The U.S. Environmental Protection Agency is proposing a new rule that would require a number of additional controls to prevent pollution from refineries including fenceline air monitoring for benzene, tighter controls on storage tanks and changes to flare operation.

In announcing the proposed new rule Thursday, EPA officials said it would have a “negligible impact” on the cost of petroleum products. Nationwide, EPA estimates the cost of the proposed rule would be about $240 million.

In exchange for that investment at 185 refineries around the country, EPA expects to see a reduction of 5,600 tons per year of toxic air pollution, 52,000 tons per year of volatile organic compounds and 700,000 metric tons of carbon dioxide equivalents.

“This proposed rule is important and historic. Benzene, a known human cancer causing agent, will be monitored at the fenceline of refineries for the first time,” Marylee Orr, executive director of the Louisiana Environmental Action Network, said in an email.

She added, “Since there are more than 10 refineries along the corridor from Baton Rouge to below New Orleans this rule would have a huge positive impact on all the communities.”

There are 17 refineries in Louisiana, according to Richard Metcalf, director of environmental affairs at Louisiana Mid-Continent Oil and Gas Association.

Benzene will be the targeted pollutant because it is a good surrogate, or indicator, for other air toxins, said Liz Purchia, EPA press secretary, in an email.

“The number of monitors will vary depending on the size of the refinery,” she wrote. “At a minimum, for small refineries, 12 monitors at 30 degrees or 1 every 2,000 feet.”

The proposed rule also includes improved controls at storage tanks to reduce the amount of pollution that gets into the air.

“We are requiring that tanks with floating roofs have better gaskets and seals and extending these requirements to smaller tanks,” Purchia wrote.

Another aspect of the rule involves ensuring more efficient operation of flares that act as emergency values to burn off hydrocarbons before they’re released into the air.

A study done in Texas exposed how the efficency of flares in burning off hydrocarbons can fluctuate, depending on certain conditions, Metcalf said.

Infrared cameras that can show releases of hydrocarbons that are not ordinarily normally visible showed some flares working very efficiently while others allowed large amounts of hydrocarbons to escape.

Although he hadn’t read through the proposed rule yet, Metcalf said EPA is expected to require closer monitoring of flares and adjustments to the conditions that can reduce efficiency.

Those conditions include the flow rate of gas to the flare, consideration of the BTUs of that material and the amount of steam added to the mix. A likely reduction in the amount of steam that is currently added to flaring events likely will result in more flames than occurs now, he said.

“That will be a visual difference on how flares are operated,” Metcalf said.

The proposed rule also would impose new emission controls on delayed coking units at refineries.

Metcalf said those units are used to take very heavy crude oil and heat it at high temperatures. At such temperatures, the heavy molecules are broken up into a gas that is taken off and made into gasoline feed stock.

After that process is completed, water is put into the units, producing large amounts of steam that is captured when any remaining hydrocarbons are sent to other places in the plant. At the end, when the unit has cooled enough and is opened, there is some residual vapors that can escape, he said.

Purchia, with EPA, said these were previously unregulated sources of toxic air emissions at refineries.

“This is a significant step towards protecting the health and safety of the workers and the community that surrounds these industries,” Orr said.

There will be a 60-day comment period that will open as soon as the proposed rule is published in the Federal Registry in mid-June.

Follow Amy Wold on Twitter @awold10.