Pennsylvania Power & Light Co. recently completed use of an innovative cleanup system that extracted coal tar from deep in the ground at a former manufactured gas plant site in Stroudsburg, Monroe County.
"This was the first major use of this technology in the world and it has worked extremely well," said Jim Villaume, an environmental scientist and PP&L's coordinator of remediation programs. "The system was used until no more coal tar could be extracted from the ground. We now are in the process of assessing exactly how much coal tar was removed."
The federal Environmental Protection Agency endorsed PP&L's use of the new technology at the 12-acre Superfund site, located between the Route 209 and Interstate 80 bridges, because of the depth of the contamination at the site.
"The alternative to using this technology was to excavate the area and haul the material to a landfill," Villaume said. "The method we used was more like a surgical strike that targeted the coal tar and didn't disrupt the dike system or the watershed in the area. We took out only the pollutants and saved money for our customers in the process."
The technology is called Contained Recovery of Oily Waste System, or CROW. It's an elaborate system that uses a hot-water injection process. Hot water is pumped into the ground through wells. The heat changes the coal tar's ability to flow, allowing it to be pumped to the surface with ground water by a series of recovery wells. The mixture is captured and the coal tar removed.
The site is contaminated by coal tar from a former manufactured gas plant that operated at the location from 1888 to 1944. Coal tar is a byproduct of the process of making gas by heating coal. It's a thick, black oily substance that looks and smells like driveway sealant. In an era before environmental laws, coal tar was not managed well and some of it ended up in the ground.
Coal tar contains chemicals that can pose a risk to human health and the environment if ingested for long periods of time. The primary reason for cleaning up subsurface coal tar is to keep it from reaching drinking water sources and nearby streams.
"PP&L never owned or operated the manufactured gas plant, but does own property at the location for an electric substation and transmission lines," said Paul Canevari, PP&L's community development director in Stroudsburg. "As a property owner, PP&L is partly liable for cleanup costs under the Superfund law."
The site was placed on the Superfund list in 1982. Numerous actions have been taken during the last 14 years to investigate and remove coal tar from the site. The CROW technology was put into use in 1995, primarily to remove a dense concentration of coal tar from a large underground pocket.
"The system worked just as we expected it would," Villaume said. "This is not only good news for the Stroudsburg area, but for the thousands of communities throughout the United States and the world that have areas contaminated by coal tar from former manufactured gas plants."
PP&L will submit a full report on the remediation work to the EPA. The agency then will determine if cleanup work is done at the site. There still is a large amount of coal tar in the ground that poses no threat to human health or the environment. The EPA has determined that coal tar is technically infeasible to remove, Villaume said.
"If the EPA certifies that PP&L has completed all the remedial work necessary at the site, the agency still will review the site every five years to ensure that conditions have not changed to the point where additional cleanup may be required," Villaume said.