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March 17, 2016 <br /> Page 2 <br /> GCC reports that soil moisture was noted when the fault was encountered but that it does not produce or <br /> transmit any notable water. <br /> A cross section oriented southwest to northeast along the stratigraphic dip is presented on Figure 2(see <br /> Figure 1 for the cross section location). This cross section and stratigraphic thicknesses and dip are based on <br /> drill hole logs,stratigraphic sections,and mapping provided by or performed for GCC and the regional <br /> geologic map(Scott, 1969). The only strata capable of laterally transmitting significant groundwater that <br /> could potentially infiltrate from the quarry and plant site are the Fort Hayes Limestone and Codell Sandstone. <br /> If that were to occur,such water would likely accumulate at either the Fort Hayes-Codell contact or the <br /> Codell-Blue Hills Shale contact,and move laterally to the northeast in the direction of the stratigraphic dip. <br /> If such infiltration occurred in recent time, it is expected that saturation would first occur in the Fort Hayes, <br /> and then over time also in the Codell. <br /> The quarry has not exposed any groundwater and the only water that occurs in the quarry is direct <br /> precipitation and minor amounts of run-on. Water that occurs in the quarry is routed to an in-pit <br /> sedimentation basin located in the northern downslope end of the Years 1-5 mine panel(Figure 1). This <br /> basin was expanded in 2011 and is designed to contain the entire 25-year,24-hour flood events,plus <br /> sediment loads. Water is allowed to accumulate a maximum of three days before being discharged by pump <br /> to Arroyo B, in accordance with GCC's Colorado Discharge Permit. GCC plans to maintain the current <br /> location of the in-pit sedimentation basin through mining of the first three panels(Mine Years 1 -25). The <br /> basin is excavated into the Codell Sandstone. GCC reports that given the pump setting,the water level in the <br /> basin stays below the Fort Hayes/Codell contact. The limited water that accumulates in the basin primarily <br /> evaporates. Some limited amount of water may persist at times in the basin due the impracticability of <br /> pumping it completely dry. <br /> The average precipitation at Pueblo is approximately 12 inches/year. The average potential <br /> evapotranspiration in the area is reported to be 12.2 to 15.8 inches/year(Sanford and Selnick,2013). Pan <br /> evaporation rates in the Pueblo area are much higher,typically 50 to 60 inches between May and September <br /> (Colorado Climate Center,2016). Given precipitation,climate conditions,topography and soil types in the <br /> area,there is little potential for deep percolation and shallow groundwater except for in alluvium along <br /> creeks and rivers. This is substantiated by the absence of groundwater in the GCC quarry,history of dry <br /> wells at the site, St.Charles River being under losing conditions in the area,and lack of any nearby shallow <br /> wells used for domestic or livestock supply. A check of Colorado Division of Water Resource records did <br /> not reveal any Fort Hayes wells cross gradient or downgradient of the site within 5 miles. <br /> Former and current site monitoring and production wells are shown on Figure 1. In 2002,a Dakota <br /> Sandstone production well,DW-I (screened at depth of 504-614 feet),was installed to supply water for the <br /> plant(Leonard Rice Engineers,Inc.,2003). Within 100 to 130 feet of DW-I are two Dakota monitoring <br /> wells and two other monitoring wells located in the underlying Cheyenne Sandstone aquifer(depth of 666- <br /> 806 feet). The monitoring wells were used as observation wells for aquifer testing,which revealed no <br /> hydraulic communication between the Dakota and Cheyenne aquifers. Both aquifers are confined,with the <br /> Cheyenne aquifer being artesian(flowing)and the Dakota wells having static water levels approximately 65 <br /> feet below surface. During drilling of DW-1 and associated monitoring wells,no water was noted except for <br /> "trace groundwater"at a depth of 130 feet(possibly at the base of the Codell). DW-I is still in use and <br /> supplying water for plant operations. Initial water quality sampling at DW-I revealed no exceedance of <br /> primary drinking water standards,with the exception of radium. These exceedances are not unexpected <br /> given the presence of uranium deposits in the Dakota Sandstone(Kirkham and Ladwig, 1980). <br /> Close Consulting Group LLC <br />