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Request#5: Additional Detail of Hydrogeology in Plate 31— Section C-C' <br /> The cross-section submitted on December 9th as Plate 31 does not show enough detail to <br /> adequately display the nature of the Grassy Valley perched aquifer in relation to the areas <br /> identified on Plate 9 (Rev. 1) as "post-mining Grassy Valley capture zone" and "area where <br /> drainage tunnels do not cause significant head change in diatreme". The vertical scale of the <br /> figure is too small to show the requested details. The Division did not request the Carlton <br /> Tunnel elevation be shown on this cross-section, as it is displayed on other figures submitted. <br /> Please increase the vertical scale of the figure and show more detail for the requested <br /> features. The features of interest occur from surface to approximately 9,500 foot elevation <br /> (below the surface). Additionally, please ensure all features are labeled on the figure, <br /> including Grassy Valley Creek and monitoring wells, if appropriate. <br /> Response: <br /> The requested additional section detail for Plate 31 is presented in Plate 31a, both of which are <br /> attached. <br /> There are a large number of piezometric monitoring strings along Grassy Valley, which are shown <br /> in plan in Plate 28 (Rev.3), and those which are within approximately 500 feet of the section have <br /> been projected onto the section to provide a very detailed three dimensional hydrogeologic picture <br /> of the groundwater conditions along Grassy Valley. <br /> There is generally a strong vertical head gradient and flow in the diatremal rocks in Grassy Valley, <br /> with lesser gradient—and flow— in the Precambrian granitic rocks outside the main diatreme. <br /> Page 6 of 8 <br />