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2.8.4 Metals 



The WHG laboratory digested 10 samples for metals analysis by EPA SW-846 

 Method 3051 (EPA 1997), which provides a rapid multi-element acid leach of sediments. 

 A representative sample of approximately 1 to 2 g wet weight of sediment was digested in 

 a microwave using concentrated nitric acid. Digestates were analyzed by instrumental 

 techniques appropriate for meeting reporting limit requirements. The samples were 

 analyzed using inductively coupled argon plasma-atomic emission spectroscopy (ICAP- 

 AES), using EPA SW-846 Method 6010 (EPA 1997), for aluminum (Al), chromium (Cr), 

 lead (Pb), copper (Cu), nickel (Ni), and zinc (Zn). Arsenic (As; Method 7060) and 

 Cadmium (Cd; Method 7131) were analyzed by graphite furnace atomic absorption 

 spectroscopy (GFAA). Mercury was analyzed by cold vapor atomic absorption 

 spectroscopy (CVAA), Method 7471 (EPA 1997). Results were reported on a dry weight 

 basis in units of mg/kg. 



2.8.5 Quality Assurance/Quality Control 



Data quality was assessed in relation to specified criteria for precision, accuracy, 

 representativeness, comparability, and completeness (PARCC). Analytical precision was 

 expressed as the percentage of the difference between results of replicate samples (Relative 

 Percent Difference [RPD]). Analytical accuracy of the laboratory was evaluated 

 quantitatively as the percent recovery of a spiked standard compound or surrogate 

 compound added at a known concentration to the sample before the analysis. When spiked 

 duplicates were run, the results were expressed as an RPD to evaluate precision of the 

 analysis of the spiked compounds. By inference, the precision of analysis of other related 

 compounds should be similar. Laboratory accuracy also was evaluated qualitatively by 

 evaluating the laboratory QC information on sample holding times, method blank results, 

 recovery of internal standards, and laboratory quality control samples. The following 

 section defines the various QA/QC requirements and summarizes the data quality 

 objectives for this project. 



2.8.5.1 Sample Tracking and Holding Times 



SAIC Standard Operating Procedures for sample tracking and custody were 

 followed. All sediment containers and bags were stored at 0-4° C prior to analysis. 

 Chain-of-custody records were maintained for all samples. One container was received 

 with a crack on the bottom of the jar; this sample was selectively sampled only for grain 

 size from the top of the container. All other samples were logged as received in good 

 condition. 



Monitoring Cruise at the WLIS Disposal Site, September 1997 and March 1998 



