Jackson Hole Airport is considering a $1.5 million state-of-the-art wastewater treatment facility to replace three aging, undersize septic systems.

The decision to proceed with the plant is not final, but the airport’s board of directors unanimously approved beginning the planning process at a meeting last week.

The proposal is for a “tertiary” system that discharges water that is up to drinking standards, airport Director Ray Bishop said.

“We’re looking at five options, and the one that looks the most promising is the tertiary system,” Bishop said. “The output is potable drinking water.”

Although the tertiary system is relatively expensive, and the Department of Environmental Quality typically discourages new small-scale distributed wastewater treatment plants, it’s the most viable option, Bishop said.

“The problem that we have is that the sewer is in Jackson, and the airport is 12 miles north,” Bishop said.

The distance makes it prohibitively expensive to connect to the city.

Grand Teton National Park, which surrounds the airport, drew the same conclusion in April when park officials explored a new wastewater system in Moose. The park went with an on-site system.

A change in regulations makes the upgrade necessary, airport board president Jack Larimer said in the meeting. Under new rules, the airport is required to have a septic system that is 2.5 acres — twice as large as the existing system, Larimer said.

Among the benefits of the tertiary system is that it will open up space that’s currently off-limits due to the septic system, Bishop said.

“If we got rid of the septic system, we’d have more land to use for the rental cars,” he said. “You can’t build on top of [the septic system].”

Other airport projects hang in the balance pending the wastewater plant’s completion, Larimer said.

“As it turns out, this wastewater thing has to be completed before anything else can be done,” he said.

Those other projects include creating more parking for rental cars and building a new car wash, Bishop said. The rental companies would likely help pay for whatever infrastructure goes in above the old leach field, he said.