The Wisconsin Court of Appeals, Dist. IV last week issued a decision rejecting three out of four challenges by the Sierra Club to an air pollution permit for the construction of a coal-fired power plant in Weston, Wisconsin.

In its appeal, the Sierra Club challenged a lower court’s decision affirming the Wisconsin Department of Natural Resources’ (DNR) “best available technology” (BACT) determinations for the air emissions construction permit.

Upholding the trial court, the appellate court ruled that the BACT limits set by the DNR for sulfur dioxide and nitrogen oxide emissions were reasonable. In addition, the appellate court upheld the DNR’s selection of dry flue gas desulfurization technology (rather than wet dry flue gas desulfurization) to control sulfur dioxide. The DNR further found that the DNR’s BACT emissions limits and its selection of dry flue gas desulfurization technology were supported by substantial evidence.

Last, the court ruled that the DNR erred by not including a visible emissions standard for the main boiler at the Weston 4 plant. The power plant and DNR argued that establishing BACT emissions limits for the pollutants that make up visible emissions exiting the boiler smoke stack achieves the same result as establishing a visible emissions standard, and therefore it was not necessary to set a visible emissions standard. The court disagreed, ruling that the definition of BACT requires the DNR to set a visible emissions standard and that simply setting BACT limits for pollutants that make up visible emissions is insufficient under the definition.