A public hearing on a change to the Volkswagen plant's emissions is set for Dec. 3 at 5 p.m. at the Development Resource Center on Market Street.
Volkswagen officials gave an incorrect estimate when they originally calculated some emissions for the Chattanooga plant, and the company is seeking a 20 percent hike over its initial projection.
Documents filed with city regulators also show new details for potential plant expansion that would double production with the addition of new assembly, body and press shops.
Bob Colby, who heads the Chattanooga-Hamilton County Air Pollution Control Bureau, said VW used "an incorrect number" when it originally sought an emissions permit in 2008 while the plant was still under design.
VW officials have discovered they selected a wrong number for emission of nitrogen oxides in its paint shop, Colby said.
"The end result ... is they were off by 20 percent," he said.
Guenther Scherelis, general manager of communications for VW in Chattanooga, said that, in 2008, pollution equipment hadn't yet been specified for the plant but estimates had to be given for the permitting process.
"During production it became obvious that the estimates were too low," he said, so VW has applied for the elevated emission levels.
Colby said the new levels sought in the revised permit are comparable to other auto assembly plants. The bureau's staff has issued a preliminary recommendation approving the change.
The bureau will hold a public-comment meeting on Dec. 3.
Scherelis said that, even with the revision, nitrogen oxides emissions will be 77 percent lower than the industry standard for comparable paint shops.
"The Chattanooga paint shop continues to be an industry benchmark with its low environmental impact," he said.
Late last year, the VW plant received Platinum Leadership in Energy and Environmental Design certification, the only auto factory in the world to gain such LEED status, according to the U.S. Green Building Council.
Concerning potential future expansion, Scherelis said VW wanted to be prepared for growth and submitted the information to the bureau. Obtaining a full air pollution permit is a lengthy process, he said, and "there are no plans so far" related to expansion of the plant.
Documents given to the air pollution bureau said production could double to more than 300,000 vehicles a year.