BANGOR, Maine — Bangor International Airport is close to starting one project to expand capacity and is considering others as more passengers and planes pass through.

Passenger numbers, flights, and parking usage are all up over the last 13 months, and this week the finance committee of the Bangor City Council approved a $5 million reconstruction project for BIA’s general aviation apron.

If the full council approves it, the project — to be awarded to Old Town-based Sargent Corp., the lowest of three bidders — will begin as early as late April and finish around September, weather permitting.

The project primarily involves underground drainage and resurfacing work on the paved surface area — or apron — in front of the BIA terminal used for parking airplanes. The work will increase the apron’s weight capacity.

“Currently, we can handle aircraft weighing less than 100,000 pounds in that area,” said interim BIA director Tony Caruso, who said the apron’s capacity now ranges from 40 to 50 airplanes, depending on their size. “After this apron reconstruction, we can handle aircraft up to 150,000 pounds.”

The project will be completed in phases and Caruso said he expects little negative impact on the boarding and deplaning of passengers.

The project will be paid for largely by the federal Airport Improvement Program, which will provide 90 percent of the funding. The city of Bangor will provide 7.5 percent of the funding and the Maine Department of Transportation will provide 2.5 percent.

If current trends continue, Caruso and other airport officials may soon have to discuss another project with the City Council.

“We’ve seen a 30 percent increase in cars parking in the airport lots so far this year, and last year it went up 17 percent,” said Caruso. “We are beyond maxed out as far as our parking capacity goes.”

Both the long-term and short-term lots bear witness to that. Canadian cars, in particular, are currently jamming the parking spots.

“We do experience a lot of Canadian passengers this time of year. They come down to fly out of Bangor,” Caruso said. “We’re currently in our peak demand period from February into early April. It’s kind of the snowbird effect with school vacations, spring breaks, and such.”

Caruso, who was named BIA’s interim director after former director Rebecca Hupp resigned to take a job in Boise, Idaho, said he’d like to open up discussions with city personnel about adding more parking capacity either with a parking garage or a satellite parking lot with shuttle service.

“I think what we’d like to do is wait, get through this peak demand period, and get some facts and figures back, and then start discussions this spring,” he said.

BIA’s domestic air travel numbers are up. The number of passengers on domestic flights to and from Bangor increased 17 percent from 26,653 in 2010 to 31,282 last year. The monthly numbers are also up 15.8 percent from January 2011 to January 2012. Bangor’s domestic flights were 70 percent full, on average, in 2011.

“Really, the key driver is the load factor in terms of percentage of filled seats,” said Caruso. “I think certainly these are some very pleasing numbers. Certainly the demand is there.”

One area of lower demand is military flights, which went from 944 in 2009 and 945 in 2010 to 650 last year.

“That’s something we’ve been expecting since the change in the last [presidential] administration,” said Caruso. “We’ve been budgeting conservatively and will continue to do so as military flights continue to decline.”

As for finding a permanent airport director, Bangor City Manager Cathy Conlow said the position has been advertised internally for several weeks and will soon be advertised externally. She hopes to start interviewing candidates in May.

“We’re looking at July 1 as an informal deadline to have a new permanent director,” she said.