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4 <br />23 SAMPLE PRESERVATION <br />As discussed above, all samples were unfiltered. Unfiltered groundwater samples were taken <br />so that metals and cyanide samples were comparable, instead of taking filtered metals <br />samples and unfiltered cyanide samples. All samples were checked after collection to ensure <br />that they were preserved to the proper pH. Cyanide samples were preserved with solid <br />NaOH to pH >_ 12, and metals samples were preserved with nitric acid to pH <_ 2. <br />3.0 SUMMARY AND ASSESSMENT OF ANALYTICAL ACTMTIES <br />3.1 ANALYTICAL RESULTS <br />The field parameters and analytical results are displayed in Tables 2 and 3, respectively. A <br />discussion of any elevated concentrations or unusual results and comparison to previous <br />results is provided below. <br />3.1.1 Surface Water <br />RS-5. The pH of Rito Seco was significantly higher than pH values in March, April and <br />May, 1993 and was appro~dmately the same as the pH measured in November, 1992, <br />indicating that there may be seasonal pH fluctuations of over one pH unit (6.42 to 7.96). <br />Total and WAD cyanide were again below detection (at 20 pg/1) at this location, as was <br />copper (at 10 µg/1). Iron concentrations (560 µg/1) were very similar to those measured <br />during the November 1992 third-party monitoring trip. Iron and pH may co-vary throughout <br />the year, with lower pH values being associated with elevateduon concentrations in the <br />stream. <br />3.1.2 Process Points <br />Total cyanide concentrations were once again highest in the collection impoundment and <br />were above detection in all process point samples. WAD cyanide concentrations were above <br />detection but below 1 mg/1 in all process point samples and were lower than those measured <br />in May, 1993. Acceptance criteria for laboratory duplicate analyses of total cyanide were <br />not met for either the upper or lower tailings impoundment samples. Core Laboratories <br />reran these samples for total cyanide but did so after the 14-day holding time had elapsed. <br />The QC problems associated with total cyanide concentrations make it difficult to assess <br />whether total cyanide concentrations are higher than WAD cyanide in October, 1993. <br />Under Tailings Impoundment. Measured lab duplicate total cyanide concentrations in the <br />upper tailings impoundment were 160 and 260 µg/t. This results in a relative percent <br />RCG/Hagler, Badly, Iac. <br />