Four environmental groups say they are planning to sue Allegheny County and a Pittsburgh-area steel plant for violating the Clean Air Act. The groups filed a notice of intent to sue over Allegheny Ludlum’s Brackenridge plant, which makes specialty metals.

The suit centers on the plant’s electric arc furnaces, which were installed in 2002. Since they were installed, they’ve never met pollution limits set by the Allegheny County Health Department. Then last fall, the county raised the amount of pollution allowed from the furnaces in a draft air quality permit.

“Instead of taking action to crack down and enforce these violations, the county proposed to just raise the permit limits,” says Patton Dycus, an attorney with the Environmental Integrity Project, one of four groups suing the facility.

Dycus says the furnace emissions include particulates, sulfur oxides and nitrogen oxide — a chemical that contributes to smog. “That’s a problem because Allegheny County has problems meeting federal attainment for smog,” Dycus says.

The health department says that because electric arc furnaces are rare, it had limited data on how to estimate their emissions when it set the original permit. With more data, it set a higher limit for the furnaces and limits the amount of time the plant can run the furnaces to control emissions.

“These are electric arc furnaces. There aren’t really any similar pieces of equipment in this country — and these pieces you can’t put emissions controls on them,” says Jim Kelly, deputy director of environmental health for the Allegheny County Health Department.

Allegheny Technologies, the plant’s parent company, says it was working with the county to control emissions and replace old equipment. The company recently opened a $1.2-billion steel rolling mill, replacing a decades-old plant.