Johnson Wright performed a phased engineering evaluation and financial audit of the environmental costs claimed by one of the top four U.S. oil companies. The claim included costs for nine refineries, three Superfund sites, and approximately 3,000 service stations. The total costs associated with the claim were approximately $390 million in past costs, and $490 million in future costs. Phase I of the project involved a review of the technical information documenting the environmental activities at the sites, an accounting evaluation of the claim, interviews with key corporate financial and technical project personnel, and a critical evaluation of the methodologies used to document the claimed past and future costs. Phase I also included the development of site-specific future cost models to independently assess the claimed future costs. The second phase of the project involved the application of a defensible sampling protocol such that the findings could be extrapolated to all sites within the claim. As a result of the evaluation, Johnson Wright determined that over 75% of the claimed costs were questionable.