The Effectiveness of a Tall Stack for Reduction of Ambient Sulfur Dioxide Concentrations:A Field Investigation

Of many available methods for limiting ground level pollutant concentrations, tall stacks are many times the simplest, most effective, and least costly. Although this is theoretically explicit, field validation of the soundness of this approach is often hampered by lack of comparable "before" and "after" data. In this study at the Alma Power Plant, appropriate air quality and meteorological measurements were made for several years before and after conversion from short to tall stacks. Comparison of these data show that the tall stack has reduced ambient levels of SO₂ by from 50 to 95 % in the vicinity of the plant. This study also found that use of a Turner-Briggs dispersion model in a valley situation gave fairly accurate and reliable estimates of air quality. The model was useful in designing the tall stack, assessing its impact and locating air quality monitors.