51 

 Associates Limited and illustrated cross sections of the dykes, indicated a reduction in 



dyke stability. The water level is not exceeding the critical failure surface. A review of 



the hydrographs for October 1991 , on piezometers associated with these cross sections 



does not indicate an increasing trend that would suggest the critical failure surface line 



will be reached. 



7.4 Lagoon Water Levels 



Figure 7.1 illustrates operating levels for Ash Lagoon No. 1, Ash Lagoon No. 2, Ash 

 Lagoon No. 3 North and the polishing pond for the period 1 983 to 1 991 . Freeboard limits 

 were not exceeded during this reporting period for Ash Lagoon No. 2, Ash Lagoon No. 

 3 North and the polishing pond. 

 767 



753 



MMMMMMMMM 

 83 I 84 I 85 I 86 I 87 I 88 I 89 I 90 I 91 



Figure 7.1 Ash Lagoon Water Levels and Polishing Pond Level, 1983 to 1991. 



