CHARLESTON, W.Va. -- Management at DuPont Co.'s chemical plant in Belle waited more than two days before reporting a toxic material leak to state and local authorities last week, government and company officials confirmed Tuesday.

The leak of sulfur trioxide started at 11 a.m. on July 22, but was not reported to the state until 4:36 p.m. on July 24, according to state Environmental Protection and Homeland Security officials.

No injuries were reported, and DuPont officials described the leak as a minor incident.

"It was essentially a non-event when you get right down to it," said DuPont Plant Manager Bill Menke. "Normally, we wouldn't have said anything."

The leak occurred in a sulfuric acid production unit that was the subject of a major federal enforcement action. In April, DuPont agreed to pay $2 million in fines for not upgrading pollution-control technology when the company added equipment to increase production.

Kanawha County Commission President Kent Carper said he was shocked that DuPont did not report the incident, especially given the public furor over Bayer CropScience's withholding of information about the fatal explosion and fire at its Institute plant in August 2008.

"I'm very disappointed," Carper said.

Initially, DuPont officials estimated the leak at 300 to 400 pounds of sulfur trioxide. Federal law requires companies to immediately notify federal, state and local officials of leaks of 100 pounds or more of sulfur trioxide.

Menke said the company later downgraded its estimate of the leak's size to about 18 pounds -- an amount that would not kick in the required notifications to government agencies.

Sulfur trioxide itself is very hazardous. It can burn the skin and eyes, and inhalation can damage the respiratory tract. Sulfur trioxide can also combined with water vapor in the air to form sulfuric acid.

Last week's incident occurred in the Belle plant's "SAR" unit, where sulfuric acid is produced by burning spent sulfuric acid to form sulfur dioxide. The sulfur dioxide is then converted to sulfur trioxide, and then to sulfuric acid.

The unit had recently been shut down, and had just started back up when a two- to three-inch hole was discovered in a duct on the unit when workers saw "puffs" of sulfur trioxide coming out of it. "It was puffing intermittently," Menke said.

Company officials attached an "elephant trunk" hose to capture the leaking material and funnel it back into the SAR unit, Menke said. The goal was to control the leak until the unit could be shut down for repairs, he said.

The leak of sulfur trioxide started at 11 a.m. on July 22, but was not reported to the state until 4:36 p.m. on July 24, according to state Environmental Protection and Homeland Security officials.

No injuries were reported, and DuPont officials described the leak as a minor incident.

"It was essentially a non-event when you get right down to it," said DuPont Plant Manager Bill Menke. "Normally, we wouldn't have said anything."

The leak occurred in a sulfuric acid production unit that was the subject of a major federal enforcement action. In April, DuPont agreed to pay $2 million in fines for not upgrading pollution-control technology when the company added equipment to increase production.

Kanawha County Commission President Kent Carper said he was shocked that DuPont did not report the incident, especially given the public furor over Bayer CropScience's withholding of information about the fatal explosion and fire at its Institute plant in August 2008.

"I'm very disappointed," Carper said.

Initially, DuPont officials estimated the leak at 300 to 400 pounds of sulfur trioxide. Federal law requires companies to immediately notify federal, state and local officials of leaks of 100 pounds or more of sulfur trioxide.

Menke said the company later downgraded its estimate of the leak's size to about 18 pounds -- an amount that would not kick in the required notifications to government agencies.

Sulfur trioxide itself is very hazardous. It can burn the skin and eyes, and inhalation can damage the respiratory tract. Sulfur trioxide can also combined with water vapor in the air to form sulfuric acid.

Last week's incident occurred in the Belle plant's "SAR" unit, where sulfuric acid is produced by burning spent sulfuric acid to form sulfur dioxide. The sulfur dioxide is then converted to sulfur trioxide, and then to sulfuric acid.

The unit had recently been shut down, and had just started back up when a two- to three-inch hole was discovered in a duct on the unit when workers saw "puffs" of sulfur trioxide coming out of it. "It was puffing intermittently," Menke said.

Company officials attached an "elephant trunk" hose to capture the leaking material and funnel it back into the SAR unit, Menke said. The goal was to control the leak until the unit could be shut down for repairs, he said.

But the shutdown didn't occur for 18 hours. And, Menke said, it is unlikely that the "elephant trunk" caught all of the sulfur trioxide that may have leaked from the hole.

"Did the elephant trunk capture 100 percent of that material? The answer is likely not," Menke said.

Menke said that it was not safe to shut down the unit right away for repairs.

"It takes a little time to actually de-pressure and turn it down," Menke said. "There would have been production to be sure we had the facility in line."

Menke said he was personally aware of the incident the day it began, but did not think to call government authorities.

After the unit was shut down, Menke said, a plant environmental official asked for a calculation of the size of the leak. That produced the initial estimate of 300 to 400 pounds, Menke said.

Based on those figures, DuPont then notified state and local authorities late in the afternoon on July 24, a Friday. U.S. Environmental Protection Agency officials said that neither they nor the National Response Center were notified.

DuPont officials quickly realized that estimate did not take into account any material captured by the "elephant trunk." A rough recalculation then produced the 18-pound estimate, Menke said. So, they called back state and local officials with the lower estimate, he said.

Jesse Adkins, assistant chief for enforcement at the Department of Environmental Protection's Division of Air Quality, said his agency is waiting for a written report from DuPont before considering further action.

Dale Petry, Kanawha County's emergency services director, said he is still looking into the matter.

"I'm waiting for a report on exactly what went on," Petry said. "I want more information myself."

Reach Ken Ward Jr. at kw...@wvgazette.com or 304-348-1702.