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The 1988 calculated seepage has Increased from that calculated for 

 1987. The calculated total seepage, however, remains well below the 

 seepage limits (5.0 L/s to Cookson Reservoir and 2.0 L/s to the East 

 Poplar River) proposed in 1979 by the International Poplar River Water 

 Quality Board of the IJC. The calculated permeability liners for Ash 

 Lagoons No. 1 and 2 and the Polishing Lagoon was of the same order 

 of magnitude (4 to 28.7 x 10 9 cm/s) as originally calculated by T.A. 

 Prickett. The calculated liner permeability for Ash Lagoon No. 3 



Q 



North was 10.6 x 10 cm/s. The consulting geotechnical engineer 

 for the Poplar River Power Station has recommended that the method 

 of seepage calculation be replaced with a more technologically ad- 

 vanced method of seepage analysis using computer technology. This 

 recommendation is being considered and may be implemented in 1989. 



The advancement of the ground water front toward the reservoir in the 

 oxidized till was calculated to be 10.79 m since the lagoons were 

 initially filled, which is an increase of 2.48 m since 1987. The 

 front in the Empress Gravel formation was calculated to have advanced 

 1032 m southeast of the lagoons, an increase of 120 m since 1987. 

 Examination of the chemistry of water from the Empress Gravel 

 formation and till generally shows no significant changes attributable 

 to lagoon seepage except for increasing boron levels at one location. 

 Monitoring will be continued and remedial action will be undertaken 

 if required. Leachate flow into Cookson Reservoir and into the East 

 Poplar River, however, has not been measurable. 



The Saskatchewan Department of Environment and Public Safety requires 

 that the Saskatchewan Power Corporation maintain the stability of the 

 ash lagoon system dykes. In addition to the regular visual inspec- 

 tions, an annual investigation by a geotechnical engineer was con- 

 ducted in October 1988. The geotechnical consultant indicated that 

 the ash lagoon dykes and liners have good integrity and the ash is 

 contained effectively. The consultant noted that the lagoon system 

 is performing as designed. Some recommendations were made regarding 

 remedial measures for erosion protection and continued monitoring. 



