Developers of the Beech Hollow Energy Project in Robinson, Washington County, must prove they will use the strictest possible pollution controls for their proposed power plant.

The state Department of Environmental Protection has given Robinson Power Co. until Sept. 15 to submit a plan showing how they will limit emissions of 188 hazardous air pollutants.

Construction of the waste coal-fired power plant will be subject to the DEP approving the plan, as required by federal Clean Air Act rules revised this year to include power plants.

"They are required to demonstrate to the department that they have planned for the most effective technologies for removing hazardous pollutants from the emissions," DEP spokeswoman Helen Humphreys said.

Pollutants include mercury, acids, volatile organic compounds and heavy metals such as chromium and cadmium, she said.

Spurred by citizens from Robinson, McDonald and Oakdale, the Environmental Integrity Project, a nonprofit based in Washington, D.C., helped bring the Robinson project to the attention of the state DEP in June.

The new requirement is significant, according to Jennifer Peterson, an attorney with the environmental group, which promotes better enforcement of clean air and water laws.

Environmental consultant Joe Pezze, president of The Hillcrest Group in Wexford, is working on Robinson Power's application. He said Thursday that the new requirement would not necessarily change Beech Hollow's pollution control plans because they already incorporate the most effective technology.

"We don't see any major changes," Mr. Pezze said. "We are continually looking for ways to tweak our system to better our controls, but the technology in my opinion will stay the same."

Lisa Graves Marcucci, a Jefferson Hills resident who works with the environmental group, updated Robinson supervisors on the new power plant requirement during a public meeting Tuesday.

She contended that initial power plant plans weren't as safe as Robinson Power representatives previously said.

Starting in 2005, power plants were exempt from the Clean Air Act's hazardous air pollutant regulations. But in February, a federal court ruled that the U.S. Environmental Protection Agency had to again subject all power plants to the same rules as other pollution sources.

Supervisor Brian Coppola, the township's liaison to the Beech Hollow project, said Robinson Power had not told him about the new emissions requirements.

Ms. Graves Marcucci expressed surprise because conditions in the supervisors' September 2006 power plant approval called for the company to keep the township informed of such changes.

Mr. Pezze said Robinson Power will submit its application to the DEP, and the township will receive a copy, as required under the conditional use agreement.

Plans for the Beech Hollow Energy Project include a 272-net-megawatt electrical power generator fueled by waste coal, along with facilities for power transmission, coal mining and fly ash disposal. Project costs could total roughly $800 million.

The power plant site is adjacent to the nearly 800-acre Champion Processing Inc. gob pile, bounded by routes 22 and 980 and Candor and Beech Hollow roads. The land contains 38 million tons of waste coal -- remains of former coal processing -- that would be burned to make electricity.

In a March letter to the DEP, Robinson Power owner Raymond Bologna said the company has moved about 400,000 tons of earth to level the power plant site and has built the foundation for a small building to receive waste coal. He expected commercial operations to begin in September 2012.