(STMW) — A hydrogen sulfide leak at a southwest suburban oil refinery in March was the subject of a complaint filed in court by state and Will County officials hoping to prevent a recurrence.

The complaint was filed in Will County Court on Thursday against ExxonMobil Oil Corp., where the alleged air pollution violations occurred March 1 at a refinery near Interstate 55 and Arsenal Road in unincorporated Channahon, according to AG’s office spokesman Scott Mulford.

An equipment malfunction at the Channahon Township facility caused an “uncontrolled release of hydrogen sulfide that lasted more than 9 1/2 hours,” the complaint, filed by Attorney General Lisa Madigan and Will County State’s Attorney James Glasgow, charges.

It seeks to force ExxonMobil to take immediate corrective actions to prevent a similar occurrence, and asks for civil penalties of more than $50,000.

According to the complaint, a “pressure relief valve failed at the refinery’s coker debutanizer, resulting in approximately 4,066 pounds of hydrogen sulfide and other contaminants escaping into the air.”

The leak started just after 9 p.m. March 1 and was not discovered by refinery workers until 6:45 a.m. March 2, when ExxonMobil notified the Illinois Emergency Management Agency, Will County emergency officials and other agencies, the complaint states.

Hydrogen sulfide, known for its rotten egg odor, is a flammable, colorless gas that when breathed into the lungs in high concentrations can “cause the loss of consciousness, shock, convulsions and death,” the complaint states.

The complaint asks the judge to order the refinery to stop violating environmental protection laws by taking “immediate corrective and preventive actions.” It also seeks civil penalties of $50,000 with an additional penalty of $10,000 per day of the alleged violation as determined by the judge, Mulford said.

Glasgow said in the statement county and state officials are trying “to hold companies accountable for the release of dangerous pollutants that impact the health and safety of our citizens. Such violations of our state’s environmental regulations will be prosecuted aggressively in court.”

In a statement, Exxon Mobil said it’s aware of the complaint.

“We will continue to work with the AG to resolve issues related to this filing. As a matter of practice we are committed to environmental performance excellence. Our goal is to drive operational incidents with environmental impacts to zero,” the company said.

(Source: Sun-Times Media Wire © Chicago Sun-Times 2013. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)