As the South Coast Air Quality Management District moves to curb metal processors' dangerously high emissions of hexavalent chromium in Paramount, the agency is also considering a rule that would for the first time regulate emissions from processors' grinding and cutting operations.
Proposed Rule 1430 is intended to reduce the toxic air contaminants – including hexavalent chromium, arsenic and nickel – that can result from part of the metal forging process. It would order metal processors to install appropriate pollution control equipment and take other steps to ensure metal particulates don't escape into the atmosphere from their facilities' grinders and cutting equipment.
The draft rule grew out of a 2013 AQMD investigation that was prompted by community complaints about metallic odors in Paramount, which is home to about 80 metal processors.
The air district eventually linked elevated nickel levels to the grinding area of a metal processor, Carleton Forge. Once the facility implemented voluntary pollution control measures, monitors showed that nickel emissions dropped.
The AQMD doesn't currently regulate emissions from metal grinding and cutting operations, but the Carleton Forge episode demonstrated that the agency should start regulating them, says Susan Nakamura, the air district's acting assistant deputy executive officer.
"The amount of emissions that were created from this was pretty substantial and it was a source category that we weren't aware of until we started looking at Carleton Forge and then going to other grinding facilities," Nakamura says.
Nakamura says she is not aware of any other air districts that regulate emissions from metal grinding and cutting operations.
The AQMD already has regulatory oversight over other aspects of metal processing plants' operations.
On Thursday, the agency's independent Hearing Board will consider a plan to curb emissions of hexavalent chromium - also known as chromium 6 - that the air district says came from Paramount metal processing firm Anaplex Corp. The agency has already ordered another processor, Aeorcraft Heat Treating Co., to take similar steps.
The draft rule for grinding and cutting operations has been met with cautious acceptance by metal processing firms and area residents.
One Paramount company, Weber Metals, has voiced support for the development of a rule, while suggesting several changes.
For example, it believes the AQMD should exempt certain metal cutting operations, such as band saw cutting, from the rule, company vice president Doug McIntyre wrote in a Dec. 13 letter to the agency.
"Band saw cutting generates metal chips but these are of such large dimensions (i.e., greater than 1 mm) that they fall to the ground immediately and are swept up or collect in a chip collection system," said McIntyre.
Weber also wants the air district to exempt "low volume" grinding and cutting operations, because they "are likely insignificant in terms of emissions," he wrote.
Meanwhile, Paramount residents are circulating a petition asking the AQMD for more stringent requirements for grinding operations near schools.
The proposed rule says facilities located within 1,000 feet of a school must install the best-available emission control equipment. The petition calls on the agency to extend that radius.
While three of the city's four large forging businesses are located very close to schools, only one is within 1,000 feet, according to the petition. It says one firm is 1,056 feet from a school, and another is 1,584 feet away.
"We respectfully demand that rule 1430 be revised to require best available retrograde emission controls be required for forging facilities that conduct grinding within 2,000 feet of a school (0.3 miles) so that all three elementary schools are included in rule 1430," the petition says.
The AQMD's Nakamura says she hasn't seen the petition, but argues that the 1,000-foot distance is more than adequate, because the health risk posed by these emissions drops by about 90 percent at 300 feet from the source.
The AQMD is hosting a public workshop regarding the proposed rule on January 19, and a public consultation meeting January 25. The agency is expected to finalize the rule in March.