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 conclusion. For example, seepage activity should reduce chloride levels to equal those 



of the ash lagoons but instead chloride levels are increasing. 



7.8 Leachate Review 



Historically, the leachate review has been presented through the aid of graphs to show 

 developing trends. This report uses maps to show changes in piezometric surface, in 

 chloride and boron for the oxidized, unoxidized and Empress layers. A total of eighteen 

 maps are provided in Appendix 5 of this report to demonstrate these changes. 



The piezometric surface for the oxidized strata shows a groundwater mound beneath the 

 lagoons. As shown on the change in piezometric surface map, the groundwater mound 

 extends from the east side of Ash Lagoon No. 2 where a six metre increase has been 

 noted, to the west side of the polishing pond where levels have increased about four 

 metres. Moving toward the reservoir, the oxidized till piezometers have shown a 

 decreasing trend, reacting to lower reservoir levels. 



The largest changes in chloride and boron levels in the oxidized till have occurred where 

 the piezometric levels have changed the most. This would be expected because 

 changing water levels does suggest water movement. The increasing boron results on 

 the east and south side of Ash Lagoon No. 2 along with the decreasing chloride levels 

 suggests a leachate influence. On the west side of the polishing pond, the boron levels 

 have changed little but the chloride levels have increased greatly, moving opposite to 



