Ground-water quality in the vicinity of the ash lagoons can potentially be affected by leachate 

 movement through the ash lagoon liner systems. The piezometers listed in the Technical Monitoring 

 Schedules are used to assess leachate movement and calculate seepage rates. Piezometric water level, 

 boron, and chloride are the chosen indicator parameters to assess leachate movement. 



The ground-water monitoring program was expanded in 1994 as a result of Ash Lagoon #3 South 

 construction. In total, 20 new pneimiatic piezometers and 28 new standpipe piezometers were 

 completed within their target zones. Testing of these piezometers began in 1995. The limited data so 

 far do not show any xmusual or imexpected values. 



Due to the sampling program reduction approved by Saskatchewan Environment in late 2003 several 

 piezometers previously referenced in this report are no longer monitored. These piezometers are C867A, 

 C868A, C871 A, C886A, C887A, C868B, C869C, and C767. 



Piezometers C867A, C868A and C871A are completed immediately above the liner system, within the 

 ash stack of Ash Lagoon #L The 1995-2003 monitoring results of these piezometers suggest 

 confirmation of the trend first observed in 1993 that the boron concentration decreases with depth within 

 the ash stack. The effect of ash thickness on leachate quality is, however, not completely understood. 



The chemistry of water immediately above the liner systems is therefore expected to differ from the 

 surface water of the lagoons. Meaningful information is only available from piezometers installed 

 within Ash Lagoon #1 where ash has been deposited for many years. Monitoring of all piezometers 

 completed above the lagoon liner systems will continue in the future with the purpose of confirming the 

 boron trend noted above and to improve the understanding of leachate quality and flow from the ash 

 lagoons. 



The piezometric surface measurements for the oxidized till continue to show the presence of a ground- 

 water mound beneath the ash lagoons. The mound extends from the west side of the Polishing Pond to 

 the east side of Ash Lagoon No. 2. Isolated ground- water mounds have developed within the area of the 

 oxidized ground-water mound. Piezometers located in the oxidized till suggest limited leachate activity. 

 No seepage activity is evident in the unoxidized till. 



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