2008-01-16_REVISION - M1977208 - Laserfiche WebLink

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Ms. Erica Crosby January 11, 2008 Page 2 Analytical Results: October 23, 2007 Sample Date Parameter Units C-Pit CEM-001 CEM-004 pH (field) su 8.86 7.68 6.97 Chloride mg/L 1100 2000 90 Sulfate mg/L 4000 <5 350 Dissolved Solids mg/L 7000 4400 820 Selenium, dissolved (ICP-DRC-MS) mg/L 0.17 0.0036 0.0045 Thallium, dissolved mg/L 0.002 <0.001 <0.001 ICP-DRC-MS - Inductively-Coupled Plasma Dynamic Reaction Cell Mass Spectrometry su - standard units mg/1 - milligrams per liter Water Elevation CEMEX continues to monitor the water elevation in the C-Pit pond by using a data logger to record head data. Another data logger is installed in CEM-003, and the water elevation in CEM-001 was established through a direct measurement taken on October 23, 2007. The water elevation data at these locations are plotted on the attached figure as time series that commence in March 2007. The figure also includes the flow in the Boulder Feeder Canal during this period. (Flow was shut off in the Canal during the first week of November.) Measurement of the depth to water at compliance well CEM-005 on October 23, 2007 confirmed that this well continues to show no significant change since it was drilled in May 2007. The 400-foot deep well has less than 6 feet of standing water, which CEMEX believes reflects residual water that drained into the well from the surrounding sand pack after the initial drilling and development. As agreed upon in TR-9, we will continue to monitor the depth to water at CEM-005 on a semi-annual basis, and in the event the well shows signs of increased water volume sufficient to sample, an attempt will be made to obtain a sample. CEMEX also had pressure transducers in some of the piezometers to help identify surrounding groundwater elevations, however during a routine site inspection several of these monitors were found vandalized and a police report was filed. These monitors were removed, and held until next irrigation system. Although conclusive evidence as to the source of inflow into C-Pit has not been established, The Northern Colorado Water Conservancy District completed lining a portion of the Boulder Feeder Canal to the southwest of the C-Pit area, in case this is a contributing source. A partial visual inspection of the Swede Ditch found no obvious leaks in the buried metal culvert or seams. Observations and investigations continue. No seeps or springs down gradient of C-Pit have been observed. To reduce water levels, CEMEX has purchased a new pump and motor sufficient to pump water into the spray tower for use as cooling water. This is a consumptive use consistent with all applicable permit (DRMS and CDPHE) conditions. The parts are on site and provisions are in place to install the pump during the next quarter. The pumping system CEMEX Transmittal 4th QTR 2007 Analytical Data