Florida Rock Industries Inc disclosed Wednesday that it received a request for information from the US Environmental Protection Agency about whether its subsidiary illegally disposed of construction materials during the 1970s.   The probe concerns possible illegal disposal of cement kiln dust at the Jernigan Trucking Dump Site in Hillsborough County, Fla, by Florida Rock unit Florida Cement Inc.  
 
Florida Rock, based in Jacksonville, Fla, received the EPA request this month, the company said in its annual report to the Securities and Exchange Commission.  The EPA is looking into potential violations of two environmental statutes: the Comprehensive Environmental Response, Compensation, and Liability Act and the Resource Conservation and Recovery Act.  
 
The company said it has begun an internal investigation, but doesn’t yet know if it had any related liability or what the extent of the liability might be, according to the filing.  Florida Rock acquired Florida Cement from Lafarge North America Inc in 2003.