Laserfiche WebLink
A significant difference in concentration of barium was observed in the leachate <br />from the ash compaced [o [he ash-gypsum. This can be seen in Figure 4.3-11. The <br />high concentrations of barium (10-90 mg/1) observed. in [he ash leachate were con- <br />siderably above the primary drinking water limit of 1 mg/1. <br />The concentration of barium in the ash gypsum leachate vas typically below the <br />drinking eater limit of 1 mg/1. This significant reduction in barium concentra- <br />tion due to the presence of calcium sulfate in the leachate may be due to the <br />limited solubility of barium sulfate. <br />Concentrations of aluminum (30-100 mg/1) in the ash leachate were slightly higher <br />than those observed in the ash-gypsum leachate (5-20 mg/1). The high concentra- <br />tions of aluminum were more likely the result of the high pH's. <br />The leaching behavior of chromium and molybdenum for both the ash and ash-gypsum <br />columns were comparatively equal. The concentrations of chromium and molybdenum <br />were initially quite high (approximately 2-5 mg/1) then dropped off rapidly to <br />levels which approximated or were below applicable water quality Limits of 0.05 <br />and 0.01 mg/1 foc chromium and molybdenum, respectively. This leaching behavior <br />is graphically presented in Figure 4.3-12. <br />The concentration of vanadium leached from the ash-gypsum mixture was approxi- <br />mately 0.3 mg/1, slightly above [he irrigation limit of 0.1 mg/1. The concentra- <br />tion of vanadium in the ash leachate was slightly lower than the limit (approxi- <br />mately 0.02-0.1 mg/1) as shown in Figure 4.3-13. <br />As expected, significant differences in sulfate concentration were observed <br />between [he two materials as shown in Figure 4.3-13. The concentration for sul- <br />fate in the ash-gypsum mixture was equivalent to [hat predicted by the solubility <br />of gypsum. The small quantities of sulfate present in the ash appear to be <br />leached from the ash during the passage of the firs[ aliquot of water. The con- <br /> centration for sulfate in all [he ash-gypsum leacha[es and in the firs[ leachate <br /> from [he ash column are significantly above the 250 mg/liter secondary drinking <br /> water limit. <br />4-75 <br />