- 41 - 

 Water Quality in the Empress Gravels 



Figure 9 shows that there are no significant trends in total dissolved 

 solids in the Empress Gravels. At location 8a, piezometer C726E 

 showed a decrease in IDS concentration in July 1986, but returned to 

 a higher level in October of that year. 



At location 9a, the water quality in piezometer C728E is similar to 

 that of C726E. Boron values are generally slightly larger, and the 

 uranium concentration is generally less than the detection limit, 

 with the exception of the 3.0 Ug/L value obtained in October, 1986. 



At piezometer C533, south of the Ash Lagoon, the chloride concen- 

 trations have stabilized, and no other chemical parameters have 

 increased consistently. Uranium and boron have remained relatively 

 stable since the beginning of monitoring in all the Empress-completed 

 piezometers (0533, C534, C726E, and C728E). 



The higher hydraulic conductivity of the Empress Gravels allows a 

 much greater volume of water to flow through them than through the 

 tills. The amount of leakage from the overlying tills is therefore 

 very small compared to the through-flow in the Empress Gravels. 

 Because of this, the dilution effect would be large enough that 

 water quality effects are not expected from the Ash Lagoons or the 

 Polishing Pond. As a consequence, there is no verifiable water 

 quality change in the gravels attributable to seepage from the 

 lagoons. 



