When you’re deicing more than 5,500 airplanes each winter, you need a lot of deicing fluid.

A lot.

But getting deicing fluid isn’t the hard part – it’s what you do after you spray those thousands of planes down that’s tricky. And Pittsburgh International Airport has that process down to a science, from safe collection to environmentally conscious recycling, both of which it’s been doing since 1998.

“We look closely at every process here at the airport to find the safest, most efficient way of doing it,” said Kevin Gurchak, the airport’s Director of Environmental & Workplace Safety. “But just as importantly, we prioritize methods that have the least environmental impact. We’ve been recycling spent deicing fluid long before most other airports.”

PIT has three deicing pads: Atlantic Aviation, Charlie and Sierra. Charlie, which recently underwent a $27 million renovation, can hold up to five planes, and Sierra can hold up to six. If a plane departing Pittsburgh needs to be deiced, pilots will be directed to one of those three sites.

Deicing occurs at dedicated sites because doing it at the gates would be a logistical nightmare; deicing trucks moving from gate to gate amid all the airline employees, aircraft, baggage carts, tugs and other vehicles on the ramp can cause too many problems. Plus, deicing fluid is slippery, which would make the pavement dangerous; it’s also more difficult to recycle fluid when it’s applied at the gate.

The deicing pads are essentially acres of concrete with trench drains running in and around them. They offer plenty of space for aircraft of all sizes, as well as the numerous trucks from the deicing company called Integrated Deicing Services that orbit around them during the process.

Last year, PIT deiced 5,556 aircraft between October and May, requiring the application of more than 338,000 gallons of propylene glycol mixed with water. The ratio of that mixture changes constantly depending on weather, temperature and other factors.

“To remove the snow and ice, it’s really a combination of how much [deicing fluid] and the type [of weather],” Gurchak said. “If it’s a real wet, heavy snow or ice, it takes more. If it’s a light, fluffy snow, they can use air to blow the snow off the aircraft wing and put even less glycol on.”

By the end of that October-to-May period last season, PIT had collected more than 5.4 million gallons of fluid – a blend of propylene glycol, water and the ice and snow that comes off the aircraft and what precipitation has fallen on the deicing pad – which runs down the trench drains into above-ground storage tanks that are regularly monitored.

Inland Technologies, which owns Integrated Deicing Services and recycles fluid at 19 airports in North America, then separates the propylene glycol from the water. The product is trucked to a facility they operate in Portland, Maine, and the water is processed by the Moon Township Municipal Authority sanitary treatment plant according to local, state and federal regulations.

“We can take low-concentrated fluid locally and process it [in Portland] up to a 50 percent [concentration] product,” said Dan Gronowski, Inland’s director of northern U.S. operations. “We have our own patented technology for that.”

Inland’s Portland plant takes the spent chemical and recycles it back into usable propylene glycol to again deice planes at several other airports — or for other uses, such as windshield wiper fluid or lavatory fluid. That process takes several months.

Since 1998, PIT has captured and recycled nearly 150 million gallons of deicing fluid. Gurchak said it’s a track record in which the airport takes pride.

“Our partners at Inland and IDS do a great job of helping us achieve our goal of serving the community by being environmentally responsible,” Gurchak said. “It’s not just about adding flights or destinations, it’s also being good stewards of this public asset and its resources.”