The battle over Sunflower Electric Cooperative’s plans to build an 895-MW coal-fired power plant in Holcomb, Kan., returned to court on Friday.

The Sierra Club, represented by Earthjustice, filed a lawsuit challenging a new air pollution permit recently issued by the Kansas Department of Health and Environment (KDHE) to Sunflower to build its proposed Holcomb 2 coal plant.

The Kansas Supreme Court in October 2013 invalidated a permit previously granted to Sunflower in 2010 by KDHE for the plant, ruling in favor of the environmental group. It upheld the Sierra Club’s contentions that KDHE erroneously interpreted the Clean Air Act and the Kansas Air Quality Act when it failed to apply Environmental Protection Agency rules regarding 1-hour emission limits for nitrogen dioxide and sulfur dioxide during its permitting process for the project. Those federal regulations “became effective before the Holcomb 2 permit was issued,” the court said as it remanded the matter to the state regulator.

In January 2014, KDHE initiated the process to reissue the permit with modifications, and on May 30, it issued the permit to Sunflower, paving the way for the new coal plant to begin construction and operation.

But in an appeal filed with the Kansas Appellate Court on Friday, the Sierra Club challenges the legality of the permit, saying it fails to address deficiencies in the permit identified by the Kansas Supreme Court. The permit still violates the Clean Air Act and Kansas law, it says.

“Specifically, KDHE did not comply with the Court’s instructions by failing to include adequate limitations for hazardous air pollutants such as mercury and acid gases, nitrogen dioxide, and sulfur dioxide in the final permit,” the group said in a statement on Friday. The appeal also argues that the permit does not heed emission limits for greenhouse gases, and current best available control technology limits.

The Sierra Club’s appeal is the latest development in a long-standing dispute about the project’s necessity and its environmental impacts between the Sierra Club, Sunflower Electric, and the state.

Sunflower in 2006 filed an application with the KDHE—under then-governor (and now U.S. Secretary for Health and Human Services) Kathleen Sebelius (D)—for a prevention of significant deterioration (PSD) permit to add three 700-MW units to its existing 360-MW plant in Holcombe, Kan. Soon after, Tri-State Generation and Transmission Association obtained an option from the company for rights to a portion of the new power and facilities.

But in October 2007, though KDHE staff had recommended the PSD permit be approved, the KDHE secretary denied the permit based on the level of carbon dioxide emissions from the proposed plant, declaring greenhouse gas emissions “an imminent and substantial hazard to public health and the environment.” Between 2007 and 2009, the Kansas Legislature passed four bills to try to force approval of the permit, all of which Sebelius vetoed. In 2009, Sebelius’ successor, Mark Parkinson (D), brokered a bipartisan compromise that allowed Sunflower to resume the permitting process for one 895-MW unit.

The project received its PSD permit in December 2010. The state’s current governor, Sam Brownback (R), is a strong backer of the utility’s plans.

Sonal Patel, associate editor (@POWERmagazine, @sonalcpatel)