27 



in May, 1995, the highest recorded concentration to date, before decreasing to near 35 mg/1 in 

 October, 1995. The chloride concentration for C766 has shown little movement since 1987 and 

 remains within the 20 to 30 mg/1 range, similar to the ash lagoon surface water concentration. 



Up to April 1988 the boron concentration for C767 was increasing and peaked at 49.4 mg/1. From 

 this peak the boron concentration has steadily decreased to the end of 1991 where the 

 concentration levelled off near 5 mg/I. The October 1995 result is 5.28 mg/1. The reduction in 

 boron concentrations for samples from C767 suggest the movement of a slug of leachate and not 

 a continuous plume. There has been an increasing trend in chloride for C767 ranging from 25 

 mg/1 in 1989 to 75 mg/1 in 1991. Since 1991 the concentration has remained near 70 mg/1 with 

 an October 1994 result of 73.4 mg/1. In 1995 the concentration showed a moderate increase, 

 ranging between 94 and 99 mg/1. 



Boron concentrations for piezometer 712B were initially below 1.0 mg/1 until an increasing trend 

 began in 1987 with the concentration peaking in April 1992 at 26.6 mg/1. The boron 

 concentration then decreased and levelled off near 18 mg/1 with an October 1995 result of 20 mg/1. 

 Chloride concentrations trended down for C712B to 50 mg/1 in 1988 from over 200 mg/1 in 1984. 

 Since 1988 chloride levels have changed little with an October 1995 result of 50.8 mg/1. 



In 1994 it was reported that no vertical seepage or liner permeability could be calculated for Ash 

 Lagoon #3 North due to the measured pore pressure exceeding what the lagoon water level could 

 physically produce. As expected this situation has corrected. 



The total calculated seepage from the ash lagoons in 1995 was determined to be 1.61 litres per 

 second. This value is not significantly different from the 1994 and 1993 calculated seepage rates 

 of 1.67 and 1.62 litres per second, respectively. There was a negligible total calculated seepage 

 rate for Ash Lagoon #3 South at 0.001 litres per second. This result was not unexpected as the 

 lagoon has only been in service since May, 1995 and no gradients have developed. 



Liner permeabilities for all lagoons except Ash Lagoon 3 South remain in the order of lO^cm/sec. 

 The liner permeability determined for Ash Lagoon 3 South, based on the above permeability, is 

 not considered realistic and was not reported. 



