500 pS /cm <br />contour also indicates a narrowing and closure of the seepage path north of the cutoff <br />wall. <br />• The 1,000 pS /cm and 500 pS /cm contours indicate that geological structures (exposed <br />bedrock to the east and west of the drainage) control and contain seepage within the <br />broader drainage. <br />• Sample EV -18 (1,626 pS /cm), which lies on the eastern extent of the field area, and EV- <br />27 (1,284 pS /cm) at the western extent, indicate that high EC waters originate along the <br />reach of Robinson Lake Dam. <br />• Groundwater elevations (Figure 3.6) suggest a groundwater flow pattern that supports <br />the water quality observations. Groundwater flow generally converges on the valley <br />containing the Robinson seep and cutoff wall. <br />As illustrated in Figure 3.5, results of the field investigations suggest that some component of <br />groundwater flow may be migrating through the shallow fractured bedrock on either side of the <br />drainage in which the seepage collection system and cut -off wall are located. To the east, this <br />may be a result of changes in bedrock fabric of the Minturn Formation associated with the <br />intrusion of the Elk Mountain Porphyry. Contact metamorphism of the Minturn Formation during <br />the intrusion event and more rapid cooling of the margins of the intrusive may have produced <br />fractures allowing migration of groundwater through the Minturn Formation and through margins <br />of the intrusive. The tight contours along the eastern flank indicate an abrupt change in flow <br />path. To the west, the wider spacing of the contours indicates a more dispersive pathway, <br />possibly associated with more regular fractures within the Elk Mountain Porphyry. This is <br />supported by the field observations of outcropping material that indicated that the Elk Mountain <br />Porphyry has a greater fracture network (Figure 3.2a) compared with the Minturn Formation <br />(Figure 3.2b). <br />Tetra Tech, Inc. November 2013 33 <br />