2011-06-05_HYDROLOGY - M1977208 - Laserfiche WebLink

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Mr. Michael Cunningham Environmental Protection Specialist Division of Reclamation, Mining and Safety 1313 Sherman Street, Room 215 Denver, Colorado 80203 Re: CEMEX Lyons Mine Permit M -1977 -208 4.- T- etlinical Revision N. 10, C -Pit Hydrogeologic Investigations 1 St Quarter 2011 Monitoring Data k'' Dear Mr. Cunningham: July 1, 2011 Via Certified Mail Return Receipt Requested 7007 2680 0001 6296 0101 RECEIVED 'In 5 Zoi I Division of Reclamation, Mining & Safety This letter transmits surface water and groundwater data from sampling the C -Pit pond and related wells for the first quarter 2011. For your convenience, data from all of 2010 is also included in the Table 1. On March 30, 2011, CEMEX personnel sampled the water in the pond at the north end of C -Pit, as well as the CEM -001 and CEM -004 wells. CEMEX also monitored the water elevation in C- Pit and several piezometers. Please refer to the text, figures, and appendices of the C -Pit Hydrogeologic Investigations report (Brown and Caldwell, August 31, 2007) for site details, well construction, and related historical information. C -Pit water continues to be used in the manufacturing process and is pumped into a cooling tower to reduce the C -Pit water level. The pond fluctuates with process use as can be seen in the attached C -Pit Water Level Elevation graph year 2010 and 2011. The y axis on the graph corresponds to the water surface elevation. Water was pumped in November to the lowest possible levels, within the constraints of the pump mounting. The C -Pit pond water and groundwater samples taken were analyzed for pH, chloride, sulfate, dissolved solids, dissolved selenium and dissolved thallium. The most recent analytical laboratory results are enclosed with this letter, as an attachment. Samples were analyzed shortly after collection for pH; this value is reported instead of the value by the laboratory due to hold time changes that occur in pH values