29 



ground-water movement. Oxidized till piezometers C868B and C869B located in the middle of the 

 lagoons, between Ash Lagoon No.l and No. 2, have shown increased levels but no chemical 

 information to suggest leachate influence. On the west side of the polishing pond, the boron levels 

 have changed slightly in the oxidized till piezometers C728A and C728D, which is in sharp contrast 

 to the chloride results. 



The chloride level for C728A has decreased from 403 mg/1 in 1983 to 247 mg/1 in 1999, a decrease of 

 156 mg/1. The chloride level for C728D has increased, moving from 185 mg/1 in 1983 to 421 mg/1 in 

 1 999. 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 gravels 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 obvious seepage activity with the majority of the 

 analyses showing little real change in boron or chloride results. 



Sand lens piezometers C712B, C766 and C767 are located between the polishing pond and the cooling 

 water canal. C767 is located on the top of dyke G and C766 and C712B are located at the toe of dyke 

 G. These piezometers have historically been of interest as the sand lens provides a preferential pathway 

 for leachate migration of boron concentrations. C766 shows an increasing trend up to October 1988 

 with a peak of 43.0 mg/1 in 1995 April. Since that time the boron levels have declined modestly and 

 have remained stable between 25 to 35 mg/1. 



Up to April 1 988 the boron concentration for C767 was increasing and peaked at 49.4 mg/1. Since this 

 peak, the boron concentration steadily decreased to the end of 1991 where the concentration levelled 

 off near 5 mg/1 and has since remained. 



Piezometer C712B had been monitored for several years. Historically, boron levels have been below 

 1 mg/1. From 1992 to 1999 boron levels have remained steady around 20 mg/1. Up to 1992 April the 

 boron trends for C712B and C766 looked very similar. 



