On Tuesday, April 8, 1997, at approximately 8:59 a.m., a 5,700-gallon hydrochloric acid (HCl) storage tank ruptured during filling. The failure of the HCl tank caused a significant portion of its liquid contents (which totaled about 4,800 gallons of 31% HCl) to suddenly surge over the secondary containment. The force of the liquid also caused a break in the secondary containment wall. Witnesses described seeing greenish-yellow fumes drifting offsite as well as liquid material running offsite and along the street curb to the storm drains. As a consequence of the incident, 8 workers and 32 others were taken to the hospital. A 10-block area, including nearby businesses and residences, was evacuated. Based on the impacts of the incident and the potential for lessons-learned, EPA and OSHA decided to undertake a joint chemical accident investigation to determine the immediate and root causes of the HCl tank failure and to make recommendations to Surpass, government, industry, and others that could assist in preventing similar incidents from occurring in the future. The Joint Chemical Accident Investigation Team (JCAIT) determined that the immediate cause of the incident was the overpressurization of the HCl tank. The team identified the root causes as: