MISSOURI ELECTRIC WORKS SUPERFUND SITE CLEANUP PROGRESSES; MAY BE DONE BY APRIL

The new year is expected to bring round-the-clock cleanup of the Missouri Electric Works Superfund site in Cape Girardeau.

All of the PCB-contaminated soil could be cleaned by April, said AmerenUE's Warren Mueller, project coordinator for the potential responsible parties, which are paying much of the cost to clean up the site at 824 S. Kingshighway.

It could take longer if the winter is severe and the ground frozen for a prolonged time, he said.

The government has been seeking to address the contamination problem at the former motor and transformer repair business for 15 years. The site was listed on the EPA's national priority list for cleanup in February 1990.

The project, expected to cost $3 million or more , involves excavation and treatment of 20,000 to 30,000 tons of soil contaminated with polychlorinated biphenyls

More than 100 potential responsible parties, which were customers of the former business, are footing about 80 percent of the cost. The EPA is paying about 20 percent.

The contractor, Williams Environmental Services Inc. of Stone Mountain, Ga., just completed a shakedown period for the heat-treatment system. The shakedown period began around October and ended Saturday, Mueller said.

During that time about 5,600 tons of soil were treated. The treated soil, which looks black, is being stored in plastic-covered 600-ton piles. Eventually it will be spread over the site.

Assuming that the EPA signs off on the latest test results, the cleanup could move full speed ahead.

The heat-treatment equipment is expected to operate 24 hours a day, seven days a week for six to eight weeks beginning by mid-January.

Once the soil is cleaned up, it could take another month or two to do grading work and remove the equipment, Mueller said.

Top soil will be brought in to cover the ground to a depth of 6 inches to allow grass to grow on the six-acre site. The treated soil is sterile and won't grow grass, said Sheila Hockel, who oversees the project for the potential responsible parties from an office on the site.

As part of the cleanup soil contaminated with PCBs greater than 10 parts per million is being excavated. The excavated soil is processed through a screen and, or shredder to obtain materials less than 2 inches in size.

The excavated soil is stockpiled and then moved in a front-end loader to a metering unit. The unit weighs the soil before treatment. The soil is then taken via a conveyor belt and other equipment to a rotary dryer, where air flows in the opposite direction of the soil. The soil is heated to temperatures that reach 800 degrees Fahrenheit before exiting the system.

Water is then added to cool the soil and hold down dust. The treated soil is then stockpiled and samples taken to verify that the soil is no longer contaminated. Once the treated soil has been approved, it can be used to backfill excavated areas at the site.

During the soil-treatment process, gases from the soil are treated to meet air emission standards. The gas stream first passes through a baghouse to remove the particulate matter.

After the baghouse, the gas stream goes through a thermal oxidizer where volatile organic compounds are destroyed. The temperature inside the oxidizer is kept at 1,800 degrees.

The gases leaving the oxidizer are cooled with water. The cooled gasses travel through a scrubber to remove acid gasses and any missed particulate matter. Ultimately they are vented into the air as steam emissions through a 76-foot-tall stack. The stack is the most noticeable piece of equipment on the hilly site, which borders busy South Kingshighway.

The cleanup work hasn't led to any odor problems, say the operators of two businesses that border the site.

Mueller said the cleanup effort has gone smoothly. "This is a tried and true technology," he said. The contractor has done 14 other jobs like this one.

"Overall, we have progressed to the point we feel that the equipment is operating well and we are going to be able to get this site done in the near future," he said.

But that won't end all the environmental work at the site. Once the soil is cleaned up, a groundwater study will be done to determine the extent of any groundwater contamination.

PCB contamination already has been found in three mud-filled underground caves at the site.