After years of questions and few answers, residents of Eight Mile had the opportunity to hear state and local officials discuss the effects and document mitigation efforts related to a 2008 release of a chemical used to odorize natural gas.

Sonja Massey, Alabama Department of Environmental Management groundwater branch chief, told the group of residents during a We Matter Eight Mile Community meeting that a 2008 lightning strike was the cause of a methyl mercaptan release from a plant in Eight Mile. ADEM started getting complaints about the release in 2011 after the chemical began traveling to the surface, Massey said.

“It took about three years for the groundwater to travel from the source to the nearby springs,” she said.

The tank holding the mercaptan had a capacity of 5,000 gallons and Massey said “several hundred of those gallons” is enough to cause environmental contamination.

She said while the chemical was released in 2008, it took three years for it to travel into a nearby stream system, which then allowed it to be released into the air where residents could smell it.

That’s when mitigation efforts began, she told residents. Among those efforts, ADEM requires Mobile Gas to treat the groundwater with ozone. Because air dilutes the mercaptan, Massey said ozone is mixed into the affected water to neutralize the chemical. A series of pumps have been installed through a closed system to help pull water up from the ground and treat it, she said.

“Ozone is a powerful … chemical,” Massey said. “It breaks down the mercaptan and the odor dissipates.”

The first ozone system was installed in 2013. Since treatment began, the amount of mercaptan exposure in the water, which had been “off the charts,” has dropped “precipitously,” Massey said.

In fact, in treated water, ADEM is finding no residual mercaptan, Massey said. Although, she added, ADEM is currently looking for other sources.

“We’re not calling our job complete here,” she said. “We think we’ve completed a lot, but we’re very carefully reviewing data … We’ve required everything we know to require at this point.”

After Massey’s presentation, a panel of doctors from the Mobile County Health Department and the Alabama Department of Public Health took questions from residents. Residents in the affected area have complained of health issues they say could have been caused by mercaptan exposure.

Carletta Davis, president of We Matter Eight Mile Community Association, has previously said residents have complained about numerous issues, including dizziness, nausea, asthma and nosebleeds. More than 1,000 residents have filled out health surveys, which have been forwarded to state agencies.