Abstract: Employee #1 and a coworker, both working for a contractor constructing new clarifier pits at a wastewater treatment facility, were working from ladders while drilling bolt holes and installing platform brackets inside and near the top of a 10 ft deep by 75 ft diameter concrete pit. At approximately 4:15 p.m., Employee #1 was found suffering from the effects of hyperpyrexia. He was taken to the local emergency room, where his core temperature was measured at 106.5 degrees F. Employee #1 was subsequently airlifted to a larger hospital, where he died 2 1/2 days later from a heat-induced stroke. The recorded maximum outside air temperature at the site that day was 96 degrees F. Supervisors ensured fresh drinking water and ice were available to employees, but the schedule of rest periods was up to the individual employees. In addition, supervisors did not periodically check for symptoms of heat stress. Employee #1 was a new hire who may not have been acclimated to outdoor construction activity in temperatures ranging from 90 to105 degrees F. He may also have had medical or physical conditions that were aggravated by high temperatures.