The greatest changes in chloride and boron concentrations within the oxidized till have occurred where 

 piezometric levels have changed the most. Although increasing water levels do not automatically 

 suggest that the water affecting the piezometers is leachate, changing piezometric levels do indicate 

 ground-water movement. On the west side of the Polishing Pond, the boron levels have changed only 

 slightly in the oxidized till piezometers C728A and C728D, where the chloride levels have changed 

 more significantly. The chloride level for C728A has decreased from 403 mg/L in 1983 to 246 mg/L in 

 2004. The chloride level for C728D has increased from 185 mg/L in 1983 to 384 mg/L in 2004. 

 Although these piezometers are close in proximity and installed at the same level, they are being 

 influenced by different water. Chloride results for C728A suggest initial seepage and it is to be expected 

 that over time the same observation will be seen in C728D. 



The piezometric surface of the Empress Gravel indicates a regional flow from northwest to southeast 

 below Morrison Dam. As a general observation. Empress piezometers respond to changing reservoir 

 levels. Results for the Empress layer do not indicate seepage activity with the majority of the analyses 

 showing little real change in boron or chloride concentrations. 



Sand lens piezometers C712B and C766 are located the toe of dyke G between the Polishing Pond and 

 the cooling water canal. These piezometers have historically been of interest as the sand lens provides a 

 preferential pathway for leachate migration of boron concentrations. C766 showed an increasing trend 

 up to October 1988 with a peak of 43.0 mg/L in April 1995. Between 1995 and 2002, the boron 

 concentrations decHned modestly and remained between 25 and 38 mg/L. 



Up to April 1988 the boron concentration for C767 was increasing and peaked at 49.4 mg/L. Since this 

 peak, the boron concentration steadily decreased to the end of 1991 where it leveled off near 5 mg/L and 

 remained through 2003 with one exception, a concentration of 1 1.7 mg/L in October 2000. 



Piezometer C712B has been monitored for several years. Historically, boron concentrations were below 

 1 mg/L. From 1992 to 2004, boron concentrations have remained relatively steady around between 12 

 and 20 mg/L. 



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