ChemMix Company is a subsidiary of Diversified Industries Inc. ChemMix operates a hazardous waste disposal site. Electrical Supply Corporation is one of many parties who generate waste disposed of at the site. ChemMix borrows money from First State Bank, which takes over the site when ChemMix goes bankrupt. The Environmental Protection Agency discovers a leak at the site. Can any of these private parties be forced to pay for the clean up? If so, who?

Any of the private parties mentioned in the question can be required to pay the entire cost for the clean up of the site.
Under the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA), potentially responsible parties on whom such costs may be imposed include persons who generated wastes disposed of at the site (Electrical Supply)and persons who owned or operated the site at the time of the disposal (ChemMix). ChemMix's parent Diversified Industries may also be liable, as may First State Bank and any other lender who actually participates in managing a hazardous waste disposal site that requires a clean up.