 When the odor problem began, the Army asked several health agencies to study the problem to determine if there were any long-term or acute health effects.Toxicologists from Colorado State Health Department, United States Agency for Toxic Substance and Disease Registry, United States Environmental Protection Agency, Shell Oil Company, Tri-County Health, the Army's Surgeon General's Office, and Foster-Wheeler (or previously, Ebasco, the contractor for the project) identified the compounds and determined that there were no acute health effects.The odors ended with the completion of the excavation in December 1988.