INDIANAPOLIS – Two environmental groups that oppose Purdue University’s plans for a new coal-fired power unit challenged the school’s air permit Thursday in an appeal that says regulators failed to fully assess how much pollution the project is expected to emit.

The appeal by the Sierra Club and the Hoosier Environmental Council also contends that the state permit approved this month lacks sufficient protections to control those emissions.

The two groups say the planned $53 million coal boiler will worsen air pollution and breathing disorders on and near the West Lafayette campus at a time when other schools are embracing cleaner energy sources.

“Purdue is supposed to be a place where students can take pride in being part of an institution that leads the country in innovation and clean tech. Instead, Purdue is doubling down on the dirty energy technology of yesteryear,” Bowden Quinn of the Hoosier Chapter of the Sierra Club said in a statement.

The appeal was received Thursday by the Office of Environmental Adjudication, which settles disputes over decisions made by the Indiana Department of Environmental Management.

IDEM spokesman Rob Elstro said the agency will defend the permit and demonstrate that the final permit complies with all applicable rules and regulations.

Purdue officials have said that replacing the Wade Power Plant’s 50-year-old coal boiler with a cleaner-burning version and adding a $7.5 million natural gas-fired boiler will significantly lower soot and mercury emissions on the campus.

The power plant supplies steam for electricity and heating as well as chilled water for cooling the campus’ buildings. It has two coal boilers – the aging boiler and a cleaner unit built in 1991 that’s similar to the new planned unit.

Purdue estimates the cleaner-burning coal boiler and natural gas unit will reduce emissions significantly by between 40 percent and 90 percent.