While most of Charleston International Airport's terminal will remain in construction upheaval for about 18 more months, a piece of the work will soon be completed.

The new 6,200-square-foot rental car pavilion on the left end of the airport terminal should be ready for operation by mid-March, said Matt McCoy of Michael Baker Inc., the firm overseeing the $189 million upgrade.

Rental car companies, currently housed inside the terminal near the baggage claim area, can begin building their stations in the newly added wing Feb. 17, McCoy said. Substantial construction will be completed by March 7. Systems then will be checked over the next week to make sure everything is operating correctly, he said.

Work began on the area more than a year ago as the first part of the of the 29-year-old building's expansion and renovation.

McCoy also said the removal of asbestos found between outside masonry walls during demolition should not affect the construction schedule.

Airports Director Paul Campbell said the asbestos was in the tar-based waterproofing materials used to build the terminal before it opened in 1985.

"It is not as prevalent as we thought it was going to be," he said.

McCoy added that the asbestos removal is being monitored under the direction of state environmental officials.

The asbestos was discovered in the outside wall near Concourse A, where the building is being expanded, and along the front brick facade.

The entire terminal is undergoing a makeover to meet growing passenger demand at the state's busiest airport.

Last year, Charleston International saw a record 2.9 million people pass in and out of its gates. That number is projected to swell to 3.5 million by 2022.

The airport is adding five new gates to its existing 10 as well as a third baggage carousel. Security checkpoints will be consolidated in a new area behind the airline check-in counters, and a dome will rise over the central hall area to brighten the building's interior.

The flow of traffic through the airport will change as well. Passengers will go through the new security area and be separated from the outside lobby area by a glass wall before passing on to their gates. Numerous other structural and cosmetic changes are underway as well.

Work is set for completion in August 2015.

Reach Warren L. Wise at 937-5524 or twitter.com/warrenlancewise.