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exposed and re-graded during the fill process, Most of [he material used is spoil from the <br />nearby Lyons Quarry, from the same shale formation through which C-Pi[ was originally <br />excavated. <br />Significant progress has been made eliminating the water surface in C-Pit. In 2006, the <br />C-Pit water surface exceeded 7 acres. After some re-grading at the south end of the pit, <br />this was reduced to approximately 4.3 acres by late January 2007. The fill process that <br />commenced in March 2007 has since reduced the surface acreage of exposed water at the <br />north end of C-Pit to less than 0.8 acre. <br />The original calculation of the amount of fill required to eliminate the water surface was <br />250,000- 400,000 cubic yards (CY). This estimate was based principally on two <br />assumptions: <br />• Modeling of the pit bottom below the water surface, based on available data, <br />resulted in a calculated water volume in late January 2007 of 15.9 million gallons. <br />• An assumed void ratio of the fill material of 0.30 resulted in an estimated volume <br />of fill of less than 400,000 CY that would be required to contain the water. <br />To date 470,589 CY from Lyons Quarry has been placed in C-Pit, and an additional <br />41,494 tons of shale from Dowe Flats was used as dust suppressant cover for CKD. We <br />think this increased volume (over the initial estimate) is due to a combination of factors. <br />The modeled pit floor topography under the water surface likely was not accurate. The <br />void ratio of the placed fill likely is lower than our assumption of 0.30. Further, <br />additional water has entered the system since late January due to precipitation and up- <br />gradient inflow, increasing the required amount of fill material. <br />Monitoring of Water Levels and Chemistry <br />Daily visual monitoring of C-Pit has been conducted since the fill process began, and on <br />March 9, 2007, in-situ water depth and quality instrumentation was installed in both C-Pit <br />and monitoring well CEM-001. These devices record the following field parameters <br />every 5 minutes: <br />• Pressure headwater depth <br />• pH <br />• Temperature <br />• Dissolved oxygen (mg/L) <br />• Conductivity (ms/cm) <br />• Oxidation/Reduction Potential (ORP in mV) <br />No adverse impacts have been recorded to date. No seeps or springs have been observed <br />outside of C-Pit. The only wildlife observed near C-Pit has been several rabbits and <br />pigeons. <br />