The Louisiana Department of Environmental Quality has given Noranda Alumina one month to say how it plans to determine the breadth and severity of possible unpermitted mercury air emissions from its St. James Parish facility.

In a new compliance order signed Friday that threatens a host of fines, DEQ also directed Noranda to conduct and submit the results of those efforts just 30 days after the agency grants its approval to the monitoring plan, known as an air modeling protocol.

The order’s quick-turnaround commands on the mercury emissions come 10 months after Noranda first informed DEQ that mercury appeared to be unexpectedly emitting from steam vents at the company’s large Mississippi River complex near Gramercy, possibly for decades.

Noranda workers ran across specks of elemental mercury on March 26 in scale that had built up in tubing being replaced for one of the plant’s heaters. Small liquid drops of mercury were also on concrete below the heater.

But Noranda’s initial warning letters to DEQ and Noranda’s continued operation without an apparent resolution of the issue or an order from DEQ came to light in news accounts last month. Some environmentalists criticized DEQ for not issuing fines, despite Noranda’s self-reporting of the problem.

Mercury is a heavy metal that has been found to be harmful to people and the environment. Some environmentalists say mercury should especially raise worries, even in small amounts, because it doesn’t break down and accumulates in animals that people eat.

The DEQ mercury directives are part of a much broader compliance order that also takes Noranda to task for the unpermitted release of 12 tons of alumina dust in November 2013, other deviations from its permits for particulate matter between 2012 and 2014 and the failure to submit a variety of reports to DEQ between 2011 and 2014.

The new order calls the possible releases of mercury a violation of state law. The order says the department can assess $27,500 in civil penalties for each day of violation before Aug. 15, 2004. After that point, possible daily penalties can go up to $32,500.

DEQ and Noranda officials have said the mercury releases appear to be very small and do not pose a risk to the public, but both parties say they have been trying to figure out how to more accurately measure the releases and estimate how mercury may be dispersing into the air.

The new directives on the air modeling would inform any future permit request from Noranda to continue releasing mercury into the air.

Noranda officials asked DEQ last year for permission to release up to 250 pounds of mercury annually from their facility as an interim step while the company determines precisely how much mercury the 55-year-old former Kaiser Aluminum plant was releasing.

If granted, that amount would make the plant one of the largest mercury polluters of Louisiana’s air.

The DEQ order says that if Noranda determines it does not need a permit, the company has to submit a detailed written report, within 30 days of submitting the modeling results, that outlines modifications to operating and maintenance procedures to prevent future recurrences.

DEQ officials referred comments Tuesday to the order. Noranda officials said DEQ’s order was not unexpected.

John Parker, Noranda vice president of communication and investor relations, said by email that the company, in fact, asked DEQ for just such an order “to address a mercury emissions issue which we self-reported.”

“We are in the process of reviewing the Order and will respond within the time frame provided within the Order,” Parker wrote.

”Protecting the safety of our employees and the surrounding community is a Noranda value that is never questioned and never compromised, and we will continue to work closely with the LDEQ to ensure that safety.”

A proposed administrative order that Noranda submitted to DEQ last year did not suggest penalties. The proposed order, however, did note it would not preclude the agency from issuing them.

The Noranda plant, which is near the Veterans Memorial Bridge and La. 3213, turns bauxite ore into alumina, which supplies the company’s aluminum smelter near New Madrid, Missouri.

Noranda officials suspect the mercury is coming from bauxite, which stains the facility a rust color, and is the source rock from which the plant extracts up to 1.3 million tons of alumina annually. The ore is mined in Jamaica and shipped up the Mississippi River to Gramercy.

Noranda has long been permitted to release mercury from ore processing through water or mixed and diluted in leveed-off piles of waste “red mud” on the company’s site in between Airline Highway and River Road.

With just those permitted discharges, the Noranda complex is regularly one of the largest emitters of mercury or mercury compounds in Louisiana.

Noranda officials told DEQ in letters last year they had believed all the mercury from the bauxite was bound to other chemicals used in its process, and could not escape into the air.

Follow David J. Mitchell on Twitter, @NewsieDave.