2008-04-28_HYDROLOGY - M1977208 - Laserfiche WebLink

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DRMS CEMEX M1977-208 Quarterly Report Apri122, 2008 Page 2 Analytical Results Parameter Units Limits October 23, 2007 March 11, 2008 C-Pit CEM-001 CEM-004 C-Pit CEM-001 CEM-004 pH su 8.9 8.86 7.68 6.97 7.8 7.7 7.4 Chloride mg/L 1100 2000 90 1100 2000 110 Sulfate mg/L 4000 <5 350 3300 <5 350 Dissolved Solids mg/L Bk 7000 4400 820 6800 4600 880 Selenium, dissolved (ICP- DRC-MS mg/L .02 A 0.17 0.0036 0.0045 .067 .07 .0045 Thallium, dissolved mg/L .002 0.002 <0.001 <0.001 .0029 .001 <0.001 ICP-DRC-MS -Inductively-Coupled Plasma Dynamic Reaction Cell Mass Spectrometry su -standard units mg/1-milligrams per liter Limits Under TR-04, DRMS indicated that some migration without treatment for water with elevated parameters might be acceptable as long as the migration was minimal. The compliance well, CEM-005, still shows no migration of water. The closest well CEM-001 did show an increase in selenium levels. Note this is an agricultural standard for groundwater. CEMEX is resampling the well to confirm the elevated concentration. 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.. 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 vas shut off in the Canal during the first week of November, 2007.) Measurement of the depth to water at compliance well CEM-005 on March 11, 2008 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 almost no 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 asemi-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. 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. However, inflow into C-Pit at the southwestern high walls continued to be significant throughout the winter season. Some ponding in the southern portion of the active pit approximately one foot in depth have expressed. CEMEX has undertaken periodic efforts to fill these lower areas with shale. The source of the water is not immediately apparent, K:IEHS1EnvirolCompliance Forms and SubmidalslDMRS C Pitlquartedy repor1s1Y08Q11CEMEX Transmittal 1st QTR 2008 Malytical Data.doc