The Pennsylvania Department of Environmental Protection (PDEP) sued Lockheed Martin under the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) and Pennsylvania environmental laws, seeking to recover $20 million it claims to have spent cleaning up the Quehanna Wild Area Nuclear Site in Clearfield County, Pennsylvania. PDEP claims Lockheed Martin’s corporate predecessor, Martin Marietta Corporation, caused the site to be contaminated with Strontium-90, a radioactive and hazardous substance used in the manufacture of prototype systems for nuclear auxiliary power thermoelectric generators.