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Red Creek Quarry Baseline Water Investigation Section 6 <br /> <br /> <br />6-14 <br />DRAFT for review purposes only. Use of contents on this sheet is subject to the limitations specified at the end of this docu ment. <br />6.3 Groundwater Elevation and Flow <br />Groundwater at the Site occurs mainly in the Codell Sandstone and Red Creek bed sediments. Water <br />was observed in the Fort Hays limestone at the Well 2N location as the borehole drilled through a <br />fault/fractured zone. Water was not observed below the fault/fractured zone in the limestone unit. <br />Groundwater flow may flow within other permeable geologic structures (faults and fracture zones) on <br />the Site that were not observed on the surface or during drilling operations. <br />6.3.1 Groundwater Flow Predictions <br />Potential impacts to groundwater flow due to the mining operations were evaluated through the <br />groundwater modeling effort (BC 2023b, Appendix 3.7). Field observations of surface water flow, <br />flow rates measured from Red Creek, groundwater well water level elevations and slug test results <br />were utilized in the groundwater modeling effort. <br />6.3.1.1 Hydraulic Conductivity <br />Slug test response plots for each test analysis can be found in Appendix I. In general, the response <br />plots for each test fit the Butler (2019) inertial or Springer-Gelhar (1991) inertial calculation <br />solutions. While these solutions followed the general curve for each test, in some cases the solution <br />was slightly under or over predicted the data: <br />• Well 1 under predicts early time data and over predicts late time data. <br />• Well 2S over predicts late time data. <br />• Well 3 fits the data with the exception of the late time data due water being removed for <br />sampling during recovery. <br />• Well 4 fits the data. <br />A summary of hydraulic conductivity for each well is provided in Table 6-1. Geometric mean was <br />chosen as the best measure of central tendency for these data because the data represent physical <br />parameters that are distributed spatially. In addition, two tests were performed in Well 1 therefore <br />the reported value represents the geometric mean of the individual tests analyzed. The wells for the <br />slug tests were screened in the Codell Sandstone. Table 6-1 compares this geometric mean to a <br />stratigraphically similar site, BCQ, approximately 10 miles northwest of the RCQ. The hydraulic <br />conductivity at BCQ is from the same sandstone unit as the RCQ (Table 6-1) and aids in a <br />comparison for the hydraulic conductivity (RGI 1999). The estimated sandstone hydraulic <br />conductivity from the BCQ site is within the range of hydraulic conductivity estimated from analysis of <br />the RCQ slug tests. <br />Table 6-1. Hydraulic Conductivity <br />Monitoring <br />Well ID <br />Hydraulic Conductivity <br />(feet/day) <br />Well 1 0.5 <br />Well 2S 0.0017 <br />Well 3 0.0038 <br />Well 4 0.0042 <br />Site Average 0.011 <br />Bear Creek 0.0028 <br />