- 26 - 



At location 9a, at the west end of the polishing lagoon data are 

 reported for piezometer C728A, which was dry from 1980 to 1987. 

 Uranium values in the piezometers at location 8a are quite high, 

 relative to other locations. Piezometer C728B shows no consistent 

 water-quality trends over the period of record. Piezometer C728C may 

 show a vaguely-defined long-term trend to lower boron and aluminum, 

 and higher sulphate concentrations over the entire period 1981-1985, 

 but these species have been relatively constant since 1985. Monitor- 

 ing data obtained over 1986-1988 show that the uranium concentration 

 in C728C has remained fairly constant, and that the long-term trend 

 to higher concentration postulated in the 1988 report did not occur. 



Piezometer C534 is located to the south of the ash lagoon. The TDS 

 concentration has remained fairly constant at around 4,500 mg/L . 

 The aluminum concentration data for 1988 from C534 remained below 

 the 0.01 mg/L detection limit. No trends are seen in the other 

 species monitored. 



Water Quality in the Empress Gravels 



Figure 12 shows that there are no significant trends in TDS in the 

 Empress Gravels. Piezometer C726E at location 8a, west of ash lagoon 

 cell No. 1, displays a greater variability in TDS concentration than 

 the other piezometers, possibly due to variable recharge from the 

 overlying tills under certain conditions. 



Ground water-quality characteristics at locations 2a and 9a (piezom- 

 eters C726E and C728E, respectively) are generally similar. Boron 

 remains consistently higher in C728E (near 1.2 mg/L) than in C726E 

 (near 0.7 mg/L). 



At location C533, south of the ash lagoon, there are no trends evi- 

 dent in any of the water-quality parameters monitored. 



