Two employees are killed inside tank due to hydrogen sulfide

At 8:00 a.m. on June 26, 2022, two employees were emptying and cleaning an open topped frack tank (Tank #4) at an oil and gas services site. There were no eyewitnesses, and the employees were working at remote site by themselves, so few details are known about what occurred. At the time of the investigation, hyrdrogen sulfide (H2S) gas was detected at levels between 3 parts per million (ppm) and 5 ppm, which is non-lethal. The two employees died. But, it is not possible to estimate what the H2S levels might have been when the employees were killed. The tank contained approximately 2 feet of water/oil. Autopsy results are pending.

Source: https://www.osha.gov