Construction of a treatment facility at the McGaffey and Main Ground Water Plume Superfund Site is complete.
The polluted site consists of a groundwater plume that extends southeast about 1.5 miles from the intersection of Main and McGaffey streets.
The contamination is linked to multiple dry cleaning businesses that operated in the area from 1956-1963. The contaminant of concern is perchloroethylene, a chlorinated solvent commonly used in the dry cleaning industry.
Environmental Protection Agency remedial project manager Michael Torres said the state found PCE in 1994 while cleaning up an underground storage tank in the area. The site was later referred to the superfund program at EPA, which listed the site on its national priority list in 2002.
Torres said it took the EPA several years to confirm the extent of the contamination before it closed its remedial investigation phase in 2008 and wrote a record of decision that proposed how the site would be cleaned up. In 2009 and 2010, estimates placed the project in a price range of about $25 million in federal funds. Torres said at this point he decided to prioritize taking care of the health risks associated with indoor air vapor intrusion in six buildings located in the 1100 block of South Main Street.
Ron Courts, Roswell Environmental Services officer, said the treatment facility is connected via PVC plumbing under the foundation of these buildings, and through a process of filtration that involves sizable carbon filters, ensures that harmful vapors do not rise up into the buildings.
Courts said the contaminants do not affect the safety of drinking water in Roswell. “Our drinking aquifer is not effected whatsoever, and everybody is on city water anyway, so fortunately, nobody is impacted from it. But it’s still there; that’s why they’re dealing with it.”
Torres said most of the contaminant resides in the upper aquifers. “The residents of Roswell are very lucky to have such a beautiful artesian aquifer, and that aquifer is protected by about a 200-foot clay bed. So right now, the drinking water resources are spared.
“Most of this contaminant resides in the upper aquifers, but since it’s migrating into the unincorporated areas, there is a risk for some of those people there.
“… The state is conducting sampling and analysis to make sure that the residents at the leading edge [of the plume] are protected. And if they do get concentrations above the drinking water level, then we would be doing something to mitigate that. But to date, no one is using the water for drinking purposes.”
Torres said the treatment facility is designed to take care of three remedial components: vapor intrusion mitigation system contamination, soil vapor contamination and groundwater pump and treatment systems. He said he believes the facility will run the vapor control systems for about 10 years and the ground water components for 20 years. “Now that we’ve taken care of the indoor air and the vapor issues, we’re trying to attack the best way to try to keep that plume from migrating further down. That will be the next phase.”
Courts, who has been involved since 2002, said the treatment facility’s completion brings great reward to all parties involved. “There was just a lot of background work. It just had a lot of learning about the issues before they could really address the issues. What is actually here?
Where is the problem? Can we find a real pocket of the source?
“… There’s just satisfaction to see it finally getting to this particlar completion point. It’s been a decade in the working, and it’s [great] to finally see it get there.”