2012-02-28_REVISION - M1980244 (85)

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was requested to assess the potential for HCN generation within the impoundment, and if significant, to provide separate containment for either the wash vessel or mix tank. Therefore, following the onsite portion of the recertification audit, CC &V performed an assessment to determine the potential for HCN generation within the impoundment in a scenario in which the vessel and tank failed simultaneously. Based on the secondary containment volume, the amount and moisture content of saturated carbon within the acid wash vessel and its cyanide concentration, CC &V determined that approximately 1.67 ppm of HCN gas would be generated in such an event. The alarm set point for the HCN detection system within the ADR facility is 4.7 ppm; therefore, a concentration of 1.67 ppm would not cause the system to alarm. Based its assessment, CC &V concluded that HCN generation would not be significant and that separate secondary containment is unwarranted. CC &V provided the audit team a copy of its assessment, including the analytical test results and supporting calculations. Pipelines are located above ground with the exception of the short segment of drainpipe running from the ADR Plant overflow sump to the VLF. However, this pipe is located above the geomembrane underliner system, which drains to the VLF. Additional containment measures include differential flow /pressure and interlock systems. Based on direct field observations and interviews with CC &V personnel, the risk to local surface water quality from an unplanned pipeline rupture is extremely low. CC &V uses carbon steel, stainless steel, HDPE, and polyvinyl chloride (PVC) piping materials and piping system components. All cyanide process tanks are constructed of carbon steel. These materials are compatible with cyanide and high pH solutions. 4.8 Implement quality control/quality assurance procedures to confirm that cyanide facilities are constructed according to accepted engineering standards and specifications. The operation is: • in full compliance ❑ in substantial compliance ❑ not in compliance...with Standard of Practice 4.8. Describe the basis for the Finding/Deficiencies Identified: Subsequent to the June 2007 certification audit, CC &V has constructed /implemented several new cyanide facilities and made several modifications to existing cyanide facilities at the Cresson Project. These include: • Construction of the Phase IVc isolation barrier; • Commissioning and decommissioning of a temporary carbon train at the ADR Plant; Cresson Project Name of Mine September 22, 2010 Signature of Lead Auditor Date Page 19 of 36