27 



began increasing again peaking at 35.2 mg/1 in June 1993 before falling to 26.7 mg/1 in October 

 1993. The boron concentration began an increasing trend throughout 1994 and peaked at 43 mg/1 

 in May, 1995, the highest recorded concentration to date, before decreasing to 28 mg/1 in October, 

 1996. 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/1. The October 1996 result is 4.58 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. In 1996, the concentration showed a moderate decrease with 

 results going from 99 mg/1 in April to 78.2 mg/1 in October. 



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 1996 result of 

 16.5 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 1996 result of 50.9 

 mg/1. 



The total calculated seepage from the ash lagoons in 1995 was determined to be 1.56 litres per 

 second. This value is not significantly different from the 1995 and 1994 calculated seepage rates 

 of 1.61 and 1.67 litres per second, respectively. There was a total calculated seepage rate for ash 

 lagoon #3 south of 0.024 litres per second. In 1995 it was reported that ash lagoon #3 south had 

 a negligible total calculated seepage rate due to no developed gradient. As expected this has 

 changed. Liner permeabilities for all lagoons are in the order of 10' cm/sec. 



