BANGOR – After decades of aircraft de-icer flowing into and polluting the mile-long Birch Stream, changes will be made at the city’s airport complex by this fall to divert the fluid into the city’s wastewater treatment facility at no cost to taxpayers.

Officials from the city and the Air National Guard, gathered Thursday night at City Hall, said they hoped to have diversion systems operating by Oct. 1 – the beginning of the de-icing season – thereby preventing the pollutant from ever again flowing into the polluted stream.

In the past three years, use of propylene glycol-based de-icer by Bangor International Airport and the Guard has tripled. Last winter, the airport complex used 165,000 gallons during the de-icing season. Department of Environmental Protection officials believe the chemical may be causing a pungent, yeastlike odor coming from Birch Stream and irritating residents of nearby Griffin Park. Some residents believe the odor is linked to headaches, bouts of nausea and respiratory problems experienced by people in the park.

In diverting the de-icer, BIA will designate an area for de-icing operations and a pipe will tie from the collection point into the existing sewer line, according to Assistant City Engineer John Murphy. The city expects to front the unknown cost for modifications through airport revenues and recoup the funding next year through a federal airport improvement grant. The Guard already has set aside $125,000 to build a catch basin and drainage line to tie into the existing sewer line.

The new pipe system would incorporate a valve that would be opened during and just after de-icing season and closed during the rest of the year, according to City Engineer Jim Ring. Most other storm water runoff would continue to flow into Birch Stream, he said.

That strategy still had holes, according to Michael Belliveau, executive director of the Environmental Health Strategy Center in Bangor. Because of petroleum byproducts and other runoff from planes, storm water into the stream still would contain industrial pollutants even without the de-icer, he said.

“You’re going to have contamination every time it rains,” Belliveau said.

The alternative, putting all storm water from the airport through the city’s wastewater treatment facility, would not be feasible or allowable under federal regulations, Ring said.

The diversion systems at the airport are only the first step in the revitalization of the stream, said Ed Logue, DEP’s regional director for eastern Maine. The second step would include a dedicated cleanup plan for the removal of debris such as shopping carts and a possible flushing of the water.

“My goal is to bring this stream back to something people feel good about,” Logue said.

Work also continues in an effort to address health issues for people living near the stream, Logue said. Anyone experiencing symptoms believed to be connected to the quality of the stream is asked to contact the Bureau of Public Health at 262-9904.