Fumes from a cleanup project at a defunct manufactured-gas plant on Augusta's Eighth Street remained a concern this week, despite a host of tactics employed by contractors to reduce emissions.
The site, owned by Atlanta Gas Light, operated from 1852 to 1955, during which time coal tar seeped into the ground and released benzene, naphthalene and other chemicals.
Some activities associated with the $50 million cleanup that began in January were halted after air monitors indicated that excessive fumes were being released.
"It's still in (excess) this week, and they're addressing it in a number of different ways," said Madeleine Kellam, the program manager for the Georgia Environmental Protection Division's Hazardous Waste Management Branch.
The plant site includes an old tar well with higher concentrations of pollutants that can emit airborne fumes.
"As they move through treating the worst of the waste on the site, this problem will diminish," she said. "But they're at the heart of the area right now, so additional measures are necessary."
Efforts to correct the problem with more mist sprayers and a suppressor foam were insufficient, so the next step involves constructing a temporary building so contaminated soil can be treated inside.
Inside the building, gases will be run through carbon canisters that will absorb any volatile fumes, Ms. Kellam said.
Workers at the site will continue to monitor the fumes with a portable gas chromatograph and collect samples to be scrutinized in off-site labs, she said.
Shawn Davis, a spokesman for Williams Environmental, the cleanup contractor, said daily levels appear to be down considerably, but the latest calculation of cumulative levels of constituents was unchanged since last week.
According to air monitoring data on the company's Web site, the Augusta site's hazard index - which requires action when cumulative levels of multiple chemicals exceeds 1.0 - remained at 1.37, the same as last week.
"The daily levels are down considerably, but it will take longer to bring down the cumulative index," Mr. Davis said, adding that engineers are trying to determine the specific cause of the higher readings.
The temporary building could be completed as early as this weekend, he said.
"But until we finish our review of modeling and sampling, there are no plans to resume full-scale operations until that's done."
The project will include the eventual removal of 120,000 tons of contaminated soil and other remediation along the nearby Augusta Canal.
"The daily levels are down considerably, but it will take longer to bring down the cumulative index." - Shawn Davis, on emissions levels at the former Atlanta Gas Light site
Reach Robert Pavey at (706) 868-1222, Ext. 119, or firstname.lastname@example.org.