Ameren, under the direction of the federal and state environmental protection agencies, recently inspected the gas supply equipment at Alton Middle School and 12 residences in East St. Louis.
The gas equipment in the school did not contain PCBs but three liquid collection points outside the school were found to have liquids contaminated with PCBs and Ameren removed them.
Low levels of PCBs were discovered in liquids in gas meters outside three of the residences in East St. Louis. Ameren replaced the meters and cleaned up the soil beneath them.
The investigation is an outgrowth of Nicor Gas' recent disclosure to the federal EPA that PCB liquids were found in a Park Ridge, Illinois gas distribution system.
Nicor Gas is one of the nation's largest gas distribution companies, serving two million customers in northern Illinois.
After Nicor's disclosure, the EPA requested that other Illinois natural gas utilities review their records for similar incidents.
As a result, Ameren disclosed that they had found liquids in their systems in certain buildings in Alton and East St. Louis during the 1980s. These buildings were then re-inspected by the agencies and Ameren.
Polychlorinated biphenyls are mixtures of up to 209 individual chlorinated compounds that were once widely used as coolants and lubricants in transformers, capacitors, and other electrical equipment because they do not burn easily and are good insulators. The manufacture of PCBs was stopped in the United States in 1977 because of evidence that they build up in the environment and can cause harmful health effects.
The EPA and the International Agency for Research on Cancer have determined that PCBs are 'probably carcinogenic' to humans and PCBs are known to cause liver damage in humans and animals.
PCBs were used historically in some natural gas distribution equipment, typically as a compressor lubricant or valve sealant. If sources of PCBs are found, the U.S. EPA will require that they be removed.
The federal agency has specified that Ameren revise a draft inspection plan for buildings where the PCBs were previously found. EPA also asked for Ameren to use specific procedures for sample collection, analysis and further investigation, if warranted.
EPA anticipates a response from Ameren in the next few days. Ameren's proposed approach will be reviewed by EPA and partner agencies including the Illinois EPA and the Illinois Attorney General's office.