How do you balance the safety of airline passengers with the life of Buckeye Brook? You don’t.

You can’t have the airline winning some of the time and the brook the rest. The airlines have the best chance to travel safely all the time by using chemical deicers on their wings, which can run off the tarmac into Buckeye Brook.

The odds for Buckeye Brook just got a lot better, although building a system that will collect, store and treat the deicing fluid will take three years and cost $25 million. Even after RIAC builds the system that airport’s President Kevin Dillon says will put Green Airport in the forefront of many airports, Buckeye Brook will suffer. The difference is that the brook will be better off.

It is estimated the system will collect 60 percent of deicing fluid – propylene glycol – used to ensure that ice does not build up on the fuselage and wings of departing aircraft in freezing rain. The existing system of vacuum trucks collected only 43 percent of the fluid last year.

On Dec. 21, the RIAC board entered into a memorandum of agreement with the Department of Environmental Management that outlines the terms of a new Rhode Island Pollution Discharge Elimination System (RIPDES) permit. The draft permit terms will be aired at a public meeting followed by a 30-day comment period. It could be as much as three months before the department responds to the comments and the permit is finalized.

The system, DEM Director Janet Coit said, meets the needs of T.F. Green Airport, an important transportation hub, while protecting Buckeye Brook and other sensitive aquatic resources.

“I’m excited, for sure, to see they are actively working on it,” said Buckeye Brook Coalition president Paul Earnshaw.

He said he is concerned whether RIAC will have the funds to implement the plan and recommended that runway extension “should not go forward until it is solved and fully implemented.”

The brook, which is named for its spring runs of herring and alewives commonly called buckeyes, has been the object of abuse for decades. It has been a collection point for tires, shopping carts and debris of all sorts, although, thanks to the educational efforts of the Buckeye Brook Coalition and its annual cleanups, conditions have improved vastly. In the 1970s the section of the brook flowing out of Warwick Pond, which meanders through woods and wetlands and then under Warwick Avenue and West Shore Road to Mill Cove and Narragansett Bay, was severely impacted. The waters took on hues of green, blue and brown. Fern-like strands of slimy growth adhered to rocks and sticks. Fish, turtles and other wildlife disappeared.

The major cause was a landfill operated by Truk-Away, a waste hauling company, at the end of Industrial Drive. Fifty-gallon drums of waste chemicals were openly drained off the backs of trucks at the site to mingle with runoff leaching into the brook. Measures were taken to stop the dumping and contain the runoff, but it wasn’t until the airport bought and closed the landfill that conditions showed marked improvement.

The late Steve Insana, the founder of the coalition, focused attention on the harmful effects of the deicing fluid in the wake of winters in the late 1990s and early 2000s. Following ice storms, glycol was so prevalent that its sweet odor was easily detected at the Warwick Avenue Bridge and as far down stream as Tidewater Drive.

Insana didn’t buy that the glycol would evaporate, leaving no harm to the brook or the buckeyes in their spawn run to Warwick Pond. Glycol was identified as the cause of an orange coating on rocks and vegetation. The coating, an iron oxide-loving bacteria, depletes the water’s dissolved oxygen. But other compounds added to prevent corrosion of the planes are especially toxic.

Because of lower water temperatures in the spring, which helps retain dissolved oxygen, Earnshaw doesn’t believe the herring are affected. However, he thinks it may have an effect on the juveniles that stay in the pond and stream until they migrate to the bay in the fall.

As Insana brought attention to what was happening, DEM clamped down and RIAC implemented programs to collect the glycol. Negotiations on a permit started in 2004, Angelo Liberti, DEM chief of surface water protection, said Friday.

“I can’t believe it took this long,” he said.

He attributed the delay to changes in staff and the lengthy exchange of proposals. At one point a mediator was brought to the discussions in an effort to reach an agreement.

“It was not like we were trying to ignore it,” Liberti said. Capturing all of the glycol is impossible. A certain amount stays on the plane and shears off when taking off, Liberti said.

Alternate methods of deicing were considered, including an infrared system, but that would have required routing planes through a shed and delay operations.

The system as planned has monitors that would activate pumps sending storm water and glycol to storage tanks and then to the treatment plant when detected. The treatment plant depends on bacteria to break down the glycol in the wastewater before it is sent to the city treatment plant.

It’s not like the airport has ignored the problem either, said Liberti. He pointed out that stations were built to properly mix the glycol to meet conditions, rather than using higher than needed levels of glycol all the time, and that was in addition to the system of vacuum trucks.

The fact the airport did not have an agreement for treating deicer has been used to justify an appeal of the Federal Aviation Administration record of decision for a runway extension and other improvements. Ward 9 Councilman Steve Merolla has questioned why, when RIAC is going to do more to the brook and nothing has happens, it should be trusted to deliver on other promises.

In an interview last Thursday, Dillon expressed his frustration that he couldn’t talk about the agreement with DEM until it had been finalized. He also made it clear that this project is independent of other airport projects.

“We’re doing this, not withstanding what happens [with the council’s appeal],” he said.

While RIAC has submitted a 30 percent design of the system and has agreed to have field construction activities completed by Aug. 30, 2014 and plans to have the system up by March 30, 2015, it has not lined up all the funding. Dillon said RIAC has a $2.5 million FAA grant for design but doubts the agency will pay for construction costs. He said grants are being sought from the EPA and other sources and, as a backup, RIAC will turn to the airlines. He said RIAC has had discussions with the airlines and they will “work hand-in-hand to fund this through rates and charges.”

Assuming that this financing course is followed, the project would be bonded and probably paid off over 20 years.

Dillon called the DEM agreement a “significant milestone” and the culmination of a long process that puts the airport “at the forefront of similarly sized airports in the Northeast by using a state-of-the-art system to collect and treat storm water.”

With some modifications, the system will use the existing infrastructure of drains, sending runoff from around the terminal and the cargo area to two enclosed storage tanks near Industrial Drive. After on-site biological treatment, the wastewater would be discharged into the Airport Road sewer line and on to the city’s wastewater treatment plant for further treatment before being discharged into the Pawtuxet.

There are signs that the brook is reviving.

Since starting its annual fish count nine years ago, Earnshaw said this year was the largest run ever, with an estimated 54,000 herring. He said Buckeye Brook was the state’s largest run.

Yet that pales compared to what used to happen. The fish were once so plentiful that they filled the stream and many flopped on the shore. Overall, herring runs have seen dramatic reductions that Earnshaw attributes to offshore fishing of the various species.