On July 13, 2024, Employee #1, 41, entered a manhole to tape piping in preparation for pouring concrete inverts. Shortly after entry, a coworker stationed topside observed that Employee #1 appeared pale and profusely sweating. When asked, Employee #1 indicated difficulty breathing. As Employee #1 attempted to climb the steps to exit the manhole, he experienced a medical incident, lost consciousness, and fell back to the bottom of the manhole.