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Request#4: 3.4.2 Water Table(continued) <br /> Please provide a cross-section oriented roughly perpendicular to the southern portion of the <br /> ECOSA (at the location of GVMW-8A and GVMW-8B monitoring wells), displaying the ECOSA, <br /> the Grassy Valley perched aquifer, Grassy Valley Creek, the groundwater monitoring wells listed <br /> above, and the areas identified on Plate 9 (Rev. 1) as "post-mining Grassy Valley capture zone" <br /> and "area where drainage tunnels do not cause significant head change in diatreme". <br /> Please ensure all cross-sections show shallow bedrock groundwater, groundwater flow direction, <br /> and indicate the saturated zone (either visually or in notes provided on the cross-section). These <br /> cross-sections should provide a unifying picture of the hydrogeology of the area specified, <br /> showing the relationships between the ECOSA, the ECOSA underdrains, Grassy Valley Creek, <br /> the contact between the diatreme and Precambrian rocks, and the additional features shown on <br /> Plate 9 (Rev. 1) and Plate 17(Rev. 1), with the local groundwater regime. <br /> Response: <br /> The location of the cross section is presented in Plate 28. The section selected passes through <br /> the southern edge of the ECOSA, approximately normal to the axis of the overburden storage <br /> facility, and passes through the GVMW-08A/08B monitor well pair, as requested. The section is <br /> underlain predominantly with volcanic diatremal rock, and shows the effect of this rock on the <br /> groundwater flow in this area. <br /> The resulting cross section is Section B-B', presented in Plate 30. <br /> The section has been prepared by the following process: <br /> 1. Assembling all groundwater data for the colluvial ("soil") surface aquifer in the vicinity of the <br /> section and plotting the resulting "water table" which represents the top of the zone of <br /> saturation (where present) in the colluvium on the section. <br /> 2. Assembling all groundwater head/pressure data for the underlying bedrock in the vicinity of <br /> the section, selecting the elevation at each monitored location that best represents the top <br /> of the zone of saturation in the bedrock, and plotting these values on the section. <br /> 3. Drawing direction arrows on the section to indicate groundwater flow direction, as <br /> requested. It should be noted that the section cuts through a three-dimensional flow <br /> regime, and the flow arrows indicate the component of flow in the plane of the section. In <br /> this section flow is predominantly vertically downward in the colluvial aquifer, vertically <br /> downward in the unsaturated bedrock, and both downward and of the southwest in the <br /> saturated bedrock (ultimately flowing toward groundwater collection by the Carlton Tunnel, <br /> to the southwest of this section). <br /> Page 6 of 16 <br />