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Update to Wildlife Resources Assessment, Cemex C-Pit and CKD Disposal Site <br />Page 2 of 7 <br />2. A portion of the Boulder Feeder Canal west of the pit has been relined. The rest of the canal <br />in this area has been scheduled for relining in the near future (Figure 2). <br />3. The "Brick Pond", a small reclamation pond to the southwest of C-Pit, has been partially <br />filled and is now shallow. Plans are being made for the complete drying up this pond. <br />4. C-Pit was filled with waste rock from Dowe Flats in June of 2007. This has resulted in <br />reducing the surface area of the water from several acres to the current one-half acre, as <br />displayed on the attached photos (Figure 3). <br />5. Since the pit has been filled with waste rock, the remaining water in the pit is no longer in <br />contact with CKD. This has resulted in the pH of the remaining ponded water dropping to <br />8.5, which is no longer hazardous to wildlife that makes contact with this water. <br />6. The remaining pond at the northeast end of the pit has a small float for a water pump, is <br />surrounded by high banks with a steep angle of repose, and has overhead cables with red <br />streamers (Figure 3D). <br />7. Cemex has retained the ability to use water from C-Pit to be used in the cooling tower at the <br />plant. This use will be further enhanced when Cemex installs a pump to mix this water with <br />water from A-Pit, which concept is in an early planning stage. <br />8. Cemex has significantly reduced the amount of CKD that needs to be disposed in the pit. <br />Results <br />These actions have resulted in a dramatic decline of ground water infiltration into the pit, drastic <br />reduction in the surface area and total size of the ponded water, and a dramatic reduction in the <br />pH of the water in the pit. <br />Cemex has conducted quarterly water quality monitoring since 2004, and will continue to do so <br />into the future, as required by the Lyons Quarry Permit No. M-1977-208 with the Division of <br />Reclamation, Mining and Safety. Assuming that the pH of the remaining ponded water remains <br />in the 7.0 to 9.0 range, there should be no threat to wildlife that come into contact with this water. <br />Because water is regularly pumped from this pond, and the pond configuration has changed <br />dramatically in the past year, there are no food sources for wildlife in the pond such as rooted <br />aquatic plants or aquatic invertebrates. <br />Cemex has been required to monitor wildlife in C-Pit on a daily basis since 2004. As predicted in <br />the 2004 report, wildlife use of C-Pit has been minimal. A few rock doves may have perished <br />from contact with water in the pit, although they may have also died from other causes and fallen <br />into the pit from their roost sites. Rock doves are not protected under state and federal wildlife <br />statutes. <br />Selenium <br />Selenium is naturally occurring in shale and limestone bedrock. Cemex has monitored selenium <br />at C-Pit, with recent results varying between 0.17 to 0.30 mg/L. The current agricultural water <br />standard for selenium is 0.2 mg/L. The US Fish & Wildlife Service has compiled research on <br />recommended thresholds for selenium that vary between 2.0 u/L to 10y+g/g (USFWS 2008, <br />Hamilton 2002). Current selenium concentrations are therefore somewhat higher than the <br />agricultural standard, but well below recommended amounts thought to be toxic to aquatic birds. <br />Further, these wildlife standards are not truly applicable to the situation at C-Pit. These wildlife <br />thresholds apply to situations where waterfowl and shorebirds congregate, feed, and nest at water <br />bodies for prolonged periods of time. Selenium found in the water bodies bioaccumulates <br />through the food chain, particularly through aquatic invertebrates consumed by waterfowl and