Abstract: At 11:42 a.m. on August 25, 2020, Employee #1 removed a sanitary manhole cover to determine whether the confined space had any water accumulation. Employee #1 then entered the manhole and was followed by Employees #2 and #3. A nearby coworker noticed the employees entering the space and at some point went over to see how they were doing. The coworker found Employees #2 and #3 trying to revive Employee #1. The coworker went to call emergency services and upon return to the manhole, the coworker could no longer hear any sounds from the employees in the space. All three employees were killed due to low oxygen levels in the space (measured at 5%).