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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 asses leachate 

 movement. 



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

 construction. In total 20 new pneumatic piezometers and 28 new standpipe piezometers were 

 completed within their target zones. Testing of these piezometers began in 1995. Due to the 

 limited amount of data collected to date from these piezometers, a meaningfiil review is not yet 

 possible. 



Piezometers 867A, 868A and 871 A are completed immediately above the liner system, within the 

 ash stack of Ash Lagoon #1 . The 1995 monitoring results continue to 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 suspected 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. New piezometers 

 886A, 887A, 890A and 893A have been completed above the liner system of new Ash Lagoon #3 

 South and are now being monitored. Future monitoring of all piezometers completed above the 

 lagoon liner systems will continue 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. Relative to the 1994 position, the size and extent 

 of the ground- water mound has not significantly changed. The mound extends from the east side 

 of Ash Lagoon 2, where levels have increased 7 metres, to the west side of the polishing pond, 

 where levels have increased 4 metres. Oxidized till piezometers located closer to the reservoir 

 have shown a decreasing trend in piezometric levels reacting to lower reservoir levels. 



