NATCHEZ — Plans for the replacement of the historic tollbooth colonnade are under way, and construction should begin in approximately six months, City Engineer David Gardner said.

The City of Natchez has received preliminary approval for the work from the Mississippi Department of Archives and History, Gardner said. The Jackson office of Smith, Seckman and Reid has been hired as the engineering firm.

“The engineers and architect are working in full force (on plans) as we speak,” Gardner said.

Once those plans are finished, they will go to MDAH for final approval, Gardner said.

The work will involve replacing the columns of the colonnade, which was officially approved as a Mississippi landmark in January 2012.

Gardner said the columns of the colonnade are plagued by rot.

“The wood is so far gone, it’s pretty much going to have to be torn out and replaced,” he said.

Because the columns support the top beam of the colonnade, the replacement of the columns will be done in phases, Gardner said. That work may reveal deeper damage to the colonnade.

“There are going to be some unknowns,” Gardner said. “Once you start removing rotten wood, you may uncover some other problems we are not anticipating.”

Plans for the project should be completed in two to three months, Gardner said, which should allow the city to receive construction bids in four or five months and begin construction in six months.

“We’re making a lot of progress,” Gardner said. “A lot of people don’t see it because it’s planning, but I always say the design phase of the project is the longest.”

The city has received $150,000 from the Mississippi Development Authority. The city will also receive $200,000 from the Mississippi Department of Transportation for the colonnade.

The MDOT funding, Gardner said, was originally to be used for the traffic signal near Monmouth at John Quitman Boulevard and Melrose Avenue, Gardner said.

That traffic signal is in “fairly good shape compared to the colonnade,” Gardner said, so the highway commission granted a request from Mayor Butch Brown to use the money for the colonnade since it is a transportation-related project.

The funding requires a 20-percent cost match from the city.

Historic Natchez Foundation Executive Director Mimi Miller has said the colonnade was erected in 1940 as part of the construction of the original Mississippi River bridge.

A tollbooth, at which drivers paid 10 cents to enter Louisiana or Mississippi, sat between the colonnade, Miller has said.