British Columbia Mine Reclamation Symposium

Design of in-situ water treatment of acid contaminated lake Jensen, S. E.; Sharp, Tom; Allen, Dianne; Wilson, Ian


An in-situ treatment system was designed for Nero Lake, an acid contaminated lake in northern Saskatchewan. The purpose of the treatment system was to neutralize the lake water, which would be accomplished by adding lime to the entire lake. The process design was based on a pilot trial and a water and load balance model study. The pilot trial showed that lime could be delivered to the lake as a dilute lime solution to 10% to 20% of the lake water without significant loss of lime utilization and allowing the natural seasonal turnover of the lake to mix the lime throughout the lake. In-line injection of lime resulted in similar performance as mixing lime slurry and lake water in a mix tank. A water and load balance model was developed to determine whether addition of excess alkalinity (lime) was warranted as a way of mitigating acidity that may report to the lake in the future. The model was developed as a simple spreadsheet based model. The modelling results showed that since 1978, the annual load of alkalinity to Nero Lake has been greater than the annual load of acidity. This means that the lake will not become acidic following neutralization. The model also showed that any reduction in the current acidity loadings reporting to the lake is unlikely to significantly affect the long-term water quality of Nero Lake.

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