54 



Metals. Metal concentrations were exceedingly consistent among the ten SE-REF 

 samples, with CV values all < 10% except for Cd (15%; Table 3-9). All metals were 

 reported above instrument detection limits in all samples. Station GR-1 had the highest 

 concentrations of Cd, Cr, Cu, Pb, and Zn, but there was no consistent pattern of metal 

 concentrations among any of the other stations. 



The mean metal values were compared with historical reference values compiled 

 from other WLIS reference areas (Murray 1995). The mean values measured in the SE- 

 REF stations were higher than all mean values reported for the historical data (Table 3-9). 

 Cadmium, Pb, Ni, and Zn were within one standard deviation of the historical mean, while 

 the remaining metals (As, Cr, Cu, and Hg) were all within two standard deviations. The 

 95 % confidence levels for SE-REF stations and the WLIS Reference Area dataset were 

 compared (Figure 3-15). The 95% confidence intervals were determined by multiplying 

 the standard deviation of the SE-REF dataset (n= 10) by 2.26 and of the WLIS-REF 

 dataset (n>20) by 1.96 (Mendenhall 1979). The overlapping intervals for each metal 

 indicates no significant statistical difference between the potential reference area and the 

 compiled reference area dataset. 



Metals were also evaluated normalized to the fine-grained fraction (Table 3-10). The 

 normalized metals data were overall more variable than the metals data, with CVs ranging 

 from 5 to 22%. All of the normalized metal mean values were within two standard 

 deviations of the WLIS compiled reference area normalized mean, and the mean values for 

 Cd, Ni, and Zn were within one standard deviation. Metals also were normalized to Al, 

 resulting in similar ranges and CVs as the data normalized to fine grain size. 



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



