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. 6.2 Operate and monitor cyanide facilities to protect worker health and <br />safety and periodically evaluate the effectiveness of health and <br />safety measures. <br />The operation is: ^ in full compliance <br />^ in substantial compliance <br />^ not in compliance ...with Standard of Practice 6.2. <br />Describe the basis for the Finding/Deficiencies Identified: <br />SOPS require that pH targets for process solutions be > 10; pH levels are <br />monitored by process operators through inline sensors and portable pH meters, <br />and data are recorded on Daily Solution sheets. pH of the cyanide solutions in <br />the ADR are maintained by application of caustic during the batch and pre- <br />treatment batch mixing process. In the batch mixing process, the pH alarm is set <br />at 12; the pretreatment batch procedure requires a pH >12. <br />The barren feed sent from the plant to the VLF is maintained at pH 10 -10.5. The <br />pH of the pregnant solution (plant feed) is maintained by the addition of lime to <br />the leach pad. The low cyanide solutions returning from the Phase I and II pads <br />are mixed with Phase IV pregnant solutions, resulting in a current plant feed pH <br />• of about 9; however, process improvements to increase the application of heavier <br />doses of lime are underway and are expected to raise the feed pH to >10. <br />SOPs specify when personal gas-monitoring units must be used for specific <br />operations. Where operators or maintenance personnel need to work in areas <br />where there is a potential for HCN exposure they wear personal HCN detectors. <br />Two types of personal portable detectors are used: Monotox and Toxipro. The <br />Monotox device is calibrated 5 ppm (low alarm) and 10 ppm (high alarm). The <br />newer Toxipro monitors are calibrated to alarm at 4.7 ppm. These detectors have <br />rarely (2 or 3 times in past 10 years) alarmed, indicating that continuous 8 hr <br />exposures above 4.7 ppm do not occur. CC&V is moving towards using Toxipro <br />portable monitors as these units are easier to use, can be calibrated to 4.7 ppm, <br />and can be calibrated in-house. 'There are presently five of these units, which are <br />also calibrated monthly. <br />Monitoring equipment is part of regular preventive maintenance schedules. <br />There are 10 Senalert systems permanently located in key locations throughout <br />the ADR, which are tested and calibrated monthly. The Monotox devices are <br />• Cresson Project <br />Name of Mine <br />/~' <br />Signature of Lead Auditor <br />10 September 2007 <br />Date <br />Page 27 of 41 <br />