Along the banks of the Ohio River in Beaver County, less than 15 miles from Pittsburgh International Airport, huge cranes dominate the skyline as construction continues on the region’s first ethylene cracker plant.

Royal Dutch Shell is building the $6 billion plant on a 400-acre site in Potter Township. Slated to open in 2021, the plant is expected to generate jobs and other economic benefits, and could boost passenger travel and land development initiatives at the airport.

A cracker plant takes ethane from natural gas and, using extreme heat, “cracks” it into ethylene, a petrochemical used in many plastics and other synthetics.

The plant will be the first ethane cracker of its size to be located in the Marcellus shale region, one of the largest deposits of natural gas in North America.

The 3,500 workers currently building the Shell site eventually will double in number, according to David Ruppersberger, president of the Pittsburgh Regional Alliance.

“Those are people who are well-paid,” he said. “They’re buying meals, buying gas, going to Walmart. So I think there’s already been a significant impact that’s only going to increase as the number of workers on that site goes up to 7,000.”

Shell expects to employ 600 people there once construction is done, but Ruppersberger expects the development to create many more jobs outside the plant.

“There’s going to be truck drivers, people working for railroad companies. Shell doesn’t do their own security, so they will subcontract for that,” he said. “Ultimately, I think you’re looking at two to three times that 600 number outside of the plant.”

Shell spokesman Joseph Minnette would not comment on whether the massive undertaking is proceeding on schedule but said, “Our project continues to ramp up construction and we anticipate begin operational early next decade.”

Most of the equipment and materials used to construct the plant are coming in by rail or barge. That will change once the plant is up and running, said Bryan Dietz, the Allegheny County Airport Authority’s vice president for air service development.

Dietz expects more goods to be shipped by air, such as the high-density plastic used to create 3D printers. The plant also will increase passenger traffic between PIT and cities with energy company headquarters, such as Dallas, Denver and Houston, the location of Shell’s U.S. headquarters.

“We can demonstrate that there’s a market they can serve now by servicing the construction project and then serve later when more broad energy-focused economic development initiatives provide reasons for business travelers to come here,” he said.

The airport’s two international carriers may also see passenger increases, Dietz added. British Airways and Condor may serve as conduits for executives from Shell’s global headquarters in The Hague, Netherlands.

Businesses that support the plant could anchor on the 2,200 acres of developable land that the authority owns in the airport corridor nearby, according to David Storer, the authority’s manager of real estate development.

“You will see suppliers for the cracker plant that will need land,” he predicted. “From a zoning and land availability standpoint, we can meet their needs, be they for business offices, manufacturing or other things.

“We definitely have a strategy in place to make sure we aren’t missing those opportunities.”